Nup358 regulates microridge length by controlling SUMOylation-dependent activity of aPKC in zebrafish epidermis

Par polarity complex, consisting of Par3, Par6 and atypical protein kinase C (aPKC), plays a crucial role in establishment and maintenance of cell polarity. Although activation of aPKC is critical for polarity, how this is achieved is unclear. The zebrafish developing epidermis, along with its apical actin based projections called microridges, offers a genetically tractable system for unraveling mechanisms of the cell polaritycontrol. The zebrafish aPKC regulates elongation of microridges by controlling levels of apical Lgl, which acts as a pro- elongation factor. Here, we show that the nucleoporinNup358 - a component of the nuclear porecomplex and a part of cytoplasmic annulate lamellae(AL) - SUMOylates zebrafish aPKC. Nup358-mediated SUMOylation controls aPKC activity to regulate Lgl-dependent microridge elongation. Our data further suggest that cytoplasmic AL structures are the possible site for Nup358-mediated aPKC SUMOylation. We have unraveled hitherto unappreciated contribution of Nup358-mediated aPKC SUMOylation in cell polarityregulation.