Ca2+ dependent purinergic regulation of p42 and p44 MAP kinases in astroglial cultured cells

Adenosine triphosphate (ATP) is a signaling molecule for brain cells including astrocyles. In these cells, it has been shown that ATP stimulates myelin basic protein (MBP) kinase activity which is believed to represent the Erk family of MAP kinases. Indeed, we show that ATP activates simultaneously MBP kinase activity and phosphotyrosine incorporation in p42 Erk2 and p44 Erk1. Maximal effect of ATP is obtained at 50 μM after 5 min and disappears after 60 min. Effect of ATP is mimicked by 2-methylthio-ATP whereas αβ-melhyleneadenosine 5′ triphosphate (AMP-CPP) and adenosine do not promote any effect. Uridine triphosphate (UTP) activates also p42 and p44 MAP kinases. These observations indicate that p42-p44 MAP kinases activation can be obtained through P2y and P2u receptors. Purinergic stimulation of Erk is insensitive to pertussis toxin which inactivates heterotrimeric Gi protein. It is not inhibited by a PLA2 inhibitor (4 bromophenacyl bromide [BθB]) and the P13 kinase inhibitor, wortmannin. In contrast, purinergic stimulation of Erk is partially inhibited by the PKC inhibitor, GF109203X, at 5 μM and suppressed when extracellular calcium is complexed by ethylene glycol-bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA). © 1998 Elsevier, Paris.