Inhibition of Fis1 by Novel Peptide Pep213 or Molecular Suppression Reverses Diabetic- and High Glucose-Induced Endothelial Dysfunction in Human Resistance Arteries

Mitochondrial dysfunction is one of several factors that drive development of vascular endothelial dysfunction in type 2 diabetes (T2DM). In endothelial cells from T2DM patients, mitochondrial networks are highly fragmentated with increased expression of mitochondrial fission protein 1 (Fis1). However, whether manipulation of Fis1 expression and activity in endothelial vessels from T2DM patients alters endothelial function remains unknown. Here, molecular suppression of Fis1 reversed impaired endothelium-dependent vasodilation of vessels from T2DM patients, as well as healthy human vessels exposed to high (33 mM) or low (2.5 mM) glucose, while preserving NO bioavailability and improving endothelial cell layer integrity. Conversely, overexpression of Fis1 in healthy vessels impaired vasodilation and increased mitochondrial superoxide, suggesting a causative role. Application of a novel and specific Fis1 inhibitor, pep213, improved endothelium-dependent vasodilation of vessels from T2DM patients, as well as healthy vessels exposed to high glucose or Fis1 overexpression, by improving NO bioavailability and decreasing excess mitochondrial ROS generation. The specificity of pep213 was determined through multiple biophysical techniques and a 1.85 [A] crystal structure of pep213 in complex with Fis1. These data support that excessive mitochondrial fragmentation drives endothelial vessel dysfunction and supports a potential novel therapeutic route for treating diabetic microvascular disease through pharmacological inhibition of Fis1.