Late Cornified Envelope Protein 1D (LCE1D)

Lep4 was expressed in cultured mouse keratinocytes only after calcium induction. It was not associated with cornified cells until 4 to 5 days after calcium induction. In situ assays showed that Lep4 was a transglutaminase substrate and was incorporated at the cell periphery in a calcium-dependent manner. The incorporated protein was resistant to heat and detergent, consistent with stable crosslinking of Lep4 into the cornified envelope. Expression LCE1 genes, including LCE1D/E, was upregulated in cultured normal human keratinocytes by ultraviolet irradiation, but not by calcium. Real-time PCR of skin biopsies from 4 normal individuals revealed an individual who lacked LCE1D/E almost completely. This individual did not have a major skin defect, suggesting that loss of 1 of these genes has only minor consequences.