An examination of chromatin-associated hsp70 during heat shock in Drosophila

grantor: University of TorontoThe heat shock (hs) response is activated in cells subjected to stress. It is regulated at the molecular level by the heat shock transcription factor HSF. During exposure to stress, inactive monomeric HSF trimerizes and acquires high DNA binding activity to a well-conserved sequence, the hs element (HSE). During prolonged hs, attenuation of the hs response is marked by HSF dissociation from HSEs and the return to its monomeric form. One of the products of hs genes, hsp70, has been implicated in autoregulation of the hs response. We have examined the chromosomal accumulation of hsp70 during heat shock and its possible colocalisation with several different factors. We have found a 78% colocalisation between HSF and hsp70. Subsequent experiments have demonstrated that chromosomal accumulation of hsp10 during hs does not depend on the presence of HSE-bound HSF or the presence of mRNA. A possible role of hsp70 in HSF inactivation is discussed, along with other targets of hsp70 during hs.M.Sc