Role of cadherins in maintaining the compartment boundary between the cortex and striatum during development

In ventricular cells of the mouse telencephalon, differential expression of cadherin cell adhesion molecules defines neighbouring regions; R-cadherin delineates the future cerebral cortex, while cadherin-6 delineates the late ral ganglionic eminence. By using cell labelling analyses in the whole embr yo culture system, we demonstrated that the interface between R-cadherin an d cadherin-6 expression is a boundary for cell lineage restriction at embry onic day 10.5, Interestingly, when a group of cells with exogenous cadherin -6 were generated to straddle the cortico-straital boundary by electroporat ion at embryonic day 11.0, ectopic cadherin-6-expressing cortical cells wer e sorted into the striatal compartment, and the reverse was the trend for e ctopic R-cadherin-expressing striatal cells. Although cadherin-6 gene knock out mice engineered in this study showed no obvious phenotype in telencepha lic compartmentalisation, the preferential sorting of ectopic cadherin-6-ex pressing cells was abolished in this mutant background. Thus, the different ial expression pattern of cadherins in the embryonic telencephalon is respo nsible for maintaining the cortico-striatal compartment boundary.