LAMININ AND FIBRONECTIN GUIDEPOSTS SIGNAL SUSTAINED BUT OPPOSITE EFFECTS TO PASSING GROWTH CONES

Guidepost cells are known to alter the behavior of growth cones in viv o, yet the nature of communication and the type of signals employed ar e largely undefined. The present study demonstrates that model guidepo sts, composed of a single molecular species, are sufficient to change the navigation and the behavior of advancing growth cones well beyond the time of contact. Laminin on model guideposts caused a sustained in crease in growth cone velocity, whereas fibronectin led to a sustained de,crease. A spatially discrete array of multiple laminin-model guide posts maintained increased growth rates on fibronectin, as expected fo r homogeneous laminin, and also provided unambiguous directional guida nce information. Laminin-evoked growth cone responses required activat ion of protein kinase C-dependent intracellular signaling mechanisms.