Dermatology Online Journal

Roles of En1, Wnt7a and Lmx1b in Nail Patterning and Development
P. Kraus, C.X. Tong, and C.A. Loomis
Dermatology Online Journal 7(1): 23D

Ronald O. Perelman Department of Dermatology, NYU School of Medicine

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We and others have recently identified three genes ciritical for normal nail development: Engrailed-1 (En1), Wnt7a, and Lmx1b. These genes are involved in a complex interplay between ectoderm and mesenchyme to govern dorsal-ventral patterning during early limb development. Our studies suggest that during limb development Wnt7a, a putative signaling molecule expressed by dorsal (backside) limb ectoderm, and Lmx1b, a homeodomain containing transcriptional regulator expressed by dorsal limb mesenchyme, are critical for nail mesenchyme specification as well as for shaping the mouse claws. However, neither appear to be critical for specification of nail identity. In contrast, En1, a homeodomain-containing transcriptional regulator expressed by volar ectoderm, represses both early nail patterning and morphogenesis as well as later nail differentiation of the ectoderm. In the absence of En1 gene function, the ectoderm overlying ventral paw pads is capable of differentiating into nail-like structures, even if these pads are duplicated on the dorsal surface of the limb, as they are in Wnt7a and Lmx1b mutant mice.

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