The MAPK-dependent regulation of the Jagged/Notch gene expression by VEGF, bFGF or PPAR gamma mediated angiogenesis in HUVEC.

The Jagged-Notch signalling, plays a crucial role in cell differentiation. Angiogenesis, is regulated by VEGF, bFGF as well as by the free fatty acid metabolites , which are regulators of transcription factors such as peroxisome proliferation activating receptors (PPARs). The study analyzed the signalling pathways involved in the regulation of Jagged-1/Notch-4 expression in endothelial cells (HUVECs) in response to VEGF, bFGF and PPAR-gamma exogenous activator - ciglitazone. HUVECs were incubated with investigated substances for 24 hours, with or without the presence of the MAP-kinases inhibitors were used. Jagged-1 and Notch-4 gene expression was determined using quantitative Real-Time PCR. The Jagged-1/Notch-4 protein expression was compared by flow cytometry, when the phosphorylation-dependent activation of kinases was estimated by Western-blot method. The opposite effect of VEGF, bFGF, or ciglitazone on the Jagged-1/Notch-4 expression on HUVEC was connected with the different activation of MAPKs. Ciglitazone, activated p38 MAPK pathway and simultaneously inhibited phosphorylation of p42/44 MAPK. The pro-angiogenic: bFGF and VEGF, also activated the p38 MAPK, but they did not attenuate the p42/44 MAPK phosphorylation. Maintaining of the Jagged/Notch interactions by VEGF, when down-regulation by bFGF and ciglitazone, seems to be dependent on the different effect on p38 MAPK and p42/44 MAPK pathway regulation.