Heat shock factor 1 is a key regulator of the stress response in Chlamydomonas

We report here on the characterization of heat shock factor 1 (HSF1), encoded by one of two HSF genes identified in the genome of Chlamydomonas reinhardtii. Chlamydomonas HSF1 shares features characteristic of class A HSFs of higher plants. HSF1 is weakly expressed under non-stress conditions and rapidly induced by heat shock. Heat shock also resulted in hyperphosphorylation of HSF1, and the extent of phosphorylation correlated with the degree of induction of heat shock genes, suggesting a role for phosphorylation in HSF1 activation. HSF1, like HSFs in yeasts, forms high-molecular-weight complexes, presumably trimers, under non-stress, stress and recovery conditions. Immunoprecipitation of HSF1 under these conditions led to the identification of cytosolic HSP70A as a protein constitutively interacting with HSF1. Strains in which HSF1 was strongly under-expressed by RNAi were highly sensitive to heat stress. 14C-labelling of nuclear-encoded proteins under heat stress revealed that synthesis of members of the HSP100, HSP90, HSP70, HSP60 and small HSP families in the HSF1-RNAi strains was dramatically reduced or completely abolished. This correlated with a complete loss of HSP gene induction at the RNA level. These data suggest that HSF1 is a key regulator of the stress response in Chlamydomonas.     

Expression of heat shock and cold shock proteins in the gorgonian Leptogorgia virgulata

In this study, we analyzed the response of the temperate, shallow-water gorgonian, Leptogorgia virgulata, to temperature stress. Proteins were pulse labeled with (35)S-methionine/cysteine for 1 h to 2 h at 22 degrees C (control), or 38 degrees C, or for 4 h at 12.5 degrees C. Heat shock induced synthesis of unique proteins of 112, 89, and 74 kDa, with 102, 98 and 56 kDa proteins present in the control as well. Cold shock from 22 degrees C-12.5 degrees C induced the synthesis of a 25 kDa protein, with a 44 kDa protein present in the control as well. Control samples expressed unique proteins of 38, and 33 kDa. Non-radioactive proteins expressed under the same conditions as above, as well as natural field conditions, were tested for reactivity with antibodies to heat shock proteins (HSPs). HSP60 was the major protein found in L. virgulata. Although HSP47, HSP60, and HSP104 were present in all samples, the expression of HSP60 was enhanced in heat stressed colonies, while HSP47 and HSP104 expression were greatest in cold shocked samples. Inducible HSP70 was expressed in cold-shocked, heat-shocked, and field samples. Constitutively expressed HSP70 was absent from all samples. The expression of HSP90 was limited to heat shocked colonies. The expression of both HSP70 and HSP104 suggests that the organism may also develop a stress tolerance response.     

Proteome analysis on differentially expressed proteins of the fat body of two silkworm breeds, Bombyx mori, exposed to heat shock exposure

Proteomes of heat tolerant (multivoltine) and heat susceptible (bivoltine) silkworms (Bombyx mori) in response to heat shock were studied. Detected proteins from fat body were identified by using MALDI-TOF/TOF spectrometer, MS/MS, and MS analysis. Eight proteins, including small heat shock proteins (sHSPs) and HSP70, were expressed similarly in both breeds, while 4 protein spots were expressed specifically in the bivoltine breed and 12 protein spots were expressed specifically in the multivoltine breed. In the present proteomics approach, 5 separate spots of sHSP proteins (HSP19.9, HSP20.1, HSP20.4, HSP20.8, and HSP21.4) were identified. Protein spot intensity of sHSPs was lower in the multivoltine breed than in the bivoltine breed after the 45°C heat shock treatment, while the difference between two breeds was not significant after the 41°C heat shock treatment. These results indicated that some other mechanisms might be engaged in thermal tolerance of multivotine breed except for the expression of sHSP and HSP70. There were visible differences in the intensity of heat shock protein expression between male and female, however, differences were not statistically significant.     

hsp82 is an essential protein that is required in higher concentrations for growth of cells at higher temperatures.

hsp82 is one of the most highly conserved and abundantly synthesized heat shock proteins of eucaryotic cells. The yeast Saccharomyces cerevisiae contains two closely related genes in the HSP82 gene family. HSC82 was expressed constitutively at a very high level and was moderately induced by high temperatures. HSP82 was expressed constitutively at a much lower level and was more strongly induced by heat. Site-directed disruption mutations were produced in both genes. Cells homozygous for both mutations did not grow at any temperature. Cells carrying other combinations of the HSP82 and HSC82 mutations grew well at 25 degrees C, but their ability to grow at higher temperatures varied with gene copy number. Thus, HSP82 and HSC82 constitute an essential gene family in yeast cells. Although the two proteins had different patterns of expression, they appeared to have equivalent functions; growth at higher temperatures required higher concentrations of either protein. Biochemical analysis of hsp82 from vertebrate cells suggests that the protein binds to a variety of other cellular proteins, keeping them inactive until they have reached their proper intracellular location or have received the proper activation signal. We speculate that the reason cells require higher concentrations of hsp82 or hsc82 for growth at higher temperatures is to maintain proper levels of complex formation with these other proteins.     

美国白蛾热激蛋白70基因的鉴定及功能分析

[目的]探究热激蛋白70 (heat shock protein 70,HSP70)基因在美国白蛾Hyphantria cunea抵御高温胁迫过程中的作用,为揭示美国白蛾的扩散机制以及预测潜在分布区提供理论支撑.[方法]利用PCR技术克隆美国白蛾HSP70基因,并进行生物信息学分析;利用qPCR技术检测新蜕皮的美国白蛾...     

Identification of an Arabidopsis thaliana cDNA encoding a HSP70-related protein belonging to the HSP110/SSE1 subfamily

Heat-shock protein 70 (HSP70)-related proteins are classified in two main subfamilies: the DnaK subfamily and the HSP110/SSE1 subfamily. We have characterized the first plant member of the HSP110/SSE1 subfamily, HSP91. At least two, tightly linked genes encoding HSP91 are present per haploid Arabidopsis genome. HSP91 is constitutively expressed in non-stressed Arabidopsis plants and is transiently induced by heat shock.     

Murine 86- and 84-kDa heat shock proteins, cDNA sequences, chromosome assignments, and evolutionary origins

The two forms of the approximately 90-kDa murine heat shock protein, referred to as HSP86 and HSP84, are coded for by separate but related genes. A full-length nucleotide sequence of the cDNA coding for HSP86 from a chemically induced tumor, Meth A, was determined. Sequences from a number of peptides from HSP86 were found to be in complete agreement with the nucleotide sequence. The HSP84 sequence from the same tumor was also completed. HSP86 and HSP84 are acidic polypeptides 733 and 724 amino acids long with calculated molecular weights of 84,796 and 83,290, respectively. The two proteins are 86% homologous. HSP86 was found to contain internal peptide repeats of Glu-Lys-Glu within a region of highly charged amino acid residues. The coding regions of the cDNAs were 76% homologous; however, this homology did not extend to the 5'- and 3'-untranslated regions. The 5'-untranslated region of hsp86 cDNA was considerably longer than that of hsp84 cDNA and, unlike that of hsp84, contained extraneous ATG triplets. Hsp86-related sequences were assigned to chromosomes 12, 11, and 3. An evolutionary tree constructed from HSP90-related protein sequences indicated that HSP86 and HSP84 were likely to have diverged more than 500 million years ago. The findings presented herein suggest that HSP86 and HSP84 may have different functions.     

Expression, synthesis, and phosphorylation of HSP28 family during development and decay of thermotolerance in CHO plateau-phase cells.

We investigated a correlation between development of thermotolerance and expression, synthesis, or phosphorylation of HSP28 family in CHO plateau phase cells. After heating at 45.5 degrees C for 10 min, thermotolerance developed rapidly and reached its maximum 12-18 hr after heat shock. This acquired thermal resistance was maintained for 72 hr and then gradually decayed. In parallel, the levels of three 28 kDa heat shock proteins, HSP28a along with its two phosphorylated isoforms (HSP28b,c), increased and reached their maximum 24-48 hr after heat shock. The levels of these polypeptides, except HSP28c, remained elevated for 72 hr and then decreased. The level of HSP28 mRNA increased rapidly and reached its maximum 12 hr after heat shock. However, unlike thermotolerance and the levels of HSP28 family proteins, the level of HSP28 mRNA decreased rapidly within 72 hr. These results demonstrate a correlation between the amount of intracellular HSP28 family proteins and development and decay of thermotolerance.     

Seasonal variation in expression pattern of genes under HSP70

Heat shock protein 70 (HSP70) is one of the most abundant and best characterized heat shock protein family that consists of highly conserved stress proteins, expressed in response to stress, and plays crucial roles in environmental stress tolerance and adaptation. The present study was conducted to identify major types of genes under the HSP70 family and to quantify their expression pattern in heat- and cold-adapted Indian goats (Capra hircus) with respect to different seasons. Five HSP70 gene homologues to HSPA8, HSPA6, HSPA1A, HSPA1L, and HSPA2 were identified by gene-specific primers. The cDNA sequences showed high similarity to other mammals, and proteins have an estimated molecular weight of around 70 kDa. The expression of HSP70 genes was observed during summer and winter. During summer, the higher expression of HSPA8, HSPA6, and HSPA1A was observed, whereas the expression levels of HSPA1L and HSPA2 were found to be lower. It was also observed that the expression of HSPA1A and HSPA8 was higher during winter in both heat- and cold-adapted goats but downregulates in case of other HSPs. Therefore, both heat and cold stress induced the overexpression of HSP70 genes. An interesting finding that emerged from the study is the higher expression of HSP70 genes in cold-adapted goats during summer and in heat-adapted goats during winter. Altogether, the results indicate that the expression pattern of HSP70 genes is species- and breed-specific, most likely due to variations in thermal tolerance and adaptation to different climatic conditions.     

Heat shock protein expression in thermotolerant and thermosensitive lines of cotton

The expression of heat shock proteins (HSPs) was compared between genetically characterized heat tolerant and heat sensitive lines of cotton (Gossypium hirsutum andG. barbadense) using electrophoretic analysis ofin vivo labelled proteins. No differences were observed between the two lines with regard to: the temperature at which HSP synthesis was induced (37°C); the temperature at which HSP synthesis was maximal (45°C); the rates of recovery from HSP synthesis; the duration of HSP synthesis; or the major size classes of HSPs expressed in these two lines. Several HSPs were identified on 2D gels which were expressed uniquely in either the tolerant or sensitive cotton line. However, the HSP pattern displayed in a heat tolerant BC-3 individual was that of the heat sensitive parent.Abbreviations HSPs heat shock proteins - IEF isoelecticfocusing     

Differential gene expression of HSC70/HSP70 in yellowtail cells in response to chaperone-mediated autophagy

A cell line derived from the tailfin of the marine teleost yellowtail fish Seriola quinqueradiata was established to examine cellular temperature regulation in an ectothermic animal. Three cytosolic members of the HSP70 family, heat-shock cognate proteins HSC70-1, HSC70-2 and heat-shock protein HSP70, were isolated from cultured yellowtail cells as stress-responsive biomarkers. Expression of hsp70 was heat-inducible, in contrast to the hsc70-1 gene product, which was expressed constitutively. In addition, expression of hsc70-2 was only induced under severe heat-shock conditions. Subcellular fractionation and immunocytochemistry showed localization of HSC70/HSP70 in the lysosomes, indicating that chaperone-mediated autophagy is induced by heat shock. Thus, chaperone-mediated autophagy is assisted by HSC70/HSP70, and heat-inducible expression of the genes encoding these proteins may be responsible for survival and adaptation under heat-shock conditions in fish cells.     

Cloning and expression of the coding regions of the heat shock proteins HSP10 and HSP16 from Piscirickettsia salmonis

The genes encoding the heat shock proteins HSP10 and HSP16 of the salmon pathogen Piscirickettsia salmonis have been isolated and sequenced. The HSP10 coding sequence is located in an open reading frame of 291 base pairs encoding 96 aminoacids. The HSP16 coding region was isolated as a 471 base pair fragment encoding a protein of 156 aminoacids. The deduced aminoacid sequences of both proteins show a significant homology to the respective protein from other prokaryotic organisms. Both proteins were expressed in E. coli as fusion proteins with thioredoxin and purified by chromatography on Nicolumn. A rabbit serum against P. salmonis total proteins reacts with the recombinant HSP10 and HSP16 proteins. Similar reactivity was determined by ELISA using serum from salmon infected with P. salmonis. The possibility of formulating a vaccine containing these two proteins is discussed.