The Tight-Junction Protein Claudin-6 Induces Epithelial Differentiation from Mouse F9 and Embryonic Stem Cells

Abstract

During epithelialization, cell adhesions and polarity must be established to maintain tissue assemblies and separate the biological compartments in the body. However, the molecular basis of epithelial morphogenesis, in particular, a role of cell adhesion molecules in epithelial differentiation from stem cells, remains unclear. Here, we show that the stable and conditional expression of a tight-junction protein, claudin-6 (Cldn6), triggers epithelial morphogenesis in mouse F9 stem cells. We also demonstrate that Cldn6 induces the expression of other tight-junction and microvillus molecules including Cldn7, occludin, ZO-1α+, and ezrin/radixin/moesin-binding phosphoprotein50. These events were inhibited by attenuation of Cldn6 using RNA interference or the C-terminal half of Clostridium Perfringens enterotoxin. Furthermore, similar results were obtained in mouse embryonic stem cells. Thus, we have uncovered that the Cldn6 functions as a novel cue to induce epithelial differentiation.

Cell Adhesion in Epidermal Development and Barrier Formation

“…Loss of claudin 1 not only affects tight-junction activity, but also cornified layer composition and morphology (Sugawara et al, 2013). These data, along with reports that expression of claudin 6 can induce epithelial differentiation (Sugimoto et al, 2013), suggest that claudins may also play auxiliary roles in regulating differentiation. This is consistent with their broad expression pattern in the epidermis.…”

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

“…The failure of terminal differentiation of the tubule cells when XCldn6 was knockeddown is likely a secondary effect of incomplete epithelization due to defected cell adhesions and polarity. Consistent with our data, overexpression of Cldn6 in mouse stem cells was shown able to induce the expression of other tight-junction and microvillus molecules and triggers epithelial morphogenesis [20]. Collectively, our work uncovered a novel role for XCldn6 in embryonic kidney development.…”

“…Cldn6 has also been suggested to be a surface marker for mouse pluripotent stem cells [19] and overexpression of Cldn6 is able to trigger epithelial morphogenesis in mouse stem cells [20]. There are 2 Cldn6 genes reported in Xenopus, Cldn6.1 (also known as Cldn4L2) and Cldn6.2 (also known as Cldn4L1), both of which are expressed in the developing pronephros with similar patterns [21].…”

Role of cell–cell adhesion complexes in embryonic stem cell biology

“…Therefore, various strategies to ablate claudin-6-positive cells have been proposed to eliminate residual, undifferentiated and putative teratoma-forming cells from human cultures that are intended for regeneration purposes (Ben-David et al, 2013). By contrast, the expression of claudin-6 (but not claudin-7) in mESCs induces epithelial differentiation (Turksen and Troy, 2001;Sugimoto et al, 2013), further emphasizing the difference between hESCs and mESCs. These findings imply that specific forms of tight junctions have key roles in the fate of specific pluripotent stem cells.…”