Transcription Factor For Heat Shock Proteins Research Articles

Role of HSF1 and FoxO3 in proteotoxic stress induced Macroautophagy

Autophagy or Macroautophagy and the ubiquitin‐proteasome pathways are the two major catabolic pathways in all cells. Autophagy is a cellular process in which a portion of the cytoplasm becomes enclosed in a membrane‐bound vesicle, the autophagosome, which fuses with lysosomes leading to digestion of the contents of this autolysosomes. The exact mechanism is still not clear. Autophagy appears to switch on when translation is switched off and the processes are reciprocally regulated by TORC1 kinase. In addition to induction of autophagy by nutrient starvation, this process is also triggered by various stresses. Thus, this process of autophagy is regulated by two different mechanisms: nontranscriptional inhibition by mTOR and transcription‐dependent upregulation through FoxO3. Nevertheless, transcriptional mechanisms that physiologically regulate expression of autophagy genes in tissues other than myotubes have not been characterized. We are concentrated here on autophagy stimulated by proteotoxic stresses such as heat shock. We found that FoxO3 transcription factor which is necessary and sufficient for induction of autophagy in skeletal muscle is regulated by the heat shock protein transcription factor, HSF1. Our data show that HSF1 negatively regulates FoxO3 activity in HeLa cells. FoxO3 is shown to be positively regulating autophagosome formation determined by LC3I/II expression. In this study we hypothesize that stress enhances autophagy by activating FoxO3 and MAP‐LC3I expression whereas stress induced HSF1 activation causes increase in protein folding pathway.

Heat shock factor-1 knockout induces multidrug resistance gene, MDR1b, and enhances P-glycoprotein (ABCB1)-based drug extrusion in the heart

Heat-shock factor 1 (HSF-1), a transcription factor for heat-shock proteins (HSPs), is known to interfere with the transcriptional activity of many oncogenic factors. In the present work, we have discovered that HSF-1 ablation induced the multidrug resistance gene, MDR1b, in the heart and increased the expression of P-glycoprotein (P-gp, ABCB1), an ATP binding cassette that is usually associated with multidrug-resistant cancer cells. The increase in P-gp enhanced the extrusion of doxorubicin (Dox) to alleviate Dox-induced heart failure and reduce mortality in mice. Dox-induced left ventricular (LV) dysfunction was significantly reduced in HSF-1(-/-) mice. DNA-binding activity of NF-κB was higher in HSF-1(-/-) mice. IκB, the NF-κB inhibitor, was depleted due to enhanced IκB kinase (IKK)-α activity. In parallel, MDR1b gene expression and a large increase in P-gp and lowering Dox loading were observed in HSF-1(-/-) mouse hearts. Moreover, application of the P-gp antagonist, verapamil, increased Dox loading in HSF-1(-/-) cardiomyocytes, deteriorated cardiac function in HSF-1(-/-) mice, and decreased survival. MDR1 promoter activity was higher in HSF-1(-/-) cardiomyocytes, whereas a mutant MDR1 promoter with heat-shock element (HSE) mutation showed increased activity only in HSF-1(+/+) cardiomyocytes. However, deletion of HSE and NF-κB binding sites diminished luminescence in both HSF-1(+/+) and HSF-1(-/-) cardiomyocytes, suggesting that HSF-1 inhibits MDR1 activity in the heart. Thus, because high levels of HSF-1 are attributed to poor prognosis of cancer, systemic down-regulation of HSF-1 before chemotherapy is a potential therapeutic approach to ameliorate the chemotherapy-induced cardiotoxicity and enhance cancer prognosis.

17-allylamino-17-demethoxygeldanamycin and ritonavir inhibit renal cancer growth by inhibiting the expression of heat shock factor-1

Our previous study showed that the combination of a histone deacetylase (HDAC) inhibitor and an HIV protease inhibitor is effective against renal cancer cells. Because HDAC inhibition disrupts the chaperon function of heat shock protein (HSP) 90, we hypothesized that the combination of 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of HSP90, and the HIV protease inhibitor ritonavir would also act against renal cancer. The combination of 17-AAG and ritonavir induced apoptosis and inhibited the proliferation of renal cancer cells effectively. It also suppressed the expression of cyclin-dependent kinase 4 and cyclin D1, leading to the accumulation of the cells in the sub-G1 fraction. The expression of HSPs 27, 70 and 90 was increased by 17-AAG alone but reduced by 17-AAG combined with ritonavir. The combination decreased the expression of heat shock factor-1 (HSF-1), an HSP transcription factor, and this might be one of the mechanisms of the effect of the combination. We have also found that silencing of HSF-1 by siRNA inhibited the proliferation of renal cancer cells and that in surgically resected specimens the levels of HSF-1 expression in renal cancer tissue are higher than those in normal parenchyma. This is the first study showing the beneficial effect of combining 17-AAG and ritonavir and our data suggest that HSF-1 may be a novel therapeutic target in the treatment of renal cancer.

Identification of novel cumulus cell molecular markers predictive of oocyte competence: confirmation with pregnancy outcome

To identify molecular markers predictive of human embryo implantation. Prospective Cohort Cumulus cells from all retrieved oocytes (No = 49) of 6 IVF patients who were chosen in random were mechanically separated prior to fertilization and frozen in liquid nitrogen for future evaluation. We selected heat shock protein transcription factor (HSF1), mitochondrial transcription factor A (TFAM), endoplasmic reticulum oxidoreductin1(ERO1LA), peroxiredoxin6 (PRDX6), and enolase 1(eno1), as well as 2 housekeeping genes (GAPDH and 28S RNA) for this study. Quantitative real-time Polymerase chain reaction methodology using standard curve analysis was employed to quantify the relative gene expression level. Unpaired student's t-test was used for statistical analysis. A mean of 2 ± 1.2 embryos were transferred per patient. There were three clinical pregnancies (positive group), one biochemical and two negative pregnancies (negative group). As shown in the table, among the five markers tested, HSF1 and Enolase1 were found to be significantly over expressed only in the negative group.Tabled 1GroupGADPH28SRNATFAMPRDX6ERO1 LAHSF1Enolase 1Positive Mean ± SEM21.6 ± 10.855.8 ± 4.130.7 ± 0.2319.9 ± 12.53.2 ± 1.387.5 ± 4.5269.8 ± 35.35Negative Mean ± SEM70.1 ± 29.3120.2 ± 12.212.8 ± 1.3546.9 ± 17.4111.2 ± 5.0∗∗81.3 ± 38.2∗P=0.04; P=0.03283.5 ± 115.3∗ P=0.04; P=0.03 Open table in a new tab Because of limited information provided by morphological assessment of embryos, IVF programs choose to transfer several rather than a single embryo to increase the odds of pregnancy. The unfortunate consequence of this practice is higher multiple pregnancy rates. Our study demonstrates a significant down regulation in the expression of HSF1 and enolase 1 in the cumulus cells of the oocytes that resulted in pregnancy. We conclude that low cumulus expression of HSF1 (playing a role in environmental and pathophysiological stresses) and Enolase1 (an enzyme of the glycolytic energetic pathway) may prove useful in selection of embryos most suitable for transfer.

Glutamine: the first clinically relevant pharmacological regulator of heat shock protein expression?

It is well known that enhanced heat shock protein expression protects organisms against morbidity and mortality following experimental injury/illness. Presently, chemical/gene therapy based laboratory methods of enhancing heat shock protein expression are impractical for clinical application. Our laboratory has shown glutamine enhances heat shock protein expression following models of experimental illness/injury. The purpose of this review is to examine recent data supporting the use of glutamine as a clinically relevant enhancer of heat shock protein expression. Recent studies indicate glutamine induces heat shock protein-70, HO-1 (heat shock protein-32), and heat shock protein-27 in models of illness/injury. Enhanced expression of heat shock proteins correlates with improved outcome in these models. Further, in-vitro data reveal glutamine enhances DNA binding of heat shock factor-1 (heat shock protein transcription factor) to its promoter. Finally, recently published pilot data show that glutamine enhances serum heat shock protein-70 expression in critically ill patients and this enhanced expression correlates with improved outcome. Currently, extensive data support glutamine as a gene level regulator of heat shock protein expression. Glutamine depletion, following critical illness/injury, is likely to lead to a state in which organisms are unable to induce heat shock proteins appropriately. Further, pharmacologic supplementation of glutamine potentiates the heat shock protein response prior to and following a stress. Pharmacologic trials utilizing glutamine to enhance heat shock proteins in humans are indicated.