Abstract：
Primary cilia are essential cellular antennae that transmit external signals into intracellular responses. These sensory organelles perform crucial tasks in triggering intracellular signaling pathways, including those initiated by G protein-coupled receptors (GPCRs). Given the involvement of GPCRs in serum-induced signaling, we investigated the contribution of ciliary proteins in mitogen perception and cell proliferation. We found that depletion of cilia via IFT88 silencing impaired cell growth and repressed YAP activation against serum and its mitogenic constituents, namely lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P). To identify the key player of serum mitogen signaling, a mutant cell line library with 30 ablated individual ciliary proteins was established and screened based on YAP dephosphorylation and target gene induction. While 9 of them had altered signaling, ablation of IFT38 or IFT144 led to a particularly robust repression of YAP activation upon LPA and S1P. The deficiency of IFT38 and IFT144 attenuated cell proliferation, as corroborated in either 2-dimensional cultures or tumor spheroids. In subcutaneous skin melanoma patients, expression of IFT38 and IFT144 was associated with unfavorable outcomes in overall survival. In conclusion, our study demonstrates the involvement of ciliary proteins in mitogen signaling and identifies the regulatory roles of IFT38 and IFT144 in serum-mediated Hippo pathway signaling and cellular growth.
摘要：
初级纤毛是将外部信号传递到细胞内反应的重要细胞触角。这些感觉器官在触发细胞内信号通路中执行关键任务，包括由G蛋白偶联受体（GPCRs）启动的那些。鉴于GPCRs参与血清诱导的信号传导，我们研究了纤毛蛋白在丝裂原感知和细胞增殖中的作用。我们发现通过IFT88沉默纤毛的消耗会损害细胞生长并抑制YAP对血清及其促有丝分裂成分的激活，即溶血磷脂酸(LPA)和1-磷酸鞘氨醇(S1P)。为了确定血清丝裂原信号的关键参与者，基于YAP去磷酸化和靶基因诱导，建立并筛选了具有30个消融的单个纤毛蛋白的突变细胞系文库。虽然其中9人改变了信号，IFT38或IFT144的消融导致对LPA和S1P的YAP激活的特别强烈的抑制。IFT38和IFT144的缺乏减弱了细胞增殖，在二维培养物或肿瘤球体中得到证实。在皮下皮肤黑色素瘤患者中，IFT38和IFT144的表达与总生存期的不良结局相关.总之,我们的研究表明纤毛蛋白参与丝裂原信号传导,并确定了IFT38和IFT144在血清介导的Hippo途径信号传导和细胞生长中的调节作用.
