US EPA

1284273 

Journal Article 

The claudins 

Lal-Nag, M; Morin, PJ 

2009 

Yes 

Genome Biology
ISSN: 1474-7596
EISSN: 1474-760X 

BioMed Central Ltd. 

10 

8 (2009) 

235. 

Claudins are crucial components of tight junctions and are important in regulating permeability and maintaining cell polarity in cell sheets. The claudin multigene family encodes tetraspan membrane proteins that are crucial structural and functional components of tight junctions, which have important roles in regulating paracellular permeability and maintaining cell polarity in epithelial and endothelial cell sheets. In mammals, the claudin family consists of 24 members, which exhibit complex tissue-specific patterns of expression. The extracellular loops of claudins from adjacent cells interact with each other to seal the cellular sheet and regulate paracellular transport between the luminal and basolateral spaces. The claudins interact with multiple proteins and are intimately involved in signal transduction to and from the tight junction. Several claudin mouse knockout models have been generated and the diversity of phenotypes observed clearly demonstrates their important roles in the maintenance of tissue integrity in various organs. In addition, mutation of some claudin genes has been causatively associated with human diseases and claudin genes have been found to be deregulated in various cancers. The mechanisms of claudin regulation and their exact roles in normal physiology and disease are being elucidated, but much work remains to be done. The next several years are likely to witness an explosion in our understanding of these proteins, which may, in turn, provide new approaches for the targeted therapy of various diseases. 

Polarity; Membrane proteins; Permeability; Cancer; Membrane permeability; Tight junctions; Signal transduction; Animal models; Mutation; Endothelial cells; Structure-function relationships