Patnaik Sarita Rani, Zhang Xun, Biswas Lincoln, Akhtar Saeed, Zhou Xinzhi, Kusuluri Deva Krupakar, Reilly James, May-Simera Helen, Chalmers Susan, McCarron John G, Shu Xinhua
Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland.
Institute of Molecular Physiology, Johannes Gutenberg-Universität Mainz, D-55128 Mainz, Germany.
Oncotarget. 2018 May 1;9(33):23183-23197. doi: 10.18632/oncotarget.25259.
Ciliopathies are a group of genetically heterogeneous disorders, characterized by defects in cilia genesis or maintenance. Mutations in the gene and its interacting partners, and , cause ciliopathies, but the function of their proteins remains unclear. Here we show that knockdown (KD) of or in hTERT-RPE1 cells results in abnormal actin cytoskeleton organization. The actin cytoskeleton rearrangement is regulated by the small GTPase RhoA via the planar cell polarity (PCP) pathway. RhoA activity was upregulated in the absence of RPGR, RPGRIP1 or RPGRIP1L proteins. In or KD cells, we observed increased levels of DVl2 and DVl3 proteins, the core components of the PCP pathway, due to impaired proteasomal activity. or KD cells treated with thapsigargin (TG), an inhibitor of sarcoendoplasmic reticulum Ca- ATPases, showed impaired store-operated Ca entry (SOCE), which is mediated by STIM1 and Orai1 proteins. STIM1 was not localized to the ER-PM junction upon ER store depletion in or KD cells. Our results demonstrate that the RPGR protein complex is required for regulating proteasomal activity and for modulating SOCE, which may contribute to the ciliopathy phenotype.
纤毛病是一组基因异质性疾病，其特征是纤毛发生或维持存在缺陷。该基因及其相互作用伙伴、 和 的突变会导致纤毛病，但其蛋白质的功能仍不清楚。在这里，我们表明，在hTERT-RPE1细胞中敲低 或 会导致肌动蛋白细胞骨架组织异常。肌动蛋白细胞骨架重排由小GTP酶RhoA通过平面细胞极性（PCP）途径调节。在缺乏RPGR、RPGRIP1或RPGRIP1L蛋白的情况下，RhoA活性上调。在 或 敲低的细胞中，由于蛋白酶体活性受损，我们观察到PCP途径的核心成分Dvl2和Dvl3蛋白水平升高。用毒胡萝卜素（TG）（一种肌浆内质网Ca-ATP酶抑制剂）处理的 或 敲低细胞显示，由STIM1和Orai1蛋白介导的储存性钙内流（SOCE）受损。在 或 敲低细胞的内质网储存耗竭时，STIM1未定位于内质网-质膜交界处。我们的结果表明，RPGR蛋白复合物是调节蛋白酶体活性和调节SOCE所必需的，这可能导致纤毛病表型。
