High impact information on ash1

• Thus, histone methylation by Ash1 may provide a specific signal for the establishment of epigenetic, active transcription patterns [1].
• Transcriptional activation by Ash1 coincides with methylation of these three lysine residues at the promoter of Ash1 target genes [1].
• Here we show that the epigenetic activator Ash1 (ref. 5) is a multi-catalytic histone methyl-transferase (HMTase) that methylates lysine residues 4 and 9 in H3 and 20 in H4 [1].
• In contrast, the trxG protein Ash1 is only bound in the ON state; not at PREs but downstream of the transcription start site [2].

Biological context of ash1

• Here we report that in extreme ash1 mutants, no H3-K4 methylation is detectable [3].
• Analysis of the effects of ash1 mutations on the activity of this regulatory region indicates that it also contains ash1 response element(s) [4].
• Recessive loss of function mutations in ash1 cause homeotic transformations of imaginal disc derived tissue which resemble phenotypes caused by partial loss or gain of function mutations in genes of the Antennapedia Complex and bithorax Complex [5].
• The cytogenetic location of ash1 was determined to be 76B6-11 by the breakpoint of a translocation recovered in the F1 screen [5].
• Molecular genetic analysis of the Drosophila melanogaster gene absent, small or homeotic discs1 (ash1) [5].

Anatomical context of ash1

• ASH1 was expressed both in embryonic proneural clusters--within which an individual cell retained ASH1 expression, enlarged, segregated, and became a neural precursor--and in larval wing discs in putative sensory mother cells [6].
• The ASH1 protein is localized on polytene chromosomes of larval salivary glands at > 100 sites [7].

Associations of ash1 with chemical compounds

• Two genes with mutant versions that act as dominant suppressors of the wing phenotype were identified: the PKA-C1/DCO gene, encoding the catalytic subunit of cyclic AMP protein kinase, and ash1, a member of the trithorax group (trxG) of chromatin modifiers [8].

Regulatory relationships of ash1

• Using immunocolocalization, we showed that the ASH1 protein is specifically expressed in the majority of the dCBP-overexpressing cells, suggesting that these proteins have the potential to interact biochemically [8].

Other interactions of ash1

• The gene Shal, which is located cytogenetically nearby ash1, was used to initiate an 84-kb genomic walk within which the ash1 gene was identified [5].
• In this paper we examine the consequences of ash1 and ash2 mutations on the expression of homeotic selector genes in imaginal discs [9].
• The absent, small or homeotic discs1 gene (ash1) is one of the trithorax set of genes [5].
• The histone methyltransferases Trithorax and Ash1 prevent transcriptional silencing by Polycomb group proteins [10].

References