The extensive morphological changes of oligodendrocytes during axon ensheathment and myelination involve assembly of the Ilk-Parvin-Pinch (IPP) heterotrimeric complex of proteins to relay essential mechanical and biochemical signals between integrins and the actin cytoskeleton. Binding of Pinch 1 and 2 isoforms to Ilk is mutually exclusive and allows the formation of distinct IPP complexes with specific signaling properties. Using tissue-specific conditional gene ablation in mice, we reveal an essential role for Pinch2 during central nervous system myelination. Unlike Pinch1-gene ablation, loss of Pinch2 in oligodendrocytes results in hypermyelination and in the formation of pathological myelin outfoldings in white matter regions. These structural changes concurred with inhibition of Rho GTPases RhoA and Cdc42 activities and phenocopied aspects of myelin pathology observed in corresponding mouse mutants. We propose a dual role for Pinch2 in preventing excess of myelin wraps through RhoA-dependent control of membrane growth and in fostering myelin stability via Cdc42-dependent organization of cytoskeletal septins. Together, these findings indicate that IPP-containing Pinch2 is a novel critical cell-autonomous molecular hub ensuring synchronous control of key signaling networks during developmental myelination.

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