Canonical Heat Shock Element in the αB-crystallinGene Shows Tissue-specific and Developmentally Controlled Interactions with Heat Shock Factor

Thaiyalbaga Somasundaram,Suraj P Bhat

doi:10.1074/jbc.m000304200

Abstract

Oligomerization of the heat shock factor (HSF) and its interaction with the heat shock element (HSE) are the hallmark of active transcriptional response to tangible physical or chemical stress. It is unknown if these interactions are subject to control and modulation by developmental cues and thus have tissue or stage specificity. By using promoter sequences containing a canonical HSE from the alphaB-crystallin gene, we demonstrate a tissue-specific transition from monomeric (in fetal and early neonatal stages that lack oligomeric HSF.HSE complexes) to oligomeric HSF-HSE interactions by postnatal day 10-21 in the ocular lens. Developmental control of these interactions is further demonstrated by induction of oligomeric HSF.HSE complexes in neonatal extracts by in vitro manipulations, interestingly, only in the lens and not in the brain, heart, or liver extracts. The exclusive presence of oligomeric HSF.HSE complexes in the postnatal/adult lens corresponds to known highly increased number of alphaB-crystallin transcripts in this tissue.

Highlights

The heat shock response entails activation of transcription from genes containing the heat shock promoter
Developmental control of these interactions is further demonstrated by induction of oligomeric HSF1⁄7HSE complexes in neonatal extracts by in vitro manipulations, interestingly, only in the lens and not in the brain, heart, or liver extracts
Activation of the ␣B heat shock promoter-reporter gene constructs upon exposure to heat stress in cultured cells [26] and HSF1 binding to heat shock element (HSE) in the ␣B promoter in rat astrocytes, exposed to osmotic and chemical stress, have been demonstrated [27]

Summary

Introduction

The heat shock response entails activation of transcription from genes containing the heat shock promoter. By using promoter sequences containing a canonical HSE from the ␣B-crystallin gene, we demonstrate a tissue-specific transition from monomeric (in fetal and early neonatal stages that lack oligomeric HSF1⁄7HSE complexes) to oligomeric HSF-HSE interactions by postnatal day 10 –21 in the ocular lens.

Results

Conclusion