Diabetes and the associated hyperglycemia affect pulmonary physiology and biochemistry inducing endothelial impairment, as the first step in lung vascular dysfunction. Caveolin-1, a characteristic protein of endothelial caveolae, acts as a scaffolding protein involved in signal transduction, cholesterol homeostasis, and vesicular trafficking. To document the effect of hyperglycemia on lung endothelial cells, we designed experiments on streptozotocin-induced diabetes and on double transgenic diabetic mice and investigated (1) the early morphological changes occurring in endothelial cells, (2) the ACE activity and cholesterol content of caveolae-rich membrane microdomains, and (3) the protein and gene expression of caveolin-1. We provide evidence that in diabetic lung, the endothelial cell displays an increased number of caveolae and enlarged surface area and a well-developed synthetic machinery, changes that correlate with an overall augmented ACE activity and cholesterol content and overexpression (gene and protein) of caveolin-1. Targeting the endothelial cell surface molecules modulated by hyperglycemia, such as caveolin-1 and ACE could be an additional therapeutic strategy in diabetes.
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