STRIPAK controls cell-cell communication by promoting cytoneme biogenesis through the membrane-sculpting function of Slik.

Abstract

Cytonemes are signaling filopodia that facilitate long-range cell-cell communication by forming synapses between cells. Initially discovered in Drosophila for transporting morphogens during embryogenesis, they have since been identified in mammalian cells and recently implicated in carcinogenesis. Yet, despite their importance, the mechanisms controlling cytoneme biogenesis remain elusive. Here, we demonstrate that the Ser/Thr kinase Slik drives remote cell proliferation by promoting cytoneme formation. We discovered that this function depends on the coiled-coil domain of Slik (SlikCCD), which directly sculpts membranes into tubules. Importantly, Slik plays paradoxical roles in cytoneme biogenesis. While its membrane-sculpting activity promotes cytoneme formation, it is counteracted by its kinase activity, which enhances actin association with the plasma membrane via Moesin phosphorylation. In vivo, SlikCCD enhances formation of cytonemes in one epithelial layer of the wing disc to promote cell proliferation in an adjacent layer. Finally, we found that this function relies on the STRIPAK complex, which controls cytoneme formation and governs proliferation at a distance by regulating Slik association with the plasma membrane. Our study unveils the first family of kinases that directly sculpts membranes, a function crucial for cytoneme-mediated control of cell proliferation.