heat shock factor

Background: Asparagus (Asparagus officinalis L.) is one of the most ancient vegetables, and it is rich in asparagine. Enzyme-treated asparagus extract (ETAS™; Amino Up Chemical Co., Ltd., Sapporo, Japan) is the final product of enzyme-treatment of asparagus stems and subsequent extraction. Two constituents were purified from ETAS and identified: 5-hydroxymethyl-2-furfural (HMF), an abundant constituent, and (S)-asfural, a novel constituent, which is a derivative of HMF. ETAS has been reported to increase the expression of heat shock proteins (HSPs), which are essential for the repair or removal of defective proteins. The expression of Hsp family genes is regulated by the transcription factor heat shock factor 1 (HSF1). It is unknown whether ETAS and its constituents elicit anti-inflammatory effects, such as the suppression of nitric oxide (NO), an inflammatory mediator synthesized by inducible nitric oxide synthase (iNOS) in interleukin (IL)-1β-treated hepatocytes.

Objective: To examine the anti-inflammatory effects of ETAS, we treated rat hepatocytes with ETAS, or its constituents (S)-asfural or HMF, and IL-1β and then analyzed the expression of the iNOS gene and other genes involved in inflammation.

Methods: Primary cultured rat hepatocytes were prepared by collagenase perfusion. ETAS, (S)-asfural, or HMF was added to the medium with IL-1β and incubated at 37 °C. When necessary, an inhibitor of HSF1 was added. NO in the medium was measured by the Griess method, and the half-maximal inhibitory concentration (IC50) values were determined. To analyze the mRNA expression, a reverse transcription-quantitative polymerase chain reaction was performed. Antibody arrays were used to determine the levels of cytokines and chemokines in the medium.

Results: ETAS suppressed NO production in IL-1β-treated hepatocytes without causing cytotoxicity. ETAS decreased the levels of both iNOS mRNA and the antisense transcript, whereas it increased the levels of Hsf1 mRNA and Hsp70 mRNA. ETAS also suppressed the production of pro-inflammatory cytokines and chemokines in hepatocytes. When (S)-asfural and HMF were added to the medium, they suppressed NO production and iNOS gene expression. The IC50 value of (S)-asfural was approximately 3-fold lower than that of HMF. In contrast, (S)-asfural increased the levels of Hsf1 mRNA. Interestingly, the KRIBB11, an inhibitor of HSF1, reduced the expression of the iNOS gene. When both (S)-asfural and KRIBB11 were added, the level of iNOS mRNA was lower than when (S)-asfural alone was added.

Conclusion: ETAS and its constituents (S)-asfural and HMF suppressed NO production and the expression of pro-inflammatory cytokines and chemokines, thus showing anti-inflammatory effects. Our data suggest the possibility that the increased HSF1 level is involved in suppression of NO by ETAS and its constituents, although HSF1 is essential for the expression of the iNOS gene.

A new group of proteins, small ubiquitin-like modifier (SUMO) proteins, has recently been identified and protein sumoylation has been shown to play a major role in various signal transduction pathways. Here, we report that transient global cerebral ischemia induces a marked increase in protein sumoylation. Mice were subjected to 10 mins severe forebrain ischemia followed by 3 or 6 h of reperfusion. Transient cerebral ischemia induced a massive increase in protein sumoylation by SUMO2/3 both in the hippocampus and cerebral cortex. SUMO2/3 conjugation was associated with a decrease in levels of free SUMO2/3. After ischemia, protein levels of the SUMO-conjugating enzyme Ubc9 were transiently decreased in the cortex but not in the hippocampus. We also exposed HT22 cells to arsenite, a respiratory poison that impairs cytoplasmic function and induces oxidative stress. Arsenite exposure induced a marked rise in protein sumoylation, implying that impairment of cytoplasmic function and oxida...

Based on phylogeny of DNA-binding domains and the organization of hydrophobic repeats, two families of heat shock transcription factors (HSFs) exist in plants. Class A HSFs are involved in the activation of the heat shock response, but the role of class B HSFs is not clear. When transcriptional activities of full-length HSFs were monitored in tobacco protoplasts, no class B HSFs from soybean or Arabidopsis showed activity under control or heat stress conditions. Additional assays confirmed the finding that the class B HSFs lacked the capacity to activate transcription. Fusion of a heterologous activation domain from human HSF1 (AD2) to the C-terminus of GmHSFB1-34 gave no evidence of synergistic enhancement of AD2 activity, which would be expected if weak activation domains were present. Furthermore, activity of AtHSFB1-4 (class B) was not rescued by coexpression with AtHSFA4-21 (class A) indicating that the class A HSF was not able to provide a missing function required for class B...

Mammalian cells coexpress a family of heat shock factors (HSFs) whose activities are regulated by diverse stress conditions to coordinate the inducible expression of heat shock genes. Distinct from HSF1, which is expressed ubiquitously and activated by heat shock and other stresses that result in the appearance of nonnative proteins, the stress signal for HSF2 has not been identified. HSF2 activity has been associated with development and differentiation, and the activation properties of HSF2 have been characterized in hemin-treated human K562 erythroleukemia cells. Here, we demonstrate that a stress signal for HSF2 activation occurs when the ubiquitin-proteasome pathway is inhibited. HSF2 DNA-binding activity is induced upon exposure of mammalian cells to the proteasome inhibitors hemin, MG132, and lactacystin, and in the mouse ts85 cell line, which carries a temperature sensitivity mutation in the ubiquitin-activating enzyme (E1) upon shift to the nonpermissive temperature. HSF2 i...

Heatshocktranscriptionfactors(HSFs)mediatetheinducibletranscriptionalresponseofgenesthatencode heat shock proteins and molecular chaperones. In vertebrates, three relatedHSFgenes (HSF1to -3) and the respective gene products (HSFs) have been characterized. We report the cloning and characterization of human HSF4 (hHSF4), a novel member of the hHSF family that shares properties with other members of the HSF family yet appears to be functionally distinct. hHSF4 lacks the carboxyl-terminal hydrophobic

Macromolecules such as proteins are continuously exposed to potential damaging agents that can cause loss of molecular function and depletion of cell populations over the lifetime of essential organs. One of the key homeostatic responses involved in maintaining longevity is the ...

All organisms respond to environmental, chemical and physiological stresses by enhanced synthesis of an evolutionarily conserved family of proteins known as heat shock proteins (HSPs) or stress proteins. Certain HSPs are also expressed constitutively during cell growth and development, and they function as molecular chaperones. The transcriptional regulation of hsp genes is mediated by the heat shock transcription factor (HSF). The stress response has been studied mostly in mammalian cell lines or organisms normally maintained under constant laboratory conditions. There is much less information on the regulation of the stress response of animals, such as fish, that have to tolerate large fluctuations in environmental and internal conditions. To characterize the regulation of the heat shock response in fish, we have cloned the first heat shock transcription factor from fish, zebrafish Danio rerio. Phylogenetic analysis confirms that the isolated zebrafish HSF belongs to the HSF1 fami...

In Drosophila larvae, acquired synaptic thermotolerance after heat shock has previously been shown to correlate with the induction of heat shock proteins (Hsps) including HSP70. We tested the hypothesis that synaptic thermotolerance would be significantly diminished in a temperature-sensitive strain ( Drosophila heat shock factor mutant hsf4), which has been reported not to be able to produce inducible Hsps in response to heat shock. Contrary to our hypothesis, considerable thermoprotection was still observed at hsf4 larval synapses after heat shock. To investigate the cause of this thermoprotection, we conducted DNA microarray experiments to identify heat-induced transcript changes in these organisms. Transcripts of the hsp83, dnaJ-1 ( hsp40), and glutathione- S-transferase gstE1 genes were significantly upregulated in hsf4 larvae after heat shock. In addition, increases in the levels of Hsp83 and DnaJ-1 proteins but not in the inducible form of Hsp70 were detected by Western blot ...

Transcriptional activation of heat shock genes is a reversible and multistep process involving conversion of inactive heat shock factor 1 (HSF1) monomers into heat shock element (HSE)-binding homotrimers, hyperphosphorylation, and further modifications that induce full transcriptional competence. HSF1 is controlled by multiple regulatory mechanisms, including suppression by additional cellular factors, physical interactions with HSP70, and integration into different cellular signaling cascades. However, the signaling mechanisms by which cells respond to stress and control the HSF1 activation-deactivation pathway are not known. Here we demonstrate that HSP90, a cellular chaperone known to regulate several signal transduction molecules and transcription factors, functions in the regulation of HSF1. The existence of HSF1-HSP90 heterocomplexes was shown by coimmunoprecipitation of HSP90 with HSF1 from unshocked and heat-shocked nuclear extracts, recognition of HSF1-HSE complexes in vitr...