Disruption of the nectin-afadin complex recapitulates features of the human cleft lip/palate syndrome CLPED1

Abstract

Cleft palate (CP), one of the most common congenital conditions, arises from failures in secondary palatogenesis during embryonic development. Several human genetic syndromes featuring CP and ectodermal dysplasia have been linked to mutations in genes regulating cell-cell adhesion, yet mouse models have largely failed to recapitulate these findings. Here, we use <i>in utero</i> lentiviral-mediated genetic approaches in mice to provide the first direct evidence that the nectin-afadin axis is essential for proper palate shelf elevation and fusion. Using this technique, we demonstrate that palatal epithelial conditional loss of afadin (<i>Afdn</i>) - an obligate nectin- and actin-binding protein - induces a high penetrance of CP, not observed when <i>Afdn</i> is targeted later using <i>Krt14-Cre</i> We implicate <i>Nectin1</i> and <i>Nectin4</i> as being crucially involved, as loss of either induces a low penetrance of mild palate closure defects, while loss of both causes severe CP with a frequency similar to <i>Afdn</i> loss. Finally, expression of the human disease mutant <i>NECTIN1^W185X</i> causes CP with greater penetrance than <i>Nectin1</i> loss, suggesting this alteration may drive CP via a dominant interfering mechanism.