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
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
Heat shock proteins are a family of molecular chaperones that are involved in many aspects of protein homeostasis. In the present study, a full-length cDNA, encoding the constitutively expressed 70-kDa heat shock cogn...Heat shock proteins are a family of molecular chaperones that are involved in many aspects of protein homeostasis. In the present study, a full-length cDNA, encoding the constitutively expressed 70-kDa heat shock cognate protein （Hsc70）, was isolated from swordtail fish （Xiphophorus helleri） and designated as XheHsc70. The Xhehsc70 cDNA was 2 104 bp long with an open reading frame of 1 941 bp, and it encoded a protein of 646 amino acids with a theoretical molecular weight of 70.77 kDa and an isoelectric point of 5.04. The deduced amino acid sequence shared 94.1%-98.6% identities with the Hsc70s from a number of other fish species. Tissue distribution results show that the Xhehsc70 mRNA was expressed in brain, heart, head kidney, kidney, spleen, liver, muscle, gill, and peripheral blood. After immunization with formalin-killed Vibrio alginolyticus cells there was a significant increase in the XhehscT0 mRNA transcriptional level in the head kidney of the vaccinated fish compared with in the control at 6, 12, 24, and 48 h as shown by quantitative real time RT-PCR. Based on an analysis of the amino acid sequence of XheHsc70, its phylogeny, and Xhehsc70 mRNA expression, XheHsc70 was identified as a member of the cytoplasmic Hsc70 （constitutive） subfamily of the Hsp70 family of heat shock proteins, suggesting that it may play a role in the immune response. The Xhehsc70 cDNA sequence reported in this study was submitted to GenBank under the accession number JF739182.展开更多
The research progress in molecular chaperones, unfolded protein response （UPR） and ER-associated degradation （ERAD） involved in the protein quality control was summarized in this paper, and then the existing probl...The research progress in molecular chaperones, unfolded protein response （UPR） and ER-associated degradation （ERAD） involved in the protein quality control was summarized in this paper, and then the existing problems and the future devel- opment prospect were also discussed. It was pointed out that the life process of protein experienced four stages including synthesizing, folding, assembling and degradation, while each stage required strict quality control. In endoplasmic reticulum （ER）, a variety of proteins had been synthesized, folded and modified to form func- tional proteins with certain conformation. When the folding was blocked in ER, the unfolded proteins would aggregate and induce the UPR, which up-regulated the level of modification enzymes folded by a series of molecular chaperones and proteins to help them accomplish folding and assembling. If these proteins were still folded incorrectly, they would enter into ERAD for being degraded.展开更多
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.
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Supported by the National Key Technology R&D Program of China(No.2012BAD25B02)the Natural Science Foundation of Guangdong Province of China (Nos.7004728,06024033)
文摘Heat shock proteins are a family of molecular chaperones that are involved in many aspects of protein homeostasis. In the present study, a full-length cDNA, encoding the constitutively expressed 70-kDa heat shock cognate protein （Hsc70）, was isolated from swordtail fish （Xiphophorus helleri） and designated as XheHsc70. The Xhehsc70 cDNA was 2 104 bp long with an open reading frame of 1 941 bp, and it encoded a protein of 646 amino acids with a theoretical molecular weight of 70.77 kDa and an isoelectric point of 5.04. The deduced amino acid sequence shared 94.1%-98.6% identities with the Hsc70s from a number of other fish species. Tissue distribution results show that the Xhehsc70 mRNA was expressed in brain, heart, head kidney, kidney, spleen, liver, muscle, gill, and peripheral blood. After immunization with formalin-killed Vibrio alginolyticus cells there was a significant increase in the XhehscT0 mRNA transcriptional level in the head kidney of the vaccinated fish compared with in the control at 6, 12, 24, and 48 h as shown by quantitative real time RT-PCR. Based on an analysis of the amino acid sequence of XheHsc70, its phylogeny, and Xhehsc70 mRNA expression, XheHsc70 was identified as a member of the cytoplasmic Hsc70 （constitutive） subfamily of the Hsp70 family of heat shock proteins, suggesting that it may play a role in the immune response. The Xhehsc70 cDNA sequence reported in this study was submitted to GenBank under the accession number JF739182.
基金Supported by National Natural Science Foundation of China (Grant No.30840002,30970223)Science Foundation for Returned Chinese Scholars in Heilongjiang (Grant No.LC08C03)+3 种基金Specialized Fund for Basic Scientific Research in Higher Education Institutions of China (Grant No.DL09DA02)Scientific Research Starting Foundation for Introduced Talents in Northeast Forestry University (Grant No.015-602042)National Science Foundation for Post-doctoral Scientists of China (Grant No.200902365)Preferred Foundation of Science-Technology Program for Returned Chinese Scholars in Heilongjiang (Grant No.2009-HLJLixinLi)~~
文摘The research progress in molecular chaperones, unfolded protein response （UPR） and ER-associated degradation （ERAD） involved in the protein quality control was summarized in this paper, and then the existing problems and the future devel- opment prospect were also discussed. It was pointed out that the life process of protein experienced four stages including synthesizing, folding, assembling and degradation, while each stage required strict quality control. In endoplasmic reticulum （ER）, a variety of proteins had been synthesized, folded and modified to form func- tional proteins with certain conformation. When the folding was blocked in ER, the unfolded proteins would aggregate and induce the UPR, which up-regulated the level of modification enzymes folded by a series of molecular chaperones and proteins to help them accomplish folding and assembling. If these proteins were still folded incorrectly, they would enter into ERAD for being degraded.
