Differential expression of a gene homologous to a G-alpha protein gene in neonatal mouse skin during development of hair follicles

The development of mouse hair follicles depends on the proliferation, diffe rentiation and migration of epithelial matrix cells in the follicle bulb. I n particular, induction of the proliferation of epithelial cells is thought to be signalled by the dermal papilla at the base of the bulb. Neonatal mo use skin is useful for studying changes in gene expression during developme nt of the follicles, as the mitotic activity of skin cells changes shortly after birth. Using RNA differential display, a 248-bp message has been iden tified, which is expressed in the skin, specifically on day 2 and day 3 but not on day 4 after birth. Confirmation of expression of this gene by ribon uclease protection assay showed that strong expression is seen on day 2 and day 3, but weak expression is also shown on day 1, day 4 and day 5. In sit u hybridization data revealed that it is mainly localized in the dermal pap illa. Analysis of its nucleotide sequence showed 99% identity between nucle otide 2 and 232 of the mouse uncoupled S49 cell mRNA for stimulatory GTP-bi nding protein (G(S)) alpha subunit, suggesting it is a segment of G(S)alpha . As the G(S)alpha subunit is involved in transducing extracellular signals across the cell, the finding of its expression in the papilla suggests it may be a molecular signal to the induction of epithelial proliferation in t he follicle bulb. Evidence of strong expression on day 2, at the time when the mitotic activity of epithelial matrix cells starts to increase, also su ggests that the G(S)alpha is a potential candidate for involvement in the i nitiation of follicle growth. (C) 2001 Elsevier Science Ireland Ltd. All ri ghts reserved.