A potential role for N-cadherin in mediating endothelial cell-smooth muscle cell interactions in the rat vasculature

The cadherins are a family of calcium-dependent cell adhesion molecules that play a critical role in morphogenetic cell interactions in the embryo. N-cadherin has been identified in neural and non-neural tissues, including developing muscle; however, there are few reports of N-cadherin expression in adult mammals. We attempted to identify N-cadherin in the rat vasculature and to ask whether it has a role in mediating vascular cell interactions.

Vascular tissues were isolated from Fischer rats and analyzed immunohistochemically and by Western blotting using pan-cadherin and N-cadherin antibodies. Anti-N-cadherin antibodies were used in an in vitro cell adhesion assay to determine if N-cadherin mediates interactions between smooth muscle cells (SMC) and endothelial cells (EC).

Western blot analysis of vascular tissues reveals a 135 kilodalton (kd) band that is recognized by anti-N-cadherin antibodies. N-cadherin localizes in the rat aorta to the endothelium and to the smooth muscle cell layer beneath the internal elastic membrane. A cell adhesion assay demonstrates that rat SMCs and ECs adhere to each other in a Ca(2+)-dependent manner, and an anti-N-cadherin antibody inhibits approximately 25% of this adhesion.

Our data indicate that N-cadherin is expressed in large vessels of the rat and is capable of mediating EC-SMC adhesion in vitro. It is noteworthy that N-cadherin localizes to a population of SMCs in the rat aorta adjacent to ECs suggesting that N-cadherin may mediate EC-SMC interactions in vivo.