High glucose-mediated effects on endothelial cell proliferation occur via p38 MAP kinase.
The mitogen-activated protein (MAP) kinases contribute to altered cell growth and function in a variety of disease states. However, their role in the endothelial complications of diabetes mellitus remains unclear. Human endothelial cells were exposed for 72 h to 5 mM (control) or 25 mM (high) glucose or 5 mM glucose plus 20 mM mannitol (osmotic control). The roles of p38 and p42/44 MAP kinases in the high glucose-induced growth effects were determined by assessment of phosphorylated MAP kinases and their downstream activators by Western blot and by pharmacological inhibition of these MAP kinases. Results were expressed as a percentage (means +/- SE) of control. High glucose increased the activity of total and phosphorylated p38 MAP kinase (P < 0.001) and p42/44 MAP kinase (P < 0.001). Coexposure of p38 MAP kinase blocker with high glucose reversed the antiproliferative but not the hypertrophic effects associated with high-glucose conditions. Transforming growth factor (TGF)-beta1 increased the levels of phosphorylated p38 MAP kinase, and p38 MAP kinase blockade reversed the antiproliferative effects of this cytokine. The high glucose-induced increase in phosphorylated p38 MAP kinase was reversed in the presence of TGF-beta1 neutralizing antibody. Although hyperosmolarity also induced antiproliferation (P < 0.0001) and cell hypertrophy (P < 0.05), there was no change in p38 activity, and therefore inhibition of p38 MAP kinase had no influence on these growth responses. Blockade of p42/44 MAP kinase had no effect on the changes in endothelial cell growth induced by either high glucose or hyperosmolarity. High glucose increased p42/44 and p38 MAP kinase activity in human endothelial cells, but only p38 MAP kinase mediated the antiproliferative growth response through the effects of autocrine TGF-beta1. High glucose-induced endothelial cell hypertrophy was independent of activation of the MAP kinases studied. In addition, these effects were independent of any increase in osmolarity associated with high-glucose exposure.
McGinn
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Renal Research Group, Kolling Institute, Royal North Shore Hospital, University of Sydney, New South Wales 2065, Sydney, Australia.
Saad
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Poronnik
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Pollock
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D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010940:Plant Proteins; D014470:Umbilical Cord / Q000098:blood supply / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
D010940:Plant Proteins; C101691:MMK4 protein, Medicago sativa; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D005947:Glucose