RpS13 controls the homeostasis of germline stem cell niche through Rho1-mediated signals in the Drosophila testis.

OBJECTIVES Stem cell niche regulated the renewal and differentiation of germline stem cells (GSCs) in Drosophila. Previously, we and others identified a series of genes encoding ribosomal proteins that may contribute to the self-renewal and differentiation of GSCs. However, the mechanisms that maintain and differentiate GSCs in their niches were not well understood. MATERIALS AND METHODS Flies were used to generate tissue-specific gene knockdown. Small interfering RNAs were used to knockdown genes in S2 cells. qRT-PCR was used to examine the relative mRNA expression level. TUNEL staining or flow cytometry assays were used to detect cell survival. Immunofluorescence was used to determine protein localization and expression pattern. RESULTS Herein, using a genetic manipulation approach, we investigated the role of ribosomal protein S13 (RpS13) in testes and S2 cells. We reported that RpS13 was required for the self-renewal and differentiation of GSCs. We also demonstrated that RpS13 regulated cell proliferation and apoptosis. Mechanistically, we showed that RpS13 regulated the expression of ribosome subunits and could moderate the expression of the Rho1, DE-cad and Arm proteins. Notably, Rho1 imitated the phenotype of RpS13 in both Drosophila testes and S2 cells, and recruited cell adhesions, which was mediated by the DE-cad and Arm proteins. CONCLUSION These findings uncover a novel mechanism of RpS13 that mediates Rho1 signals in the stem cell niche of the Drosophila testis.