Lysophosphatidic acid- and G beta-dependent activation of Dictyostelium MAP kinase ERK2

Exogenous lysophosphatidic acid (LPA) has been shown to evoke a chemotactic response in aggregative cells of the social amoeba Dictyostelium discoideu m, In this paper, we demonstrate that extracellular LPA is also able to ind uce activation of mitogen-activated protein (MAP) kinase DdERK2 (extracellu lar signal regulated kinase 2) in these cells. This activation is independe nt of cyclic AMP receptors, yet fully dependent on the single GP subunit, h inting to the presence of functional heptahelical LPA receptors in a primit ive eukaryote, We did not observe LPA-dependent cyclic GMP accumulation, wh ich suggests that the pathways for LPA-induced and "classical" chemotaxis o f D, discoideum cells are substantially different. (C) 2001 Academic Press.