Targeted ablation of the murine involucrin gene

Involucrin is synthesized in abundance during terminal differentiation of k eratinocytes. Involucrin is a substrate for transglutaminase and one of the precursors of the cross-linked envelopes present in the corneocytes of the epidermis and other stratified squamous epithelia. These envelopes make an important contribution to the physical resistance of the epidermis. We hav e generated mice lacking involucrin from embryonic stem cells whose involuc rin gene had been ablated by homologous recombination. These mice developed normally, possessed apparently normal epidermis and hair follicles, and ma de cornified envelopes that could not be distinguished from those of wild-t ype mice. No compensatory increase of mRNA for other envelope precursors wa s observed.