Abstract：
Primary cilia are thin hair-like organelles that protrude from the surface of most mammalian cells. They act as specialized cell antennas that can vary widely in response to specific stimuli. However, the effect of changes in cilia length on cellular signaling and behavior remains unclear. Therefore, we aimed to characterize the elongated primary cilia induced by different chemical agents, lithium chloride (LiCl), cobalt chloride (CoCl2), and rotenone, using human retinal pigmented epithelial 1 (hRPE1) cells expressing ciliary G protein-coupled receptor (GPCR), melanin-concentrating hormone (MCH) receptor 1 (MCHR1). MCH induces cilia shortening mainly via MCHR1-mediated Akt phosphorylation. Therefore, we verified the proper functioning of the MCH-MCHR1 axis in elongated cilia. Although MCH shortened cilia that were elongated by LiCl and rotenone, it did not shorten CoCl2-induced elongated cilia, which exhibited lesser Akt phosphorylation. Furthermore, serum readdition was found to delay cilia shortening in CoCl2-induced elongated cilia. In contrast, rotenone-induced elongated cilia rapidly shortened via a chopping mechanism at the tip of the cilia. Conclusively, we found that each chemical exerted different effects on ciliary GPCR signaling and serum-mediated ciliary structure dynamics in cells with elongated cilia. These results provide a basis for understanding the functional consequences of changes in ciliary length.
摘要：
初级纤毛是从大多数哺乳动物细胞的表面突出的薄薄的毛发样细胞器。它们充当专门的细胞天线，可以响应特定的刺激而变化很大。然而,纤毛长度的变化对细胞信号和行为的影响尚不清楚.因此,我们旨在表征由不同化学试剂诱导的细长初级纤毛，氯化锂(LiCl),氯化钴(CoCl2),和鱼藤酮,使用表达睫状G蛋白偶联受体（GPCR）的人视网膜色素上皮1（hRPE1）细胞，黑色素浓缩激素（MCH）受体1（MCHR1）。MCH主要通过MCHR1介导的Akt磷酸化诱导纤毛缩短。因此,我们验证了MCH-MCHR1轴在细长纤毛中的正常功能。尽管MCH缩短了LiCl和鱼藤酮延长的纤毛，它没有缩短CoCl2诱导的细长纤毛，表现出较少的Akt磷酸化。此外，发现血清重新添加会延迟CoCl2诱导的细长纤毛的纤毛缩短。相比之下,鱼藤酮诱导的细长纤毛通过纤毛尖端的切碎机制迅速缩短。最后，我们发现,在纤毛延长的细胞中,每种化学物质对纤毛GPCR信号传导和血清介导的纤毛结构动力学产生不同的影响.这些结果为理解纤毛长度变化的功能后果提供了基础。
