Altered expression of the D1.1 ganglioside in the cerebellum of the Weaver mouse.

Expression of the D1.1 ganglioside was studied immunohistochemically in developing cerebella from normal and weaver mutant mice. In the normal cerebellum at postnatal day 7 (P7), D1.1 expression was restricted to the external granule-cell layer (EGL). At later ages, D1.1 disappeared as the developing granule neurons ceased mitosis and began migrating toward the internal granule-cell layer. In the weaver cerebellum, D1.1 was expressed in the EGL in apparently normal fashion at P7, but failed to disappear at later ages. As late as P35, D1.1 immunoreactivity was observed throughout the weaver cerebellar cortex. The relative amounts of D1.1 ganglioside in weaver and normal cerebella were compared by thin layer chromatography of total gangliosides, followed by overlay of the chromatogram with anti-D1.1 and 125I-labelled second antibody. Autoradiograms showed that at P12 and P35 the weaver tissue contains six- to tenfold more D1.1 than normal tissue. These findings suggest that one result of the weaver mutation is prolonged expression of D1.1. We speculate that the D1.1 ganglioside might be involved in adhesive interactions that regulate the timing of granule-cell migration from the EGL. The prolonged expression of D1.1 could be responsible, in part, for the failure of granule-cell migration in the weaver cerebellum.