hsp70, Hsp70A, hsp-70, hsp70 87A, heat-shock protein 70
Gene model reviewed during 5.46
There is only one protein coding transcript and one polypeptide associated with this gene
Forms a complex with Hsp83 and Dpit47.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Hsp70Aa using the Feature Mapper tool.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Hsp70Aa in GBrowse 2
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Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
Flies with no copies of the Hsp70 genes (Hsp70Aa, Hsp70Ab, Hsp70Ba, Hsp70Bb, Hsp70Bbb and Hsp70Bc) are unable to survive a severe heat shock. These flies show a lengthened heat-shock response and developmental delay following a non-lethal heat shock.
New annotation (CG31366) in release 3 of the genome annotation.
Natural variation in Hsp70 expression is analysed to study thermotolerance.
The rate and intensity of Hsp70Aa protein expression has been compared with tissue damage after heat shock.
Expression is rapidly induced in the testis after heat stress. Activation of Hsp70 in testes and heads necessitates the presence of a functional Hsf.
There is significant variation among 74 different 2nd chromosome lines and 70 different 3rd chromosome lines in response to heat shock, measured by mRNA accumulation.
d(GA.TC)n sequences can be found in the promoters of Hsp26 and the Hsp70 genes. In vitro assembly of mononucleosomes into short DNA fragments carrying d(GA.TC)n sequences of different lengths is very efficient. Nucleosome assembly is inhibited strongly when the d(GA.TC)n sequence forms a triple-stranded conformation. Triplex formation requires partial destabilisation of the nucleosome. Results indicate nucleosome assembly and triplex formation are competing processes.
Chromosome homologies of Muller's element D (J chromosome in the Paleartic species and XR chromosome arm in Nearctic species) and of element E (O chromosome in the Paleartic species and 2 chromosome in Nearctic species) have been confirmed by single copy probes in the species of the obscura group and in D.melanogaster.
Sodium salicylate induces activation of Hsf binding activity in salivary gland cells and Schneider SL2 tissue cells. Puffing of heat shock gene loci occurs in salivary glands but Hsp70 transcription is not induced suggesting puffing and transcription are separable events.
The in vitro binding of Hsf protein to the promoter region of a number of heat shock genes has been analysed.
UV cross linking technique has been used to study the in vivo distribution of Trl protein on Hsp70 and Hsp26. Prior to heat shock Trl protein is associated with the promoter regions of the uninduced Hsp70 and Hsp26 genes. Upon heat shock induction Trl protein is recruited to their transcription units with its distribution coincident with that of RNA polymerase II.
RNA levels do not increase with age, so the observed increase in protein levels is due to post-transcriptional regulation. Aging-specific expression may be a result of oxidative damage.
Transcription downstream of the polyadenylation site is detected both in cultured cells and in intact flies. Continuous transcripts are detected extending as far as 2kb downstream of the normal polyadenylation site. The predominant extended transcript was 0.45kb long, apparently produced by cleavage of longer transcripts. Its amount relative to the mature message increases with the duration and severity of the heat shock. This data and other lines of evidence suggest that this extended transcript results from an alternative mode of stable 3'-end formation.
Synthesis of heat shock proteins is inhibited by both short-chain fatty acids and their corresponding alcohols, compounds which have no observable effect on histone acetylation.
Gene contains an RNA polymerase II complex which pauses after synthesis of a short transcript. In vivo ultraviolet crosslinking techniques demonstrate phosphorylation of the carboxy terminal domain (CTD) of the large subunit of RNA polymerase II could either regulate the transition of polymerase from a paused to an elongated complex or be a consequence of the transition from paused to elongated.
Introduction of Trl protein during or after nucleosome assembly in vitro results in disruption of nucleosome structure at the Hsp70Aa promoter. Hsp70Aa promoter deletion analysis reveals that disruption of a preassembled nucleosome requires three or four GA/CT elements, nucleosome displacement requires at least two GA/CT elements. The disruption is characterised by hypersensitivity to DNase I digestion and a realignment of adjacent nucleosomes. Disruption is facilitated by the presence of hydrolysable ATP.
Activation of Hsp70Aa is a multistep process. RNA polymerase II is engaged, release of the polymerase and start of transcription requires the binding of heat shock transcription factors (HSF), whose binding is in turn conditional on binding of Trl.
RNA polymerase distribution on uninduced Hsp70 genes has been compared with the distribution of RNA polymerase on DRB (5,6,-Dichloro-1-β-D-ribofuranosylbenzimidazole)-inhibited induced Hsp70 genes.
Psoralen cross-linking studies reveal that the Hsp70A and 18S rRNA DNA is wound with a significant level of superhelical tension irrespective of state of transcriptional activation. Conversely DNA flanking Hsp70A shows substantially less tension, indicating stable, torsionally stressed topological domains. Thus the relaxing activity of topoisomerases is not ubiquitous throughout the nucleus but is tightly regulated.
Hsp70 proteins are of prime importance to heat tolerance.
Members of the hsc70 gene family (heat shock cognate genes) that reside within the same intracellular compartment in different organisms share greater amino acid identity than hsc70 proteins from the same organism but different organelles. This pattern of conservation indicates specialisation of hsc70 function.
Identified in 2D gels of CMW W2 wing imaginal disc cell proteins.
Nascent chain nuclear run-on assays in KC161 cells reveal different responses to heat shock for different genes. Transcription of His1 is severely inhibited under mild heat shocks, of Act5C decreases proportionally with increasing temperature while that of the core histone genes or the heat shock cognates is repressed only under extreme heat shock. In unshocked cells Hsp83 is moderately transcribed while transcription from the other heat shock genes is undetectable. Engaged but paused RNA molecules are found at the various Hsp70 and Hsp26 genes but not at the other heat shock genes. Increased transcription of the heat shock genes is observed within 1-2 mins of heat shock and maximal rates were reached within 2-5 minutes. Rates of transcription vary over a 20-fold range. Hsrω is transcribed at a very high rate under non-heat shock conditions, and its response to elevated temperatures is different from that of the protein coding heat shock genes.
The Hsp70Aa and Hsp70Ab loci are flanked by special chromatin structures, scs and scs'. Each structure is defined by a pair of nuclease hypersensitivity sites bordering a nuclease resistant core of 250-350bp in length. Both scs and scs' have properties that suggest they may correspond to the boundaries of the 87A7 chromomere. scs and scs' are capable of establishing a domain of independent gene activity: w gene flanked by scs and scs' inserted into the genome by P element mediated transformation is isolated against both positive and negative position effects at most insertion sites. scs and scs' also have enhancer blocking activities: when inserted between a Yp1 enhancer and a heat shock promoter-Ecol\lacZ fusion little or no Ecol\lacZ expression is detected even though the promoter is fully heat shock inducible.
The Hsp70A promoter is unsuitable for use in fusion gene constructs for long term expression studies where repeated heat shocks are required as the amount of RNA is substantially reduced.
Probes from D.melanogaster used in chromosome in situ hybridisation to study response to heat shock in D.guanche, D.madeirensis and D.subobscura. Results suggest that the 18C, 94A, 89A and 27A loci of the three obscura group species are homologous to the D.melanogaster loci Hsp83, Hsp70A, Hsp68 and the small Hsp group Hsp22, Hsp23, Hsp26 and Hsp27 respectively.
Translation of Hsp70 mRNAs and to a lesser extent the mRNAs for the small heat shock proteins is almost independent of eIF-4E.
Induction of heat shock protein after metal ion exposure is studied.
Exposure of cells to pulses of elevated temperature initiates the heat-shock response. A restricted subset of genes, the Hsp genes, is activated and the majority of transcription and translation is shut down. However, mitochondrial- and histone-gene activities persist (Spradling et al., 1977). This response follows a pulse of 36oC to 40oC; treatments above 40oC inhibit all activity and lead to death; treatments of 30oC-35oC induce heat-shock-protein synthesis without repressing normal protein synthesis (Tissieres, Mitchell and Tracy, 1974). Similar response inducible by other stressful treatments. The response may be elicited at all stages of the life cycle and in cultured cells. Stage specific phenocopies result from heat shocking early stages of Drosophila development (Mitchell and Petersen, 1982). In polytene cells existing puffs regress and a novel group quickly appears at 33B, 63C, 64F, 67B, 70A, 87A, 87C, 93D, 95D (Ashburner, 1970; Tissieres, Mitchell and Tracy, 1974). Activation of transcription of Hsp genes apparently involves the sequential binding of two or more protein factors in vicinity of TATA box (Wu, 1984). Binding sites for these proteins are multiple short upstream sequence elements called HSEs or heat shock consensus elements (Pelham, 1982; Xiao and Lis, 1988). Polymerase II dissociates from most chromosome regions and accumulates at the new puff sites (Bonner and Kerby, 1982). 3H-uridine incorporation ceases at its usual positions and commences at new puff sites. Preexisting polysomes disaggregate and within a few minutes a new population of polysomes appears containing newly transcribed mRNA; this RNA hybridizes to some of the heat-shock puffs. The effects of heat shock may be abrogated to some degree by pretreatment with a pulse of a slightly lower temperature (Mitchell, Moller, Petersen and Lipps-Sarmiento, 1979; Peterson and Mitchell, 1981). For reviews of the heat-shock response see Ashburner and Bonner (1978).
One of five structural genes (in two clusters, Hsp70A and Hsp70B) that code for the 70,000 dalton heat-shock protein (HSP70), the most abundant of the heat-shock proteins. Hsp70A usually includes two HSP70 encoding genes (Hsp70Aa (proximal), Hsp70Ab (distal)) (Holmgren et al., 1979) with slightly different restriction maps (Artavanis-Tsakonas et al., 1978). HSP70 returns to preshock levels more rapidly than other heat-shock proteins following return to 25oC (DiDomenico, Bugaisky and Lindquist, 1982). The protein becomes concentrated in nuclei during heat shock; disperses to cytoplasm during recovery; returns to nucleus upon further heat shock (Velazquez and Lindquist, 1984). Appears not to be expressed in the testis in response to heat-shock stimulation (Bonner et al., 1984). Deletion of either Hsp70A or Hsp70B does not eliminate the HSP70 heat-shock response; simultaneous deletion of both does (Ish-Horowicz et al., 1979).