Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism.However,under prolonged storage or high temperature stress,insulin tends to unfold and aggregate i...Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism.However,under prolonged storage or high temperature stress,insulin tends to unfold and aggregate into toxic amyloid fibrils,leading to loss of physiological function.Inspired by natural chaperones,a series of temperature-sensitive polycaprolactone-based micelles were designed to prevent insulin from deactivation.The micelles were fabricated through the self-assembly of amphiphilic copolymers of methoxy poly(ethylene glycol)-poly(4-diethylformamide caprolactone-co-caprolactone)(mPEG_(17)-P(DECL-co-CL)),which had a regular spherical morphology with particle sizes of about 100 nm.In addition,the lower critical solution temperature(LCST)of the micelles could be tuned to 9 and 29℃by changing the ratio of DECL to CL.Benefiting from the temperature-sensitivity of DECL segment,the binding ability of micelles to insulin could be modulated by changing the temperature.Above LCST,micelles effectively inhibited insulin aggregation and protected it from thermal inactivation due to the strong binding ability between the hydrophobic segment DECL and insulin.Below LCST,DECL segment returned to hydrophilic and bound weakly with insulin,leading to the release of insulin and assisting in its recovery of secondary structure.Thus,these temperature-sensitive micelles provided an effective strategy for insulin protection.展开更多
The Clp/Hsp100 family,part of the ATPase associated with various cellular activities(AAA+)superfamily,includes caseinolytic peptidase B(ClpB),a highly conserved protein found in bacteria,fungi,protozoa,and plants.Nota...The Clp/Hsp100 family,part of the ATPase associated with various cellular activities(AAA+)superfamily,includes caseinolytic peptidase B(ClpB),a highly conserved protein found in bacteria,fungi,protozoa,and plants.Notably,ClpB is present in all ESKAPE pathogens:Enterococcus faecium,Staphylococcus aureus,Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,and Enterobacter spp.ClpB plays a crucial role in reactivating and disaggregating proteins,enabling pathogens to survive under host-induced stress and conferring thermotolerance to bacterial cells.Infections caused by ESKAPE pathogens are particularly challenging due to their resistance to broad-spectrum antibiotics and biofilm formation,posing a significant global health threat as they are often multidrug-resistant,extensively drug-resistant,and pan-drug-resistant.Given its absence in human cells and its essential role in bacterial survival under stress,ClpB is a promising target for antimicrobial therapy.Targeting Hsp100 family proteins could lead to the development of novel antifungal and antiprotozoal treatments.This review explores the function of ClpB in the survival of ESKAPE pathogens and the protozoan Plasmodium falciparum.Relevant research findings were compiled using academic databases,and data analysis was performed using Clustal Omega Multiple Sequence Alignment and Boxshade tools.展开更多
Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis...Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis, and cell survival. These roles offer significant insight for understanding homeostasis of normal physiologic processes, and the pathophysiologic consequences of disruption of normal function. Because of the broad nature of chaperone action, S1R agonists and antagonists represent potential drug discovery goals for the pharmacotherapeutic treatment of a variety of disorders that result from dysfunctional proteins. The present study summarizes the S1R as a pharmacologic chaperone crucial for protein folding and cellular homeostasis. Through literature review and thermodynamic analysis, it explores how S1R stabilizes target proteins, influencing neuroprotection and potential drug therapies. The binding of chaperones to target proteins is thermodynamically favorable, offering insights into treating diseases linked to protein misfolding.展开更多
Objective To investigate the effect of ischemic preconditioning on chaperone hsp70 expression and protein aggregation in the CA1 neurons of rats, and to further explore its potential neuroprotective mechanism. Methods...Objective To investigate the effect of ischemic preconditioning on chaperone hsp70 expression and protein aggregation in the CA1 neurons of rats, and to further explore its potential neuroprotective mechanism. Methods Two-vesseloccluded transient global ischemia rat model was used. The rats were divided into sublethal 3-min ischemia group, lethal 10- min ischemia group and ischemic preconditioning group. Neuronal death in the CA1 region was observed by hematoxylineosin staining, and number of live neurons was assessed by cell counting under a light microscope. Immunochemistry and laser scanning confocal microscopy were used to observe the distribution of chaperone hsp70 in the CA1 neurons. Differential centrifuge was used to isolate cytosol, nucleus and protein aggregates fractions. Western blot was used to analyze the quantitative alterations of protein aggregates and inducible chaperone hsp70 in cellular fractions and in protein aggregates under different ischemic conditions. Results Histological examination showed that ischemic preconditioning significantly reduced delayed neuronal death in the hippocampus CA1 region （P 〈 0.01 vs 10-min ischemia group）. Sublethal ischemic preconditioning induced chaperone hsp70 expression in the CA1 neurons after 24 h reperfusion following 10-min ischemia. Induced-hsp70 combined with the abnormal proteins produced during the secondary lethal 10-min ischemia and inhibited the formation of cytotoxic protein aggregates（P〈0.01 vs 10-min ischemia group）.Conelusion Ischemic preconditioning induced chaperone hsp70 expression and inhibited protein aggregates formation in the CA1 neurons when suffered secondary lethal ischemia, which may protect neurons from death.展开更多
目的采用RNA干扰技术沉默CCS(copper chaperone for SOD1)基因,构建相关小干扰RNA(siRNA),探索出针对CCS的高效siRNA序列。方法合成用于人脐静脉内皮细胞(HUVEC)细胞中沉默CCS基因的siRNA。应用脂质体转染的方法在HUVEC细胞中对CCS基因...目的采用RNA干扰技术沉默CCS(copper chaperone for SOD1)基因,构建相关小干扰RNA(siRNA),探索出针对CCS的高效siRNA序列。方法合成用于人脐静脉内皮细胞(HUVEC)细胞中沉默CCS基因的siRNA。应用脂质体转染的方法在HUVEC细胞中对CCS基因进行RNA沉默。蛋白免疫印迹Western blotting检测沉默前后CCS蛋白表达变化的情况,甲基四唑蓝法MTT检测转染前后细胞活力。最后用单因素方差分析对数据进行统计学分析,以确定有效的siRNA序列。结果转染前后细胞形态无肉眼可见变化,转染后细胞活力分别为98.5%和98.8%。CCS蛋白沉默率分别为63.7%和61.4%。结论采用siCCS-2和siCCS-3序列转染条件对HUVEC细胞活力损伤小,CCS沉默效率高,实验条件稳定,重复性好。为我们继续研究沉默CCS后抑制血管内皮细胞的生长增殖、血管形成提供了稳定的实验基础。展开更多
Cytosolic chaperonin CCT (also known as TRiC) is a hetero-oligomeric cage-like molecular chaperone that assists in protein folding by ATPase cycle-dependent conformational changes. However, role of the nucleo-tide bin...Cytosolic chaperonin CCT (also known as TRiC) is a hetero-oligomeric cage-like molecular chaperone that assists in protein folding by ATPase cycle-dependent conformational changes. However, role of the nucleo-tide binding and hydrolysis in CCT-assisted protein folding is still poorly understood. We purified CCT by using ATP-Sepharose and other columns, and found that CCT possesses ability to hydrolyze GTP, with an activity level very similar to the ATPase activity. CCT was more resistant to proteinase K treatment in the presence of GTP or ATP. These results suggest that the GTPase activity of CCT may play a role in chaperone-assisted protein folding.展开更多
One of the most common lesions present in the spermatozoa of human infertility patients is an idiopathic failure of sperm-egg recognition. Although this unique cellular interaction can now be readily by-passed by assi...One of the most common lesions present in the spermatozoa of human infertility patients is an idiopathic failure of sperm-egg recognition. Although this unique cellular interaction can now be readily by-passed by assisted reproductive strategies such as intracytoplasmic sperm injection （ICSI）, recent large-scale epidemiological studies have encouraged the cautious use of this technology and highlighted the need for further research into the mechanisms responsible for defective sperm-egg recognition. Previous work in this field has established that the sperm domains responsible for oocyte interaction are formed during spermatogenesis prior to being dynamically modified during epididymal maturation and capacitation in female reproductive tract. While the factors responsible for the regulation of these sequential maturational events are undoubtedly complex, emerging research has identified the molecular chaperone, heat shock protein A2 （HSPA2）, as a key regulator of these events in human spermatozoa. HSPA2 is a testis-enriched member of the 70 kDa heat shock protein family that promotes the folding, transport, and assembly of protein complexes and has been positively correlated with in vitro fertilization （IVF） success. Furthermore, reduced expression of HSPA2 from the human sperm proteome leads to an impaired capacity for cumulus matrix dispersal, sperm-egg recognition and fertilization following both IVF and ICSI. In this review, we consider the evidence supporting the role of HSPA2 in sperm function and explore the potential mechanisms by which it is depleted in the spermatozoa of infertile patients. Such information offers novel insights into the molecular mechanisms governing sperm function.展开更多
The hepatitis C virus(HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases includ...The hepatitis C virus(HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases including cirrhosis and hepatocellular carcinoma. HCV is the most common indication for liver transplantation in patients with cirrhosis worldwide. HCV is an enveloped RNA virus classified in the genus Hepacivirus in the Flaviviridae family. The HCV viral life cycle in a cell can be divided into six phases:(1) binding and internalization;(2) cytoplasmic release and uncoating;(3) viral polyprotein translation and processing;(4) RNA genome replication;(5) encapsidation(packaging) and assembly; and(6) virus morphogenesis(maturation) and secretion. Many host factors are involved in the HCV life cycle. Chaperones are an important group of host cytoprotective molecules that coordinate numerous cellular processes including protein folding, multimeric protein assembly, protein trafficking, and protein degradation. All phases of the viral life cycle require chaperone activity and the interaction of viral proteins with chaperones. This review will present our current knowledge and understanding of the role of chaperones in the HCV life cycle. Analysis of chaperones in HCV infection will provide further insights into viral/host interactions and potential therapeutic targets for both HCV and other viruses.展开更多
Chromatin structure is important for controlling gene expression, but mechanisms underlying chromatin remodel- ing are not fully understood. Here we report that an FKBP （FK506 binding protein） type immunophilin, AtF...Chromatin structure is important for controlling gene expression, but mechanisms underlying chromatin remodel- ing are not fully understood. Here we report that an FKBP （FK506 binding protein） type immunophilin, AtFKBP53, possesses histone chaperone activity and is required for repressing ribosomal gene expression in Arabidopsis. The At- FKBP53 protein is a multidomain FKBP with a typical peptidylprolyl isomerase （PPIase） domain and several highly charged domains. Using nucleosome assembly assays, we showed that AtFKBP53 has histone chaperone activity and the charged acidic domains are sufficient for the activity. We show that AtFKBP53 interacts with histone H3 through the acidic domains, whereas the PPIase domain is dispensable for histone chaperone activity or histone binding. Ri- bosomal RNA gene （18S rDNA） is overexpressed when AtFKBP53 activity is reduced or eliminated in Arabidopsis plants. Chromatin immunoprecipitation assay showed that AtFKBP53 is associated with the 18S rDNA gene chro- matin, implicating that AtFKBP53 represses rRNA genes at the chromatin level. This study identifies a new histone chaperone in plants that functions in chromatin remodeling and regulation of transcription.展开更多
Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compar...Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.展开更多
Objective:To clone,express and purify a putative parasitic nematode specific protein of Setaria digitata(S.digitata),filarial nematode that infects livestock and cause significant economic losses in Far East and Asia ...Objective:To clone,express and purify a putative parasitic nematode specific protein of Setaria digitata(S.digitata),filarial nematode that infects livestock and cause significant economic losses in Far East and Asia to he used for structural and functional analyses.Methods:To characterize uneharacterized gene of,S.digitata(SDUG),the herterologous expression of SDUG was carried out in the pET[cloned into pET45b(+)]expression system initially and co-expression of SDUC using chaperoiie plasmids pG-KJE8,pGro 7,pKJE7,pG-Tf2 and pTf16 containing chapcrone proteins of dnaK-dnaJ-grpE-groES-gro-E,groES-groEL,dnaK-dnaJ-grpE,groES-groEL-tig,and tig respectively,was carried out subsequently.Results:Expression of SDUG was seen when Escherichia coli strain BI.21(DE3)is used,while concentrating protein largely into the insoluble fraction.The co-expression of SDUG using chaperoiie plasmid mediated system indicated a significant increase of the protein in the soluble fraction.Of the chaperon plasniid sets,the highest amount of recombinant SDUP in the soluble fraction was seen when pGro7 was used in the presence of2 mg/mL L-arabinosc and 0.6M IPTG concentration in the culture medium and for 3 h of incubation at the temperature of 28℃.Recombinant SDUG was purified both from soluble and insoluble fractions using Ni affinity chromatography.SDS-PAGE and western blot analyses of these proteins revealed a single band having expected size of^24 kDa.Conclusions:SDUG seems to be more aggregate-prone and hydrophobic in nature and such protein can make soluble by correct selecting the inducer concentrations and induction temperature and its duration.展开更多
Hypoxic-ischemic encephalopathy（HIE） is a disease that occurs when the brain is subjected to hypoxia,resulting in neuronal death and neurological deficits,with a poor prognosis.The mechanisms underlying hypoxic-isch...Hypoxic-ischemic encephalopathy（HIE） is a disease that occurs when the brain is subjected to hypoxia,resulting in neuronal death and neurological deficits,with a poor prognosis.The mechanisms underlying hypoxic-ischemic brain injury include excitatory amino acid release,cellular proteolysis,reactive oxygen species generation,nitric oxide synthesis,and inflammation.The molecular and cellular changes in HIE include protein misfolding,aggregation,and destruction of organelles.The apoptotic pathways activated by ischemia and hypoxia include the mitochondrial pathway,the extrinsic Fas receptor pathway,and the endoplasmic reticulum stress-induced pathway.Numerous treatments for hypoxic-ischemic brain injury caused by HIE have been developed over the last half century.Hypothermia,xenon gas treatment,the use of melatonin and erythropoietin,and hypoxic-ischemic preconditioning have proven effective in HIE patients.Molecular chaperones are proteins ubiquitously present in both prokaryotes and eukaryotes.A large number of molecular chaperones are induced after brain ischemia and hypoxia,among which the heat shock proteins are the most important.Heat shock proteins not only maintain protein homeostasis; they also exert anti-apoptotic effects.Heat shock proteins maintain protein homeostasis by helping to transport proteins to their target destinations,assisting in the proper folding of newly synthesized polypeptides,regulating the degradation of misfolded proteins,inhibiting the aggregation of proteins,and by controlling the refolding of misfolded proteins.In addition,heat shock proteins exert anti-apoptotic effects by interacting with various signaling pathways to block the activation of downstream effectors in numerous apoptotic pathways,including the intrinsic pathway,the endoplasmic reticulum-stress mediated pathway and the extrinsic Fas receptor pathway.Molecular chaperones play a key role in neuroprotection in HIE.In this review,we provide an overview of the mechanisms of HIE and discuss the various treatment strategies.Given their critical role in the disease,molecular chaperones are promising therapeutic targets for HIE.展开更多
Stroke-induced immunosuppression is a process that leads to peripheral suppression of the immune system after a stroke and belongs to the central nervous system injury-induced immunosuppressive syndrome.Stroke-induced...Stroke-induced immunosuppression is a process that leads to peripheral suppression of the immune system after a stroke and belongs to the central nervous system injury-induced immunosuppressive syndrome.Stroke-induced immunosuppression leads to increased susceptibility to post-stroke infections,such as urinary tract infections and stroke-associated pneumonia,worsening prognosis.Molecular chaperones are a large class of proteins that are able to maintain proteostasis by directing the folding of nascent polypeptide chains,refolding misfolded proteins,and targeting misfolded proteins for degradation.Various molecular chaperones have been shown to play roles in stroke-induced immunosuppression by modulating the activity of other molecular chaperones,cochaperones,and their associated pathways.This review summarizes the role of molecular chaperones in stroke-induced immunosuppression and discusses new approaches to restore host immune defense after stroke.展开更多
Chaperone-mediated autophagy （CMA）, one of the main pathways of lysosomal proteolysis, is characterized by the selective targeting and direct translocation into the lysosomal lumen of substrate proteins containing a...Chaperone-mediated autophagy （CMA）, one of the main pathways of lysosomal proteolysis, is characterized by the selective targeting and direct translocation into the lysosomal lumen of substrate proteins containing a targeting motif biochemically related to the pentapeptide KFERQ. Along with the other two lysosomal pathways, macro- and micro-autophagy, CMA is essential for maintaining cellular homeostasis and survival by selectively degrading misfolded, oxidized, or damaged cytosolic proteins. CMA plays an important role in pathologies such as cancer, kidney disorders, and neurodegenerative diseases. Neurons are post-mitotic and highly susceptible to dysfunction of cellular quality-control systems. Maintaining a balance between protein synthesis and degradation is critical for neuronal functions and homeostasis. Recent studies have revealed several new mechanisms by which CMA protects neurons through regulating factors critical for their viability and homeostasis. In the current review, we summarize recent advances in the understanding of the regulation and physiology of CMA with a specific focus on its possible roles in neuroprotection.展开更多
RNAs are functionally diverse macromolecules whose proper functions rely strictly upon their correct tertiary structures. However, because of their high structural flexibility, correct folding of RNAs is challenging a...RNAs are functionally diverse macromolecules whose proper functions rely strictly upon their correct tertiary structures. However, because of their high structural flexibility, correct folding of RNAs is challenging and slow. Therefore, cells and viruses encode a variety of RNA remodeling proteins, including helicases and RNA chaperones. In RNA viruses, these proteins are believed to play pivotal roles in all the processes involving viral RNAs during the life cycle. RNA helicases have been studied extensively for decades, whereas RNA chaperones, particularly virus-encoded RNA chaperones, are often overlooked. This review describes the activities of RNA chaperones encoded by RNA viruses, particularly the ones identified and characterized in recent years, and the functions of these proteins in different steps of viral life cycles, and presents an overview of this unique group of proteins.展开更多
Pseudoalteromonas sp. SM9913 is a phychrotmphic bacterium isolated from the deep-sea sediment. The genes encoding chaperones DnaJ and DnaK of P. sp. SM9913 were cloned by normal PCR and TAIL - PCR （GenBank accession ...Pseudoalteromonas sp. SM9913 is a phychrotmphic bacterium isolated from the deep-sea sediment. The genes encoding chaperones DnaJ and DnaK of P. sp. SM9913 were cloned by normal PCR and TAIL - PCR （GenBank accession Nos DQ640312, DQ504163 ）. The chaperones DnaJ and DnaK from the strain SM9913 contain such conserved domains as those of many other bacteria, and show some cold-adapted characteristics in their structures when compared with those from psychro-, meso-and themophilic bacteria. It is indicated that chaperones DnaJ and DnaK of P. sp. SM9913 may be adapted to low temperature in deep-sea and function well in assisting folding, assembling and translocation of proteins at low temperature. This research lays a foundation for the further study on the cold-adapted mechanism of chaperones DnaJ and DnaK of cold-adapted microorganisms.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52273009 and 21674037).
文摘Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism.However,under prolonged storage or high temperature stress,insulin tends to unfold and aggregate into toxic amyloid fibrils,leading to loss of physiological function.Inspired by natural chaperones,a series of temperature-sensitive polycaprolactone-based micelles were designed to prevent insulin from deactivation.The micelles were fabricated through the self-assembly of amphiphilic copolymers of methoxy poly(ethylene glycol)-poly(4-diethylformamide caprolactone-co-caprolactone)(mPEG_(17)-P(DECL-co-CL)),which had a regular spherical morphology with particle sizes of about 100 nm.In addition,the lower critical solution temperature(LCST)of the micelles could be tuned to 9 and 29℃by changing the ratio of DECL to CL.Benefiting from the temperature-sensitivity of DECL segment,the binding ability of micelles to insulin could be modulated by changing the temperature.Above LCST,micelles effectively inhibited insulin aggregation and protected it from thermal inactivation due to the strong binding ability between the hydrophobic segment DECL and insulin.Below LCST,DECL segment returned to hydrophilic and bound weakly with insulin,leading to the release of insulin and assisting in its recovery of secondary structure.Thus,these temperature-sensitive micelles provided an effective strategy for insulin protection.
文摘The Clp/Hsp100 family,part of the ATPase associated with various cellular activities(AAA+)superfamily,includes caseinolytic peptidase B(ClpB),a highly conserved protein found in bacteria,fungi,protozoa,and plants.Notably,ClpB is present in all ESKAPE pathogens:Enterococcus faecium,Staphylococcus aureus,Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,and Enterobacter spp.ClpB plays a crucial role in reactivating and disaggregating proteins,enabling pathogens to survive under host-induced stress and conferring thermotolerance to bacterial cells.Infections caused by ESKAPE pathogens are particularly challenging due to their resistance to broad-spectrum antibiotics and biofilm formation,posing a significant global health threat as they are often multidrug-resistant,extensively drug-resistant,and pan-drug-resistant.Given its absence in human cells and its essential role in bacterial survival under stress,ClpB is a promising target for antimicrobial therapy.Targeting Hsp100 family proteins could lead to the development of novel antifungal and antiprotozoal treatments.This review explores the function of ClpB in the survival of ESKAPE pathogens and the protozoan Plasmodium falciparum.Relevant research findings were compiled using academic databases,and data analysis was performed using Clustal Omega Multiple Sequence Alignment and Boxshade tools.
文摘Initially thought to be an opioid receptor subtype, Sigma-1 receptors (S1R) are now known to be unique proteins that have chaperone-like properties. As such, they play critical roles in cellular signaling, homeostasis, and cell survival. These roles offer significant insight for understanding homeostasis of normal physiologic processes, and the pathophysiologic consequences of disruption of normal function. Because of the broad nature of chaperone action, S1R agonists and antagonists represent potential drug discovery goals for the pharmacotherapeutic treatment of a variety of disorders that result from dysfunctional proteins. The present study summarizes the S1R as a pharmacologic chaperone crucial for protein folding and cellular homeostasis. Through literature review and thermodynamic analysis, it explores how S1R stabilizes target proteins, influencing neuroprotection and potential drug therapies. The binding of chaperones to target proteins is thermodynamically favorable, offering insights into treating diseases linked to protein misfolding.
基金the grants from the Department of Science and Technology of Jilin Province, China (No. 20070721)the Bureau of Science and Technology of Changchun, Jilin Province, China (No. 2007129).
文摘Objective To investigate the effect of ischemic preconditioning on chaperone hsp70 expression and protein aggregation in the CA1 neurons of rats, and to further explore its potential neuroprotective mechanism. Methods Two-vesseloccluded transient global ischemia rat model was used. The rats were divided into sublethal 3-min ischemia group, lethal 10- min ischemia group and ischemic preconditioning group. Neuronal death in the CA1 region was observed by hematoxylineosin staining, and number of live neurons was assessed by cell counting under a light microscope. Immunochemistry and laser scanning confocal microscopy were used to observe the distribution of chaperone hsp70 in the CA1 neurons. Differential centrifuge was used to isolate cytosol, nucleus and protein aggregates fractions. Western blot was used to analyze the quantitative alterations of protein aggregates and inducible chaperone hsp70 in cellular fractions and in protein aggregates under different ischemic conditions. Results Histological examination showed that ischemic preconditioning significantly reduced delayed neuronal death in the hippocampus CA1 region （P 〈 0.01 vs 10-min ischemia group）. Sublethal ischemic preconditioning induced chaperone hsp70 expression in the CA1 neurons after 24 h reperfusion following 10-min ischemia. Induced-hsp70 combined with the abnormal proteins produced during the secondary lethal 10-min ischemia and inhibited the formation of cytotoxic protein aggregates（P〈0.01 vs 10-min ischemia group）.Conelusion Ischemic preconditioning induced chaperone hsp70 expression and inhibited protein aggregates formation in the CA1 neurons when suffered secondary lethal ischemia, which may protect neurons from death.
文摘目的采用RNA干扰技术沉默CCS(copper chaperone for SOD1)基因,构建相关小干扰RNA(siRNA),探索出针对CCS的高效siRNA序列。方法合成用于人脐静脉内皮细胞(HUVEC)细胞中沉默CCS基因的siRNA。应用脂质体转染的方法在HUVEC细胞中对CCS基因进行RNA沉默。蛋白免疫印迹Western blotting检测沉默前后CCS蛋白表达变化的情况,甲基四唑蓝法MTT检测转染前后细胞活力。最后用单因素方差分析对数据进行统计学分析,以确定有效的siRNA序列。结果转染前后细胞形态无肉眼可见变化,转染后细胞活力分别为98.5%和98.8%。CCS蛋白沉默率分别为63.7%和61.4%。结论采用siCCS-2和siCCS-3序列转染条件对HUVEC细胞活力损伤小,CCS沉默效率高,实验条件稳定,重复性好。为我们继续研究沉默CCS后抑制血管内皮细胞的生长增殖、血管形成提供了稳定的实验基础。
文摘Cytosolic chaperonin CCT (also known as TRiC) is a hetero-oligomeric cage-like molecular chaperone that assists in protein folding by ATPase cycle-dependent conformational changes. However, role of the nucleo-tide binding and hydrolysis in CCT-assisted protein folding is still poorly understood. We purified CCT by using ATP-Sepharose and other columns, and found that CCT possesses ability to hydrolyze GTP, with an activity level very similar to the ATPase activity. CCT was more resistant to proteinase K treatment in the presence of GTP or ATP. These results suggest that the GTPase activity of CCT may play a role in chaperone-assisted protein folding.
文摘One of the most common lesions present in the spermatozoa of human infertility patients is an idiopathic failure of sperm-egg recognition. Although this unique cellular interaction can now be readily by-passed by assisted reproductive strategies such as intracytoplasmic sperm injection （ICSI）, recent large-scale epidemiological studies have encouraged the cautious use of this technology and highlighted the need for further research into the mechanisms responsible for defective sperm-egg recognition. Previous work in this field has established that the sperm domains responsible for oocyte interaction are formed during spermatogenesis prior to being dynamically modified during epididymal maturation and capacitation in female reproductive tract. While the factors responsible for the regulation of these sequential maturational events are undoubtedly complex, emerging research has identified the molecular chaperone, heat shock protein A2 （HSPA2）, as a key regulator of these events in human spermatozoa. HSPA2 is a testis-enriched member of the 70 kDa heat shock protein family that promotes the folding, transport, and assembly of protein complexes and has been positively correlated with in vitro fertilization （IVF） success. Furthermore, reduced expression of HSPA2 from the human sperm proteome leads to an impaired capacity for cumulus matrix dispersal, sperm-egg recognition and fertilization following both IVF and ICSI. In this review, we consider the evidence supporting the role of HSPA2 in sperm function and explore the potential mechanisms by which it is depleted in the spermatozoa of infertile patients. Such information offers novel insights into the molecular mechanisms governing sperm function.
文摘The hepatitis C virus(HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases including cirrhosis and hepatocellular carcinoma. HCV is the most common indication for liver transplantation in patients with cirrhosis worldwide. HCV is an enveloped RNA virus classified in the genus Hepacivirus in the Flaviviridae family. The HCV viral life cycle in a cell can be divided into six phases:(1) binding and internalization;(2) cytoplasmic release and uncoating;(3) viral polyprotein translation and processing;(4) RNA genome replication;(5) encapsidation(packaging) and assembly; and(6) virus morphogenesis(maturation) and secretion. Many host factors are involved in the HCV life cycle. Chaperones are an important group of host cytoprotective molecules that coordinate numerous cellular processes including protein folding, multimeric protein assembly, protein trafficking, and protein degradation. All phases of the viral life cycle require chaperone activity and the interaction of viral proteins with chaperones. This review will present our current knowledge and understanding of the role of chaperones in the HCV life cycle. Analysis of chaperones in HCV infection will provide further insights into viral/host interactions and potential therapeutic targets for both HCV and other viruses.
基金We thank Veder Garcia （University of California, Berkeley, USA） for critically reading the paper, Zengyong He for providing the AtFKBP53：：GUS transgenic line and Masami Horikoshi （The University of Tokyo, Japan） for the pET-6His-SpFkbp39P plasmid. This work was supported by grants from the National Science Foundation and US Department of Energy （toSL）.
文摘Chromatin structure is important for controlling gene expression, but mechanisms underlying chromatin remodel- ing are not fully understood. Here we report that an FKBP （FK506 binding protein） type immunophilin, AtFKBP53, possesses histone chaperone activity and is required for repressing ribosomal gene expression in Arabidopsis. The At- FKBP53 protein is a multidomain FKBP with a typical peptidylprolyl isomerase （PPIase） domain and several highly charged domains. Using nucleosome assembly assays, we showed that AtFKBP53 has histone chaperone activity and the charged acidic domains are sufficient for the activity. We show that AtFKBP53 interacts with histone H3 through the acidic domains, whereas the PPIase domain is dispensable for histone chaperone activity or histone binding. Ri- bosomal RNA gene （18S rDNA） is overexpressed when AtFKBP53 activity is reduced or eliminated in Arabidopsis plants. Chromatin immunoprecipitation assay showed that AtFKBP53 is associated with the 18S rDNA gene chro- matin, implicating that AtFKBP53 represses rRNA genes at the chromatin level. This study identifies a new histone chaperone in plants that functions in chromatin remodeling and regulation of transcription.
基金the National Natural Science Foundation in China(No.20705028)the Foundation of Key Laboratory of Modem Separation Science in Shaanxi Province(No.05JS61).
文摘Artificial molecular chaperone （AMC） and ion exchange chromatography （IEC） were integrated, thus a new refolding method, artificial molecular chaperone-ion exchange chromatography （AMC-IEC） was developed. Compared with AMC and IEC, the activity recovery of lysozyme obtained by AMC-IEC was much higher in the investigated range of initial protein concentrations, and the results show that AMC-IEC is very efficient for protein refolding at high concentrations. When the initial concentration of lysozyme is 180 mg/mL, its activity recovery obtained by AMC-IEC is still as high as 76.6%, while the activity recoveries obtained by AMC and IEC are 45.6% and 42.4%, respectively.
基金supported by a grant(SIDA/2006/BT/04) awarded by National Science Foundation of Sri Lanka
文摘Objective:To clone,express and purify a putative parasitic nematode specific protein of Setaria digitata(S.digitata),filarial nematode that infects livestock and cause significant economic losses in Far East and Asia to he used for structural and functional analyses.Methods:To characterize uneharacterized gene of,S.digitata(SDUG),the herterologous expression of SDUG was carried out in the pET[cloned into pET45b(+)]expression system initially and co-expression of SDUC using chaperoiie plasmids pG-KJE8,pGro 7,pKJE7,pG-Tf2 and pTf16 containing chapcrone proteins of dnaK-dnaJ-grpE-groES-gro-E,groES-groEL,dnaK-dnaJ-grpE,groES-groEL-tig,and tig respectively,was carried out subsequently.Results:Expression of SDUG was seen when Escherichia coli strain BI.21(DE3)is used,while concentrating protein largely into the insoluble fraction.The co-expression of SDUG using chaperoiie plasmid mediated system indicated a significant increase of the protein in the soluble fraction.Of the chaperon plasniid sets,the highest amount of recombinant SDUP in the soluble fraction was seen when pGro7 was used in the presence of2 mg/mL L-arabinosc and 0.6M IPTG concentration in the culture medium and for 3 h of incubation at the temperature of 28℃.Recombinant SDUG was purified both from soluble and insoluble fractions using Ni affinity chromatography.SDS-PAGE and western blot analyses of these proteins revealed a single band having expected size of^24 kDa.Conclusions:SDUG seems to be more aggregate-prone and hydrophobic in nature and such protein can make soluble by correct selecting the inducer concentrations and induction temperature and its duration.
文摘Hypoxic-ischemic encephalopathy（HIE） is a disease that occurs when the brain is subjected to hypoxia,resulting in neuronal death and neurological deficits,with a poor prognosis.The mechanisms underlying hypoxic-ischemic brain injury include excitatory amino acid release,cellular proteolysis,reactive oxygen species generation,nitric oxide synthesis,and inflammation.The molecular and cellular changes in HIE include protein misfolding,aggregation,and destruction of organelles.The apoptotic pathways activated by ischemia and hypoxia include the mitochondrial pathway,the extrinsic Fas receptor pathway,and the endoplasmic reticulum stress-induced pathway.Numerous treatments for hypoxic-ischemic brain injury caused by HIE have been developed over the last half century.Hypothermia,xenon gas treatment,the use of melatonin and erythropoietin,and hypoxic-ischemic preconditioning have proven effective in HIE patients.Molecular chaperones are proteins ubiquitously present in both prokaryotes and eukaryotes.A large number of molecular chaperones are induced after brain ischemia and hypoxia,among which the heat shock proteins are the most important.Heat shock proteins not only maintain protein homeostasis; they also exert anti-apoptotic effects.Heat shock proteins maintain protein homeostasis by helping to transport proteins to their target destinations,assisting in the proper folding of newly synthesized polypeptides,regulating the degradation of misfolded proteins,inhibiting the aggregation of proteins,and by controlling the refolding of misfolded proteins.In addition,heat shock proteins exert anti-apoptotic effects by interacting with various signaling pathways to block the activation of downstream effectors in numerous apoptotic pathways,including the intrinsic pathway,the endoplasmic reticulum-stress mediated pathway and the extrinsic Fas receptor pathway.Molecular chaperones play a key role in neuroprotection in HIE.In this review,we provide an overview of the mechanisms of HIE and discuss the various treatment strategies.Given their critical role in the disease,molecular chaperones are promising therapeutic targets for HIE.
基金the National Natural Science Foundation of China,Nos.82172147(to YL),81571880(to YL),81373147(to YL),30901555(to JZ),30972870(to YL)the Natural Science Foundation of Hunan Province,Nos.2021JJ30900,2016JJ2157(both to YL)。
文摘Stroke-induced immunosuppression is a process that leads to peripheral suppression of the immune system after a stroke and belongs to the central nervous system injury-induced immunosuppressive syndrome.Stroke-induced immunosuppression leads to increased susceptibility to post-stroke infections,such as urinary tract infections and stroke-associated pneumonia,worsening prognosis.Molecular chaperones are a large class of proteins that are able to maintain proteostasis by directing the folding of nascent polypeptide chains,refolding misfolded proteins,and targeting misfolded proteins for degradation.Various molecular chaperones have been shown to play roles in stroke-induced immunosuppression by modulating the activity of other molecular chaperones,cochaperones,and their associated pathways.This review summarizes the role of molecular chaperones in stroke-induced immunosuppression and discusses new approaches to restore host immune defense after stroke.
基金partially supported by the FMMU Research FoundationNational Basic Research Development Program of China (2011CB510000)the National Natural Science Foundation of China (31371400)
文摘Chaperone-mediated autophagy （CMA）, one of the main pathways of lysosomal proteolysis, is characterized by the selective targeting and direct translocation into the lysosomal lumen of substrate proteins containing a targeting motif biochemically related to the pentapeptide KFERQ. Along with the other two lysosomal pathways, macro- and micro-autophagy, CMA is essential for maintaining cellular homeostasis and survival by selectively degrading misfolded, oxidized, or damaged cytosolic proteins. CMA plays an important role in pathologies such as cancer, kidney disorders, and neurodegenerative diseases. Neurons are post-mitotic and highly susceptible to dysfunction of cellular quality-control systems. Maintaining a balance between protein synthesis and degradation is critical for neuronal functions and homeostasis. Recent studies have revealed several new mechanisms by which CMA protects neurons through regulating factors critical for their viability and homeostasis. In the current review, we summarize recent advances in the understanding of the regulation and physiology of CMA with a specific focus on its possible roles in neuroprotection.
基金supported by the National Basic Research Program of China (973 Program, 2014CB542603 to XZ)the National High-tech R&D Program of China (863 Program, 2015AA020939 to XZ)+2 种基金the National Natural Science Foundation of China grants No. 31400141 (to JY) and No. 31270190 (to XZ)the Natural Science Foundation of Hubei grant No. 2015CFB351 (to JY)the National Science Foundation for Post-doctoral Scientists of China grant No. 2015M572190 (to JY)
文摘RNAs are functionally diverse macromolecules whose proper functions rely strictly upon their correct tertiary structures. However, because of their high structural flexibility, correct folding of RNAs is challenging and slow. Therefore, cells and viruses encode a variety of RNA remodeling proteins, including helicases and RNA chaperones. In RNA viruses, these proteins are believed to play pivotal roles in all the processes involving viral RNAs during the life cycle. RNA helicases have been studied extensively for decades, whereas RNA chaperones, particularly virus-encoded RNA chaperones, are often overlooked. This review describes the activities of RNA chaperones encoded by RNA viruses, particularly the ones identified and characterized in recent years, and the functions of these proteins in different steps of viral life cycles, and presents an overview of this unique group of proteins.
基金The work was supported by the Hi-Tech Research and Development Program of China under contract Nos 2006AA09Z414 and 2007AA091903；the China Ocean Mineral Resources R ＆ D Association under contract No. DYXM - 115 - 02 - 2 - 6；the National Natural Science Foundation of China under contract No. Z2004D02；the Natural Science Foundation of Shandong Province of China under contract No. Z2004D02；the Foundation for Young Excellent Scientists in Shandong Province of China under contract No. 2006BS02002；the Program for New Century Excellent Talents in University under contract No. NCET - 06 - 0578.
文摘Pseudoalteromonas sp. SM9913 is a phychrotmphic bacterium isolated from the deep-sea sediment. The genes encoding chaperones DnaJ and DnaK of P. sp. SM9913 were cloned by normal PCR and TAIL - PCR （GenBank accession Nos DQ640312, DQ504163 ）. The chaperones DnaJ and DnaK from the strain SM9913 contain such conserved domains as those of many other bacteria, and show some cold-adapted characteristics in their structures when compared with those from psychro-, meso-and themophilic bacteria. It is indicated that chaperones DnaJ and DnaK of P. sp. SM9913 may be adapted to low temperature in deep-sea and function well in assisting folding, assembling and translocation of proteins at low temperature. This research lays a foundation for the further study on the cold-adapted mechanism of chaperones DnaJ and DnaK of cold-adapted microorganisms.
