AKT1 mediates multiple phosphorylation events that functionally promote HSF1 activation

AbstractThe heat stress response activates the transcription factor heat shock factor 1 (HSF1), which subsequently upregulates heat shock proteins to maintain the integrity of the proteome. HSF1 activity requires nuclear localization, trimerization, DNA binding, phosphorylation, and gene transactivation. Phosphorylation at S326 is an important regulator of HSF1 transcriptional activity. Phosphorylation at S326 is mediated by AKT1, mTOR, p38, and MEK1. mTOR, p38, and MEK1 all phosphorylated S326 but AKT1 was the more potent activator. Mass spectrometry showed that AKT1 phosphorylated HSF1 at T142, S230, and T527 in addition to S326 whereas the other kinases did not. Subsequent investigation revealed that phosphorylation at T142 is necessary for HSF1 trimerization and that S230, S326, and T527 are required for HSF1 gene transactivation and recruitment of TFIIB and CDK9. This study suggests that HSF1 activity is regulated by phosphorylation at specific residues that promote different stages of HSF1 activation. Furthermore, this is the first study to identify the functional role of these phosphorylation events.

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Role of heat shock factor-1 activation in the doxorubicin-induced heart failure in mice

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01047.2009 ◽

2010 ◽

Vol 298 (6) ◽

pp. H1832-H1841 ◽

Cited By ~ 39

Author(s):

Kaushik Vedam ◽

Yoshinori Nishijima ◽

Lawrence J. Druhan ◽

Mahmood Khan ◽

Nicanor I. Moldovan ◽

...

Keyword(s):

Oxidative Stress ◽

Heart Failure ◽

Heat Shock ◽

Mrna Level ◽

Heat Shock Factor ◽

Heat Shock Factor 1 ◽

Knock Out ◽

Apoptotic Protein ◽

Shock Proteins

Treating cancer patients with chemotherapeutics, such as doxorubicin (Dox), cause dilated cardiomyopathy and congestive heart failure because of oxidative stress. On the other hand, heat shock factor-1 (HSF-1), a transcription factor for heat shock proteins (Hsps), is also known to be activated in response to oxidative stress. However, the possible role of HSF-1 activation and the resultant Hsp25 in chemotherapeutic-induced heart failure has not been investigated. Using HSF-1 wild-type (HSF-1+/+) and knock-out (HSF-1−/−) mice, we tested the hypothesis that activation of HSF-1 plays a role in the development of Dox-induced heart failure. Higher levels of Hsp25 and its phosphorylated forms were found in the failing hearts of Dox-treated HSF-1+/+ mice. More than twofold increase in Hsp25 mRNA level was found in Dox-treated hearts. Proteomic analysis showed that there is accumulation and aggregation of Hsp25 in Dox-treated failing hearts. Additionally, Hsp25 was found to coimmunoprecipitate with p53 and vice versa. Further studies indicated that the Dox-induced higher levels of Hsp25 transactivated p53 leading to higher levels of the pro-apoptotic protein Bax, but other p53-related proteins remained unaltered. Moreover, HSF-1−/− mice showed significantly reduced Dox-induced heart failure and higher survival rate, and there was no change in Bax upon treating with Dox in HSF-1−/− mice. From these results we propose a novel mechanism for Dox-induced heart failure: increased expression of Hsp25 because of oxidant-induced activation of HSF-1 transactivates p53 to increase Bax levels, which leads to heart failure.

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The heat-shock, or HSF1-mediated proteotoxic stress, response in cancer: from proteomic stability to oncogenesis

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2016.0525 ◽

2017 ◽

Vol 373 (1738) ◽

pp. 20160525 ◽

Cited By ~ 24

Author(s):

Chengkai Dai

Keyword(s):

Stress Response ◽

Heat Shock ◽

Heat Shock Proteins ◽

Protein Misfolding ◽

Heat Shock Factor 1 ◽

Growth And Survival ◽

Proteotoxic Stress ◽

Shock Proteins ◽

Misfolding Diseases

The heat-shock, or HSF1-mediated proteotoxic stress, response (HSR/HPSR) is characterized by induction of heat-shock proteins (HSPs). As molecular chaperones, HSPs facilitate the folding, assembly, transportation and degradation of other proteins. In mammals, heat shock factor 1 (HSF1) is the master regulator of this ancient transcriptional programme. Upon proteotoxic insults, the HSR/HPSR is essential to proteome homeostasis, or proteostasis, thereby resisting stress and antagonizing protein misfolding diseases and ageing. Contrasting with these benefits, an unexpected pro-oncogenic role of the HSR/HPSR is unfolding. Whereas HSF1 remains latent in primary cells without stress, it becomes constitutively activated within malignant cells, rendering them addicted to HSF1 for their growth and survival. Highlighting the HSR/HPSR as an integral component of the oncogenic network, several key pathways governing HSF1 activation by environmental stressors are causally implicated in malignancy. Importantly, HSF1 impacts the cancer proteome systemically. By suppressing tumour-suppressive amyloidogenesis, HSF1 preserves cancer proteostasis to support the malignant state, both providing insight into how HSF1 enables tumorigenesis and suggesting disruption of cancer proteostasis as a therapeutic strategy. This review provides an overview of the role of HSF1 in oncogenesis, mechanisms underlying its constitutive activation within cancer cells and its pro-oncogenic action, as well as potential HSF1-targeting strategies. This article is part of the theme issue ‘Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective’.

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