Myelin proteolipid protein forms a complex with integrins and may participate in integrin receptor signalling in oligodendrocytes

Abstract

Myelination of axons in the CNS by oligodendrocytes is a process critical to rapid and efficient impulse conduction. A new role for the myelin proteolipid protein (PLP), the most abundant protein of CNS myelin, has been identified, in studies showing PLP interaction with signalling proteins in oligodendrocytes. In particular, these studies suggest that the PLP protein may be involved in signalling through integrins in oligodendrocytes. Stimulation of muscarinic acetylcholine receptors on oligodendrocytes induced formation of a tripartite complex containing PLP, calreticulin, and αv-integrin. PLP interacted directly with the cytoplasmic domain of the αv-integrin. Complex formation was mediated by phospholipase C and Ca2+ binding to the high affinity binding site on calreticulin. This complex appears important for binding of fibronectin to oligodendrocytes. These data establish a novel function for PLP as a part of the integrin signalling complex in oligodendrocytes and suggest that neurotransmitter-mediated integrin receptor signaling may be involved in myelinogenesis.