Expression of guanine nucleotide binding proteins, Gs and Gi, in mRNAs in epidermal keratinocytes

The stimulation or inhibition of adenylate cyclase by hormones and chemicals is mediated by the stimulatory or inhibitory guanine nucleotide-binding proteins, Gs and Gi respectively. Although the presence of these G-proteins in the epidermis has been suggested, no direct information regarding their nature has been available. Using cDNAs for these G-proteins as a probe, we investigated the nature of the G-proteins of various keratinocytes. FRSK cells, a cell line derived from fetal rat epidermal cells, and SV-40-transformed human epidermal cells, both of which are highly proliferative keratinocytes, contained mRNAs for both Gs-alpha and two Gi-alpha proteins (Gi-2 alpha and -3 alpha). No evidence for the presence of Gi-1 alpha or Go-alpha was obtained. Normal human or pig epidermis had a relatively small amount of mRNAs for these G-proteins in the stable (hypoproliferative) condition. Tape-stripping-induced, and UVB-induced hyperproliferative epidermis contained an increased amount of these G-protein messages. However, all Gs-alpha, Gi-2 alpha and -3 alpha, as well as beta-actin mRNAs, were increased to a similar extent, and no specific expression of G-protein messages could be detected in the hyperproliferative epidermis.