Roy Kasturi, Jerman Stephanie, Jozsef Levente, McNamara Thomas, Onyekaba Ginikanwa, Sun Zhaoxia, Marin Ethan P
From the Department of Internal Medicine, Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut 06520-8029 and.
the Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06520-8029.
J Biol Chem. 2017 Oct 27;292(43):17703-17717. doi: 10.1074/jbc.M117.792937. Epub 2017 Aug 28.
Primary cilia are hairlike extensions of the plasma membrane of most mammalian cells that serve specialized signaling functions. To traffic properly to cilia, multiple cilia proteins rely on palmitoylation, the post-translational attachment of a saturated 16-carbon lipid. However, details regarding the mechanism of how palmitoylation affects cilia protein localization and function are unknown. Herein, we investigated the protein ADP-ribosylation factor-like GTPase 13b (ARL13b) as a model palmitoylated ciliary protein. Using biochemical, cellular, and studies, we found that ARL13b palmitoylation occurs in mouse kidneys and that it is required for trafficking to and function within cilia. Myristoylation, a 14-carbon lipid, is shown to largely substitute for palmitoylation with regard to cilia localization of ARL13b, but not with regard to its function within cilia. The functional importance of palmitoylation results in part from a dramatic increase in ARL13b stability, which is not observed with myristoylation. Additional results show that blockade of depalmitoylation slows the degradation of ARL13b that occurs during cilia resorption, raising the possibility that the sensitivity of ARL13b stability to palmitoylation may be exploited by the cell to accelerate degradation of ARL13b by depalmitoylating it. Together, the results show that palmitoylation plays a unique and critical role in controlling the localization, stability, abundance, and thus function of ARL13b. Pharmacological manipulation of protein palmitoylation may be a strategy to alter cilia function.
初级纤毛是大多数哺乳动物细胞质膜的毛发状延伸物，具有特殊的信号传导功能。为了正确运输到纤毛，多种纤毛蛋白依赖于棕榈酰化，即一种饱和16碳脂质的翻译后附着。然而，关于棕榈酰化如何影响纤毛蛋白定位和功能的机制细节尚不清楚。在此，我们研究了蛋白ADP-核糖基化因子样GTP酶13b（ARL13b）作为一种典型的棕榈酰化纤毛蛋白。通过生化、细胞和研究，我们发现ARL13b的棕榈酰化发生在小鼠肾脏中，并且它是运输到纤毛并在纤毛内发挥功能所必需的。肉豆蔻酰化，一种14碳脂质，在ARL13b的纤毛定位方面很大程度上可以替代棕榈酰化，但在其在纤毛内的功能方面则不能。棕榈酰化的功能重要性部分源于ARL13b稳定性的显著增加，而肉豆蔻酰化则未观察到这种情况。其他结果表明，去棕榈酰化的阻断减缓了纤毛吸收过程中发生的ARL13b的降解，这增加了一种可能性，即细胞可能利用ARL13b稳定性对棕榈酰化的敏感性，通过使其去棕榈酰化来加速ARL13b的降解。总之，结果表明棕榈酰化在控制ARL13b的定位、稳定性、丰度以及功能方面发挥着独特而关键的作用。蛋白质棕榈酰化的药理学操纵可能是一种改变纤毛功能的策略。
