Studies on the control of myelinogenesis. IV. Neuronal induction of Schwann cell myelin-specific protein synthesis during nerve fiber regeneration

The temporal sequence of axon-Schwann cell interaction during regeneration is examined in cat tibial nerves surgically denervated for 8 weeks, and subsequently, coapted to a freshly severed peroneal nerve for 3 weeks. Prior to association with regenerating axons. Schwann cells resident in denervated and reinnervated stumps failed to synthesize proteins co-migrant with P₀, P₁, and P₂ synthesis of amino acid-labeled protein co-migrating with myelin-specific proteins prior to elaboration of myelin lamellae. Radioactivity from these peaks was precipitated by antibodies raised against myelin-specific proteins. The synthesis of P₁ and P₂ proteins was evident before P₀ synthesis in reinnervated stumps. Immunocytochemical staining with antibody to P₀, P₁, P₂ and myelinassociated glycoprotein (MAG) appeared only after myelin lamellae had been formed. These data suggest that Schwann cells; synthesize protein co-migrant with P₁, P₂, P₀, and MAG in normal cat nerves; cease detectable manufacture of these proteins after axonal loss; regain their capacity to synthesize these proteins upon re-establishment of axonal association; and during regeneration, express the synthesis of P₁ and P₂ before that of P₀.