Department of Genetics, University of Cambridge, Cambridge, UK.
Institute of Biochemistry and Biophysics, Polish Academy of Science, Warsaw, Poland.
J Cell Biol. 2020 Sep 7;219(8). doi: 10.1083/jcb.201912154.
Rcd4 is a poorly characterized Drosophila centriole component whose mammalian counterpart, PPP1R35, is suggested to function in centriole elongation and conversion to centrosomes. Here, we show that rcd4 mutants exhibit fewer centrioles, aberrant mitoses, and reduced basal bodies in sensory organs. Rcd4 interacts with the C-terminal part of Ana3, which loads onto the procentriole during interphase, ahead of Rcd4 and before mitosis. Accordingly, depletion of Ana3 prevents Rcd4 recruitment but not vice versa. We find that neither Ana3 nor Rcd4 participates directly in the mitotic conversion of centrioles to centrosomes, but both are required to load Ana1, which is essential for such conversion. Whereas ana3 mutants are male sterile, reflecting a requirement for Ana3 for centriole development in the male germ line, rcd4 mutants are fertile and have male germ line centrioles of normal length. Thus, Rcd4 is essential in somatic cells but is not absolutely required in spermatogenesis, indicating tissue-specific roles in centriole and basal body formation.
Rcd4 是一种特征不明显的果蝇中心粒组成部分，其哺乳动物对应物 PPP1R35 被认为在中心粒伸长和转化为中心体中发挥作用。在这里，我们表明 rcd4 突变体表现出较少的中心粒、异常的有丝分裂和感觉器官中基底体减少。Rcd4 与 Ana3 的 C 端部分相互作用，该部分在有丝分裂前期加载到前中心粒上，先于 Rcd4 并在有丝分裂之前。因此，Ana3 的耗竭阻止了 Rcd4 的募集，但反之则不然。我们发现，Ana3 和 Rcd4 都没有直接参与中心粒向中心体的有丝分裂转化，但两者都需要加载 Ana1，这对于这种转化是必不可少的。虽然 ana3 突变体是雄性不育的，反映了 Ana3 对雄性生殖系中心粒发育的要求，但 rcd4 突变体是可育的，并且具有正常长度的雄性生殖系中心粒。因此，Rcd4 在体细胞中是必需的，但在精子发生中不是绝对必需的，这表明在中心粒和基底体形成中具有组织特异性作用。
