MTCL2 is a new Golgi-resident microtubule-regulating protein, essential for organizing asymmetric microtubule network

Abstract The Golgi apparatus plays important roles in organizing the asymmetric microtubule network essential for polarized vesicle transport. The Golgi-associated coiled-coil protein MTCL1 is crucially involved in Golgi functioning by interconnecting and stabilizing microtubules on the Golgi membrane through its N- and C-terminal microtubule-binding domains. Here, we report the presence of a mammalian paralog of MTCL1, named MTCL2, lacking the N-terminal microtubule-binding domain. MTCL2 localizes to the Golgi membrane through the N-terminal region and directly binds microtubules through the conserved C-terminal domain without promoting microtubule stabilization. Knockdown experiments demonstrated essential roles of MTCL2 in accumulating MTs around the Golgi and regulating the Golgi ribbon structure. In vitro wound healing assays further suggested a possible intriguing activity of MTCL2 in integrating the centrosomal and Golgi-associated microtubules around the Golgi ribbon, thus supporting directional migration. Altogether, the present results demonstrate that cells utilize two members of the MTCL protein family to differentially regulate the Golgi-associated microtubules for controlling cell polarity.