Bidirectional interaction between Protocadherin 8 and transcription factor Dbx1 regulates cerebral cortex development

Abstract

SUMMARYBrain development requires correct tissue patterning and production of appropriate cell types. Transcription factors (TFs) play essential roles in these processes, regulating the expression of target genes responsible for neuronal subtypes specific features. Cell adhesion molecules are key components of neuronal identities that control cell sorting, migration, neurite outgrowth/guidance and synaptogenesis. To date, the link between TFs and cell adhesion molecules is considered to be unidirectional. Here, we demonstrate that ectopic expression of Dbx1 leads to spatio-temporally restricted increased expression ofPcdh8and cell aggregation, together with changes in neuronal identity. Surprisingly, Pcdh8 overexpression also induces Dbx1 expression as well as a complete reorganisation of apico-basal polarity and dorso-ventral patterningviaNotch signalling. Altogether, our work therefore points to cell adhesion molecules as unexpected, yet important, players in the regulation of cell identity and, in particular, Pcdh8 through its bidirectional interaction with the Dbx1 transcription factor.