Cadherin function in epidermal morphogenesis and barrier formation
Zusammenfassung der Projektergebnisse
Components of intercellular adhesive junctions are crucial for the formation and maintenance of both integrity, barrier function and skin homeostasis. Previously, we showed that the adherens junction molecule E-cadherin is essential for in vivo skin barrier function by regulating tight junctions. The overall aim of the project was to addresses the underlying mechanisms by which E-cadherin regulates epidermal barrier formation and if classical cadherins are important for skin morphogenesis and homeostasis using a combination of in vivo and in vitro models. Previous studies had suggested an E-cadherin specific function in the regulation of tight junctions. Using E-cadherin-/- keratinocytes we found that the dysfunction of epidermal tight junctional barrier function induced by the loss of E-cadherin can be rescued by lentiviral overexpression of either E-cadherin or P-cadherin, indicating that levels but not cadherin specificity regulates tight junctional function. Surprisingly, membrane recruitment of key tight junctional proteins, such as claudin-1 and ZO-1, is unaffected by the loss of E-cadherin even though these junctions were unable to form a functional ion- and size barrier. This for the first time uncouples membranen recruitment from barrier function and suggests that classical cadherins regulate a late step in this transition. Our previus results identified the atypical kinase C (aPKC) and its upstream regulator Rac, a small GTPase, as potential mediators of E-cadherin mediated regulation of barrier function. However, thus far we were unsuccessful in generating lines in which the majority of cells overexpress either aPKC or Rac, which is necessary to perform functional assays. At present we are setting up an inducible lentiviral expression system to overcome these problems. To examine overlapping and separate functions of E- and P-cadherin in epidermal morphogenesis and homeostasis, we generated mice with a tetracycline inducible P- cadherin specific short hair pin RNA. These mice are now ready to be crossed with epidermal specific E-cadherin knockout mice. In addition, using lentiviral expression of short hair pin RNAs in keratinocytes, we found that classical cadherins are key regulators for the establishment of intercellular contacts and desmosomes, as well as growth properties of keratinocytes. Overall, our results reveal crucial roles for classical cadherins in skin morphogenesis and barrier functions that has important implications for very common diseases such as skin barrier associated diseases, as well as more rare hair disorders.
Projektbezogene Publikationen (Auswahl)
-
(2009) Cadherin mediated regulation of tight junctions in stratifying epithelia, N Y Acad Sci. 1165:163-8
Michels, C., Yadranji, S. and Niessen C.M.
-
(2009) Classsical cadherins regulate desmosome formation. J. Invest. Derm. 129:2072-5
Michels, C., Buchta T., Krieg, T, and Niessen C.M.
-
(2010) Adherens Junctions. In: Encyclopedia of Life Sciences (ELS). John Wiley & Sons
Michels, C. and Niessen, C.M
