Sequence requirement for expression of the Drosophila melanogaster heat shock protein hsp22 gene during heat shock and normal development.

Abstract

A 14-base-pair sequence element present in almost all Drosophia melanogaster heat shock genes has been implicated in the heat inducibility of transcription. The D. melanogaster gene encoding the smallest heat shock protein, hsp22, contains within its 5' flanking sequences three such repeats, two close to the transcription start site and a distally located third one 101 base pairs further upstream. Deletion analyses reveal that the 5' flanking sequences required for full expression of the hsp22 gene extend beyond the distal repeat. Deletion of the furthest upstream repeat results in a five to sixfold reduction of gene expression. The small heat shock genes are transiently expressed in the late third instar larval and early pupal stages without external stimulation. A deletion of 5' flanking sequences to position -194, which includes two nucleotides of the distal heat shock element, has no effect on the developmental expression, whereas removal of an additional 18 nucleotides, including 12 nucleotides of the distal heat shock element, severely reduces developmental expression.The heat shock genes of Drosophila melanogaster are coordinately induced as a response to the exposure to certain chemicals or high temperatures as well as during recovery from anoxia (for a recent review, see reference 33). All but one of these genes contain within their 5' flanking regions one to four copies of the 14-base-pair (bp) sequence element, the heat shock element (HSE) CTnGAAnTTCnAG (5,26,34,35). All of the four HSEs which are located upstream of the hsp7O gene transcription start site specifically associate with the heat shock transcription factor (HSTF) in vitro (31, 46). The two contiguous HSEs closest to the TATA box bind HSTF cooperatively (46) and are indispensable and sufficient for full induction of in vitromanipulated hsp7O genes after reintroduction into the D. melanagaster genome, whereas the two HSEs located further upstream can be deleted without detectably affecting the heat inducibility of the genes (7).The gene encoding the smallest heat shock protein, hsp22, has three HSEs upstream of the transcribed region, all of which fit the consensus sequence in 8 out of 10 positions (see Fig. 1). Two of them are closely spaced and only 26 and 46 bp from the TATA box, thus at relative positions similar to those of the two indispensable HSEs of the hsp7O genes (see Fig. 7). A third element is found 147 bp upstream of the TATA box, again positioned like one of the two dispensable HSEs in the hsp7O genes. To compare the sequence requirement for the full expression of the hsp22 and hsp7O genes during heat shock we truncated the 5' nontranscribed region of the hsp22 gene to various extents and reintroduced the manipulated genes into a fly strain which synthesizes an electrophoretic variant of hsp22 (hsp22v). Direct comparison of the amount of protein encoded by the reintroduced and the endogenous genes reveals that full gene expression requires sequences that include all three HSEs.The small heat shock genes are induced in the lat...

Organization of the Drosophila melanogaster hsp70 heat shock regulation unit.

“…Analogous observations on other hsp genes have also been reported recently (4,6,9,11,13,18,21,24). We have demonstrated here, using as an example an 88-nucleotidelong hsp70 promoter containing only two heat shock regulatory elements (in regions A and B), that deletion of either element renders the promoter inactive in homologous cells but does not affect its activity substantially in a high-copynumber heterologous system.…”

“…An indication for this may be the actual distances in other hsp promoters between upstream heat shock elements that are known to participate in regulation and downstream consensuslike elements that may be functionally analogous to hsp70 region A. In the promoters of the Drosophila hsp22 (11) and hsp27 genes (24) and of the Xenopus hsp70 gene (4) they are between about 40 and 110 nucleotides, and in those of the Drosophila hsp23 (18,21) and hsp26 genes (6) they are…”

The Small Heat Shock Protein Hsp22 of Drosophila melanogaster Is a Mitochondrial Protein Displaying Oligomeric Organization

“…mRNA for DmHsp22 has been reported to be expressed at different developmental stages and sequences required for expression of its gene during heat shock and normal development are partly defined (26,61). King and Tower (30) showed that DmHsp22 was one of the most abundant heat shock protein in aged flies.…”

Expression profiles of two small heat shock proteins and antioxidant enzyme activity in Mytilus galloprovincialis exposed to cadmium at environmentally relevant concentrations

“…sHsps also participate in toxic (Cd) resistance mechanisms in amphipod species (Shatilina et al, 2010). However, sHsp responses to heat shock and contamination have been more extensively studied in mammals and insects than in marine organisms (Klemenz and Gehring, 1986;Benndorf et al, 2001;Chowdary et al, 2004). More recently, experimental evidence has suggested that an interrelationship between sHsps and redox status exists.…”