Small ribonucleoprotein particle protein SmD3 governs the homeostasis of germline stem cells and the crosstalk between the spliceosome and ribosome signals in <i>Drosophila</i>

Abstract

The ribonucleoprotein (RNP) spliceosome machinery triggers the precursor RNA splicing process in eukaryotes. Major spliceosome defects are implicated in male infertility; however, the underlying mechanistic links between the spliceosome and the ribosome in <i>Drosophila</i> testes remains largely unresolved. Small ribonucleoprotein particle protein SmD3 (SmD3) is a novel germline stem cell (GSC) regulatory gene identified in our previous screen of <i>Drosophila</i> testes. In the present study, using genetic manipulation in a <i>Drosophila</i> model, we demonstrated that SmD3 is required for the GSC niche and controls the self-renewal and differentiation of GSCs in the testis. Using <i>in vitro</i> assays in Schneider 2 cells, we showed that SmD3 also regulates the homeostasis of proliferation and apoptosis in <i>Drosophila</i>. Furthermore, using liquid chromatography-tandem mass spectrometry methods, SmD3 was identified as binding with ribosomal protein (Rp)L18, which is a key regulator of the large subunit in the ribosome. Moreover, SmD3 was observed to regulate spliceosome and ribosome subunit expression levels and controlled spliceosome and ribosome function <i>via</i> RpL18. Significantly, our findings revealed the genetic causes and molecular mechanisms underlying the stem cell niche and the crosstalk between the spliceosome and the ribosome.-Yu, J., Luan, X., Yan, Y., Qiao, C., Liu, Y., Zhao, D., Xie, B., Zheng, Q., Wang, M., Chen, W., Shen, C., He, Z., Hu, X., Huang, X., Li, H., Chen, B., Zheng, B., Chen, X., Fang, J. Small ribonucleoprotein particle protein SmD3 governs the homeostasis of germline stem cells and the crosstalk between the spliceosome and ribosome signals in <i>Drosophila</i>.