Opposing actions of phosphatidylinositol 3-kinase and glycogen synthase kinase-3beta in the regulation of HSF-1 activity.
Elevated temperatures activate the survival promoters Akt and heat shock factor-1 (HSF-1), a transcription factor that induces the expression of heat shock proteins (HSPs), such as HSP-70. Because neuronal mechanisms controlling these responses are not known, these were investigated in human neuroblastoma SH-SY5Y cells. Heat shock (45 degrees C) rapidly activated Akt, extracellular signal-regulated kinases 1 and 2 (ERK1/2), and p38, but only Akt was activated in a phosphatidylinositol 3-kinase (PI-3K)-dependent manner, as the PI-3K inhibitors LY294002 and wortmannin blocked Akt activation, but not ERK1/2 or p38 activation. Akt activation was not blocked by inhibition of p38 or ERK1/2, indicating the independence of these signaling systems. Heat shock treatment also caused a rapid increase in HSF-1 DNA binding activity that was partially dependent on PI-3K activity, as both the PI-3K inhibitors attenuated this response. Because Akt inhibits glycogen synthase kinase-3beta (GSK-3beta), an enzyme that facilitates cell death, we tested if GSK-3beta is a negative regulator of HSF-1 activation. Overexpression of GSK-3beta impaired heat shock-induced activation of HSF-1, and also reduced HSP-70 production, which was partially restored by the GSK-3beta inhibitor lithium. Thus, heat shock-induced activation of PI-3K and the inhibitory effect of GSK-3beta on HSF-1 activation and HSP-70 expression imply that Akt- induced inhibition of GSK-3beta contributes to the activation of HSF-1.[1]References
- Opposing actions of phosphatidylinositol 3-kinase and glycogen synthase kinase-3beta in the regulation of HSF-1 activity. Bijur, G.N., Jope, R.S. J. Neurochem. (2000) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
