Hyperglycemia Regulates RUNX2 Activation and Cellular Wound Healing through the Aldose Reductase Polyol Pathway

Diabetes mellitus accelerates cardiovascular microangiopathies and atherosclerosis, which are a consequence of hyperglycemia. The aldose reductase (AR) polyol pathway contributes to these microvascular complications, but how it mediates vascular damage in response to hyperglycemia is less understood. The RUNX2 transcription factor, which is repressed in diabetic animals, promotes vascular endothelial cell (EC) migration, proliferation, and angiogenesis. Here we show that physiological levels of glucose (euglycemia) increase RUNX2 DNA binding and transcriptional activity, whereas hyperglycemia does not. However, inhibition of AR reverses hyperglycemic suppression of RUNX2. IGF-1 secretion and IGF receptor phosphorylation by autocrine IGF-1 occur equally in euglycemic or hyperglycemic conditions, suggesting that reduced RUNX2 activity in response to hyperglycemia is not because of altered IGF-1/IGF receptor activation. AR also negatively regulates RUNX2-dependent vascular remodeling in an EC wounded monolayer assay, which is reversed by specific AR inhibition in hyperglycemia. Thus, euglycemia supports RUNX2 activity and promotes normal microvascular EC migration and wound healing, which are repressed under hyperglycemic conditions through the AR polyol pathway.