Anthocyanins are important metabolites that provide a red or blue-purple hue to plants.The biosynthesis of these metabolites is mainly activated by the MYB-bHLH-WD40(MBW)complex and repressed by a wide variety of prot...Anthocyanins are important metabolites that provide a red or blue-purple hue to plants.The biosynthesis of these metabolites is mainly activated by the MYB-bHLH-WD40(MBW)complex and repressed by a wide variety of proteins.Studies have shown that MYB activators activate MYB repressors to balance anthocyanin biosynthesis.However,there is a scarcity of studies investigating this mechanism in grapes.To explore the transcription factors involved in the regulation of anthocyanin biosynthesis,we reanalyzed the RNA-seq database for different developmental stages of‘Muscat Hamburg'berries,and the R2R3-MYB gene,annotated as VvMYB3,was screened.Our study revealed the anthocyanin content of the grape cultivar‘Y73'was higher than that of its parental cultivar MH,and the putative repressor VvMYB3 was found to be highly expressed in‘Y73'by qRT-PCR.The calli transgenic assays demonstrated that the repressive activity of VvMYB3 was conferred by the b HLH-binding motif,as well as by the C1 and C2 motifs.Yeast hybridization and chip-PCR assays revealed that VvMYB3 could repress anthocyanin biosynthesis by competing with VvMYBA1 to bind to VvMYC1 and promoting histone deacetylation of VvUFGT via the C2 motif.However,the expression of VvMYB3 was activated by VvMYBA1,which forms a negative feedback regulatory loop to modulate anthocyanin accumulation.In addition,we found a 408-bp repeat tandem sequence insertion in the VvMYBA1 promoter region of‘Y73'by sequencing.The GUS activity analysis showed that this sequence enhanced the expression of VvMYBA1 and led to an excessive accumulation of anthocyanins.Overall,our results provide insights into the anthocyanin activator-repressor system in grapes that prevents overaccumulation of anthocyanins.展开更多
BACKGROUND Esophageal cancer(ESCA)poses a significant challenge in oncology because of the limited treatment options and poor prognosis.Therefore,enhancing the therapeutic effects of radiotherapy for ESCA and identify...BACKGROUND Esophageal cancer(ESCA)poses a significant challenge in oncology because of the limited treatment options and poor prognosis.Therefore,enhancing the therapeutic effects of radiotherapy for ESCA and identifying relevant therapeutic targets are crucial for improving both the survival rate and quality of life of patients.AIM To define the role of the transcription factor Snail family transcriptional repressor 1(SNAI1)in ESCA,particularly its regulation of radiosensitivity.METHODS A comprehensive analysis of TCGA data assessed SNAI1 expression in ESCA.Survival curves correlated SNAI1 levels with radiotherapy outcomes.Colony formation assays,flow cytometry,and a xenograft model were used to evaluate tumor radiosensitivity and apoptosis.Western blot validated protein expression,while Chromatin im-munoprecipitation assays examined SNAI1's role in regulating epithelial-mesenchymal transition(EMT).RESULTS SNAI1 expression in ESCA cell lines and clinical specimens emphasizes its central role in this disease.Elevated SNAI1 expression is correlated with unfavorable outcomes in radiotherapy.Downregulation of SNAI1 enhances the sensitivity of ESCA cells to ionizing radiation(IR),resulting in remarkable tumor regression upon IR treatment in vivo.This study underscores the direct involvement of SNAI1 in the regulation of EMT,particularly under IR-induced conditions.Furthermore,inhibiting deacetylation effectively suppresses EMT,suggesting a potential avenue to enhance the response to radiotherapy in ESCA.CONCLUSION This study highlights SNAI1's role in ESCA radiosensitivity,offering prognostic insights and therapeutic strategies to enhance radiotherapy by targeting SNAI1 and modulating EMT processes.展开更多
Repressor elements significantly influence economically relevant phenotypes in pigs;however,their precise roles and characteristics are inadequately understood.In the present study,we employed H3K27me3 profiling,assay...Repressor elements significantly influence economically relevant phenotypes in pigs;however,their precise roles and characteristics are inadequately understood.In the present study,we employed H3K27me3 profiling,assay for transposase-accessible chromatin with highthroughput sequencing(ATAC-seq),and RNA sequencing(RNA-seq)data across six tissues derived from three embryonic layers to identify and map 2034 super repressor elements(SREs) and 22223 typical repressor elements(TREs) in the pig genome.Notably,many repressor elements were conserved across mesodermal and ectodermal tissues.SREs exhibited tight regulation of their target genes,affecting a limited number of genes within a specific genomic region with pronounced effects,while TREs exerted broader but weaker regulation over a wider range of target genes.Furthermore,in neuronal tissues,genes regulated by repressor elements started to be repressed during the differentiation of stem cells into progenitor cells.Notably,analysis showed that many repressor elements exhibited cooperative and additive effects on the modulation of KLF4 expression.This research provides the first comprehensive map of pig repressor elements,serving as an essential reference for future studies on repressor elements.展开更多
Germlines in plants are formed de novo during post-embryonic development, while little is known about the mechanism that controls this process. In Arabidopsis, the earliest gene controlling this process is SPOROCYTELE...Germlines in plants are formed de novo during post-embryonic development, while little is known about the mechanism that controls this process. In Arabidopsis, the earliest gene controlling this process is SPOROCYTELESS （SPL）. A decade ago, we showed that loss of SPL function abolished sporogenesis in both male and female organs of Arabidopsis. However, its function is unclear up to now. In this study, we showed that SPL belongs to a novel transcription repressor family specific in embryophyte, which consists of 173 members in the land plants so far. All of them contain a conserved SPL-motif in their N-terminal and an ethylene-responsive element binding factor-associated amphiphilic repression （EAR） motif in the C-terminal, therefore designated as SPL-like, EAR-containing proteins （SPEARs）. Consis- tently, SPL acts as a transcriptional repressor in yeast and tobacco cells, and SPEAR proteins are able to form homodimer and/or het- erodimer with each other in vitro. Furthermore, SPEARs interact with the TOPLESS （TPL） co-repressors via the EAR motif and TCP family transcription factors in yeast cells. Together, we propose that SPL and SPEARs most likely belong to a novel transcription repressor family in land plants which may play a variety of developmental roles in plants.展开更多
Objective： Id2 is a natural inhibitor of the basic helix-loop-helix（bHLH） transcription factors. Although it is well known that active ld2 prevents differentiation and promotes cell cycle progression and tumorigene...Objective： Id2 is a natural inhibitor of the basic helix-loop-helix（bHLH） transcription factors. Although it is well known that active ld2 prevents differentiation and promotes cell cycle progression and tumorigenesis, the molecular events that regulate Id2 activity remain to be investigated. Methods： Yeast two-hybrid, mammalian two-hybrid, GST-pulldown and immunoprecipitation （ColP） assays were used to screen and identify novel Id2 interactors. Luciferase assays were used to detect E47-mediated transcription activity. Colony formation and BrdU incorporation assays were used to determine cellular proliferation abilities. Northorn blot, western blot and quantitative PCR methods were used to measure gene expression levels. Electrophoretic mobility shift assays （EMSAs） were performed to investigate protein/DNA binding. Results： The LIM-only protein FHL2 （four-and-a-half-LIM-only protein 2） was identified to be a novel Id2 interactor. The HLH domain within Id2 is not required for its interaction with FHL2. FHL2 antagonizes the inhibitory effect of Id2 on the basic helix-loop-helix protein E47-mediated transcription. FHL2 prevents the formation of Id2-E47 heterdimer, thus releasing E47 to its target DNA and restoring its transcriptional activity. FHL2 expression was remarkably up-regulated during retinoic acid-induced differentiation of neuroblastoma cells, during which the expression of Id2 is opposite to that. Ectopic FHL2 expression in neuroblastoma cells markedly reduces the transcriptional and cell-cycle promoting functions of Id2. Conclusion： These results indicate that FHL2 is an important repressor of the oncogenic activity of Id2 in neuroblastoma cells.展开更多
AIM: To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR).
The p27Kip1 is a cell cycle repressor protein that regulates primarily the cell cycle transition from G1 to S phase and hence the DNA replication is in the S phase and cell division in the M phase. Expression of p27Ki...The p27Kip1 is a cell cycle repressor protein that regulates primarily the cell cycle transition from G1 to S phase and hence the DNA replication is in the S phase and cell division in the M phase. Expression of p27Kip1 protein has dual roles for both cancer prevention and promotion. For example, numerous nutritional and chemopreventive anti-cancer agents specifically increase the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. On the other hand, pro-cancer agents (like glucose, insulin and other growth factors frequently seen in obesity and/or diabetes) specifically decrease the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. Unlike expression of any other cell cycle regulatory proteins, expression of p27Kip1 protein is very unusual. The mRNA of p27Kip1 has a very long and unusual 5’-untranslated region (from -575 to -1 in human). It appears that the 5’-untranslated region of p27Kip1 mRNA forms two alternative secondary structures. One increases the expression of p27Kip1 protein when anti-cancer agents are added and another decrease the expression of p27K1p1 when pro-cancer agents are added. For this short concept proposal, Dr. Albert Einstein’s “visualized thought experiments (German: Gedanken experiment)” were used as a fundamental tool for understanding how either anti- or pro-cancer agents bring the primary structure of the 5’-untranslated region of p27Kip1 mRNA into two alternative secondary structures, thereby either increasing or decreasing, respectively, the translation initiation of p27Kip1 protein.展开更多
Retrotransposons,a type of DNA fragment that can mobilize itself on genome,can generate genetic variations and develop for molecular markers based on the insertion polymorphism.Zinc finger proteins(ZNFs)are among the ...Retrotransposons,a type of DNA fragment that can mobilize itself on genome,can generate genetic variations and develop for molecular markers based on the insertion polymorphism.Zinc finger proteins(ZNFs)are among the most abundant proteins in eukaryotic animals,and their functions are extraordinarily diverse and particularly important in gene regulation.In the current study,bioinformatic prediction was performed to screen for retrotransposon insertion polymorphisms(RIPs)in six ZNF genes(ZNF2,ZNF3,ZNF7,ZNF8,ZNF10 and ZNF12).Six RIPs in these ZNFs,including one short interspersed nuclear element(SINE)RIP in intron 1 and one long interspersed nuclear element 1(L1)RIP in intron 3 of ZNF2,one SINE RIP in 5′flanking region and one SINE RIP in intron 2 of ZNF3,one SINE RIP in 3′UTR of ZNF7 and one L1 RIP in intron 2 of ZNF12,were discovered and their presence was confirmed by PCR.The impact of the SINE RIP in the first intron of ZNF2,which is close to the core promoter of ZNF2,on the gene activity was investigated by dual-luciferase assay in three cell lines.Our results showed that the SINE insertion in the intron 1 of ZNF2 repressed the core promoter activity extremely significantly(P<0.01)in cervical cancer cells and porcine primary embryonic fibroblasts(HeLa and PEF),thus SINE may act as a repressor.This SINE RIP also significantly(P<0.05)affected the corrected back fat thickness in Yorkshire pigs.The corrected back fat thickness of individuals with SINE insertion in the first intron of ZNF2 was significantly(P<0.05)higher than that of individuals without SINE insertion.In summary,our data suggested that RIPs play important roles in the genetic variations of these ZNF genes and SINE RIP in the intron 1 of ZNF2 may provide a useful molecular marker for the screening of fat deposition in the pig breeding.展开更多
L-Arginine is the precursor of nitric oxide(NO),a host immune effector against intracellular pathogens including Mycobacterium tuberculosis(M.tb).Pathogens including M.tb have evolved various strategies targeting argi...L-Arginine is the precursor of nitric oxide(NO),a host immune effector against intracellular pathogens including Mycobacterium tuberculosis(M.tb).Pathogens including M.tb have evolved various strategies targeting arginine to block the production of NO for better survival and proliferation.However,L-arginine metabolism and regulation in Mycobacterium are poorly understood.Here,we report the identification of M.smegmatis MSMEG_1415(homolog of M.tb Rv2324)as an arginine-responsive transcriptional factor regulating the arginase pathway.In the absence of L-arginine,MSMEG_1415 acts as a repressor to inhibit the transcription of the roc(for arginine,ornithine catabolism)gene cluster,thereby switching off the arginase pathway.Treatment with L-arginine relieves the transcriptional inhibition of MSMEG_1415 on the roc gene cluster to activate the arginase pathway.Moreover,the L-arginine-MSMEG_1415 complex activates the transcription of the roc gene cluster by recognizing and binding a 15-bp palindrome motif,thereby preventing the excess accumulation of L-arginine in M.smegmatis.Physiologically,MSMEG_1415 confers mycobacteria resistance to starvation and fluoroquinolones exposure,suggestive of its important role in M.smegmatis persistence.The results uncover a unique regulatory mechanism of arginine metabolism in mycobacteria and identify M.tb Rv2324 as an attractive candidate target for the design of drugs against tuberculosis.展开更多
Objectives Phenotypic switching of smooth muscle cells(SMCs) plays a critical role in the pathogenesis of atherosclerotic lesions such as coronary artery disease (CAD).Accumulating evidence demonstrates(hat a cellular...Objectives Phenotypic switching of smooth muscle cells(SMCs) plays a critical role in the pathogenesis of atherosclerotic lesions such as coronary artery disease (CAD).Accumulating evidence demonstrates(hat a cellular repressor of E1A-stimulated genes(CREG) plays a role in the maintenance of the mature phenotype of vascular SMCs. The purpose of the present study was to assess the possible association between CREG and CAD in the Han population of North China.Methods The promoter region of CREG by direct sequencing was conducted in 48 subjects.Then SNP rs2995073 and another 4 tagSNPs(rs4657669,rs3767443, rsl6859185,rs3753921) were selected for the association study.All five selected SNPs were determined in 1161 patients with angiographically proven CAD and 960 controls with normal coronary angiograms to investigate the possible involvement of CREG in CAD.Results Genotype frequencies of the five examined polymorphisms were similarly distributed between CAD group and controls(P】0.05).Further haplotype analysis also found no significant differences in the distributions between CAD group and controls(P】0.05). Conclusions This study did not show an association between common variants of CREG and CAD in the northern Chinese Han population.展开更多
The effect of repressors on ion channel gene expression was studied. The hKv4. 3 promoter and the sequence （ ＋ 2-- ＋ 160, S160） of 5＇-UTR of the hKv4. 3 gene was cloned into the pβ-gal-Basic vector. The transien...The effect of repressors on ion channel gene expression was studied. The hKv4. 3 promoter and the sequence （ ＋ 2-- ＋ 160, S160） of 5＇-UTR of the hKv4. 3 gene was cloned into the pβ-gal-Basic vector. The transient expression of the pβ-gal vector and the analysis of the relative activity of β-galactosidase were carried out. The analysis of the mRNA level was carried out with the RT-PCR method. S160 could intensively repress the expression of the hKv4. 3 gene with position-specificity. The level of mRNA did not alter obviously. A repressor（ S160）, in 5＇-UTR of the hKv4. 3 gene was found and its repression to gene expression may play a role in the post-transcription process.展开更多
Inflorescence structure of rice,including the number and length of branches,and the density of the spikelet,can greatly affect the number of grains per panicle,which is one of the key factors in yield compositions.Her...Inflorescence structure of rice,including the number and length of branches,and the density of the spikelet,can greatly affect the number of grains per panicle,which is one of the key factors in yield compositions.Here we identified five allelic mutants sb1-1/2/3/4/5 that related to branch development of rice.In these mutants,the branch meristem fate was prolonged sharply,resulting in delay of transition from branches to spikelets,and then increased the numbers of branches and spikelets per panicle.SB1 encodes a nuclear RING-like domain protein of SHI/LRP/SRS family and strongly expressed in branch meristems.The results of protein interaction and chromatin immunoprecipitation further suggested that SB1 directly repressed the expression of DEP1,TAW1,MOC1 and IPA1 by interacting with a co-repressor complex to affect acetylation level of histone H3 on target regions.Thus,we proposed that SB1 is a transcription repressor of branch meristem activity by widely and negatively regulating a series of genes that maintain branch meristem fate.展开更多
<strong>Introduction</strong>.<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> The molecular biological mechanism ...<strong>Introduction</strong>.<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> The molecular biological mechanism of the increased incidence of the various types of cancer in obesity or type 2 diabetes in rodents or humans has largely been resolved in recent years. By contrast, the molecular biological mechanism of the decreased, not increased, incidence of the various types of cancer in the homozygous long-lived Ames dwarf mice still remains unresolved. </span><b><span style="font-family:Verdana;">Objective.</span></b><span style="font-family:Verdana;"> The first objective of the present study was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the increase, not decrease, in the expression of p27Kip1, a cell cycle repressor protein. The second objective was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the decrease, not increase, in the levels of glucose or insulin. </span><b><span style="font-family:Verdana;">Methods.</span></b><span style="font-family:Verdana;"> To achieve these objectives, we first performed western immunoblot analysis of the hepatic expression of p27Kip1 protein. We then performed, using a human breast cancer cell line </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;">, the luciferase reporter plasmid assay to determine whether the translation initiation activity of the p27Kip1 mRNA is increased when the concentrations of either glucose or insulin are decreased. </span><b><span style="font-family:Verdana;">Results and Conclusion. </span></b><span style="font-family:Verdana;">The results of the first objective indicated that the hepatic expression of p27Kip1 protein was up-regulated in the homozygous long-lived Ames dwarf mice as expected. We also found that the lower concentrations of glucose or insulin increased the translation initiation activity of the p27Kip1 mRNA.</span></span></span></span>展开更多
Background Cellular Repressor of E1A-stimu-lated gene(CREG) is widely expressed in adult tissues such as the brain,heart,lung,liver,intestine and kidney in mice.It is not known whether tissue CREG is decreased in the ...Background Cellular Repressor of E1A-stimu-lated gene(CREG) is widely expressed in adult tissues such as the brain,heart,lung,liver,intestine and kidney in mice.It is not known whether tissue CREG is decreased in the common setting of myocardial infarction which may lead to heart failure.We studied the expression and protein localization of CREG and its main receptor(IFR2R) in a mouse model of myocardial infarction.Methods Male mice were randomized to proximal left anterior descending ligation.The animals were killed on day 1,3,7,14,and 28 after ligation to examine gene expression and protein production of CREG and IGF2R from the infarct,peri-infarct,and contralateral zones of infarcted heart.Results There was decreased CREG mRNA production throughout the myocardium at dav 1,and the expression gradually increased at day 28 after myocardial infarction.The decreased expression of this glycoprotein was not confined strictly to the infarct or peri-infarct zones but also expressed by cardiac myocytes within the myocardium in the contralateral normal zone.Levels of CREG protein in the infarct and peri-infarct zones declined to 1/3- to 1/2-fold of normal levels and declined to 1/2- to 2/3- fold in the contralateral zone.Finally,the expression of the IGF2R mRNA transcripts was downregulated at day 3 and 7 after ligation in the infarct and peri-infarct zones,suggesting that the signal transduction pathways necessary for CREG in the heart remain intact as CREG biosynthesis decreases. Conclusions CREG is constantly present in a model of large myocardial infarction and is decreased at the early stage within the myocardium.The decreased expression of this glycoprotein is not only confined strictly to the infarct or periinfarct zone but also is expressed by cardiac myocytes within the myocardium contralateral to the infarct.Therefore CREG production decreased due to myocardial stress response to injury.展开更多
Impact statement Arsenic is the most common toxic metalloid in the environment.Nearly all organisms have genes for arsenic detoxification.Arsenic detoxification genes are frequently organized in chromosomal or plasmid...Impact statement Arsenic is the most common toxic metalloid in the environment.Nearly all organisms have genes for arsenic detoxification.Arsenic detoxification genes are frequently organized in chromosomal or plasmid-encoded arsenic resistance(ars)operons,which are commonly regulated by members of the ArsR transcriptional repressors.To date,three As(Ⅲ)-responsive ArsRs with different As(III)binding sites have been identified.Here,we identify a new type of As(Ⅲ)-responsive ArsR repressor that has an atypical As(Ⅲ)binding site and controls transcription of the ars operon of Arsenicibacter rosenii SM-1.Our results provide new insights into the classification and evolution relationship of the ArsR transcriptional repressors.展开更多
It is generally accepted that jasmonate-ZIM domain(JAZ)repressors act to mediate jasmonate(JA)signaling via CORONATINE-INSENSITIVE1(COI1)-mediated degradation.Here,we report a cryptic signaling cascade where a JAZ rep...It is generally accepted that jasmonate-ZIM domain(JAZ)repressors act to mediate jasmonate(JA)signaling via CORONATINE-INSENSITIVE1(COI1)-mediated degradation.Here,we report a cryptic signaling cascade where a JAZ repressor,FvJAZ12,mediates multiple signaling inputs via phosphorylation-modulated subcellular translocation rather than the COI1-mediated degradation mechanism in strawberry(Fragaria vesca).FvJAZ12 acts to regulate flavor metabolism and defense response,and was found to be the target of Fv MPK6,a mitogen-activated protein kinase that is capable of responding to multiple signal stimuli.FvMPK6 phosphorylates FvJAZ12 at the amino acid residues S179 and T183 adjacent to the PY residues,thereby attenuating its nuclear accumulation and relieving its repression for FvMYC2,which acts to control the expression of lipoxygenase 3(FvLOX3),an important gene involved in JA biosynthesis and a diverse array of cellular metabolisms.Our data reveal a previously unreported mechanism for JA signaling and decipher a signaling cascade that links multiple signaling inputs with fruit trait development.展开更多
The color of red-skinned pear(Pyrus spp.)is primarily attributed to accumulation of anthocyanins,which provide nutritional benefits for human health and are closely associated with the commercial value of fruits.Here,...The color of red-skinned pear(Pyrus spp.)is primarily attributed to accumulation of anthocyanins,which provide nutritional benefits for human health and are closely associated with the commercial value of fruits.Here,we reported the functional characterization of a R2R3-MYB repressor PyMYB107,which forms an‘activator-repressor’loop to control anthocyanin accumulation in the red-skinned pear.PyMYB107 overexpression inhibited anthocyanin biosynthesis in both pear calli and fruits,while virus-induced gene silencing of PyMYB107 increased anthocyanin accumulation in pear fruits.Furthermore,ectopic expression of PyMYB107 decreased anthocyanin accumulation in tomato,strawberry and tobacco.PyMYB107 can competitively bind to PybHLH3 with PyMYB10/MYB114,thereby suppressing the transcriptional activation of key anthocyanin biosynthesis genes,PyANS and PyUFGT.Site-directed mutagenesis showed that mutations within the R3 domain and EAR motif of PyMYB107 eliminated its repressive activity.Addition-ally,PyMYB107 exhibited a comparable expression pattern to PyMYB10/MYB114 and was transcriptionally activated by them.Our finding advanced comprehension of the repression mechanism underlying anthocyanin accumulation,providing valuable molecular insights into improving quality of pear fruits.展开更多
PrPSc,a misfolded,aggregation-prone isoform of the cellular prion protein(PrPC),is the infectious prion agent responsible for fatal neurodegenerative diseases of humans and other mammals.PrPSccan adopt different patho...PrPSc,a misfolded,aggregation-prone isoform of the cellular prion protein(PrPC),is the infectious prion agent responsible for fatal neurodegenerative diseases of humans and other mammals.PrPSccan adopt different pathogenic conformations(prion strains),which can be resistant to potential drugs,or acquire drug resistance,posing challenges for the development of effective therapies.Since PrPCis the obligate precursor of any prion strain and serves as the mediator of prion neurotoxicity,it represents an attractive therapeutic target fo r prion diseases.In this minireview,we briefly outline the approaches to target PrPCand discuss our recent identification of Zn(Ⅱ)-Bn PyP,a PrPC-targeting porphyrin with an unprecedented bimodal mechanism of action.We argue that in-depth understanding of the molecular mechanism by which Zn(Ⅱ)-Bn PyP targets PrPCmay lead toward the development of a new class of dual mechanism anti-prion compounds.展开更多
Single-chain repressor RRTRES is a derivative of bacteriophage 434 repressor, which contains covalently dimerized DNA-binding domains (amino acids 1-69) of the phage 434 repressor. In this single-chain molecule, the w...Single-chain repressor RRTRES is a derivative of bacteriophage 434 repressor, which contains covalently dimerized DNA-binding domains (amino acids 1-69) of the phage 434 repressor. In this single-chain molecule, the wild type domain R is connected to the mutant domain RTRES by a recombinant linker in a head-to-tail arrangement. The DNA-contacting amino acids of RTRES at the -1, 1,2, and 5 positions of the α3 helix are T, R, E, S respectively. By using a randomized DNA pool containing the central sequence -CATACAAGAAAGNNNNNNTTT-. a cyclic, in vitro DNA-binding site selection was performed. The selected population was cloned and the individual members were characterized by determining their binding affinities to RRTRES. The results showed that the optimal operators contained the TTAC or TTCC sequences in the underlined positions as above, and that the Kd values were in the 1×10-12mol/L1×10-11mol/L concentration range. Since the affinity of the natural 434 repressor to its natural operator sites is in the 1×10-9 mol/L range, the observed binding affinity increase is remarkable. It was also found that binding affinity was strongly affected by the flanking bases of the optimal tetramer binding sites, especially by the base at the 5' position. We constructed a new homodimeric single-chain repressor RrREsRtRES and its DNA-binding specificity was tested by using a series of new operators designed according to the recognition properties previously determined for the RTRES domain. These operators containing the consensus sequence GTAAGAAARNTTACN or GGAAGAAARNTTCCN (R is A or G) were recognized by RTRESRTRES specifically, and with high binding affinity. Thus, by using a combination of random selection and rational design principles, we have discovered novel, high affinity protein-DNA interactions with new specificity. This method can potentially be used to obtain new binding specificity for other DNA-binding proteins.展开更多
Enhancer of zeste homolog 2(EZH2)is a key epigenetic regulatory protein and enzyme catalytic subunit of the polycomb repressor complex 2(PRC2),responsible for catalyzing the trimethylation of histone H3K27 and subsequ...Enhancer of zeste homolog 2(EZH2)is a key epigenetic regulatory protein and enzyme catalytic subunit of the polycomb repressor complex 2(PRC2),responsible for catalyzing the trimethylation of histone H3K27 and subsequent repression of gene transcription.Abnormal EZH2 expression or mutation is associated with various cancers,particularly lymphoma,and breast and prostate cancer.EZH2 has been investigated as an important target in cancer therapy and potential EZH2-targeted drugs have been developed.This article reviews the research progress on the mechanism of transcriptional regulation of EZH2 and the development and clinical use of some inhibitors targeting EZH2.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.32202438)the China Agriculture Research System(Grant No.CARS-29)the Agricultural Science and Technology Innovation Program(Grant No.CAASASTIP-ZFRI)。
文摘Anthocyanins are important metabolites that provide a red or blue-purple hue to plants.The biosynthesis of these metabolites is mainly activated by the MYB-bHLH-WD40(MBW)complex and repressed by a wide variety of proteins.Studies have shown that MYB activators activate MYB repressors to balance anthocyanin biosynthesis.However,there is a scarcity of studies investigating this mechanism in grapes.To explore the transcription factors involved in the regulation of anthocyanin biosynthesis,we reanalyzed the RNA-seq database for different developmental stages of‘Muscat Hamburg'berries,and the R2R3-MYB gene,annotated as VvMYB3,was screened.Our study revealed the anthocyanin content of the grape cultivar‘Y73'was higher than that of its parental cultivar MH,and the putative repressor VvMYB3 was found to be highly expressed in‘Y73'by qRT-PCR.The calli transgenic assays demonstrated that the repressive activity of VvMYB3 was conferred by the b HLH-binding motif,as well as by the C1 and C2 motifs.Yeast hybridization and chip-PCR assays revealed that VvMYB3 could repress anthocyanin biosynthesis by competing with VvMYBA1 to bind to VvMYC1 and promoting histone deacetylation of VvUFGT via the C2 motif.However,the expression of VvMYB3 was activated by VvMYBA1,which forms a negative feedback regulatory loop to modulate anthocyanin accumulation.In addition,we found a 408-bp repeat tandem sequence insertion in the VvMYBA1 promoter region of‘Y73'by sequencing.The GUS activity analysis showed that this sequence enhanced the expression of VvMYBA1 and led to an excessive accumulation of anthocyanins.Overall,our results provide insights into the anthocyanin activator-repressor system in grapes that prevents overaccumulation of anthocyanins.
基金Supported by the National Key R&D Program of China,No.2022YFC2503700 and No.2022YFC2503703the National Health Commission Key Laboratory of Nuclear Technology Medical Transformation(Mianyang Central Hospital),No.2023HYX005.
文摘BACKGROUND Esophageal cancer(ESCA)poses a significant challenge in oncology because of the limited treatment options and poor prognosis.Therefore,enhancing the therapeutic effects of radiotherapy for ESCA and identifying relevant therapeutic targets are crucial for improving both the survival rate and quality of life of patients.AIM To define the role of the transcription factor Snail family transcriptional repressor 1(SNAI1)in ESCA,particularly its regulation of radiosensitivity.METHODS A comprehensive analysis of TCGA data assessed SNAI1 expression in ESCA.Survival curves correlated SNAI1 levels with radiotherapy outcomes.Colony formation assays,flow cytometry,and a xenograft model were used to evaluate tumor radiosensitivity and apoptosis.Western blot validated protein expression,while Chromatin im-munoprecipitation assays examined SNAI1's role in regulating epithelial-mesenchymal transition(EMT).RESULTS SNAI1 expression in ESCA cell lines and clinical specimens emphasizes its central role in this disease.Elevated SNAI1 expression is correlated with unfavorable outcomes in radiotherapy.Downregulation of SNAI1 enhances the sensitivity of ESCA cells to ionizing radiation(IR),resulting in remarkable tumor regression upon IR treatment in vivo.This study underscores the direct involvement of SNAI1 in the regulation of EMT,particularly under IR-induced conditions.Furthermore,inhibiting deacetylation effectively suppresses EMT,suggesting a potential avenue to enhance the response to radiotherapy in ESCA.CONCLUSION This study highlights SNAI1's role in ESCA radiosensitivity,offering prognostic insights and therapeutic strategies to enhance radiotherapy by targeting SNAI1 and modulating EMT processes.
基金supported by the Science&Technology Department of Yunnan Province (202102AE090039)National Natural Science Foundation of China (32100502)+3 种基金Yunnan Revitalization Talent Support Program Young Talent ProjectCAS “Light of West China”ProgramSpring City Plan:High-level Talent Promotion and Training Project of Kunming (2022SCP001)CAS Key Technology Talent Program to Y.G。
文摘Repressor elements significantly influence economically relevant phenotypes in pigs;however,their precise roles and characteristics are inadequately understood.In the present study,we employed H3K27me3 profiling,assay for transposase-accessible chromatin with highthroughput sequencing(ATAC-seq),and RNA sequencing(RNA-seq)data across six tissues derived from three embryonic layers to identify and map 2034 super repressor elements(SREs) and 22223 typical repressor elements(TREs) in the pig genome.Notably,many repressor elements were conserved across mesodermal and ectodermal tissues.SREs exhibited tight regulation of their target genes,affecting a limited number of genes within a specific genomic region with pronounced effects,while TREs exerted broader but weaker regulation over a wider range of target genes.Furthermore,in neuronal tissues,genes regulated by repressor elements started to be repressed during the differentiation of stem cells into progenitor cells.Notably,analysis showed that many repressor elements exhibited cooperative and additive effects on the modulation of KLF4 expression.This research provides the first comprehensive map of pig repressor elements,serving as an essential reference for future studies on repressor elements.
基金financially supported by the National Nature Science Foundation of China(No.30921003)Major Research Plan from the Ministry of Science and Technology of China(No.2013CB945100)
文摘Germlines in plants are formed de novo during post-embryonic development, while little is known about the mechanism that controls this process. In Arabidopsis, the earliest gene controlling this process is SPOROCYTELESS （SPL）. A decade ago, we showed that loss of SPL function abolished sporogenesis in both male and female organs of Arabidopsis. However, its function is unclear up to now. In this study, we showed that SPL belongs to a novel transcription repressor family specific in embryophyte, which consists of 173 members in the land plants so far. All of them contain a conserved SPL-motif in their N-terminal and an ethylene-responsive element binding factor-associated amphiphilic repression （EAR） motif in the C-terminal, therefore designated as SPL-like, EAR-containing proteins （SPEARs）. Consis- tently, SPL acts as a transcriptional repressor in yeast and tobacco cells, and SPEAR proteins are able to form homodimer and/or het- erodimer with each other in vitro. Furthermore, SPEARs interact with the TOPLESS （TPL） co-repressors via the EAR motif and TCP family transcription factors in yeast cells. Together, we propose that SPL and SPEARs most likely belong to a novel transcription repressor family in land plants which may play a variety of developmental roles in plants.
基金supported by the National Natural Science Foundation of China (No.30870507)partially supported by a grant from the Ministry of Science and Technology of China (No.2005CB522603)
文摘Objective： Id2 is a natural inhibitor of the basic helix-loop-helix（bHLH） transcription factors. Although it is well known that active ld2 prevents differentiation and promotes cell cycle progression and tumorigenesis, the molecular events that regulate Id2 activity remain to be investigated. Methods： Yeast two-hybrid, mammalian two-hybrid, GST-pulldown and immunoprecipitation （ColP） assays were used to screen and identify novel Id2 interactors. Luciferase assays were used to detect E47-mediated transcription activity. Colony formation and BrdU incorporation assays were used to determine cellular proliferation abilities. Northorn blot, western blot and quantitative PCR methods were used to measure gene expression levels. Electrophoretic mobility shift assays （EMSAs） were performed to investigate protein/DNA binding. Results： The LIM-only protein FHL2 （four-and-a-half-LIM-only protein 2） was identified to be a novel Id2 interactor. The HLH domain within Id2 is not required for its interaction with FHL2. FHL2 antagonizes the inhibitory effect of Id2 on the basic helix-loop-helix protein E47-mediated transcription. FHL2 prevents the formation of Id2-E47 heterdimer, thus releasing E47 to its target DNA and restoring its transcriptional activity. FHL2 expression was remarkably up-regulated during retinoic acid-induced differentiation of neuroblastoma cells, during which the expression of Id2 is opposite to that. Ectopic FHL2 expression in neuroblastoma cells markedly reduces the transcriptional and cell-cycle promoting functions of Id2. Conclusion： These results indicate that FHL2 is an important repressor of the oncogenic activity of Id2 in neuroblastoma cells.
基金Supported by In part by the 21st Century COE(Center Of Ex-cellence)Programs to Dr.Takenori Ochiaiby a Grant-in-Aid 18591453 to K.M from the Ministry of Education,Science,Sports and Culture of Japan
文摘AIM: To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR).
文摘The p27Kip1 is a cell cycle repressor protein that regulates primarily the cell cycle transition from G1 to S phase and hence the DNA replication is in the S phase and cell division in the M phase. Expression of p27Kip1 protein has dual roles for both cancer prevention and promotion. For example, numerous nutritional and chemopreventive anti-cancer agents specifically increase the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. On the other hand, pro-cancer agents (like glucose, insulin and other growth factors frequently seen in obesity and/or diabetes) specifically decrease the expression of p27Kip1 protein without directly affecting the expression of any other cell cycle regulatory proteins. Unlike expression of any other cell cycle regulatory proteins, expression of p27Kip1 protein is very unusual. The mRNA of p27Kip1 has a very long and unusual 5’-untranslated region (from -575 to -1 in human). It appears that the 5’-untranslated region of p27Kip1 mRNA forms two alternative secondary structures. One increases the expression of p27Kip1 protein when anti-cancer agents are added and another decrease the expression of p27K1p1 when pro-cancer agents are added. For this short concept proposal, Dr. Albert Einstein’s “visualized thought experiments (German: Gedanken experiment)” were used as a fundamental tool for understanding how either anti- or pro-cancer agents bring the primary structure of the 5’-untranslated region of p27Kip1 mRNA into two alternative secondary structures, thereby either increasing or decreasing, respectively, the translation initiation of p27Kip1 protein.
基金supported by the National Natural Science Foundation of China(32002146 and 31872977)the China Postdoctoral Science Foundation(2020M671630)+3 种基金the Jiangsu Postdoctoral Science Foundation of China(2021K221B)to Chen Caithe Jiangsu Agriculture Science and Technology Innovation Fund,China[CX(19)2016]the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe High-end Talent Support Program of Yangzhou University,China to Song Chengyi。
文摘Retrotransposons,a type of DNA fragment that can mobilize itself on genome,can generate genetic variations and develop for molecular markers based on the insertion polymorphism.Zinc finger proteins(ZNFs)are among the most abundant proteins in eukaryotic animals,and their functions are extraordinarily diverse and particularly important in gene regulation.In the current study,bioinformatic prediction was performed to screen for retrotransposon insertion polymorphisms(RIPs)in six ZNF genes(ZNF2,ZNF3,ZNF7,ZNF8,ZNF10 and ZNF12).Six RIPs in these ZNFs,including one short interspersed nuclear element(SINE)RIP in intron 1 and one long interspersed nuclear element 1(L1)RIP in intron 3 of ZNF2,one SINE RIP in 5′flanking region and one SINE RIP in intron 2 of ZNF3,one SINE RIP in 3′UTR of ZNF7 and one L1 RIP in intron 2 of ZNF12,were discovered and their presence was confirmed by PCR.The impact of the SINE RIP in the first intron of ZNF2,which is close to the core promoter of ZNF2,on the gene activity was investigated by dual-luciferase assay in three cell lines.Our results showed that the SINE insertion in the intron 1 of ZNF2 repressed the core promoter activity extremely significantly(P<0.01)in cervical cancer cells and porcine primary embryonic fibroblasts(HeLa and PEF),thus SINE may act as a repressor.This SINE RIP also significantly(P<0.05)affected the corrected back fat thickness in Yorkshire pigs.The corrected back fat thickness of individuals with SINE insertion in the first intron of ZNF2 was significantly(P<0.05)higher than that of individuals without SINE insertion.In summary,our data suggested that RIPs play important roles in the genetic variations of these ZNF genes and SINE RIP in the intron 1 of ZNF2 may provide a useful molecular marker for the screening of fat deposition in the pig breeding.
基金the National Natural Science Foundation of China(82072246,81871182)National key R&D plan(2016YFC0502304).
文摘L-Arginine is the precursor of nitric oxide(NO),a host immune effector against intracellular pathogens including Mycobacterium tuberculosis(M.tb).Pathogens including M.tb have evolved various strategies targeting arginine to block the production of NO for better survival and proliferation.However,L-arginine metabolism and regulation in Mycobacterium are poorly understood.Here,we report the identification of M.smegmatis MSMEG_1415(homolog of M.tb Rv2324)as an arginine-responsive transcriptional factor regulating the arginase pathway.In the absence of L-arginine,MSMEG_1415 acts as a repressor to inhibit the transcription of the roc(for arginine,ornithine catabolism)gene cluster,thereby switching off the arginase pathway.Treatment with L-arginine relieves the transcriptional inhibition of MSMEG_1415 on the roc gene cluster to activate the arginase pathway.Moreover,the L-arginine-MSMEG_1415 complex activates the transcription of the roc gene cluster by recognizing and binding a 15-bp palindrome motif,thereby preventing the excess accumulation of L-arginine in M.smegmatis.Physiologically,MSMEG_1415 confers mycobacteria resistance to starvation and fluoroquinolones exposure,suggestive of its important role in M.smegmatis persistence.The results uncover a unique regulatory mechanism of arginine metabolism in mycobacteria and identify M.tb Rv2324 as an attractive candidate target for the design of drugs against tuberculosis.
文摘Objectives Phenotypic switching of smooth muscle cells(SMCs) plays a critical role in the pathogenesis of atherosclerotic lesions such as coronary artery disease (CAD).Accumulating evidence demonstrates(hat a cellular repressor of E1A-stimulated genes(CREG) plays a role in the maintenance of the mature phenotype of vascular SMCs. The purpose of the present study was to assess the possible association between CREG and CAD in the Han population of North China.Methods The promoter region of CREG by direct sequencing was conducted in 48 subjects.Then SNP rs2995073 and another 4 tagSNPs(rs4657669,rs3767443, rsl6859185,rs3753921) were selected for the association study.All five selected SNPs were determined in 1161 patients with angiographically proven CAD and 960 controls with normal coronary angiograms to investigate the possible involvement of CREG in CAD.Results Genotype frequencies of the five examined polymorphisms were similarly distributed between CAD group and controls(P】0.05).Further haplotype analysis also found no significant differences in the distributions between CAD group and controls(P】0.05). Conclusions This study did not show an association between common variants of CREG and CAD in the northern Chinese Han population.
文摘The effect of repressors on ion channel gene expression was studied. The hKv4. 3 promoter and the sequence （ ＋ 2-- ＋ 160, S160） of 5＇-UTR of the hKv4. 3 gene was cloned into the pβ-gal-Basic vector. The transient expression of the pβ-gal vector and the analysis of the relative activity of β-galactosidase were carried out. The analysis of the mRNA level was carried out with the RT-PCR method. S160 could intensively repress the expression of the hKv4. 3 gene with position-specificity. The level of mRNA did not alter obviously. A repressor（ S160）, in 5＇-UTR of the hKv4. 3 gene was found and its repression to gene expression may play a role in the post-transcription process.
基金supported by the National Natural Science Foundation of China(Grant No.31971919)the National Key Program for Research and Development of China(Grant No.2017YFD0100202)+1 种基金the Project Sponsored by Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyjjqX0020)Chongqing Graduate Research and Innovation Project funding in China(Grant No.CYS20123)。
文摘Inflorescence structure of rice,including the number and length of branches,and the density of the spikelet,can greatly affect the number of grains per panicle,which is one of the key factors in yield compositions.Here we identified five allelic mutants sb1-1/2/3/4/5 that related to branch development of rice.In these mutants,the branch meristem fate was prolonged sharply,resulting in delay of transition from branches to spikelets,and then increased the numbers of branches and spikelets per panicle.SB1 encodes a nuclear RING-like domain protein of SHI/LRP/SRS family and strongly expressed in branch meristems.The results of protein interaction and chromatin immunoprecipitation further suggested that SB1 directly repressed the expression of DEP1,TAW1,MOC1 and IPA1 by interacting with a co-repressor complex to affect acetylation level of histone H3 on target regions.Thus,we proposed that SB1 is a transcription repressor of branch meristem activity by widely and negatively regulating a series of genes that maintain branch meristem fate.
文摘<strong>Introduction</strong>.<span><span><span style="font-family:;" "=""><span style="font-family:Verdana;"> The molecular biological mechanism of the increased incidence of the various types of cancer in obesity or type 2 diabetes in rodents or humans has largely been resolved in recent years. By contrast, the molecular biological mechanism of the decreased, not increased, incidence of the various types of cancer in the homozygous long-lived Ames dwarf mice still remains unresolved. </span><b><span style="font-family:Verdana;">Objective.</span></b><span style="font-family:Verdana;"> The first objective of the present study was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the increase, not decrease, in the expression of p27Kip1, a cell cycle repressor protein. The second objective was to investigate whether the decrease in the incidence of cancer in the homozygous long-lived Ames dwarf mice is due to the decrease, not increase, in the levels of glucose or insulin. </span><b><span style="font-family:Verdana;">Methods.</span></b><span style="font-family:Verdana;"> To achieve these objectives, we first performed western immunoblot analysis of the hepatic expression of p27Kip1 protein. We then performed, using a human breast cancer cell line </span><i><span style="font-family:Verdana;">in</span></i> <i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;">, the luciferase reporter plasmid assay to determine whether the translation initiation activity of the p27Kip1 mRNA is increased when the concentrations of either glucose or insulin are decreased. </span><b><span style="font-family:Verdana;">Results and Conclusion. </span></b><span style="font-family:Verdana;">The results of the first objective indicated that the hepatic expression of p27Kip1 protein was up-regulated in the homozygous long-lived Ames dwarf mice as expected. We also found that the lower concentrations of glucose or insulin increased the translation initiation activity of the p27Kip1 mRNA.</span></span></span></span>
文摘Background Cellular Repressor of E1A-stimu-lated gene(CREG) is widely expressed in adult tissues such as the brain,heart,lung,liver,intestine and kidney in mice.It is not known whether tissue CREG is decreased in the common setting of myocardial infarction which may lead to heart failure.We studied the expression and protein localization of CREG and its main receptor(IFR2R) in a mouse model of myocardial infarction.Methods Male mice were randomized to proximal left anterior descending ligation.The animals were killed on day 1,3,7,14,and 28 after ligation to examine gene expression and protein production of CREG and IGF2R from the infarct,peri-infarct,and contralateral zones of infarcted heart.Results There was decreased CREG mRNA production throughout the myocardium at dav 1,and the expression gradually increased at day 28 after myocardial infarction.The decreased expression of this glycoprotein was not confined strictly to the infarct or peri-infarct zones but also expressed by cardiac myocytes within the myocardium in the contralateral normal zone.Levels of CREG protein in the infarct and peri-infarct zones declined to 1/3- to 1/2-fold of normal levels and declined to 1/2- to 2/3- fold in the contralateral zone.Finally,the expression of the IGF2R mRNA transcripts was downregulated at day 3 and 7 after ligation in the infarct and peri-infarct zones,suggesting that the signal transduction pathways necessary for CREG in the heart remain intact as CREG biosynthesis decreases. Conclusions CREG is constantly present in a model of large myocardial infarction and is decreased at the early stage within the myocardium.The decreased expression of this glycoprotein is not only confined strictly to the infarct or periinfarct zone but also is expressed by cardiac myocytes within the myocardium contralateral to the infarct.Therefore CREG production decreased due to myocardial stress response to injury.
基金supported by the Natural Science Foundation of China(Grant Nos.42077210 and 41930758 to Ke Huang and Fang-jie Zhao,respectively).
文摘Impact statement Arsenic is the most common toxic metalloid in the environment.Nearly all organisms have genes for arsenic detoxification.Arsenic detoxification genes are frequently organized in chromosomal or plasmid-encoded arsenic resistance(ars)operons,which are commonly regulated by members of the ArsR transcriptional repressors.To date,three As(Ⅲ)-responsive ArsRs with different As(III)binding sites have been identified.Here,we identify a new type of As(Ⅲ)-responsive ArsR repressor that has an atypical As(Ⅲ)binding site and controls transcription of the ars operon of Arsenicibacter rosenii SM-1.Our results provide new insights into the classification and evolution relationship of the ArsR transcriptional repressors.
基金financially supported by the National Key Research and Development Program(2022YFD2100102)the Tianchi Talent Program(2023),the Beijing Natural Science Foundation(6232019)+1 种基金the National Key Research and Development Program(2019YFD1000200)the Construction of Beijing Science and Technology Innovation and Service Capacity in Top Subjects(CEFFPXM2019_014207_000032)。
文摘It is generally accepted that jasmonate-ZIM domain(JAZ)repressors act to mediate jasmonate(JA)signaling via CORONATINE-INSENSITIVE1(COI1)-mediated degradation.Here,we report a cryptic signaling cascade where a JAZ repressor,FvJAZ12,mediates multiple signaling inputs via phosphorylation-modulated subcellular translocation rather than the COI1-mediated degradation mechanism in strawberry(Fragaria vesca).FvJAZ12 acts to regulate flavor metabolism and defense response,and was found to be the target of Fv MPK6,a mitogen-activated protein kinase that is capable of responding to multiple signal stimuli.FvMPK6 phosphorylates FvJAZ12 at the amino acid residues S179 and T183 adjacent to the PY residues,thereby attenuating its nuclear accumulation and relieving its repression for FvMYC2,which acts to control the expression of lipoxygenase 3(FvLOX3),an important gene involved in JA biosynthesis and a diverse array of cellular metabolisms.Our data reveal a previously unreported mechanism for JA signaling and decipher a signaling cascade that links multiple signaling inputs with fruit trait development.
基金supported by the National Natural Science Foundation of China(31820103012)the National Key Research and Development Program(2022YFD1200503)the Earmarked Fund for China Agriculture Research System(CARS-28)。
文摘The color of red-skinned pear(Pyrus spp.)is primarily attributed to accumulation of anthocyanins,which provide nutritional benefits for human health and are closely associated with the commercial value of fruits.Here,we reported the functional characterization of a R2R3-MYB repressor PyMYB107,which forms an‘activator-repressor’loop to control anthocyanin accumulation in the red-skinned pear.PyMYB107 overexpression inhibited anthocyanin biosynthesis in both pear calli and fruits,while virus-induced gene silencing of PyMYB107 increased anthocyanin accumulation in pear fruits.Furthermore,ectopic expression of PyMYB107 decreased anthocyanin accumulation in tomato,strawberry and tobacco.PyMYB107 can competitively bind to PybHLH3 with PyMYB10/MYB114,thereby suppressing the transcriptional activation of key anthocyanin biosynthesis genes,PyANS and PyUFGT.Site-directed mutagenesis showed that mutations within the R3 domain and EAR motif of PyMYB107 eliminated its repressive activity.Addition-ally,PyMYB107 exhibited a comparable expression pattern to PyMYB10/MYB114 and was transcriptionally activated by them.Our finding advanced comprehension of the repression mechanism underlying anthocyanin accumulation,providing valuable molecular insights into improving quality of pear fruits.
基金supported by Telethon Italy award GGP15225(to RC and GM)Italian Ministry of Health award RF-2016-02362950(to RC and CZ)+1 种基金the CJD Foundation USA(to RC)the Associazione Italiana Encefalopatie da Prioni(AIEnP)(to RC).
文摘PrPSc,a misfolded,aggregation-prone isoform of the cellular prion protein(PrPC),is the infectious prion agent responsible for fatal neurodegenerative diseases of humans and other mammals.PrPSccan adopt different pathogenic conformations(prion strains),which can be resistant to potential drugs,or acquire drug resistance,posing challenges for the development of effective therapies.Since PrPCis the obligate precursor of any prion strain and serves as the mediator of prion neurotoxicity,it represents an attractive therapeutic target fo r prion diseases.In this minireview,we briefly outline the approaches to target PrPCand discuss our recent identification of Zn(Ⅱ)-Bn PyP,a PrPC-targeting porphyrin with an unprecedented bimodal mechanism of action.We argue that in-depth understanding of the molecular mechanism by which Zn(Ⅱ)-Bn PyP targets PrPCmay lead toward the development of a new class of dual mechanism anti-prion compounds.
基金the ICGEB fellowship to Liang Tiebing and the Innovation Fund of the Chinese Academy of Sciences to Chong Kang.
文摘Single-chain repressor RRTRES is a derivative of bacteriophage 434 repressor, which contains covalently dimerized DNA-binding domains (amino acids 1-69) of the phage 434 repressor. In this single-chain molecule, the wild type domain R is connected to the mutant domain RTRES by a recombinant linker in a head-to-tail arrangement. The DNA-contacting amino acids of RTRES at the -1, 1,2, and 5 positions of the α3 helix are T, R, E, S respectively. By using a randomized DNA pool containing the central sequence -CATACAAGAAAGNNNNNNTTT-. a cyclic, in vitro DNA-binding site selection was performed. The selected population was cloned and the individual members were characterized by determining their binding affinities to RRTRES. The results showed that the optimal operators contained the TTAC or TTCC sequences in the underlined positions as above, and that the Kd values were in the 1×10-12mol/L1×10-11mol/L concentration range. Since the affinity of the natural 434 repressor to its natural operator sites is in the 1×10-9 mol/L range, the observed binding affinity increase is remarkable. It was also found that binding affinity was strongly affected by the flanking bases of the optimal tetramer binding sites, especially by the base at the 5' position. We constructed a new homodimeric single-chain repressor RrREsRtRES and its DNA-binding specificity was tested by using a series of new operators designed according to the recognition properties previously determined for the RTRES domain. These operators containing the consensus sequence GTAAGAAARNTTACN or GGAAGAAARNTTCCN (R is A or G) were recognized by RTRESRTRES specifically, and with high binding affinity. Thus, by using a combination of random selection and rational design principles, we have discovered novel, high affinity protein-DNA interactions with new specificity. This method can potentially be used to obtain new binding specificity for other DNA-binding proteins.
基金supported by the National Natural Science Foundation of China(32360166,31760321).
文摘Enhancer of zeste homolog 2(EZH2)is a key epigenetic regulatory protein and enzyme catalytic subunit of the polycomb repressor complex 2(PRC2),responsible for catalyzing the trimethylation of histone H3K27 and subsequent repression of gene transcription.Abnormal EZH2 expression or mutation is associated with various cancers,particularly lymphoma,and breast and prostate cancer.EZH2 has been investigated as an important target in cancer therapy and potential EZH2-targeted drugs have been developed.This article reviews the research progress on the mechanism of transcriptional regulation of EZH2 and the development and clinical use of some inhibitors targeting EZH2.
