Repair of a calcium-dependent adhesive mechanism of embryonic neural retina cells: kinetic and molecular analysis

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Abstract
In this paper, we examine the restitution of a Ca2+-dependent adhesive system of embryonic chick neural retina cells following trypsinization in the absence of divalent cations. The processes involved in the restitution of this system are dissected by monitoring the effects of various drugs, alone and in specific combinations, on the kinetics of adhesion and the morphology of 24-h aggregates. In agreement with prior observations, aggregate formation can be separated into two distinct phases: the formation of adhesions and their ultimate stabilization. The formation of adhesions appears to involve two processes, de novo synthesis of protein and mobilization of an endogenous pool, while stabilization requires de novo synthesis of RNA and protein glycosylation. We also examine the appearance of two cell surface molecules previously implicated in the function of the Ca2+-dependent adhesive system. The cells are repaired in the presence or absence of the inhibitors and surface-iodinated at 3 and 5 h. The labelled molecules are then separated by two-dimensional polyacrylamide gel electrophoresis. The appearance of the two molecules, gp130/4·8 and gp70/4·8, is affected by the various drugs in a manner consistent with the effects of these agents on the kinetics of adhesion. These molecules appear to exist in endogenous pools and they are also synthesized de novo during the repair period.