Chiu Shao-Chih, Huang Yun-Ru Jaoying, Wei Tong-You Wade, Chen Jo-Mei Maureen, Kuo Yi-Chun, Huang Yu-Ting Jenny, Liao Yu-Ting Amber, Yu Chang-Tze Ricky
Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.
Department of Medical Research, Translational Cell Therapy Center, China Medical University Hospital, Taichung, Taiwan.
J Cell Physiol. 2022 Jan;237(1):1033-1043. doi: 10.1002/jcp.30589. Epub 2021 Sep 19.
The Golgi apparatus (GA) translocates to the cell leading end during directional migration, thereby determining cell polarity and transporting essential factors to the migration apparatus. The study provides mechanistic insights into how GA repositioning (GR) is regulated. We show that the methyltransferase PRMT5 methylates the microtubule regulator HURP at R122. The HURP methylation mimicking mutant 122F impairs GR and cell migration. Mechanistic studies revealed that HURP 122F or endogenous methylated HURP, that is, HURP m122, interacts with acetyl-tubulin. Overexpression of HURP 122F stabilizes the bundling pattern of acetyl-tubulin by decreasing the sensitivity of the latter to a microtubule disrupting agent nocodazole. HURP 122F also rigidifies GA via desensitizing the organelle to several GA disrupting chemicals. Similarly, the acetyl-tubulin mimicking mutant 40Q or tubulin acetyltransferase αTAT1 can rigidify GA, impair GR, and retard cell migration. Reversal of HURP 122F-induced GA rigidification, by knocking down GA assembly factors such as GRASP65 or GM130, attenuates 122F-triggered GR and cell migration. Remarkably, PRMT5 is found downregulated and the level of HURP m122 is decreased during the early hours of wound healing-based cell migration, collectively implying that the PRMT5-HURP-acetyl-tubulin axis plays the role of brake, preventing GR and cell migration before cells reach empty space.
高尔基体（GA）在定向迁移过程中会转运至细胞前端，从而决定细胞极性并将重要因子运输至迁移装置。该研究为GA重新定位（GR）的调控机制提供了深入见解。我们发现甲基转移酶PRMT5使微管调节蛋白HURP的第122位精氨酸发生甲基化。模拟HURP甲基化的突变体122F会损害GR和细胞迁移。机制研究表明，HURP 122F或内源性甲基化的HURP（即HURP m122）与乙酰化微管蛋白相互作用。HURP 122F的过表达通过降低乙酰化微管蛋白对微管破坏剂诺考达唑的敏感性，稳定了乙酰化微管蛋白的成束模式。HURP 122F还通过使高尔基体对几种高尔基体破坏化学物质脱敏，使其变得僵硬。同样，模拟乙酰化微管蛋白的突变体40Q或微管蛋白乙酰转移酶αTAT1也可使高尔基体变硬，损害GR并阻碍细胞迁移。通过敲低GRASP65或GM130等高尔基体组装因子来逆转HURP 122F诱导的高尔基体硬化，可减弱122F引发的GR和细胞迁移。值得注意的是，在基于伤口愈合的细胞迁移早期，发现PRMT5表达下调，HURP m122水平降低，这共同表明PRMT5-HURP-乙酰化微管蛋白轴起到了制动作用，在细胞到达空白空间之前阻止GR和细胞迁移。
