Mechanism of activation of protein kinase D2(PKD2) by the CCK(B)/gastrin receptor.
Recently, we cloned a novel serine/threonine kinase termed protein kinase D2 (PKD2). PKD2 can be activated by phorbol esters both in vivo and in vitro but also by gastrin via the cholecystokinin/CCK(B) receptor in human gastric cancer cells stably transfected with the CCK(B)/gastrin receptor (AGS-B cells). Here we identify the mechanisms of gastrin-induced PKD2 activation in AGS-B cells. PKD2 phosphorylation in response to gastrin was rapid, reaching a maximum after 10 min of incubation. Our data demonstrate that gastrin-stimulated PKD2 activation involves a heterotrimeric G alpha(q) protein as well as the activation of phospholipase C. Furthermore, we show that PKD2 can be activated by classical and novel members of the protein kinase C (PKC) family such as PKC alpha, PKC epsilon, and PKC eta. These PKCs are activated by gastrin in AGS-B cells. Thus, PKD2 is likely to be a novel downstream target of specific PKCs upon the stimulation of AGS-B cells with gastrin. Our data suggest a two-step mechanism of activation of PKD2 via endogenously produced diacylglycerol and the activation of PKCs.
Sturany
Sabine
S
Department of Internal Medicine l, Medical University of Ulm, D-89081 Ulm, Germany.
Van Lint
Johan
J
Gilchrist
Annette
A
Vandenheede
Jackie R
JR
Adler
Guido
G
Seufferlein
Thomas
T
D002460:Cell Line; D004789:Enzyme Activation; D005755:Gastrins / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D000091283:Protein Kinase D2; D011494:Protein Kinases / Q000378:metabolism*; D011949:Receptors, Cholecystokinin / Q000378:metabolism*; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism
D005755:Gastrins; D000091283:Protein Kinase D2; D011949:Receptors, Cholecystokinin; D011494:Protein Kinases; D010738:Type C Phospholipases; D020962:Heterotrimeric GTP-Binding Proteins