P2Y-Receptors stimulating the proliferation of human mesangial cells through the MAPK42/44 pathway

1 Mesangial cell proliferation is observed in a number of kidney diseases. The sympathetic cotransmitter ATP is suspected to play a major role in proliferative processes. Therefore, the effects of exogenous ATP on human mesangial cells in culture were studied. 2 Fresh human kidney cortex was processed to obtain mesangial cells in culture. Effects of nucleotides on [H-3] thymidine incorporation, the activation of mitogen-activated protein kinase and the cell number were studied. The involved P2-receptors were characterized pharmacologically. In addition, we searched for mRNA for P2Y- and P2X-receptors by RT-PCR. 3 ATP (0.1 - 300 muM) and related nucleotides induced a significant increase in [H-3] thymidine incorporation up to 220% of control. The adenine nucleotides ATP and ADP were about equally effective. Also ATP-gamma-S, UTP, ADP-beta-S and 2-m-thio-ADP induced a weaker response. UDP and alpha-beta-methylene-ATP failed to induce an effect on [H-3] thymidine uptake. 4 ATP ( 100 muM) induced a fast activation of the MAPK(42/44) pathway. The effects of ATP on MAPK(42/44) activation and [H-3] thymidine incorporation were reduced by the MAPK inhibitor PD 98059. Platelet-derived growth factor ( PDGF 5 ng ml(-1)) increased the cell number to more than 122% of control. ATP ( 10 mm) on top of PDGF amplified PDGF induced cell proliferation to 136% of control. 5 RT-PCR products for P2Y(1,2,4,6,11,12)- and P2X(1,2,4,5,6,7)-receptor subtypes were detected in human mesangial cells. 6 ATP has mitogenic effects on human mesangial cells. DNA synthesis is increased by the activation of the MAPK(42/44) pathway. ATP amplifies PDGF-induced cell hyperplasia.