scholarly journals Stress-Specific Activation and Repression of Heat Shock Factors 1 and 2

2001 ◽  
Vol 21 (21) ◽  
pp. 7163-7171 ◽  
Author(s):  
Anu Mathew ◽  
Sameer K. Mathur ◽  
Caroline Jolly ◽  
Susan G. Fox ◽  
Soojin Kim ◽  
...  
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Heat Shock Proteins ◽  
Heat Shock Gene ◽  
Heat Shock Factors ◽  
Reversible Inactivation ◽  
Acid Analogue ◽  
Heat Shock Gene Expression ◽  
Shock Proteins ◽  
Different Levels

ABSTRACT Vertebrate cells express a family of heat shock transcription factors (HSF1 to HSF4) that coordinate the inducible regulation of heat shock genes in response to diverse signals. HSF1 is potent and activated rapidly though transiently by heat shock, whereas HSF2 is a less active transcriptional regulator but can retain its DNA binding properties for extended periods. Consequently, the differential activation of HSF1 and HSF2 by various stresses may be critical for cells to survive repeated and diverse stress challenges and to provide a mechanism for more precise regulation of heat shock gene expression. Here we show, using a novel DNA binding and detection assay, that HSF1 and HSF2 are coactivated to different levels in response to a range of conditions that cause cell stress. Above a low basal activity of both HSFs, heat shock preferentially activates HSF1, whereas the amino acid analogue azetidine or the proteasome inhibitor MG132 coactivates both HSFs to different levels and hemin preferentially induces HSF2. Unexpectedly, we also found that heat shock has dramatic adverse effects on HSF2 that lead to its reversible inactivation coincident with relocalization from the nucleus. The reversible inactivation of HSF2 is specific to heat shock and does not occur with other stressors or in cells expressing high levels of heat shock proteins. These results reveal that HSF2 activity is negatively regulated by heat and suggest a role for heat shock proteins in the positive regulation of HSF2.

Human heat shock factors 1 and 2 are differentially activated and can synergistically induce hsp70 gene transcription

1994 ◽  
Vol 14 (3) ◽  
pp. 2087-2099
Author(s):  
L Sistonen ◽  
K D Sarge ◽  
R I Morimoto
Keyword(s):  
Gene Expression ◽  
Heat Shock ◽  
Dna Binding ◽  
Gene Transcription ◽  
K562 Cells ◽  
Heat Shock Gene ◽  
Hsp70 Gene ◽  
Heat Shock Factors ◽  
Shock Gene ◽  
Heat Shock Gene Expression

Two members of the heat shock transcription factor (HSF) family, HSF1 and HSF2, both function as transcriptional activators of heat shock gene expression. However, the inducible DNA-binding activities of these two factors are regulated by distinct pathways. HSF1 is activated by heat shock and other forms of stress, whereas HSF2 is activated during hemin-induced differentiation of human K562 erythroleukemia cells, suggesting a role for HSF2 in regulating heat shock gene expression under nonstress conditions such as differentiation and development. To understand the distinct regulatory pathways controlling HSF2 and HSF1 activities, we have examined the biochemical and physical properties of the control and activated states of HSF2 and compared these with the properties of HSF1. Our results reveal that the inactive, non-DNA-binding forms of HSF2 and HSF1 exist primarily in the cytoplasm of untreated K562 cells as a dimer and monomer, respectively. This difference in the control oligomeric states suggests that the mechanisms used to control the DNA-binding activities of HSF2 and HSF1 are distinct. Upon activation, both factors acquire DNA-binding activity, oligomerize to a trimeric state, and translocate into the nucleus. Interestingly, we find that simultaneous activation of both HSF2 and HSF1 in K562 cells subjected to hemin treatment followed by heat shock results in the synergistic induction of hsp70 gene transcription, suggesting a novel level of complex regulation of heat shock gene expression.

scholarly journals Human heat shock factors 1 and 2 are differentially activated and can synergistically induce hsp70 gene transcription.

1994 ◽  
Vol 14 (3) ◽  
pp. 2087-2099 ◽  
Author(s):  
L Sistonen ◽  
K D Sarge ◽  
R I Morimoto
Keyword(s):  
Gene Expression ◽  
Heat Shock ◽  
Dna Binding ◽  
Gene Transcription ◽  
K562 Cells ◽  
Heat Shock Gene ◽  
Hsp70 Gene ◽  
Heat Shock Factors ◽  
Shock Gene ◽  
Heat Shock Gene Expression

Two members of the heat shock transcription factor (HSF) family, HSF1 and HSF2, both function as transcriptional activators of heat shock gene expression. However, the inducible DNA-binding activities of these two factors are regulated by distinct pathways. HSF1 is activated by heat shock and other forms of stress, whereas HSF2 is activated during hemin-induced differentiation of human K562 erythroleukemia cells, suggesting a role for HSF2 in regulating heat shock gene expression under nonstress conditions such as differentiation and development. To understand the distinct regulatory pathways controlling HSF2 and HSF1 activities, we have examined the biochemical and physical properties of the control and activated states of HSF2 and compared these with the properties of HSF1. Our results reveal that the inactive, non-DNA-binding forms of HSF2 and HSF1 exist primarily in the cytoplasm of untreated K562 cells as a dimer and monomer, respectively. This difference in the control oligomeric states suggests that the mechanisms used to control the DNA-binding activities of HSF2 and HSF1 are distinct. Upon activation, both factors acquire DNA-binding activity, oligomerize to a trimeric state, and translocate into the nucleus. Interestingly, we find that simultaneous activation of both HSF2 and HSF1 in K562 cells subjected to hemin treatment followed by heat shock results in the synergistic induction of hsp70 gene transcription, suggesting a novel level of complex regulation of heat shock gene expression.

Interaction between heat shock factor and hsp70 is insufficient to suppress induction of DNA-binding activity in vivo

1994 ◽  
Vol 14 (10) ◽  
pp. 6552-6560
Author(s):  
S K Rabindran ◽  
J Wisniewski ◽  
L Li ◽  
G C Li ◽  
C Wu
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Heat Shock Proteins ◽  
Expression System ◽  
Stress Protein ◽  
Binding Activity ◽  
Protein Family ◽  
Oligomeric State ◽  
Dna Binding Activity ◽  
Shock Proteins

The intracellular level of free heat shock proteins, in particular the 70-kDa stress protein family, has been suggested to be the basis of an autoregulatory mechanism by which the cell measures the level of thermal stress and regulates the synthesis of heat shock proteins. It has been proposed that the DNA-binding and oligomeric state of the heat shock transcription factor (HSF) is a principal step in the induction pathway that is responsive to the level of 70-kDa stress protein. To test this hypothesis, we investigated the association between HSF and 70-kDa stress protein by means of a coimmunoprecipitation assay. We found that 70-kDa stress proteins associate to similar extents with both latent and active forms of HSF, although unlike other 70-kDa stress protein substrates, the association with HSF was not significantly disrupted in the presence of ATP. Gel mobility shift assays indicated that active HSF trimers purified from a bacterial expression system could not be substantially deactivated in vitro with purified 70-kDa stress protein and ATP. In addition, elevated concentrations of hsp70 alone could not significantly inhibit induction of the DNA-binding activity of endogenous HSF in cultured rat cells, and the induction was also not inhibited in cultured rat cells or Drosophila cells containing elevated levels of all members of the heat shock protein family. However, the deactivation of HSF to the non-DNA-binding state after prolonged heat stress or during recovery could be accelerated by increased levels of heat shock proteins. Hence, the level of heat shock proteins may affect the rate of disassembly of HSF trimers, but another mechanism, as yet undefined, appears to control the onset of the oligomeric transitions.

A family of related proteins is encoded by the major Drosophila heat shock gene family

1982 ◽  
Vol 2 (3) ◽  
pp. 286-292
Author(s):  
S C Wadsworth
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Shock Protein ◽  
Sodium Dodecyl ◽  
Heat Shock Gene ◽  
Partial Digestion ◽  
Shock Gene ◽  
Shock Proteins

At least four proteins of 70,000 to 75,000 molecular weight (70-75K) were synthesized from mRNA which hybridized with a cloned heat shock gene previously shown to be localized to the 87A and 87C heat shock puff sites. These in vitro-synthesized proteins were indistinguishable from in vivo-synthesized heat shock-induced proteins when analyzed on sodium dodecyl sulfate-polyacrylamide gels. A comparison of the pattern of this group of proteins synthesized in vivo during a 5-min pulse or during continuous labeling indicates that the 72-75K proteins are probably not kinetic precursors to the major 70K heat shock protein. Partial digestion products generated with V8 protease indicated that the 70-75K heat shock proteins are closely related, but that there are clear differences between them. The partial digestion patterns obtained from heat shock proteins from the Kc cell line and from the Oregon R strain of Drosophila melanogaster are very similar. Genetic analysis of the patterns of 70-75K heat shock protein synthesis indicated that the genes encoding at least two of the three 72-75K heat shock proteins are located outside of the major 87A and 87C puff sites.

scholarly journals Association of heat shock proteins, heat shock factors and male infertility

2012 ◽  
Vol 1 (1) ◽  
pp. 76-84 ◽  
Author(s):  
Zi-Liang Ji ◽  
Yong-Gang Duan ◽  
Li-Sha Mou ◽  
Jean-Pierre Allam ◽  
Gerhard Haidl ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Male Infertility ◽  
Heat Shock Factors ◽  
Shock Proteins

The expression of heat-shock genes in higher plants

1986 ◽  
Vol 314 (1166) ◽  
pp. 453-468 ◽  
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Higher Plants ◽  
Structural Features ◽  
Amino Acid Sequences ◽  
Heat Shock Gene ◽  
Regulatory Sequences ◽  
Heat Shock Genes ◽  
Control Of Gene Expression ◽  
Shock Proteins

High-temperature stress or heat shock induces the vigorous synthesis of heat-shock proteins in many organisms including the higher plants. This response has been implicated in the acquisition of thermotolerance. The biological importance of a group of low-molecular-mass proteins in the response of plants is indicated by the conservation of the corresponding genes. The steady-state levels of mRNAs for these proteins shift from undetectable levels at normal temperature to about 20 000 molecules per gene in the cell after heat shock. The analysis of ‘run-off’ transcripts from isolated soybean nuclei suggests a transcriptional control of gene expression. The DNA sequence analysis of soybean heat-shock genes revealed a conservation of promoter sequences and 5'-upstream elements. A comparison of the deduced amino acid sequences of polypeptides showed a conservation of structural features in heat-shock proteins between plants and animals. The implication of a common regulatory concept in the heat-shock response makes genes belonging to this family (15-18 kDa proteins) in soybean favourable candidates for investigating thermoregulation of transcription. We have exploited the natural gene transfer system of Agrobacterium tumefaciens to introduce a soybean heat-shock gene into the genomes of sunflower and tobacco. The gene is thermoinducibly transcribed and transcripts are faithfully initiated in transgenic plants. Experiments are in progress to define the regulatory sequences 5'-upstream from the gene. The expression of heat-shock genes in a heterologous genetic background also provides the basis for studying the function of the proteins and their possible role in thermoprotection.

Depressed expression of the inducible form of HSP 70 (HSP 72) in brain and heart after in vivo heat shock

1995 ◽  
Vol 269 (3) ◽  
pp. R608-R613 ◽  
Author(s):  
S. C. Beck ◽  
C. N. Paidas ◽  
H. Tan ◽  
J. Yang ◽  
A. De Maio
Keyword(s):  
Heat Shock ◽  
Cell Types ◽  
Heat Shock Gene ◽  
Hsp 70 ◽  
Shock Gene ◽  
Heat Shock Gene Expression ◽  
Total Body ◽  
Different Levels ◽  
Low Expression

The heat shock gene expression plays a role in the protection of cells from injury. In the present study, we have analyzed the expression of heat shock protein (HSP) 72 (the major inducible form of the HSP 70 family) in different rat organs after a total body hyperthermia. The content of HSP 72 was greatest in liver and colon. In contrast, accumulation of HSP 72 was low in heart and brain (3-5% and < 1% of the amount in liver, respectively). This low expression of HSP 72 in heart and brain could not be explained by a difference in the actual temperature within these organs. Analysis of cells in culture that resemble hepatocytes, myoblast, and neurons showed a pattern of HSP 72 expression similar to that observed in liver, heart, and brain in vivo after heat shock. These results suggest that this disparate expression of HSP 72 is due to intrinsic characteristics of the cell types rather than to physiological or environmental conditions. The differential expression of HSP 72 among different cell lines could be correlated with the different levels of protein synthesis protection.

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