FIG. 10.

A tentative model for the role of nestin as a scaffold for cdk5 in myogenic tissues. There is a close relationship between the expression and organization of nestin and cdk5 during myogenic differentiation and regeneration. The cdk5-dependent phosphorylation of nestin at Thr-316 is associated with nestin disassembly. The disassembled nestin could be targeted for degradation or could be reassembled into filaments with other developmental-stage-specific IF proteins. In addition, there is cdk5-dependent turnover of p35 on nestin. Nestin could thereby act as a scaffold for cdk5 in myogenic tissue. The presence of a nestin-cdk5 signaling complex, with active turnover of associated p35, implies that nestin is likely to have a role in the regulation and/or targeting and compartmentalization of cdk5 and p35 activity.