Modification of Akt1 by methylglyoxal promotes the proliferation of vascular smooth muscle cells

Methylglyoxal (MG), a reactive dicarbonyl molecule, can modify protein to form advanced glycation endproducts. Increased MG level has been implicated in proliferative vascular diseases, but the underlying mechanisms are not clear yet. The serine/threonine kinase, Akt, regulates multiple signaling pathways that control cell proliferation. Using mass spectrometric analysis, we have detected the modification of Akt1 by MG at Cys77. This structural modification increased Akt1 phosphorylation at Ser473 and Thr308. Akt1 phosphorylation and activity were also increased by MG treatment (<50 μM) in cultured vascular smooth muscle cells (VSMCs). MG treatment of VSMCs led to increased DNA synthesis (EC50=5.8 μM), cell proliferation, phosphorylation of p21 and glycogen synthase kinase-3α/β (GSK-3α/β), and increased cyclin-dependent kinase 2 (CDK2) activity. These effects of MG were significantly inhibited by silencing Akt1 or by an Akt inhibitor. Overexpression of Akt1 Cys77Ser mutant in HEK-293 cells increased cell ...