Department of Cell Biology and Immunology, Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain.
Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain.
Sci Rep. 2019 Feb 4;9(1):1116. doi: 10.1038/s41598-018-38020-5.
The primary cilium is a single non-motile protrusion of the plasma membrane of most types of mammalian cell. The structure, length and function of the primary cilium must be tightly controlled because their dysfunction is associated with disease. Caveolin 1 (Cav1), which is best known as a component of membrane invaginations called caveolae, is also present in non-caveolar membrane domains whose function is beginning to be understood. We show that silencing of α and β Cav1 isoforms in different cell lines increases ciliary length regardless of the route of primary ciliogenesis. The sole expression of Cav1α, which is distributed at the apical membrane, restores normal cilium size in Cav1 KO MDCK cells. Cells KO for only Cav1α, which also show long cilia, have a disrupted actin cytoskeleton and reduced RhoA GTPase activity at the apical membrane, and a greater accumulation of Rab11 vesicles at the centrosome. Subsequent experiments showed that DIA1 and ROCK help regulate ciliary length. Since MDCK cells lack apical caveolae, our results imply that non-caveolar apical Cav1α is an important regulator of ciliary length, exerting its effect via RhoA and its effectors, ROCK and DIA1.
初级纤毛是大多数类型哺乳动物细胞质膜的单一非运动突起。初级纤毛的结构、长度和功能必须受到严格控制，因为它们的功能障碍与疾病有关。 caveolin 1（Cav1）作为膜内陷的组成部分（称为小窝）而广为人知，也存在于非小窝膜结构域中，其功能开始被理解。我们表明，不同细胞系中α和β Cav1 同工型的沉默会增加纤毛长度，而不论初级纤毛发生的途径如何。仅在 Cav1 KO MDCK 细胞中表达分布在顶膜上的 Cav1α，可恢复正常的纤毛大小。仅 KO Cav1α的细胞（也显示长纤毛）具有破坏的肌动蛋白细胞骨架和顶膜处 RhoA GTP 酶活性降低，以及中心体处 Rab11 囊泡的更大积累。随后的实验表明，DIA1 和 ROCK 有助于调节纤毛长度。由于 MDCK 细胞缺乏顶膜小窝，我们的结果表明，非小窝顶膜 Cav1α是纤毛长度的重要调节剂，通过 RhoA 及其效应物 ROCK 和 DIA1 发挥作用。
