Department of Anatomy and Cell Biology, Faculty of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan.
Department of Cell Biology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan; Department of Biochemistry, University of Oxford, Oxford, UK.
J Biol Chem. 2023 Mar;299(3):102985. doi: 10.1016/j.jbc.2023.102985. Epub 2023 Feb 6.
Primary cilia are organelles consisting of axonemal microtubules and plasma membranes, and they protrude from the cell surface to the extracellular region and function in signal sensing and transduction. The integrity of cilia, including the length and structure, is associated with signaling functions; however, factors involved in regulating the integrity of cilia have not been fully elucidated. Here, we showed that the Rab GTPase-binding protein EHBP1L1 and its newly identified interactors CD2AP and CIN85, known as adaptor proteins of actin regulators, are involved in ciliary length control. Immunofluorescence microscopy showed that EHBP1L1 and CD2AP/CIN85 are localized to the ciliary sheath. EHBP1L1 depletion caused mislocalization of CD2AP/CIN85, suggesting that CD2AP/CIN85 localization to the ciliary sheath is dependent on EHBP1L1. Additionally, we determined that EHBP1L1- and CD2AP/CIN85-depleted cells had elongated cilia. The aberrantly elongated cilia phenotype and the ciliary localization defect of CD2AP/CIN85 in EHBP1L1-depleted cells were rescued by the expression of WT EHBP1L1, although this was not observed in the CD2AP/CIN85-binding-deficient mutant, indicating that the EHBP1L1-CD2AP/CIN85 interaction is crucial for controlling ciliary length. Furthermore, EHBP1L1- and CD2AP/CIN85-depleted cells exhibited actin nucleation and branching defects around the ciliary base. Taken together, our data demonstrate that the EHBP1L1-CD2AP/CIN85 axis negatively regulates ciliary length via actin network remodeling around the basal body.
原发性纤毛是由轴丝微管和质膜组成的细胞器，从细胞表面突出到细胞外区域，在信号感应和转导中发挥作用。纤毛的完整性，包括长度和结构，与信号功能有关；然而，调节纤毛完整性的因素尚未完全阐明。在这里，我们表明 Rab GTPase 结合蛋白 EHBP1L1 及其新鉴定的相互作用物 CD2AP 和 CIN85，作为肌动蛋白调节剂的衔接蛋白，参与纤毛长度的控制。免疫荧光显微镜显示 EHBP1L1 和 CD2AP/CIN85 定位于纤毛鞘。EHBP1L1 耗竭导致 CD2AP/CIN85 的定位错误，表明 CD2AP/CIN85 定位于纤毛鞘依赖于 EHBP1L1。此外，我们确定 EHBP1L1 和 CD2AP/CIN85 耗竭的细胞具有延长的纤毛。EHBP1L1 耗尽细胞中异常延长的纤毛表型和 CD2AP/CIN85 的纤毛定位缺陷可以通过表达 WT EHBP1L1 来挽救，尽管在 CD2AP/CIN85 结合缺陷突变体中没有观察到这种情况，这表明 EHBP1L1-CD2AP/CIN85 相互作用对于控制纤毛长度至关重要。此外，EHBP1L1 和 CD2AP/CIN85 耗竭的细胞在纤毛基部周围表现出肌动蛋白成核和分支缺陷。总之，我们的数据表明，EHBP1L1-CD2AP/CIN85 轴通过围绕基体的肌动蛋白网络重塑负向调节纤毛长度。
