Gamma-TuRC proteins contribute to the dynamic organization of MTOCs duringDrosophilaspermatogenesis

Abstract

The initiation of microtubule formation in eukaryotes is primarily facilitated by γ-tubulin and the highly conserved protein complex called γ-Tubulin Ring Complex (γ-TuRC) in various microtubule-organizing centers (MTOCs). Non-centrosomal MTOCs have a range of functions and contribute to diverse cellular activities in different cell types. While the heterogeneity of tissue-specific MTOCs and γ-TuRC in Drosophila testis is known, their molecular composition and physiological significance are poorly understood. In this study, we investigate the testis-specific distribution of the canonical γ-TuRC by in vivo tagging of two complex members, Grip163 and Grip84. We find that both the testis-specific (t- γ-TuRC) and canonical form of γ-TuRC are simultaneously present and colocalize with each other at the basal body, apical nuclear tip, and near the mitochondrial derivatives in the post-meiotic spermatids. We propose the possibility of the formation of MTOCs containing both t-γ-TuRC and γ-TuRC complexes. We find some of the known γ-TuRC binding partners localizing to the apical nuclear tip. Additionally, we identify the Golgi localization of Grip84 in spermatocytes, alongside its centrosomal and diverse post-meiotic localization. These results highlight and prove the importance of the different γ-TuRCs in organizing the diverse MTOCs during the extensive rearrangement of cell organelles in Drosophila spermatogenesis.