Differential effects of P2Y1 and P2Y12 nucleotide receptors on ERK1/ERK2 and phosphatidylinositol 3-kinase signalling and cell proliferation in serum-deprived and nonstarved glioma C6 cells.
We have previously shown that, in glioma C6 cells, two nucleotide ADP-sensitive receptors coexist: P2Y1, coupled to PLC and responsible for Ca2+ release, and P2Y12, negatively coupled to adenylate cyclase. In the present study, we examined the effects of the stimulation of these two receptors on ERK1/2 and PI3-K activation, and cell proliferation in either serum-deprived or nonstarved C6 cells. In response to ADP and its analogues, in serum-starved cells, both p44 ERK1 and p42 ERK2 were activated in a time-dependent manner, as monitored by Western blot analysis using an antiphospho-p42/p44 MAPK antibody. The phosphorylation was reduced both by removal of the extracellular Ca2+ and partially or almost completely by MRS2179 or AR-C69931MX, specific antagonists of the P2Y1 and P2Y12 receptors, respectively. The inhibitory effect of antagonists was additive. These data indicate the involvement of both receptors, P2Y1 and P2Y12, in the ERK1/2 activation, but the P2Y12 receptor contribution predominates. ERK1/2 activity was positively correlated with cell proliferation of cultured glioma C6 cells. In nonstarved cells, ADP markedly decreased the PI3-K activity. In contrast, in serum-starved cells, ADP evoked an increase in the PI3-K activity. Blocking of the P2Y1 receptor by MRS2179 additionally increased this ADP response. These results suggest that the P2Y1 receptor has an inhibitory and the P2Y12 receptor a stimulatory effect on PI3-K signalling pathway. RT-PCR analysis revealed different mRNA expression of both receptors in starved and nonstarved cells. In nonstarved cells, the P2Y1 receptor mRNA predominates, whereas in serum-deprived cells the expression of P2Y12 mRNA becomes more pronounced. British Journal of Pharmacology (2004) 141, 497-507. doi:10.1038/sj.bjp.0705639
Czajkowski
Rafal
R
Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., Warsaw PL 02-093, Poland.
Banachewicz
Wiktor
W
Ilnytska
Olga
O
Drobot
Ludmila B
LB
Baranska
Jolanta
J
D000818:Animals; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D005910:Glioma / Q000201:enzymology / Q000378:metabolism*; D008565:Membrane Proteins / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D016895:Culture Media, Serum-Free; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; C546384:P2ry1 protein, rat; C553058:P2ry12 protein, rat