Investigation Of Atac2 And Rpd3 In The Homeostasis Of Drosophila Intestinal Stem Cells

The midgut stem cell of Drosophila melanogaster is an important model to investigate the intestinal stem cell(ISC) and the homeostasis of intestine. We took the ISC system in Drosophila midgut epithelium as a model and used the RNA interference(RNAi) technology to screen out a pair of histone acetylation modification genes, Atac2 and Rpd3, involving in the regulation of Drosophila ISC antagonistically.Histone acetylation modification is an important epigenetic modification. It can regulate the transcriptional expression of downstream target genes by changing the acetylation level of histone. The level of histone acetylation is regulated by two antagonistic enzymes, histone acetyltransferase(HAT) and histone deacetylase(HDAC). Atac2 is a HAT, Rpd3 is a HDAC. This study focused on the function of Atac2 and Rpd3 in ISC regulation. The results we got is as following:1. Overexpression of Atac2 in midgut ISC promoted its differentiation. Conversely, inhibition of Atac2 suppress the ISC differentiation. The HAT domain was required for Atac2 to regulate ISC. Overexpression of mouse Atac2(mAtac2) promotes the Drosophila ISC differentiation, indicating that the regulation of Atac2 on the ISC might be conversed in different species.2. Knockdown of Rpd3 promotes the differentiation of ISC. Conversely, Rpd3 overexpression inhibits the ifferentiation of ISC, indicating that Rpd3 and Atac2 antagonistically regulated the ISC. Further study showed that Rpd3 regulated multiple histone acetylation residues, including H2BK5、H4K5、H4K8、H4K12 and H4K16.3. We found that Rpd3 and Atac2 antagonistically regulated the ISC homeostasis。After midgut injured, the expression of Atac2 was increased, but Rpd3 expression was inhibited; Knockdown of Atac2 or Rpd3 overexpression can suppress the intestinal regeneration induced by injury.4. Rpd3 functioned downstream of multiple ISC-controlling signals. Immunostaining showed that Rpd3 functioned downstream of JNK、Notch、EGFR and Wg signal pathway.