Protein phosphatases regulate a wide array of proteins through post-translational modification and are required for a plethora of intracellular events in eukaryotes. While some core components of the protein phosphatase complexes are well characterized, many subunits of these large complexes remain unstudied. Here we characterize a loss-of-function allele of the protein phosphatase 1 regulatory subunit 35 (Ppp1r35) gene. Homozygous mouse embryos lacking Ppp1r35 are developmental delayed beginning at embryonic day (E) 7.5 and have obvious morphological defects at later stages. Mutants fail to initiate turning and do not progress beyond the size or staging of normal E8.5 embryos. Consistent with recent in vitro studies linking PPP1R35 with the microcephaly protein Rotatin and with a role in centrosome formation, we show that Ppp1r35 mutant embryos lack primary cilia. Histological and molecular analysis of Ppp1r35 mutants revealed that notochord development is irregular and discontinuous and consistent with a role in primary cilia, that the floor plate of the neural tube is not specified. Similar to other mutant embryos with defects in centriole function, Ppp1r35 mutants displayed increased cell death that is prevalent in the neural tube and an increased number of proliferative cells in prometaphase. We hypothesize that loss of Ppp1r35 function abrogates centriole homeostasis, resulting in a failure to produce functional primary cilia, cell death and cell cycle delay/stalling that leads to developmental failure. Taken together, these results highlight the essential function of Ppp1r35 during early mammalian development and implicate this gene as a candidate for human microcephaly.

蛋白磷酸酶通过翻译后修饰调节多种蛋白质，并且是真核生物中大量细胞内事件所必需的。虽然蛋白磷酸酶复合物的一些核心成分已得到很好的表征，但这些大型复合物的许多亚基仍未得到研究。在这里，我们描述了蛋白磷酸酶 1 调节亚基 35 ( Ppp1r35 ) 基因的功能丧失等位基因。缺乏Ppp1r35的纯合小鼠胚胎从胚胎第 (E) 7.5 天开始发育延迟，并在后期有明显的形态缺陷。突变体无法启动转向，也不会进展到超出正常 E8.5 胚胎的大小或阶段。与最近将 PPP1R35 与小头畸形蛋白 Rotatin 联系起来并在中心体形成中发挥作用的体外研究一致，我们表明Ppp1r35突变胚胎缺乏初级纤毛。 Ppp1r35突变体的组织学和分子分析表明，脊索发育是不规则和不连续的，与初级纤毛的作用一致，神经管的底板不明确。与其他具有中心粒功能缺陷的突变体胚胎类似， Ppp1r35突变体表现出神经管中普遍存在的细胞死亡增加和中期增殖细胞数量增加。我们假设Ppp1r35功能的丧失会破坏中心粒稳态，导致无法产生功能性初级纤毛、细胞死亡和细胞周期延迟/停滞，从而导致发育失败。 总而言之，这些结果强调了Ppp1r35在早期哺乳动物发育过程中的基本功能，并表明该基因是人类小头畸形的候选基因。