Project description:Purpose: To analysis impacts of groucho and notch on transcription in Drosophila ISCs by mRNA-seq. Methods: mRNA-seq of RNA extracted from FACS sorted Drosophila ISCs. Results: Groucho loss in ISCs leads to disruption of lateral inhibition,and knocking down notch in ISCs down-regulates expression of e(spl) factors.
Project description:Shavenbaby (Svb) transcription factor is involved in the differenciation of epidermal cells and the homeostasis of intestinal stem cells (ISCs). Svb is produced as a long repressor protein called SvbRepressor (SvbREP). In presence of Pri peptides SvbREP is processed into a shorter activator form (SvbACT) through partial proteasomal degradation of the REP domain. In ISCs, Pri triggers SvbREP to ACT maturation, while SvbREP form accumulates in differentiated enterocytes. The absence of Svb promote the apoptosis of the intestinal stem cells. In ISC, the ectopic expression of SvbREP form promote the differenciation and the SvbACT form overexpression promotes hyperplasia. (Al Hayel, et al 2020) Based on these functional analyses, Svb appears to control ISC survival and behavior, balancing proliferation and differentiation through a molecular switch between its 2 antagonistic isoforms. In this study, we determine the Svb target genes in ISCs. To this aim, we analyze the transcriptomes of ISCs upon modulation of Svb function.
Project description:We previously demonstrated that SRCAP regulates the self-renewal of ESCs and modulates lymphoid lineage commitment. We further validated that SRCAP was mainly distributed in liver, spleen and intestine by Northern blot. SRCAP was also highly expressed in Lgr5+ ISCs. We then sought to explore the physiological role of SRCAP in the regulation of self-renewal maintenance of ISCs.We then generated Srcapflox/flox mice through insertion of loxP sequences flanking at the exon5 of Srcap gene locus. We established Srcapflox/flox;Lgr5GFP-CreERT2 mice through crossing Srcapflox/flox mice with Lgr5GFP-CreERT2 mice. With administration of tamoxifen (TAM), Srcap was completely deleted in Lgr5+ ISCs. We identified that Srcap deficiency impairs the self-renewal of ISCs and intestinal epithelial regeneration. Through RNA-sequencing, we sough to identify the key gene regulated by SRCAP in ISC self-renewal.
Project description:We previously demonstrated that SRCAP regulates the self-renewal of ESCs and modulates lymphoid lineage commitment. We further validated that SRCAP was mainly distributed in liver, spleen and intestine by Northern blot. SRCAP was also highly expressed in Lgr5+ ISCs. We then sought to explore the physiological role of SRCAP in the regulation of self-renewal maintenance of ISCs.We identified that Srcap deficiency impairs the self-renewal of ISCs and intestinal epithelial regeneration. Through SRCAP ChIP-sequencing, we sough to identify the key gene regulated by SRCAP in ISC self-renewal.
Project description:Intestinal epithelial stem cells (ISCs) are the focus of recent intense study. Current in vitro models rely on supplementation with the Wnt agonist R-spondin1 to support robust growth, ISC self-renewal, and differentiation. Intestinal subepithelial myofibroblasts (ISEMFs) are important supportive cells within the ISC niche. We hypothesized that co-culture with ISEMF enhances the growth of ISCs in vitro and allows for their successful in vivo implantation and engraftment. ISC-containing small intestinal crypts, FACS-sorted single ISCs, and ISEMFs were procured from C57BL/6 mice. Crypts and single ISCs were grown in vitro into enteroids, in the presence or absence of ISEMFs. ISEMFs enhanced the growth of intestinal epithelium in vitro in a proximity-dependent fashion, with co-cultures giving rise to larger enteroids than monocultures. Co-culture of ISCs with supportive ISEMFs relinquished the requirement of exogenous R-spondin1 to sustain long-term growth and differentiation of ISCs. Mono- and co-cultures were implanted subcutaneously in syngeneic mice. Co-culture with ISEMFs proved necessary for successful in vivo engraftment and proliferation of enteroids; implants without ISEMFs did not survive. ISEMF whole transcriptome sequencing and qPCR demonstrated high expression of specific R-spondins, well-described Wnt agonists that supports ISC growth. Specific non-supportive ISEMF populations had reduced expression of R-spondins. The addition of ISEMFs in intestinal epithelial culture therefore recapitulates a critical element of the intestinal stem cell niche and allows for its experimental interrogation and biodesign-driven manipulation. Two samples of intestinal subepithelial myofibroblasts were used in this study.
Project description:The regulation of stem cell survival, self-renewal, and differentiation is critical for the maintenance of tissue homeostasis. Although the involvement of signaling pathways and transcriptional control mechanisms in stem cell regulation have been extensively investigated, the role of post-transcriptional control is still poorly understood. Here we show that the nuclear activity of the RNA-binding protein Second Mitotic Wave Missing (Swm) is critical for Drosophila melanogaster intestinal stem cells (ISCs) and their daughter cells, enteroblasts (EBs), to maintain their progenitor cell properties and function. Loss of swm causes ISCs and EBs to stop dividing and instead detach from the basement membrane, resulting in severe progenitor cell loss. swm loss is furthermore characterized by nuclear accumulation of poly(A)+ RNA in progenitor cells. Swm associates with transcripts involved in epithelial cell maintenance and adhesion, and the loss of swm, while not generally affecting the levels of these Swm-bound mRNAs, leads to elevated expression of proteins encoded by some of them, including the fly ortholog of Filamin. Taken together, this study indicates a nuclear role for Swm in adult stem cell maintenance, raising the possibility that nuclear post-transcriptional gene regulation plays vital roles in controlling adult stem cell maintenance and function.