GUINEA-PIG HISTAMINE H-1 RECEPTOR .2. STABLE EXPRESSION IN CHINESE-HAMSTER OVARY CELLS REVEALS THE INTERACTION WITH 3 MAJOR SIGNAL-TRANSDUCTION PATHWAYS

A cDNA encoding a guinea pig histamine H-1 receptor was stably express ed in Chinese hamster ovary (CHO) cells. In one resulting clone, named CHO(H-1), the H-1 receptor was found to be coupled to several major s ignal transduction pathways. In each case the involvement of a G(1)/G( 0) protein with pertussis toxin (PTX) was assessed, as well as the inf luence of extracellular Ca2+ and of protein kinase C activation by pho rbol le-myristate 13-acetate (PMA). Histamine induced, in a PTX- and P MA-insensitive manner, a biphasic increase in the intracellular Ca2+ l evel of which only the second sustained phase was dependent on the ext racellular Ca2+ level. Histamine also caused a threefold elevation of inositol phosphate production, which was PTX-insensitive, but slightly inhibited by PMA and reduced by 75% in the absence of extracellular C a2+. Histamine also caused a massive release of arachidonic acid, whic h occurred in a Ca2+- and PMA-sensitive manner, probably through the a ctivation of a cytosolic phospholipase A(2), which partly involves cou pling to a PTX-sensitive G protein. in comparison, in HeLa cells endow ed with a native H, receptor, the histamine-induced arachidonic acid r elease was also Ca2+- and PMA-sensitive, but totally PTX-insensitive. Finally, in CHO(H-1) cells, histamine in very low concentrations poten tiated the cyclic AMP accumulation induced by forskolin. This response appeared to be insensitive to PTX, extracellular Ca2+, and PMA. These various observations show that stimulation of a single receptor subty pe, the guinea pig H-1 receptor, can trigger four major intracellular signals through coupling to several G proteins that are variously modu lated by extracellular Ca2+ and protein kinase C activation.