705B Poster - 11. Cell division and cell growth
Friday April 08, 2:00 PM - 4:00 PM

Authors:
Pallavi Panda ¹; Levente Kovacs ¹; Nikola Dzhindzhe ²; Agnieszka Fatalska ²; Veronica Persico ³; Maria Giovanna Riparbelli ³; Giuliano Callaini ³; David M Glover ¹

Affiliations:
1) California Institute of Technology, United States; 2) University of Cambridge, United Kingdom; 3) University of Siena, Italy

Keywords:
d. centrosome; a. spermatogenesis

Centrosomes are macromolecular protein complexes assembled through precise protein-protein interactions. Such proteins regulating centriole duplication appear to assemble and function in sub-complexes; Sas6 bound to phosphorylated Ana2 initiates pro-centriole formation; Sas4 interacts with centriolar microtubules; the Cep135:Ana1:Asl network promotes centriole to centrosome conversion enabling recruitment of Plk4 and peri-centriolar material. We have recently described a new sub-complex formed in the Drosophila centriole between Rcd4 and the C-terminal half of Ana3. As a poorly characterized Drosophila centriolar protein, we describe null and hypomorphic rcd4 mutant flies that exhibit fewer centrioles and aberrant mitoses in several somatic tissues and show structural defects in the basal bodies of sensory organs. Structured illumination microscopy of cultured cell centrioles reveals that Rcd4 and Ana3 load onto zone I of the centriole during interphase, where Ana3 recruitment precedes Rcd4. We find that neither Ana3 nor Rcd4 participates directly in the mitotic conversion of centrioles to centrosomes, but assembly of the Rcd4:Ana3 sub-complex is a pre-requirement for the recruitment of Ana1 and subsequently for the transition to the final stage of centriole to centrosome conversion. In contrast, we show differing requirements of the sub-complex for centriole development in the male germline. Whereas ana3 mutants are male sterile indicating that Ana3 is essential for centriole formation during spermatogenesis, rcd4 mutants are male fertile, yet display a multitude of centriolar defects. Contrary to our findings in somatic cells, elongated centrioles of ana3 and rcd4 mutant spermatocytes still accumulate Ana1 and Asl. Moreover, it appears that while Rcd4 is not required for the initial recruitment of Ana3 to spermatogonia centrioles, it is needed for the recruitment/maintenance and accurate localization of Ana3 upon centriole elongation in primary spermatocytes. Taken together, our results suggest tissue-specific roles of Rcd4 and Ana3 in centriole and basal body formation.