Pmg-1 and Pmg-2 constitute a novel family of KAP genes differentially expressed during skin and mammary gland development

The epidermis, by invagination of the undifferentiated ectodermal cells, gi ves rise to several distinct structures including hair, sebaceous, eccrine sweat and mammary glands. We have recently isolated a novel gene, pmg-1, ex pressed in the pubertal mouse mammary gland. While investigating its genomi c structure, we identified a related gene in close proximity, which we have termed pmg-2. pmg-1 and pmg-2 are intron-less, are transcribed in opposite directions and are separated by a potential promoter region of 2.8 kb cont aining putative binding motifs for the developmental transcription factors Lef-1, Sox5 and D-STAT. pmg-1 and pmg-2 encode small proteins rich in G, S, F, Y and Q and contain characteristic repeats reminiscent of the keratin-a ssociated proteins (KAPs). Both genes are expressed in growing hair follicl es in skin as well as in sebaceous and eccrine sweat glands. Interestingly, expression is also detected in the mammary epithelium where it is limited to the onset of the pubertal growth phase and is independent of ovarian hor mones. Their broad, developmentally controlled expression pattern, together with their unique amino acid composition, demonstrate that pmg-1 and pmg-2 constitute a novel KAP gene family participating in the differentiation of all epithelial cells forming the epidermal appendages. (C) 1999 Elsevier S cience Ireland Ltd. All rights reserved.