26, Hsp 26, DmHsp26
Gene model reviewed during 5.55
Gene model reviewed during 5.46
Gene model reviewed during 5.56
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Hsp26 using the Feature Mapper tool.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Hsp26 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.
Expression is enriched in embryonic gonads.
Shows particularly robust cycling of transcription in adult heads, as assessed by expression analysis using high density oligonucleotide arrays with probe generated during three 12-point time course experiments over the course of 6 days.
Using Hsp26 as a model it is demonstrated that histone acetylation significantly affects the ability of RNA pol II to initiate transcription on a chromatin template by facilitating the access of key regulators to the promoter in chromatin. This finding establishes a causal relationship between histone acetylation and transcription by RNA pol II.
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.
DNA elimination as a mechanism for the loss of gene expression associated with PEV is studied using insertions of an Hsp26 construct. No significant DNA elimination is observed in diploid tissue. Heterochromatic transgenes are underrepresented in polytene tissue. Data suggests DNA loss does not correlate with the reduction in gene expression associated with PEV at pericentric and fourth chromosome sites.
The nucleosome region is not essential for heat shock induction of transcription.
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 transcription from Hsp26 promoter deletion constructs indicates that Trl mediates anti-repression of the Hsp26 promoter in extracts from unstressed embryos, while Hsf activates the Hsp26 promoter in extracts from heat shocked embryos.
Assembly of chromatin on the Hsp26 promoter in embryonic extracts has been used to determine the contribution of transcription factors to promoter architecture in chromatin. Analysis of nucleosome rearrangements by transcription factors indicates the nucleosomes are not disrupted. The basis for the observed chromatin rearrangements is energy driven nucleosome sliding. Hsf and Trl can cause nucleosome rearrangements which may lead to a refinement of nucleosome positions, nucleosome remodeling is ATP-dependent.
The wild-type Hsp26 TATA box is essential for correct binding of TFIID and for inducible expression, but not for the formation of DNase I-hypersensitive sites.
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 Hsp26 making contacts at the TATA element, initiator, +18 and +28 regions.
Distal (CT)n sequence contributes to the levels of heat shock inducibility of Hsp26 and contributes significantly to the formation of the DNase I hypersensitive (DH) sites. The (CT)n sequences are bound by Trl. Deletion of the HSEs severely reduced heat shock inducibility but only has a minor effect n the formation of DH sites.
In vivo UV cross-linking and nuclear run-on assays shows that RNA polymerase II density on the Hsp26 gene is rapidly increased by heat shock.
TATA complex formation on the Hsp70Bb core promoter shows sequence dependence at the TATA element, at the transcription start site and further downstream. Similar interactions contribute to TATA complexes formed on the Hsp26 and His4 promoters.
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.
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. 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. Similar response inducible by other stressful treatments. The response may be elicited at all stages of the life cycle and in cultured cells.
Translation of Hsp70 mRNAs and to a lesser extent the mRNAs for the small heat shock proteins is almost independent of eIF-4E.
Mutations at br reduce the transcription rate or stability of the small heat shock protein mRNAs.
Three regions of 5' DNA contribute to Hsp26 heat induced transcription, HSEs 1, 2 and 6 and the CT.GA region. The homopurine/homopyrimidine sequences in the promoter forms H-DNA in vitro.
The binding sites for the protein factors required for activation of transcription of Hsp genes are multiple short upstream sequence elements called HSEs or heat shock consensus elements.
In absence of stress, the expression of Hsp26 has been observed in spermatocytes, nurse cells, epithelium, imaginal discs, proventriculus, and neurocytes.
Heat-shock inducible in almost all cells at the stages tested.
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.
Activation of transcription of Hsp genes apparently involves the sequential binding of two or more protein factors in vicinity of TATA box.
Polymerase II dissociates from most chromosome regions and accumulates at the new heat shock puff sites upon heat shock.
Hsp26 is transcribed during certain developmental stages in the absence of heat shock.
The effects of heat shock may be abrogated to some degree by pretreatment with a pulse of a slightly lower temperature.
Mitochondrial and histone-gene activities persist transcription and translation.
In polytene cells, during heat shock response, existing puffs regress and a novel group quickly appear at 33B, 63C, 64F, 67B, 70A, 87A, 87C, 93D, 95D.
The heat shock 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.
In polytene cells, during heat shock response, existing puffs regress and a novel group quickly appear at cytological locations 33B, 63C, 64F, 67B, 70A, 87A, 87C, 93D, 95D.