Xenopus Claudin-6 is required for embryonic pronephros morphogenesis and terminal differentiation.

Claudins are tetratransmembrane tight junction proteins and play important roles in regulating paracellular permeability of different nephron segments of the kidney. However, the roles of claudins in kidney development remain largely unknown. Here we studied the expression and functions of claudin-6 in Xenopus pronephros development. Xenopus claudin-6 is expressed in the developing pronephric tubule and duct but not glomus. Knockdown of claudin-6 by specific morpholino led to severe defects in pronephros tubular morphogenesis and blocked the terminal differentiation of the tubule cells. The claudin-6 morpholino targeted tubule cells showed failure of apical accumulation of actin and reduced lateral expression of tight junction protein Na/K-ATPase, suggesting an incomplete epithelization likely due to defected cell adhesions and apical-lateral polarity. Our work uncovered a novel role for claudin-6 in embryonic kidney development.