Fasawe Ayoola S, Adams Jessica M, Engelke Martin F
School of Biological Sciences, Cell Physiology, Illinois State University, Normal, IL 61790, USA.
iScience. 2024 Feb 5;27(3):109149. doi: 10.1016/j.isci.2024.109149. eCollection 2024 Mar 15.
Primary cilia are essential signaling organelles that protrude from most cells in the body. Heterodimeric kinesin-2 (KIF3A/KIF3B/KAP3) powers several intracellular transport processes, including intraflagellar transport (IFT), essential for ciliogenesis. A long-standing question is how a motor protein is differentially regulated for specific cargos. Since phosphorylation of the KIF3A tail domain was suggested to regulate the activity of kinesin-2 for ciliogenesis, similarly as for the cytosolic cargo N-Cadherin, we set out to map the phosphosites involved in this regulation. Using well-characterized ; mouse embryonic fibroblasts, we performed ciliogenesis rescue assays with a library of phosphomimetic mutants comprising all predicted phosphosites in the KIF3A tail domain. In contrast to previous reports, we found that KIF3A tail domain phosphorylation is dispensable for ciliogenesis in mammals. Thus, mammalian kinesin-2 is differently regulated for IFT than currently thought, consistent with the idea of differential regulation for ciliary and cytosolic cargo.
初级纤毛是从体内大多数细胞伸出的重要信号细胞器。异二聚体驱动蛋白-2（KIF3A/KIF3B/KAP3）推动多种细胞内运输过程，包括鞭毛内运输（IFT），这对纤毛发生至关重要。一个长期存在的问题是运动蛋白如何针对特定货物进行差异调节。由于有人提出KIF3A尾部结构域的磷酸化可调节驱动蛋白-2对纤毛发生的活性，类似于对胞质货物N-钙黏着蛋白的调节，我们着手绘制参与这种调节的磷酸化位点。使用特征明确的小鼠胚胎成纤维细胞，我们用一个包含KIF3A尾部结构域所有预测磷酸化位点的磷酸模拟突变体文库进行了纤毛发生拯救试验。与之前的报道相反，我们发现KIF3A尾部结构域的磷酸化对于哺乳动物的纤毛发生是可有可无的。因此，哺乳动物驱动蛋白-2对IFT的调节方式与目前认为的不同，这与对纤毛和胞质货物进行差异调节的观点一致。
