Restricted expression of cadherin-8 in segmental and functional subdivisions of the embryonic mouse brain.

We have cloned full-length cDNA of a novel mouse cadherin ("mCad8"). The deduced amino acid sequence of the mature form of mCad8 shows 98.2% identity with the sequence of human cadherin-8. The expression of mCad8 was studied by in situ hybridization in mouse embryos of 9.5-14 days gestation (E9.5-E14). Results show that mCad8 expression is restricted to particular subdivisions of the early central nervous system (CNS) and to the thymus. In the CNS, mCad8 expression was observed from E11.5. In the telencephalon, mCad8 is expressed by the ventricular layer of the ganglionic eminence, by cortical areas, and by cells at the caudato-pallial angle. In the diencephalon, the margins of one mCad8-positive area correspond to the borders of the ventral thalamic neuromere, as confirmed by mapping the expression of gene regulatory proteins (Dlx-2, Pax-6, and Gbx-2). In the rhombencephalon, two large groups of mCad8-expressing cells were seen in the pons and in an area of the lateral basal plate of the myelencephalon. These groups of cells extend from the intermediate zone to the mantle zone at E12.5 and later form the anlage of the pontine and the facial nuclei. In conclusion, the expression of mCad8 reflects, in part, the neuromeric organization of the early embryonic CNS. In the mantle layer, mCad8 is expressed by developing gray matter structures, such as brain nuclei, suggesting a role for mCad8 in brain morphogenesis.