Glycated Collagen Decreased Endothelial Cell Fibronectin Alignment in Response to Cyclic Stretch Via Interruption of Actin Alignment

Hyperglycemia is a defining characteristic of diabetes, and uncontrolled blood glucose in diabetes is associated with accelerated cardiovascular disease. Chronic hyperglycemia glycates extracellular matrix (ECM) collagen, which can lead to endothelial cell dysfunction. In healthy conditions, endothelial cells respond to mechanical stimuli such as cyclic stretch (CS) by aligning their actin cytoskeleton. Other cell types, specifically fibroblasts, align their ECM in response to CS. We previously demonstrated that glycated collagen inhibits endothelial cell actin alignment in response to CS. The aim of this study was to determine the effect of glycated collagen on ECM remodeling and protein alignment in response to stretch. Porcine aortic endothelial cells (PAEC) seeded on native or glycated collagen coated elastic substrates were exposed to 10% CS. Cells on native collagen aligned subcellular fibronectin fibers in response to stretch, whereas cells on glycated collagen did not. The loss of fibronectin alignment was due to inhibited actin alignment in response to CS, since fibronectin alignment did not occur in cells on native collagen when actin alignment was inhibited with cytochalasin. Further, while ECM protein content did not change in cells on native or glycated collagen in response to CS, degradation activity decreased in cells on glycated collagen. Matrix metalloproteinase 2 (MMP-2) and membrane-associated type 1 matrix metalloproteinase (MT1-MMP) protein levels decreased, and therefore MMP-2 activity also decreased. These MMP changes may relate to c-Jun N-terminal kinase (Jnk) phosphorylation inhibition with CS, which has previously been linked to focal adhesion kinase (FAK). These data demonstrate the importance of endothelial cell actin tension in remodeling and aligning matrix proteins in response to mechanical stimuli, which is critical to vascular remodeling in health and disease.