Kruppel-like factor 8 （KLF8） transcription factor plays a critical role in cell cycle progression, oncogenic transformation, epithelial to mesenchymal transition and invasion. However, its nuclear localization signa...Kruppel-like factor 8 （KLF8） transcription factor plays a critical role in cell cycle progression, oncogenic transformation, epithelial to mesenchymal transition and invasion. However, its nuclear localization signal（s） （NLS） has not been identified. KLF8 shares with other KLFs monopartite NLSs （mNLS） and C2H2 zinc fingers （ZFs）, both of which have been shown to be the NLSs for some other KLFs. In this report, using PCR-directed mutagenesis and immunofluorescent microscopy, we show that disruption of the mNLSs, deletion of any single ZF, or mutation of the Zn^2＋-binding or DNA-contacting motifs did not affect the nuclear localization of KLF8. Deletion of 〉1.5 ZFs from Cterminus, however, caused cytoplasmic accumulation of KLF8. Surprisingly, deletion of amino acid （aa） 151-200 region almost eliminated KLF8 from the nucleus. S165A, K171E or K171R mutation, or treatment with PKC inhibitor led to partial cytoplasmic accumulation. Co-immunoprecipitation demonstrated that KLF8 interacted with importin-β and this interaction required the ZF motif. Deletion of aa 1-150 or 201-261 region alone did not alter the nuclear localization. BrdU incorporation and cyclin D1 promoter luciferase assays showed that the KLF8 mutants defective in nuclear localization could not promote DNA synthesis or cyclin D1 promoter activation as the wild-type KLF8 did. Taken together, these results suggest that KLF8 has two NLSs, one surrounding S165 and K171 and the other being two tandem ZFs, which are critical for the regulation of KLF8 nuclear localization and its cellular functions.展开更多
AIM: To characterize the nuclear import of hepatitis B virus (HBV) polymerase (P) and its relevance for the viral life cycle.METHODS: Sequence analysis was performed to predict functional motives within P. Phosphoryla...AIM: To characterize the nuclear import of hepatitis B virus (HBV) polymerase (P) and its relevance for the viral life cycle.METHODS: Sequence analysis was performed to predict functional motives within P. Phosphorylation of P was analyzed by in vitro phosphorylation. Phosphorylation site and nuclear localization signal (NLS) were destroyed by site directed mutagenesis. Functionality of the identified NLS was analyzed by confocal fluorescence microscopy and characterizing the karyopherin binding. Relevance of the structural motives for viral life cycle was studied by infection of primary Tupaia hepatocytes with HBV.RESULTS: We identified by sequence alignment and functional experiments a conserved bipartite NLS containing a casein kinase II (CKII) phosphorylation site located within the terminal protein domain (TP) of the HBV polymerase. Inhibition of CKII impairs the functionality of this NLS and thereby prevents the nuclear import of the polymerase. Binding of the import factor karyopherin-α2 to the polymerase depends on its CKII-mediated phosphorylation of the bipartite NLS. In HBV-infected primary Tupaia hepatocytes CKII inhibition in the early phase (post entry phase) of the infection process prevents the establishment of the infection.CONCLUSION: Based on these data it is suggested that during HBV infection the final import of the genome complex into the nucleus is mediated by a novel bipartite NLS localized in the TP domain of HBV polymerase.展开更多
The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base edit...The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.展开更多
The emergence of multidrug-resistant bacteria creates an urgent need for alternative antibiotics with new mechanisms of action. In this study, we synthesized a novel type of antimicrobial agent, Ac r_3-NLS, by conjuga...The emergence of multidrug-resistant bacteria creates an urgent need for alternative antibiotics with new mechanisms of action. In this study, we synthesized a novel type of antimicrobial agent, Ac r_3-NLS, by conjugating hydrophobic acridines to the N-terminus of a nuclear localization sequence(NLS), a short cationic peptide. To further improve the antimicrobial activity of our agent, dimeric(Acr_3-NLS)_2 was simultaneously synthesized by joining two monomeric Acr_3-NLS together via a disulfide linker. Our results show that Acr_3-NLS and especially(Acr_3-NLS)_2 display signifi cant antimicrobial activity against gramnegative and gram-positive bacteria compared to that of the NLS. Subsequently, the results derived from the study on the mechanism of action demonstrate that Acr_3-NLS and(Acr_3-NLS)_2 can kill bacteria by membrane disruption and DNA binding. The double targets—cell membrane and intracellular DNA—will reduce the risk of bacteria developing resistance to Acr_3-NLS and(Acr_3-NLS)_2. Overall, this study provides a novel strategy to design highly eff ective antimicrobial agents with a dual mode of action for infection treatment.展开更多
The nucleocapsid protein VP15 of white spot syndrome virus (WSSV) is a basic DNA-binding protein. Three canonical bipartite nuclear localization signals (NLSs), called NLS1 (aa 11-27), NLS2 (aa 33-49) and NLS3 (44-60)...The nucleocapsid protein VP15 of white spot syndrome virus (WSSV) is a basic DNA-binding protein. Three canonical bipartite nuclear localization signals (NLSs), called NLS1 (aa 11-27), NLS2 (aa 33-49) and NLS3 (44-60), have been detected in this protein, using the ScanProsite computer program. To determine the nuclear localization sequence of VP15, the full-length open reading frame, or the sequence of one of the three NLSs, was fused to the green fluorescent protein (GFP) gene, and transiently expressed in insect Sf9 cells. Transfection with full-length VP15 resulted in GFP fluorescence being distributed exclusively in the nucleus. NLS1 alone could also direct GFP to the nucleus, but less efficiently. Neither of the other two NLSs (NLS2 and 3) was functional when expressed alone, but exhibited similar activity to NLS1 when they were expressed as a fusion peptide. Furthermore, a mutated VP15, in which the two basic amino acids (11RR12) of NLS1 were changed to two alanines (11AA12), caused GFP to be localized only in the cytoplasm of Sf9 cells. These results demonstrated that VP15, as a nuclear localization protein, needs cooperation between its three NLSs, and that the two residues (11RR12) of NLS1 play a key role in transporting the protein to the nucleus.展开更多
Fat-1,an enzyme encoded by the fat-1 gene,is responsible for the conversion of endogenous omega-6 polyunsaturated fatty acids into omega-3 polyunsaturated fatty acids in Caenorhabditis elegans.To better investigate wh...Fat-1,an enzyme encoded by the fat-1 gene,is responsible for the conversion of endogenous omega-6 polyunsaturated fatty acids into omega-3 polyunsaturated fatty acids in Caenorhabditis elegans.To better investigate whether the expression of Fat-1 will exert a beneficial function in dyslipidemia and metabolic dysfunction-associated fatty liver disease(MAFLD),we established an adeno-associated virus 9 expressing Fat-1.We found that adeno-associated-virus-mediated expression of Fat-1 markedly reduced the levels of plasma triglycerides and total cholesterol but increased high-density lipoprotein levels in male wild-type hamsters on both chow diet and high-fat diet as well as in chow-diet-fed male LDLR^(-/-)hamsters.Fat-1 ameliorated diet-induced MAFLD in wild-type hamsters by enhancing fatty acid oxidation through the hepatic peroxisome proliferator-activated receptorα(PPARα)-dependent pathway.Mechanistically,Fat-1 increased the levels of multiple lipid derivatives as ligands for PPARα and simultaneously facilitated the nuclear localization of PPARα.Our results provide new insights into the multiple therapeutic potentials of Fat-1 to treat dyslipidemia,MAFLD,and atherosclerosis.展开更多
PAR1 is an atypical basic-helix-loop-helix （bHLH） protein that negatively regulates the shade avoidance syndrome in Arabidopsis thaliana acting as a transcriptional cofactor. Consistently with this function, PAR1 ha...PAR1 is an atypical basic-helix-loop-helix （bHLH） protein that negatively regulates the shade avoidance syndrome in Arabidopsis thaliana acting as a transcriptional cofactor. Consistently with this function, PAR1 has to be in the nucleus to display biological activity. Previous structure-function analyses revealed that the N-terminal region of PAR1 drives the protein to the nucleus. However, truncated forms of PAR1 lacking this region still display biological activity, implying that PAR1 has additional mechanisms to localize into the nucleus. In this work, we compared the primary structure of PAR1 and various related and unrelated plant bHLH proteins, which led us to suggest that PAR1 contains a non-canonical nuclear localization signal （NLS） in the N-terminal region. By overexpressing truncated and mutated derivatives of PAR1, we have also investigated the importance of other regions of PAR1, such as the acidic and the extended HLH dimerization domains, for its nuclear localization. We found that, in the absence of the N-terminal region, a functional HLH domain is required for nuclear localization. Our results suggest the existence of a dual mechanism for PAR1 nuclear localization： （1） one mediated by the N-terminal non-consensus NLS and （2） a second one that involves interaction with other proteins via the dimerization domain,展开更多
In this study, 107 types of human papillomavirus （HPV） L1 protein sequences were obtained from available databases, and the nuclear localization signals （NLSs） of these HPV L1 proteins were analyzed and predicted ...In this study, 107 types of human papillomavirus （HPV） L1 protein sequences were obtained from available databases, and the nuclear localization signals （NLSs） of these HPV L1 proteins were analyzed and predicted by bioinformatic analysis. Out of the 107 types, the NLSs of 39 types were predicted by PredictNLS software （35 types of bipartite NLSs and 4 types of monopartite NLSs）. The NLSs of the remaining HPV types were predicted according to the characteristics and the homology of the already predicted NLSs as well as the general rule of NLSs. According to the result, the NLSs of 107 types of HPV L1 proteins were classified into 15 categories. The different types of HPV L1 proteins in the same NLS category could share the similar or the same nucleocytoplasmic transport pathway. They might be used as the same target to prevent and treat different types of HPV infection. The results also showed that bioinformatic technology could be used to analyze and predict NLSs of proteins.展开更多
Homeodomains,a 60-amino acid sequence encoded by 180 nucleotides,are highly conserved DNA-binding motifs that are present in a variety of transcription factors in species ranging from yeast to humans.The NKX proteins ...Homeodomains,a 60-amino acid sequence encoded by 180 nucleotides,are highly conserved DNA-binding motifs that are present in a variety of transcription factors in species ranging from yeast to humans.The NKX proteins belong to the homeodomain(HD)-containing transcription factor family.They play vital roles in the regulation of morphogenesis.NKX1-2 is one member of the NKX subfamily.At present,information about its nuclear localization signal(NLS)sequence is limited.We studied the NLS sequence of zebrafish Nkx1.2 by introducing sequence changes such as deletion,mutation,and truncation,and identified an NLS motif(QNRRTKWKKQ)that is localized at the C-terminus of the homeodomain.Moreover,the deletion of two amino acid residues(RR)in this NLS motif prevents Nkx1.2 from entering the nucleus,indicating that the two amino acids are essential for Nkx1.2 nuclear localization.However,the NLS motif alone is unable to target cytoplasmic protein glutathione S-transferase(GST)to the nucleus.An intact homeodomain is necessary for mediating the complete nuclear transport of cytoplasmic protein.Unlike most nuclear import proteins with short NLS sequences,a long NLS is present in zebrafish Nkx1.2.We also demonstrated that the sequences of homeodomain of NKX1.2 are well conserved among different species.This study is informative to verify the function of the NKX1.2 protein.展开更多
African swine fever virus(ASFV)pB318L is an important protein for viral replication that acts as a membrane-bound trans-geranylgeranyl-diphosphate synthase(GGPPS)catalyzing the condensation of isopentenyl diphosphate(...African swine fever virus(ASFV)pB318L is an important protein for viral replication that acts as a membrane-bound trans-geranylgeranyl-diphosphate synthase(GGPPS)catalyzing the condensation of isopentenyl diphosphate(IPP)with allylic diphosphates.Recently we solved the crystal structure pB318L lacking N-terminal transmembrane region and performed a preliminary structural analysis.In this study,structure-based mutagenesis study and geranylgeranyl pyrophosphate(GGPP)production assay further revealed the key residues for the GGPPS activity.Structural comparison showed pB318L displays a strong similarity to typical GGPPSs instead of protein prenyltransferases.The phylogenetic analysis indicated pB318L may share a common ancestor with the GGPPSs from Brassicaceae plants rather than from its natural host.The subcellular localization analysis showed pB318L is localized in both nucleus and cytoplasm(including the endoplasmic reticulum membrane and mitochondria outer membrane).A unique N-terminal nuclear localization signal(NLS)following the transmembrane region was discovered in pB318L and the NLS was confirmed to be required for the nuclear import.We further revealed the NLS plays an essential role in the interaction with nuclear transporter karyopherin subunit alpha 1(KPNA1).Their interaction may suppress signal transducers and activators of transcription 1(STAT1)translocation and subsequently competitively inhibit nuclear import of IFNstimulated gene factor 3(ISGF3)complex.Our biochemical,structural and cellular analyses provide novel insights to pB318L that acts as an essential GGPPS that promotes viral replication and as a nuclear import protein that may be involved in immune evasion of ASFV.展开更多
Ribosomal RNA(rRNA)synthesis is intricately tied to cellular growth and proliferation.Basic fibroblast growth factor(FGF2),a pivotal factor for bone marrow mesenchymal stem cells(BMSCs),can stimulates rRNA transcripti...Ribosomal RNA(rRNA)synthesis is intricately tied to cellular growth and proliferation.Basic fibroblast growth factor(FGF2),a pivotal factor for bone marrow mesenchymal stem cells(BMSCs),can stimulates rRNA transcription,though the underlying mechanism remains unknown.Here,we demonstrate that the cytoplasm-nucleus translocation of FGF2 is determined by the stable nuclear localization motif.Meanwhile,the nuclear FGF2 regulates rRNA expression and BMSCs proliferation via phase separation.Next,through FGF2 related epigenomics and 3D genomes analysis,we identified chromatin architectures during BMSCs differentiation and aging.In the process,topologically associating domains(TADs)and chromatin loops profiling revealed the attenuated genomic interaction among proximal chromosomes 13,14,15,21,and 22,where phase-separated FGF2 facilitates rDNA transcription depend on specific super-enhancers(SEs).Furthermore,we validated that FGF2 orchestrates rDNA chromatin architecture in coordination with STAT5.Together,these findings underscore the pivotal role of FGF2 in rDNA chromatin architectures,which determines BMSCs cell fate.展开更多
Nuclear envelope proteins have important roles in chromatin organization and signal-dependent transcriptional regulation. A previous study reported that the inner nuclear membrane protein, Otefin （Ote）, was essentia...Nuclear envelope proteins have important roles in chromatin organization and signal-dependent transcriptional regulation. A previous study reported that the inner nuclear membrane protein, Otefin （Ote）, was essential for germline stem cell （GSC） maintenance via interaction with Smad complex. The interaction of Ore with the Smad complex recruits the barn locus to the nuclear periphery and subsequently results in bam transcriptional silencing, revealing that nuclear peripheral localization is essential for barn gene regulation. However, it remains unknown whether the nuclear peripheral localization is sufficient for barn silencing. To address this issue, we have established a tethering system, in which the Gal4 DNA binding domain （DBD） of the Flag：Gal4 DBD：Ote△LEM fusion protein physically interacts with the Gal4 binding sites upstream of bamP-gfp to artificially recruit the reporter gene gfp to the nuclear membrane. Our data demonstrated that the nuclear peripheral localization seemed to affect the expression of the target naked gene in S2 ceils. By contrast, in Drosophila germ cells, the nuclear membrane localization was not sufficient for gene silencing.展开更多
Objective To clone, express, purify human Oct-4 and detect its subcellular localization. Methods Human Oct-4 cDNA was amplified by RT-PCR strategy. Oct-4 protein was induced and expressed in BL21(DE3) strain. Furtherm...Objective To clone, express, purify human Oct-4 and detect its subcellular localization. Methods Human Oct-4 cDNA was amplified by RT-PCR strategy. Oct-4 protein was induced and expressed in BL21(DE3) strain. Furthermore, the protein was purified with Ni-NTA resin. Subsequently, site-directed mutagen-esis of Oct-4 (aa 236 - 240) was introduced. Finally, the subcellular localization of wide type Oct-4 and mutant Oct-4 was examined by immunofluorescent cytochemistry staining and confocal laser scanning microscope analysis. Results The full length cDNA of human Oct-4 was 1083 bp. Human Oct-4 encoded a 55 kd protein by prokaryotic vector in E coli. Compared with pure nuclear localization of wide type Oct-4, mutant Oct-4 was mostly enriched in the cytoplasm. Conclusion The cloning, expression and investigation of subcellular localization of human Oct-4 are basis of studying its biological function.展开更多
Hepatocellular carcinoma(HCC)expresses abundant glycolytic enzymes and displays comprehensive glucose metabolism reprogramming.Aldolase A(ALDOA)plays a prominent role in glycolysis;however,little is known about its ro...Hepatocellular carcinoma(HCC)expresses abundant glycolytic enzymes and displays comprehensive glucose metabolism reprogramming.Aldolase A(ALDOA)plays a prominent role in glycolysis;however,little is known about its role in HCC development.In the present study,we aim to explore how ALDOA is involved in HCC proliferation.HCC proliferation was markedly suppressed both in vitro and in vivo following ALDOA knockout,which is consistent with ALDOA overexpression encouraging HCC proliferation.Mechanistically,ALDOA knockout partially limits the glycolytic flux in HCC cells.Meanwhile,ALDOA translocated to nuclei and directly interacted with c-Jun to facilitate its Thr93 phosphorylation by P21-activated protein kinase;ALDOA knockout markedly diminished c-Jun Thr93 phosphorylation and then dampened c-Jun transcription function.A crucial site Y364 mutation in ALDOA disrupted its interaction with c-Jun,and Y364S ALDOA expression failed to rescue cell proliferation in ALDOA deletion cells.In HCC patients,the expression level of ALDOA was correlated with the phosphorylation level of c-Jun(Thr93)and poor prognosis.Remarkably,hepatic ALDOA was significantly upregulated in the promotion and progression stages of diethylnitrosamine-induced HCC models,and the knockdown of Aldoa strikingly decreased HCC development in vivo.Our study demonstrated that ALDOA is a vital driver for HCC development by activating c-Jun-mediated oncogene transcription,opening additional avenues for anti-cancer therapies.展开更多
Hypocotyl length is regarded to be a crucial seedling trait,influencing many subsequent plant development processes.However,little is known about this trait in Brassica campestris syn.Brasscia rapa.Here,we performed a...Hypocotyl length is regarded to be a crucial seedling trait,influencing many subsequent plant development processes.However,little is known about this trait in Brassica campestris syn.Brasscia rapa.Here,we performed a comparative observation on the early hypocotyl development between two cultivars,‘SZQ’belonging to pak-choi(B.campestris ssp.chinensis var.communis)with longer hypocotyls,and‘WTC’belonging to Tacai(B.campestris L.ssp.chinensis var.rosularis)with shortter hypocotyls,and found that the difference in auxin biosynthesis might contribute to the varied hypocotyl phenotype between these two cultivars.By applying GWAS analysis using a total of 226 B.campestris accessions,we identified that the AT-Hook motif nuclear localized(AHL)gene BcAHL24-MF1 contributed to the natural variation in hypocotyl length.Functional variation of BcAHL24-MF1 was attributed to four haplotypes featuring four SNPs within the promoter region,of which Hap I accumulated more transcripts with shorter hypocotyls.Constitutive overexpression of BcAHL24-MF1 in B.campestris caused decreased hypocotyl length under light circumstances and even constant darkness,as BcAHL24-MF1 repressed the PIFmediated transcriptional activation of auxin biosynthesis genes BcYUC6-MF2 and BcYUC8-LF.Our research uncovered the important role of BcAHL24-MF1 in regulating light-triggered inhibition of hypocotyl elongation,therefore presenting a valuable genetic target for crop breeding.展开更多
For genome mulUplication hepadnaviruses use the transcriptional machinery of the cell that is found within the nucleus. Thus the viral genome has to be transported through the cytoplasm and nuclear pore. The intracyto...For genome mulUplication hepadnaviruses use the transcriptional machinery of the cell that is found within the nucleus. Thus the viral genome has to be transported through the cytoplasm and nuclear pore. The intracytosolic translocation is facilitated by the viral capsid that surrounds the genome and that interacts with cellular microtubules. The subsequent passage through the nuclear pore complexes （NPC） is mediated by the nuclear transport receptors importin α andβ. Importin α binds to the C-terminus of the capsid protein that comprises a nuclear localization signal （NLS）. The exposure of the NLS is regulated and depends upon genome maturation and/or phosphorylation of the capsid protein. As for other karyophilic cargos using this pathway importin α interacts with importin β that facilitates docking of the import complex to the NPC and the passage through the pore. Being a unique strategy, the import of the viral capsid is incomplete in that it becomes arrested inside the nuclear basket, which is a cage-like structure on the karyoplasmic face of the NPC. Presumably only this compartment provides the factors that are required for capsid disassembly and genome release that is restricted to those capsids comprising a mature viral DNA genome.展开更多
Midkine(MK) is a heparin-binding growth factor with its gene first identified in embryonal carcinoma cells at early stages of retinoic acid-induced differentiation. MK is frequently and highly expressed in a variety o...Midkine(MK) is a heparin-binding growth factor with its gene first identified in embryonal carcinoma cells at early stages of retinoic acid-induced differentiation. MK is frequently and highly expressed in a variety of human carcinomas.Furthermore,the blood MK level is frequently elevated with advance of human carcinomas,decreased after surgical removal of the tumors.Thus,it is expected to become a promising marker for evaluating the progress of carcinomas. There is mounting evidence that MK plays a significant role in carcinogenesis-related activities,such as proliferation,migration,anti-apoptosis,mitogenesis,transforming,and angiogenesis.In addition,siRNA and anti-sense oligonucleotides for MK have yielded great effects in anti-tumor activities.Therefore,MK appears to be a potential candidate molecular target of therapy for human carcinomas.In this paper,we review MK targeting at nucleoli in different tumor cells and its role in carcinogenesis to deepen our understanding of the mechanism of MK involved in carcinogenesis.展开更多
Objective: To investigate the functions of nM-CSF in malignant cells. Methods: recombinant M-CSF was targeted into cell nucleus by employing a eukaryotic expression plasmid vector pCMV/myc/nuc. The constructed plasmid...Objective: To investigate the functions of nM-CSF in malignant cells. Methods: recombinant M-CSF was targeted into cell nucleus by employing a eukaryotic expression plasmid vector pCMV/myc/nuc. The constructed plasmid was transfected into cells of EBV transformed lymphoblastoid cell line (LCL). RT-PCR, Western blot and immunofluorescent staining showed that recombinant M-CSF was localized into LCL cell nucleus. The transgenic cells showed elevated proliferation potential, enhanced resistance to apoptosis and increased ability of in vitro migration. Conclusion: Nucleus presenting M-CSF might act as a promoting factor in the processes of cell malignancy.展开更多
Molecules can enter the nucleus by passive diffusion or active transport mechanisms, depending on their size. Small molecules up to size of 50-60 kDa or less than 10 nm in diameter can diffuse passively through the nu...Molecules can enter the nucleus by passive diffusion or active transport mechanisms, depending on their size. Small molecules up to size of 50-60 kDa or less than 10 nm in diameter can diffuse passively through the nuclear pore complex （NPC）, while most proteins are transported by energy driven transport mechanisms Active transport of viral proteins is mediated by nuclear localization signals （NLS）, which were first identified in Simian Virus 40 large T antigen and had subsequently been identified in a large number of viral they contain short stretches of lysine or arginine residues. These signals are recognized proteins. Usually by the importin super-family （importin α and β） proteins that mediate the transport across the nuclear envelope through Ran-GTP In contrast, only one class of the leucine-rich nuclear export signal （NES） on viral proteins is known at present. Chromosome region maintenance 1 （CRM1） protein mediates nuclear export of hundreds of viral proteins through the recognition of the leucine-rich NES.展开更多
Viruses including baculoviruses are obligatory parasites, as their genomes do not encode all the proteins required for replication. Therefore, viruses have evolved to exploit the behavior and the physiology of their h...Viruses including baculoviruses are obligatory parasites, as their genomes do not encode all the proteins required for replication. Therefore, viruses have evolved to exploit the behavior and the physiology of their hosts and olden coevolved with their hosts over millions of years. Recent comparative analyses of complete genome sequences of baculoviruses revealed the patterns of gene acquisitions and losses that have occurred during baculovirus evolution. In addition, knowledge of virus genes has also provided understanding of the mechanism of baculovirus infection including replication, species-specific virulence and host range. The Bm8 gene of Bombyx mori nucleopolyhedrovirus （NPV） and its homologues are found only in group I NPV genomes. The Autographa californica NPV Ac 16 gene is a homologue of Bm8 and, encodes a viral structural protein. It has been shown that BmS/Ac 16 interacts with baculoviral and cellular proteins. BmS/Ac 16 interacts with baculoviral IE1 that is facilitated by coiled coil domains, and the interaction with IE1 is important for Bin8 function. Acl6 also forms a complex with viral FP25 and cellular actin and associates with membranes via palmitoylation. These data suggested that this gene family encodes a multifunctional protein that accomplishes specific needs of group I NPVs.展开更多
文摘Kruppel-like factor 8 （KLF8） transcription factor plays a critical role in cell cycle progression, oncogenic transformation, epithelial to mesenchymal transition and invasion. However, its nuclear localization signal（s） （NLS） has not been identified. KLF8 shares with other KLFs monopartite NLSs （mNLS） and C2H2 zinc fingers （ZFs）, both of which have been shown to be the NLSs for some other KLFs. In this report, using PCR-directed mutagenesis and immunofluorescent microscopy, we show that disruption of the mNLSs, deletion of any single ZF, or mutation of the Zn^2＋-binding or DNA-contacting motifs did not affect the nuclear localization of KLF8. Deletion of 〉1.5 ZFs from Cterminus, however, caused cytoplasmic accumulation of KLF8. Surprisingly, deletion of amino acid （aa） 151-200 region almost eliminated KLF8 from the nucleus. S165A, K171E or K171R mutation, or treatment with PKC inhibitor led to partial cytoplasmic accumulation. Co-immunoprecipitation demonstrated that KLF8 interacted with importin-β and this interaction required the ZF motif. Deletion of aa 1-150 or 201-261 region alone did not alter the nuclear localization. BrdU incorporation and cyclin D1 promoter luciferase assays showed that the KLF8 mutants defective in nuclear localization could not promote DNA synthesis or cyclin D1 promoter activation as the wild-type KLF8 did. Taken together, these results suggest that KLF8 has two NLSs, one surrounding S165 and K171 and the other being two tandem ZFs, which are critical for the regulation of KLF8 nuclear localization and its cellular functions.
文摘AIM: To characterize the nuclear import of hepatitis B virus (HBV) polymerase (P) and its relevance for the viral life cycle.METHODS: Sequence analysis was performed to predict functional motives within P. Phosphorylation of P was analyzed by in vitro phosphorylation. Phosphorylation site and nuclear localization signal (NLS) were destroyed by site directed mutagenesis. Functionality of the identified NLS was analyzed by confocal fluorescence microscopy and characterizing the karyopherin binding. Relevance of the structural motives for viral life cycle was studied by infection of primary Tupaia hepatocytes with HBV.RESULTS: We identified by sequence alignment and functional experiments a conserved bipartite NLS containing a casein kinase II (CKII) phosphorylation site located within the terminal protein domain (TP) of the HBV polymerase. Inhibition of CKII impairs the functionality of this NLS and thereby prevents the nuclear import of the polymerase. Binding of the import factor karyopherin-α2 to the polymerase depends on its CKII-mediated phosphorylation of the bipartite NLS. In HBV-infected primary Tupaia hepatocytes CKII inhibition in the early phase (post entry phase) of the infection process prevents the establishment of the infection.CONCLUSION: Based on these data it is suggested that during HBV infection the final import of the genome complex into the nucleus is mediated by a novel bipartite NLS localized in the TP domain of HBV polymerase.
基金supported by the Beijing Scholars Program[BSP041]。
文摘The clustered regularly interspaced short palindromic repeats(CRISPR)–CRISPR-associated protein(Cas) system has been widely used for genome editing. In this system, the cytosine base editor(CBE) and adenine base editor(ABE) allow generating precise and irreversible base mutations in a programmable manner and have been used in many different types of cells and organisms. However, their applications are limited by low editing efficiency at certain genomic target sites or at specific target cytosine(C) or adenine(A) residues. Using a strategy of combining optimized synergistic core components, we developed a new multiplex super-assembled ABE(sABE) in rice that showed higher base-editing efficiency than previously developed ABEs. We also designed a new type of nuclear localization signal(NLS) comprising a FLAG epitope tag with four copies of a codon-optimized NLS(F4NLS^(r2)) to generate another ABE named F4NLS-sABE. This new NLS increased editing efficiency or edited additional A at several target sites. A new multiplex super-assembled CBE(sCBE) and F4NLS^(r2) involved F4NLS-sCBE were also created using the same strategy. F4NLS-sCBE was proven to be much more efficient than sCBE in rice. These optimized base editors will serve as powerful genome-editing tools for basic research or molecular breeding in rice and will provide a reference for the development of superior editing tools for other plants or animals.
基金the grants from the National Natural Science Foundation of China (81402776 and 81202400)the Key National S&T Progra m "Major New Drug Development" of the Ministry of Science and Technology of China (2012ZX09504001-003)+2 种基金the Fundamental Research Funds for the Central Universities (lzujbky-2014-142 and lzujbky-2015-169)the Specialized Research Fund for the Doctoral Program of Higher Education of China (20130211130005)China Postdoctoral Science Foundation (2013T60896)
文摘The emergence of multidrug-resistant bacteria creates an urgent need for alternative antibiotics with new mechanisms of action. In this study, we synthesized a novel type of antimicrobial agent, Ac r_3-NLS, by conjugating hydrophobic acridines to the N-terminus of a nuclear localization sequence(NLS), a short cationic peptide. To further improve the antimicrobial activity of our agent, dimeric(Acr_3-NLS)_2 was simultaneously synthesized by joining two monomeric Acr_3-NLS together via a disulfide linker. Our results show that Acr_3-NLS and especially(Acr_3-NLS)_2 display signifi cant antimicrobial activity against gramnegative and gram-positive bacteria compared to that of the NLS. Subsequently, the results derived from the study on the mechanism of action demonstrate that Acr_3-NLS and(Acr_3-NLS)_2 can kill bacteria by membrane disruption and DNA binding. The double targets—cell membrane and intracellular DNA—will reduce the risk of bacteria developing resistance to Acr_3-NLS and(Acr_3-NLS)_2. Overall, this study provides a novel strategy to design highly eff ective antimicrobial agents with a dual mode of action for infection treatment.
基金State Key Program for Basic ResearchGrants (2006CB101801)the Chinese Academy ofSciences (KSCX2-SW-302).
文摘The nucleocapsid protein VP15 of white spot syndrome virus (WSSV) is a basic DNA-binding protein. Three canonical bipartite nuclear localization signals (NLSs), called NLS1 (aa 11-27), NLS2 (aa 33-49) and NLS3 (44-60), have been detected in this protein, using the ScanProsite computer program. To determine the nuclear localization sequence of VP15, the full-length open reading frame, or the sequence of one of the three NLSs, was fused to the green fluorescent protein (GFP) gene, and transiently expressed in insect Sf9 cells. Transfection with full-length VP15 resulted in GFP fluorescence being distributed exclusively in the nucleus. NLS1 alone could also direct GFP to the nucleus, but less efficiently. Neither of the other two NLSs (NLS2 and 3) was functional when expressed alone, but exhibited similar activity to NLS1 when they were expressed as a fusion peptide. Furthermore, a mutated VP15, in which the two basic amino acids (11RR12) of NLS1 were changed to two alanines (11AA12), caused GFP to be localized only in the cytoplasm of Sf9 cells. These results demonstrated that VP15, as a nuclear localization protein, needs cooperation between its three NLSs, and that the two residues (11RR12) of NLS1 play a key role in transporting the protein to the nucleus.
基金supported by the National Natural Science Foundation of China(NSFC)82270479,82070460,and HY2021-1 to Xunde Xianthe Beijing Natural Science Foundation 7242084 to Xunde Xian+1 种基金the Fundamental Research Funds for the Central Universities to Xunde XianPeking University Medicine plus X Pilot Program-Platform Construction Project 2024YXXLHPT010 to Xunde Xian.
文摘Fat-1,an enzyme encoded by the fat-1 gene,is responsible for the conversion of endogenous omega-6 polyunsaturated fatty acids into omega-3 polyunsaturated fatty acids in Caenorhabditis elegans.To better investigate whether the expression of Fat-1 will exert a beneficial function in dyslipidemia and metabolic dysfunction-associated fatty liver disease(MAFLD),we established an adeno-associated virus 9 expressing Fat-1.We found that adeno-associated-virus-mediated expression of Fat-1 markedly reduced the levels of plasma triglycerides and total cholesterol but increased high-density lipoprotein levels in male wild-type hamsters on both chow diet and high-fat diet as well as in chow-diet-fed male LDLR^(-/-)hamsters.Fat-1 ameliorated diet-induced MAFLD in wild-type hamsters by enhancing fatty acid oxidation through the hepatic peroxisome proliferator-activated receptorα(PPARα)-dependent pathway.Mechanistically,Fat-1 increased the levels of multiple lipid derivatives as ligands for PPARα and simultaneously facilitated the nuclear localization of PPARα.Our results provide new insights into the multiple therapeutic potentials of Fat-1 to treat dyslipidemia,MAFLD,and atherosclerosis.
文摘PAR1 is an atypical basic-helix-loop-helix （bHLH） protein that negatively regulates the shade avoidance syndrome in Arabidopsis thaliana acting as a transcriptional cofactor. Consistently with this function, PAR1 has to be in the nucleus to display biological activity. Previous structure-function analyses revealed that the N-terminal region of PAR1 drives the protein to the nucleus. However, truncated forms of PAR1 lacking this region still display biological activity, implying that PAR1 has additional mechanisms to localize into the nucleus. In this work, we compared the primary structure of PAR1 and various related and unrelated plant bHLH proteins, which led us to suggest that PAR1 contains a non-canonical nuclear localization signal （NLS） in the N-terminal region. By overexpressing truncated and mutated derivatives of PAR1, we have also investigated the importance of other regions of PAR1, such as the acidic and the extended HLH dimerization domains, for its nuclear localization. We found that, in the absence of the N-terminal region, a functional HLH domain is required for nuclear localization. Our results suggest the existence of a dual mechanism for PAR1 nuclear localization： （1） one mediated by the N-terminal non-consensus NLS and （2） a second one that involves interaction with other proteins via the dimerization domain,
文摘In this study, 107 types of human papillomavirus （HPV） L1 protein sequences were obtained from available databases, and the nuclear localization signals （NLSs） of these HPV L1 proteins were analyzed and predicted by bioinformatic analysis. Out of the 107 types, the NLSs of 39 types were predicted by PredictNLS software （35 types of bipartite NLSs and 4 types of monopartite NLSs）. The NLSs of the remaining HPV types were predicted according to the characteristics and the homology of the already predicted NLSs as well as the general rule of NLSs. According to the result, the NLSs of 107 types of HPV L1 proteins were classified into 15 categories. The different types of HPV L1 proteins in the same NLS category could share the similar or the same nucleocytoplasmic transport pathway. They might be used as the same target to prevent and treat different types of HPV infection. The results also showed that bioinformatic technology could be used to analyze and predict NLSs of proteins.
基金Supported by the National Natural Science Foundation of China(No.31970429)the Shandong Provincial Natural Science Foundation(No.ZR 2022 MC 032)。
文摘Homeodomains,a 60-amino acid sequence encoded by 180 nucleotides,are highly conserved DNA-binding motifs that are present in a variety of transcription factors in species ranging from yeast to humans.The NKX proteins belong to the homeodomain(HD)-containing transcription factor family.They play vital roles in the regulation of morphogenesis.NKX1-2 is one member of the NKX subfamily.At present,information about its nuclear localization signal(NLS)sequence is limited.We studied the NLS sequence of zebrafish Nkx1.2 by introducing sequence changes such as deletion,mutation,and truncation,and identified an NLS motif(QNRRTKWKKQ)that is localized at the C-terminus of the homeodomain.Moreover,the deletion of two amino acid residues(RR)in this NLS motif prevents Nkx1.2 from entering the nucleus,indicating that the two amino acids are essential for Nkx1.2 nuclear localization.However,the NLS motif alone is unable to target cytoplasmic protein glutathione S-transferase(GST)to the nucleus.An intact homeodomain is necessary for mediating the complete nuclear transport of cytoplasmic protein.Unlike most nuclear import proteins with short NLS sequences,a long NLS is present in zebrafish Nkx1.2.We also demonstrated that the sequences of homeodomain of NKX1.2 are well conserved among different species.This study is informative to verify the function of the NKX1.2 protein.
基金supported by the grants from the National Natural Science Foundation of China to Heng Zhang(31970152)the Strategic Priority Research Program of CAS to Yu-Hui Dong(XDB37040302)the CAS Emergency Research Project on African Swine Fever to Yu-Hui Dong(Grant KJZDSW-L06-01).
文摘African swine fever virus(ASFV)pB318L is an important protein for viral replication that acts as a membrane-bound trans-geranylgeranyl-diphosphate synthase(GGPPS)catalyzing the condensation of isopentenyl diphosphate(IPP)with allylic diphosphates.Recently we solved the crystal structure pB318L lacking N-terminal transmembrane region and performed a preliminary structural analysis.In this study,structure-based mutagenesis study and geranylgeranyl pyrophosphate(GGPP)production assay further revealed the key residues for the GGPPS activity.Structural comparison showed pB318L displays a strong similarity to typical GGPPSs instead of protein prenyltransferases.The phylogenetic analysis indicated pB318L may share a common ancestor with the GGPPSs from Brassicaceae plants rather than from its natural host.The subcellular localization analysis showed pB318L is localized in both nucleus and cytoplasm(including the endoplasmic reticulum membrane and mitochondria outer membrane).A unique N-terminal nuclear localization signal(NLS)following the transmembrane region was discovered in pB318L and the NLS was confirmed to be required for the nuclear import.We further revealed the NLS plays an essential role in the interaction with nuclear transporter karyopherin subunit alpha 1(KPNA1).Their interaction may suppress signal transducers and activators of transcription 1(STAT1)translocation and subsequently competitively inhibit nuclear import of IFNstimulated gene factor 3(ISGF3)complex.Our biochemical,structural and cellular analyses provide novel insights to pB318L that acts as an essential GGPPS that promotes viral replication and as a nuclear import protein that may be involved in immune evasion of ASFV.
基金the open research project of State Key Laboratory of Oral Diseases(no.SKLOD2024OF03)the Key Project of Natural Science Research in Anhui Provincial Universities(no.2024AH050683)+1 种基金Anhui Province Outstanding Young Teachers Development Program(no.YQYB2024013)the National Natural Science Foundation of China(no.82201026,82125006).
文摘Ribosomal RNA(rRNA)synthesis is intricately tied to cellular growth and proliferation.Basic fibroblast growth factor(FGF2),a pivotal factor for bone marrow mesenchymal stem cells(BMSCs),can stimulates rRNA transcription,though the underlying mechanism remains unknown.Here,we demonstrate that the cytoplasm-nucleus translocation of FGF2 is determined by the stable nuclear localization motif.Meanwhile,the nuclear FGF2 regulates rRNA expression and BMSCs proliferation via phase separation.Next,through FGF2 related epigenomics and 3D genomes analysis,we identified chromatin architectures during BMSCs differentiation and aging.In the process,topologically associating domains(TADs)and chromatin loops profiling revealed the attenuated genomic interaction among proximal chromosomes 13,14,15,21,and 22,where phase-separated FGF2 facilitates rDNA transcription depend on specific super-enhancers(SEs).Furthermore,we validated that FGF2 orchestrates rDNA chromatin architecture in coordination with STAT5.Together,these findings underscore the pivotal role of FGF2 in rDNA chromatin architectures,which determines BMSCs cell fate.
基金supported by the Postdoctoral Science Foundation of China(No.20090460517)
文摘Nuclear envelope proteins have important roles in chromatin organization and signal-dependent transcriptional regulation. A previous study reported that the inner nuclear membrane protein, Otefin （Ote）, was essential for germline stem cell （GSC） maintenance via interaction with Smad complex. The interaction of Ore with the Smad complex recruits the barn locus to the nuclear periphery and subsequently results in bam transcriptional silencing, revealing that nuclear peripheral localization is essential for barn gene regulation. However, it remains unknown whether the nuclear peripheral localization is sufficient for barn silencing. To address this issue, we have established a tethering system, in which the Gal4 DNA binding domain （DBD） of the Flag：Gal4 DBD：Ote△LEM fusion protein physically interacts with the Gal4 binding sites upstream of bamP-gfp to artificially recruit the reporter gene gfp to the nuclear membrane. Our data demonstrated that the nuclear peripheral localization seemed to affect the expression of the target naked gene in S2 ceils. By contrast, in Drosophila germ cells, the nuclear membrane localization was not sufficient for gene silencing.
文摘Objective To clone, express, purify human Oct-4 and detect its subcellular localization. Methods Human Oct-4 cDNA was amplified by RT-PCR strategy. Oct-4 protein was induced and expressed in BL21(DE3) strain. Furthermore, the protein was purified with Ni-NTA resin. Subsequently, site-directed mutagen-esis of Oct-4 (aa 236 - 240) was introduced. Finally, the subcellular localization of wide type Oct-4 and mutant Oct-4 was examined by immunofluorescent cytochemistry staining and confocal laser scanning microscope analysis. Results The full length cDNA of human Oct-4 was 1083 bp. Human Oct-4 encoded a 55 kd protein by prokaryotic vector in E coli. Compared with pure nuclear localization of wide type Oct-4, mutant Oct-4 was mostly enriched in the cytoplasm. Conclusion The cloning, expression and investigation of subcellular localization of human Oct-4 are basis of studying its biological function.
基金supported by the National Natural Science Foundation of China(Grant No.:81473329)the Natural Science Basic Research Program of Shaanxi Province,China(Grant No.:2023-JC-JQ-61)+1 种基金the Science and Technology Project of Shaanxi Province in China(Grant No.:2022YWZX-PG-01)the Scientific Research Project of Shaanxi Administration of Traditional Chinese Medicine,China(Grant Nos.:2019-GJ-JC012,2021-04-ZZ-001,2021-QYPT-003,and 2022-SLRH-YQ-004).
文摘Hepatocellular carcinoma(HCC)expresses abundant glycolytic enzymes and displays comprehensive glucose metabolism reprogramming.Aldolase A(ALDOA)plays a prominent role in glycolysis;however,little is known about its role in HCC development.In the present study,we aim to explore how ALDOA is involved in HCC proliferation.HCC proliferation was markedly suppressed both in vitro and in vivo following ALDOA knockout,which is consistent with ALDOA overexpression encouraging HCC proliferation.Mechanistically,ALDOA knockout partially limits the glycolytic flux in HCC cells.Meanwhile,ALDOA translocated to nuclei and directly interacted with c-Jun to facilitate its Thr93 phosphorylation by P21-activated protein kinase;ALDOA knockout markedly diminished c-Jun Thr93 phosphorylation and then dampened c-Jun transcription function.A crucial site Y364 mutation in ALDOA disrupted its interaction with c-Jun,and Y364S ALDOA expression failed to rescue cell proliferation in ALDOA deletion cells.In HCC patients,the expression level of ALDOA was correlated with the phosphorylation level of c-Jun(Thr93)and poor prognosis.Remarkably,hepatic ALDOA was significantly upregulated in the promotion and progression stages of diethylnitrosamine-induced HCC models,and the knockdown of Aldoa strikingly decreased HCC development in vivo.Our study demonstrated that ALDOA is a vital driver for HCC development by activating c-Jun-mediated oncogene transcription,opening additional avenues for anti-cancer therapies.
基金supported by grants from the Key R and D Program of Zhejiang(Grant Nos.2022C02032 and 2022C02030)the SanNong JiuFang Science and Technology Cooperation Project of Zhejiang Province(Grant No.2023SNJF008)+1 种基金the Grand Science and Technology Special Project of Zhejiang Province(Grant No.2021C02065)the Science and Technology Plan Project of Jiaxing(Grant No.2023AZ11002).
文摘Hypocotyl length is regarded to be a crucial seedling trait,influencing many subsequent plant development processes.However,little is known about this trait in Brassica campestris syn.Brasscia rapa.Here,we performed a comparative observation on the early hypocotyl development between two cultivars,‘SZQ’belonging to pak-choi(B.campestris ssp.chinensis var.communis)with longer hypocotyls,and‘WTC’belonging to Tacai(B.campestris L.ssp.chinensis var.rosularis)with shortter hypocotyls,and found that the difference in auxin biosynthesis might contribute to the varied hypocotyl phenotype between these two cultivars.By applying GWAS analysis using a total of 226 B.campestris accessions,we identified that the AT-Hook motif nuclear localized(AHL)gene BcAHL24-MF1 contributed to the natural variation in hypocotyl length.Functional variation of BcAHL24-MF1 was attributed to four haplotypes featuring four SNPs within the promoter region,of which Hap I accumulated more transcripts with shorter hypocotyls.Constitutive overexpression of BcAHL24-MF1 in B.campestris caused decreased hypocotyl length under light circumstances and even constant darkness,as BcAHL24-MF1 repressed the PIFmediated transcriptional activation of auxin biosynthesis genes BcYUC6-MF2 and BcYUC8-LF.Our research uncovered the important role of BcAHL24-MF1 in regulating light-triggered inhibition of hypocotyl elongation,therefore presenting a valuable genetic target for crop breeding.
文摘For genome mulUplication hepadnaviruses use the transcriptional machinery of the cell that is found within the nucleus. Thus the viral genome has to be transported through the cytoplasm and nuclear pore. The intracytosolic translocation is facilitated by the viral capsid that surrounds the genome and that interacts with cellular microtubules. The subsequent passage through the nuclear pore complexes （NPC） is mediated by the nuclear transport receptors importin α andβ. Importin α binds to the C-terminus of the capsid protein that comprises a nuclear localization signal （NLS）. The exposure of the NLS is regulated and depends upon genome maturation and/or phosphorylation of the capsid protein. As for other karyophilic cargos using this pathway importin α interacts with importin β that facilitates docking of the import complex to the NPC and the passage through the pore. Being a unique strategy, the import of the viral capsid is incomplete in that it becomes arrested inside the nuclear basket, which is a cage-like structure on the karyoplasmic face of the NPC. Presumably only this compartment provides the factors that are required for capsid disassembly and genome release that is restricted to those capsids comprising a mature viral DNA genome.
基金Supported by The National Natural Science Foundation of China,No.30772534Science and Technology Program Fund of Zhejiang Province,No.2006C33028the Huzhou Natural Science Foundation,No.2004SZX07-11
文摘Midkine(MK) is a heparin-binding growth factor with its gene first identified in embryonal carcinoma cells at early stages of retinoic acid-induced differentiation. MK is frequently and highly expressed in a variety of human carcinomas.Furthermore,the blood MK level is frequently elevated with advance of human carcinomas,decreased after surgical removal of the tumors.Thus,it is expected to become a promising marker for evaluating the progress of carcinomas. There is mounting evidence that MK plays a significant role in carcinogenesis-related activities,such as proliferation,migration,anti-apoptosis,mitogenesis,transforming,and angiogenesis.In addition,siRNA and anti-sense oligonucleotides for MK have yielded great effects in anti-tumor activities.Therefore,MK appears to be a potential candidate molecular target of therapy for human carcinomas.In this paper,we review MK targeting at nucleoli in different tumor cells and its role in carcinogenesis to deepen our understanding of the mechanism of MK involved in carcinogenesis.
基金This work was supported by the Climbing Program Granted by the Ministry of Science and Technology of China(95-special-10) and Tianjin Science and TechnologyDevelopment Project (No. 003119311).
文摘Objective: To investigate the functions of nM-CSF in malignant cells. Methods: recombinant M-CSF was targeted into cell nucleus by employing a eukaryotic expression plasmid vector pCMV/myc/nuc. The constructed plasmid was transfected into cells of EBV transformed lymphoblastoid cell line (LCL). RT-PCR, Western blot and immunofluorescent staining showed that recombinant M-CSF was localized into LCL cell nucleus. The transgenic cells showed elevated proliferation potential, enhanced resistance to apoptosis and increased ability of in vitro migration. Conclusion: Nucleus presenting M-CSF might act as a promoting factor in the processes of cell malignancy.
基金The Startup Fund of the Hundred Talents Program of the Chinese Academy of Science (20071010-141)National Natural Science Foundation of China(30870120)+1 种基金Open Research Fund Program of the State Key Laboratory of Virology of China (2007003,2009007)Hubei Province Natural Science Foundation of Innovation Groups Project (2008CDA013)
文摘Molecules can enter the nucleus by passive diffusion or active transport mechanisms, depending on their size. Small molecules up to size of 50-60 kDa or less than 10 nm in diameter can diffuse passively through the nuclear pore complex （NPC）, while most proteins are transported by energy driven transport mechanisms Active transport of viral proteins is mediated by nuclear localization signals （NLS）, which were first identified in Simian Virus 40 large T antigen and had subsequently been identified in a large number of viral they contain short stretches of lysine or arginine residues. These signals are recognized proteins. Usually by the importin super-family （importin α and β） proteins that mediate the transport across the nuclear envelope through Ran-GTP In contrast, only one class of the leucine-rich nuclear export signal （NES） on viral proteins is known at present. Chromosome region maintenance 1 （CRM1） protein mediates nuclear export of hundreds of viral proteins through the recognition of the leucine-rich NES.
文摘Viruses including baculoviruses are obligatory parasites, as their genomes do not encode all the proteins required for replication. Therefore, viruses have evolved to exploit the behavior and the physiology of their hosts and olden coevolved with their hosts over millions of years. Recent comparative analyses of complete genome sequences of baculoviruses revealed the patterns of gene acquisitions and losses that have occurred during baculovirus evolution. In addition, knowledge of virus genes has also provided understanding of the mechanism of baculovirus infection including replication, species-specific virulence and host range. The Bm8 gene of Bombyx mori nucleopolyhedrovirus （NPV） and its homologues are found only in group I NPV genomes. The Autographa californica NPV Ac 16 gene is a homologue of Bm8 and, encodes a viral structural protein. It has been shown that BmS/Ac 16 interacts with baculoviral and cellular proteins. BmS/Ac 16 interacts with baculoviral IE1 that is facilitated by coiled coil domains, and the interaction with IE1 is important for Bin8 function. Acl6 also forms a complex with viral FP25 and cellular actin and associates with membranes via palmitoylation. These data suggested that this gene family encodes a multifunctional protein that accomplishes specific needs of group I NPVs.
