GAL4 induces transcriptionally active puff in the absence of dSAGA- and ATAC-specific chromatin acetylation in the Drosophila melanogaster polytene chromosome

Abstract

Puffs in the polytene chromosome of Drosophila melanogaster are characteristic of sites of high-level active transcription which can be observed directly under the microscope. We studied the dependence of puff formation on chromatin modifications at a site where a GAL4-inducible transgene is located in the 61C7 cytological region. Immunostaining of salivary gland polytene chromosomes indicated no increase of either dSAGA-specific histone H3 lysine 14, or ATAC-specific histone H4 lysine 5 and 12 acetylation in the puffed region. Nor did we observe increased levels of H4K8ac, H3K18ac, or H4K16ac in the puff. In accordance with the above, puff formation as well as localization of Pol II and GAL4 was detectable at the 61C region in dAda2b and dAda2a null homozygotes, which are dSAGA- and ATAC-specific mutants, respectively. Moreover, the reduced level of JIL-1-specific H3 serine 10 phosphorylation did not abolish puff formation in ATAC mutants. Surprisingly, in wild-type animals dADA3 and GCN5 shared constituents of dSAGA and ATAC, as well as JIL-1 localized specifically to the puff, where the JIL-1-phosphorylated H3S10ph level was also high. Altogether these data strongly suggest that the GAL4 activator can induce transcription and chromatin reorganization seen as a puff without dSAGA- and ATAC-specific histone acetylation and JIL-1-specific histone H3 phosphorylation.

14-3-3 Mediates Histone Cross-Talk during Transcription Elongation in Drosophila

“…Total levels of H3K79 methylation and H3K36 methylation, which mark transcription elongation, were also examined and found to be reduced in JIL-1 mutants, providing additional and independent evidence for our previous finding of a role for JIL-1 in transcription elongation (Supporting Figure 1B and 1C in Text S1). Recruitment of JIL-1 to the hsp70 promoter explains the phosphorylation of H3S10 at heat-shock puffs, which has been observed consistently by various investigators using antibodies from different sources and varying fixation protocols [11], [17], [19]–[23]; also see Supporting Figure 4A in Text S1. In agreement with this conclusion, polytene chromosomes from JIL-1 null mutants lack H3S10ph at the heat-shock puffs, while Pol II phosphorylated at Ser5 is still present [17].…”

The role of transcriptional coactivator ADA2b in Arabidopsis abiotic stress responses

“…27,28 For instance, dADA2a is present in the ATAC (Ada2a-containing) complex, 29,30 while dADA2b is present in the SAGA complex. [31][32][33] However, contrary to what the situation is in Arabidopsis, both dADA2A and dADA2b are required for normal development. 32 It remains to be learned whether AtADA2a and AtADA2b are part of different GCN5-containing complexes in Arabidopsis, which have different HAT activity and/or specificity.…”

Arabidopsis thaliana transcriptional co-activators ADA2b and SGF29a are implicated in salt stress responses

“…The Drosophila genome also encodes two ADA2 proteins, which appear to be specific components of different GCN5-containing complexes (Kusch et al 2003;Muratoglu et al 2003). For instance, dADA2a is present in the ATAC (Ada2a-containing) complex (Ciurciu et al 2006;Guelman et al 2006), while dADA2b is present in the SAGA complex (Ciurciu et al 2009;Pankotai et al 2005;Qi et al 2004). However, contrary to what the situation is in Arabidopsis, both dADA2A and dADA2b are required for normal development (Pankotai et al 2005).…”