2 GQ CLASS G-PROTEINS ARE EXPRESSED IN HUMAN KERATINOCYTES

G proteins link many cell surface receptor generated signals to activa tion of multiple cellular processes in all tissues. There is specifici ty in the receptor interaction with the G protein and in the interacti on of the specific G protein with different effector molecules. The pu rpose of this study was to determine some of the biologically relevant G proteins in keratinocytes. The Ga subunit of the heterotrimeric G p rotein was investigated because much of the biologic activity and the receptor specificity resides there. A polymerase chain reaction strate gy was used that amplified multiple G alpha gene segments between cons erved primer sites from keratinocyte first strand cDNA. Two Gq class G proteins, G alpha 16 and G alpha y, were identified. Using northern a nalysis and in situ hybridization, mRNA of both of these genes were de tected in keratinocytes in culture and in epidermal keratinocytes. G a lpha y was expressed in multiple other cell types and tissues, but G a lpha 16 was restricted in expression to keratinocytes and keratinocyte -derived adnexal structures in the skin. G alpha 16 has previously bee n reported to be limited in expression to hematopoietic cells. The phy siologic receptor to which it couples in neutrophils is reported to be a C5a receptor. The receptor to which it couples in keratinocytes has not been elucidated but by analogy may be another chemokine receptor. We hypothesize that G alpha 16 is an important conduit for responses to inflammatory signals in keratinocytes.