Overexpression of the Drosophila ATR homologous checkpoint kinase Mei-41 induces a G2/M checkpoint in Drosophila imaginal tissue

Abstract

BackgroundDNA damage generally results in the activation of ATM/ATR kinases and the downstream checkpoint kinases Chk1/Chk2. In Drosophila melanogaster, the ATR homologue meiotic 41 (mei-41) is pivotal to DNA damage repair and cell cycle checkpoint signalling. Although various mei-41 mutant alleles have been analyzed in the past, no gain-of-function allele is yet available. To fill this gap, we have generated transgenic flies allowing temporal and tissue-specific induction of mei-41.ResultsOverexpression of mei-41 in wing and eye anlagen affects proliferation and a G2/M checkpoint even in the absence of genomic stress. Similar consequences were observed following the overexpression of the downstream kinase Grapes (Grp) but not of Loki (Lok), encoding the respective Drosophila Chk1 and Chk2 homologues, in agreement with their previously reported activities. Moreover, we show that irradiation induced cell cycle arrest was prolonged in the presence of ectopic mei-41 expression. Similar to irradiation stress, mei-41 triggered the occurrence of a slower migrating form of Grp, implying specific phosphorylation of Grp in response to either signal. Using a p53R-GFP biosensor, we further show that overexpression of mei-41 was sufficient to elicit a robust p53 activation in vivo.ConclusionWe conclude that overexpression of the Drosophila ATR homologue mei-41 elicits an effectual DNA damage response irrespective of irradiation.Electronic supplementary materialThe online version of this article (10.1186/s41065-018-0066-4) contains supplementary material, which is available to authorized users.

Multiple Wnts act synergistically to induce Chk1/Grapes expression and mediate G2 arrest in Drosophila tracheoblasts

“…Taken together, our findings suggest that Wnt signaling drives high levels of Chk1 expression in tracheoblasts and that high levels of Chk1 in cells that have a basal level of ATR activity is sufficient to induce G2 arrest. Consistent with the proposed model, studies in yeast (Ford et al, 1994), Drosophila (Bayer et al, 2018) and Xenopus (Kumagai et al, 1998) have shown that the overexpression of Chk1 is sufficient to arrest cells in G2.…”

Duox-generated reactive oxygen species activate ATR/Chk1 to induce G2 arrest in Drosophila tracheoblasts

“…In light of the findings that ROS depletion does not perturb Chk1 expression but does perturb Chk1 phosphorylation and function, we hypothesized that ROS may regulate Chk1 phosphorylation in some manner. The ATR-dependent phosphorylation of Chk1 at serine 373 is thought to be necessary for its activation ( Liu et al, 2000 ; Patil et al, 2013 ; Bayer et al, 2018 ). Our immunohistochemical analyses are consistent with these findings.…”

Multiple Wnts act synergistically to induce Chk1/Grapes expression and mediate G2 arrest in Drosophila tracheoblasts

“…In other words, both pChk1 and Chk1 mRNA levels are high in L2 and early L3 and diminish at 32–40 h L3. Studies in yeast ( Ford et al, 1994 ), Drosophila ( Bayer et al, 2018 ) and Xenopus ( Kumagai et al, 1998 ) have shown that the overexpression of Chk1 is sufficient to induce G2 arrest. Thus, we hypothesized that Wnt signaling facilitates high levels of pChk1 via induction of high levels of Chk1 expression.…”