hsp70, Hsp70B, heat-shock protein 70, Hsp70Bc, hsp-70
Gene model reviewed during 5.50
There is only one protein coding transcript and one polypeptide associated with this gene
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Hsp70Bb using the Feature Mapper tool.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Hsp70Bb in GBrowse 2
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.
Some Drosophila strains, including that sequenced in the Drosophila genome project have three, not two, tandemly repeated Hsp70 genes at 87C1 (in addition to a reverse orientation Hsp70 gene, Hsp70Ba, approximately 40kb upstream). The distal-most gene of the three tandem copies is Hsp70Bc. The inner two tandem copies are Hsp70Bb and Hsp70Bbb.
The D.melanogaster strain used for sequencing the genome contains an additional, third tandem copy of an Hsp70 gene at 87C as well as the two tandemly repeated copies (Hsp70Bb and Hsp70Bc) which are found in many strains. This additional copy is named "Hsp70Bbb" (see FBrf0137034 and Bettencourt, 2002.1.16, personal communication to FlyBase).
New annotation (CG31359) in release 3 of the genome annotation.
Nucleosomes are not required for polymerase pausing on the Hsp70Bb promoter.
Variation in copy number of Hsp70Bb and Hsp70Bc demonstrates while extra Hsp70 provides additional protection against the immediate damage from heat stress, abnormally high concentrations can decrease growth, development and survival to adulthood.
Natural variation in Hsp70 expression is analysed to study thermotolerance.
The rate and intensity of Hsp70Bb 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.
Species-wide analysis demonstrates a characteristic of heat-shock-inducible genes is the absence of introns.
Construct analysis reveals deletion of the TATA box or the upstream region greatly inhibits transcription under heat shock conditions. Analysis of DNase I hypersensitivity reveals non-histone protein interactions on the mutant promoters. Paused polymerase and Tbp on the Hsp70Bb promoter is detected in intact salivary glands, but not on a promoter lacking the TATA box.
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.
Variation in copy number of Hsp70Bb and Hsp70Bc affects Hsp70 protein concentration in whole larvae and pupae, which in turn affects their tolerance of natural thermal stress and, potentially, their fitness.
Minimal secondary structure is a key determinant of preferential translation during heat shock and the specific location of a cap-proximal portion of the leader influences initiation and a cap-independent mode of translation in unlikely. Heat shock reduces the capacity to unwind 5'-UTR secondary structure, allowing only mRNAs with minimal 5'-UTR secondary structure to be efficiently translated.
RNA polymerase pauses on the Hsp70Bb and His3 promoters in a nuclear extract derived from embryos. Analysis of the transcripts produced from the Hsp70Bb promoter indicates that more than 50% of the polymerases that initiate fail to elongate beyond 40 nucleotides. Permanganate assay also detects a paused polymerase.
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.
Analysis of transgenic lines containing altered Hsp70Bb promoters (fused to reporter gene Yp1), analysed for their ability to bind Hsf protein, indicates that at least three promoter sequences facilitate the binding of Hsf to chromatin, including binding sites for Trl, Tbp and RNA polymerase II.
The molecular architecture of the Hsp70Bb promoter has been analysed by genomic footprinting.
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.
Analysis of Hsp70Bb-Ecol\lacZ constructs in which the spacing between HSEs (heat shock elements) I and II, and between HSEII and the TATA box are altered suggests that Hsf binds cooperatively to the Hsp70Bb promoter.
Heat-induced alterations in RNA-binding proteins do not mediate preferential translation of heat stress mRNAs or repression of normal mRNAs.
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.
The TFIID complex interacts with the promoter of Hsp70Bb making contacts at the TATA element, initiator, +18 and +28 regions. The complex recognises a sequence within the context of the promoter region that corresponds to an initiator consensus sequence.
The 87A7 Hsp70B region is bordered on the proximal and distal sides by two special chromatin structures, scs and scs'. An enhancer blocking assay based on the w gene demonstrates that the two nuclease hypersensitive regions that define part of the scs chromatin structure are essential for the blocking activity. The DNA sequence spanning the nuclease resistant core located between the two hypersensitive regions is dispensable.
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.
In vivo UV cross-linking and nuclear run-on assays shows that RNA polymerase II density on the Hsp70Bb gene is rapidly increased by heat shock.
Hsp70 proteins are of prime importance to heat tolerance.
TATA complex formation on the Hsp70Bb core promoter shows sequence dependence at the TATA element, at the transcription start site and further downstream. Hydroxyl radical interference assays show that these sequences contribute to the TATA complex. The TATA complex contains Tbp. Methylation interference shows that protein contact at the TATA element is in the minor groove. Similar interactions contribute to TATA complexes formed on the Hsp26 and His4 promoters.
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.
Expression of transgenes carrying Hsp70Bb and Hsp70Bc demonstrate that at early embryonic stages the accumulation of Hsp70 is a rate-limiting factor in the acquisition of thermotolerance. Genetic manipulation can improve stress tolerance.
The interaction of Top1 and Top2 gene products with transcriptionally active and inactive Hsp70B has been compared. Topoisomerase I binding sites are found in the transcribed portions of the Hsp70B gene, and only when Hsp70B is transcriptionally active. Topoisomerase II binding to Hsp70B sequences occurs on both transcriptionally active and inactive chromatin. An unusual type of topoisomerase II binding site is associated with the 5' ends of inactive Hsp70 gene, suggesting that this enzyme may be associated with repression of gene transcription.
Using Yp1 reporter gene constructs distal and proximal regions of the Hsp70 promoter have been identified that are required for formation of paused RNA polymerase II, the polymerase is transcriptionally engaged but paused about 25 nucleotides from the start site of Hsp70.
Pausing of RNA polymerase II on the Hsp70Bb gene is not restricted to uninduced cells. A number of paused and elongating RNA polymerase II molecules are detected at the 5' end of Hsp70Bb when transcribed at intermediate levels. Elongation of polymerase from the pause remains the rate limiting step in transcription.
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.
A TATA-dependent protein-DNA complex is found in fractionated embryonic nuclear extracts. DNase I footprint analysis identifies polypeptides (including Taf12, Tbp and RpII140) that require the Hsp70Bb TATA element for binding to regions of the Hsp70Bb promoter.
Analysis of Hsp70-Adh and Hsp70-Ecol\CAT constructs suggests that the Hsp70 3' untranslated region is required for the instability of Hsp70 mRNA seen at normal growth temperatures and for the selective degradation of Hsp70 mRNA seen during recovery from heat shock.
Nuclear run-on experiments investigate the interaction between RNA polymerase II and the uninduced Hsp70Bb promoter.
Deletion analysis of the 5' side of Hsp70Bb demonstrates that two nuclease-hypersensitive sites in chromatin exist upstream of Hsp70Bb. It is proposed that the hypersensitive sites are generated through the binding of a protein that renders the flanking sequence more accessible to nucleases, perhaps by preventing normal chromatin packaging.
Studies demonstrate that heat shock puffs at the site of a construct insertion can be formed if the inserted segment contains a functional heat shock promoter and the active promoter is joined to long transcription units.
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, Pardue and Penman, 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, Hsp70B) that code for the 70,000 dalton heat-shock protein (HSP70), the most abundant of the heat-shock proteins. Hsp70B usually includes three HSP70 encoding genes (Hsp70Ba (proximal), Hsp70Bb (middle), Hsp70Bc (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, Parks, Parker-Thornberg, Mortin and Pelham, 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).