Claudin family members exhibit unique temporal and spatial expression boundaries in the chick embryo

Abstract

The claudin family of proteins are integral components of tight junctions and are responsible for determining the ion specificity and permeability of paracellular transport within epithelial and endothelial cell layers. Several members of the claudin family have been shown to be important during embryonic development and morphogenesis. However, detailed embryonic expression patterns have been described for only a few claudins. Here, we provide a phylogenetic analysis of the chicken claudins and a comprehensive analysis of their mRNA expression profiles. We found that claudin family members exhibit both overlapping and unique expression patterns throughout development. Especially striking were the distinct expression boundaries observed between neural and non-neural ectoderm, as well as within ectodermal derivatives. Claudins were also expressed in endodermally-derived tissues, including the anterior intestinal portal, pharynx, lung and pancreas and in mesodermally derived tissues such as the kidney, gonad and heart. The overlapping zones of claudin expression observed in the chick embryo may confer distinct domains of ion permeability within the early epiblast and in epithelial, mesodermal and endothelial derivatives that may ultimately influence embryonic patterning and morphogenesis during development.

Keywords: :

• claudin
• chick development
• boundaries
• tight junction
• expression

Disclosure of Potential Conflicts of Interest

No potential conflict of interest was disclosed.

Acknowledgments

We would like to thank members of the Ryan lab, K. Dewar, I. Gupta and L. Jerome-Majewska for helpful discussions and comments. M.M.C. is the recipient of a doctoral studentship from the Fonds de la Recherche en Santé du Quebec (FRSQ) and A.I.B. is the recipient of a studentship from the Foundation of Stars. This work was funded by a Natural Sciences and Engineering Research of Canada Discovery Grant and a Canadian Institutes of Health Research Operating Grant to A.K.R. A.K.R. is a member of the Research Institute of the McGill University Health Centre, which is supported in part by the FRSQ.