2dCe), indicating that reduced resulted in apoptosis in the differentiated gut cells. relapse Rabbit Polyclonal to TFE3 of tumours after treatment, yet the molecular mechanism of this resistance is poorly understood. As the cell type that constantly regenerates and gives rise to differentiated cell types in a tissue, stem cells share high similarities with cancer stem cells, including unlimited regenerative capacity and resistance to genotoxic agents10. Adult stem cells in model organisms such as microenvironment11C13. In this study, we show that adult stem cells are resistant to radiation/chemical-induced apoptosis and dissect the mechanism for this protection. We show that a previously reported cell survival gene with a human homologue, acts in both stem cells and in differentiating cells to repress the transcription factor levels in mutants lead to apoptosis in differentiating cells, but not in stem cells, indicating the presence of an additional anti-apoptotic mechanism(s) in the latter. We show that this mechanism requires and orthologue. Knocking down the ligand in differentiating daughter cells made stem cells more sensitive to radiation-induced apoptosis, suggesting that from the apoptotic differentiating daughter cells protects stem cells. Results stem cells resist IR/maytansinol caused apoptosis External stress, such as ionizing radiation (IR), induces DNA damage and apoptosis in ovary, two to three germline stem cells (GSCs), marked by spherical spectrosomes (SS), are in direct contact with the somatic niche composed of terminal filaments and cap cells (Fig. 1a). The GSC divides asymmetrically along the anteriorCposterior axis from the niche, producing a GSC and a transit-amplifying (TA) daughter cystoblast (CB). The CB further divides to form a 2C16 cell cyst containing interconnected cells (Fig. 1a)15. We found that the multi-cell cysts, marked by branched fusomes, were eliminated within 3 days after exposure to 50 Gy of -rays (Fig. 1b,c,e; Supplementary Table 1), resulting in a significantly diminished region 1C2A in germarium (bracket length). Most of the remaining cells, including the 2C3 closely attached to the somatic niche, are labelled with SSs, indicating MPI-0479605 the GSC identity (Fig. 1c, dashed circles, f; Supplementary Table 1). We conclude that irradiation MPI-0479605 results in the loss of differentiating cyst cells but not GSCs. Importantly, 7 days post-IR MPI-0479605 treatment, the multi-cell cysts were observed again in the germaria (Fig. 1dCe), indicating that the irradiated GSCs are able to repopulate the tissue. Open in a separate window Figure 1 Ionizing radiation and maytansinol caused cell death in differentiated cells but not in stem cells(a) Diagram showing the germarium of ovary. GSCs (GSC, pink) indicated by anterior spectrosomes (SS, red) are located at the anterior end of the germarium adjacent to the niche cap cells (CpC, light green). Escort stem cell (ESC, lavender), differentiated CB (blue), germ cell cyst marked by the presence of branched fusomes (BS, red), somatic stem cells (SSCs, violet), follicle cells (FC, light blue). (bCd) w? germarium representative of three experiments* from 2 h, 3 days and 7 days post 50 Gy MPI-0479605 gamma-irradiation (IR). White dashed circles mark the GSCs. Brackets indicate stages 1 and 2A. Adducin and LaminC (red); cleaved caspase 3 (green); DAPI (4,6-diamidino-2-phenylindole; blue). Scale bar, 20 m. (e) Mean percentage of germaria with branched fusomes in w? females at 0 h (=398), 2 h (= 173), 1 day (=203), 3 days (=148) and 7 days (= 171) post 50 Gy IR. (f) Mean percentage of germaria with dotted spectrosome adjacent to the niche at 0 h, 2 h, 1 day, 3 days and 7 days post 50 Gy IR. Error bars, s.d. (g) Diagram of ISC and the differentiated progenies. EB MPI-0479605 (green), EC (blue), ee cells (purple). (hCi) Posterior midgut of esgGal4; UAS-GFP adults 2 h and 3 days post 50 Gy IR. Scale bar, 75 m. (j) Mean percentage of cleaved caspase3 + cells in ISC/EB (= 197), ee (=251), and EC cell types (= 818) respectively. Error bar, s.e.m. (k) Schematic diagram of the male GSC niche. SC, spermatocytes. Dotted and branched fusomes are indicated in red in GSCs and differentiated cells. (lCm) testis before and after 10 M maytansinol feeding. Cleaved caspase3 (red). Scale bar, 75 m. (nCo) Male GSC niche before and after 3 days 10 M maytansinol treatments. Arrow points at GSC adjacent to the niche; arrowhead points at differentiated germline cell with cleaved caspase3 expression. Scale bar, 20 m. *All figures are representative of at least three experiments unless stated otherwise. Another well-studied adult.