INTRACELLULAR MECHANISMS OF AXON GROWTH INDUCTION BY CAMS AND INTEGRINS - SOME UNRESOLVED ISSUES

Integrins and cell adhesion molecules (CAMs) are important neuronal re ceptors mediating substrate-induced axon growth. Signaling of axon gro wth through these receptors involves both regulation of tyrosine phosp horylation and transient increases in intracellular Ca2+. Many of the details concerning these signal transduction events and mechanisms thr ough which they regulate effecters of axon growth are poorly understoo d. This review discusses some of the gaps in our current knowledge, wi th suggestions on approaches to closing these gaps. Emphasis is on the role of tyrosine phosphatases in the regulation of axon growth, the o rigin and nature of Ca2+ signals produced by stimulation of CAMs and i ntegrins, and possible links of these two pathways to cytoskeletal rea rrangements and directed addition of plasma membrane.