The extracellular matrix glycoprotein, fibronectin, is a potent promoter of peripheral neurite outgrowth. Interactions of peripheral neurons with fibronectin have been shown to be primarily mediated by the β1 class of integrin heterodimers. In the present study, we have examined the expression and regulation of fibronectin and its integrin receptor, α5 β1, in developing and regenerating chick peripheral nerve. We show that fibronectin and α5β1 α5β1 are expressed at comparatively high levels in developing nerve with α5β1 expression on axons and non-neuronal cells. With nerve maturation, both proteins are less prominently expressed and the cellular pattern of α5β1,expression becomes more restricted. Following lesion of mature nerve, both fibronectin and α5β1, are strongly induced with prominent expression of α5β1, on regenerating neurites and Schwann cells. The elevation in fibronectin levels in the regenerating nerve is highest in the vicinity of the lesion, an area undergoing extensive cellular remodeling including Schwann cell migration and growth cone extension. Our results suggest that fibronectin and its receptor, α5β1, may mediate functionally important interactions in the development and regeneration of peripheral nerve.

Keywords:
fibronectin, integrin, peripheral nerve, chick
© 1992 by Company of Biologists
1992
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