Flow-sensitive HEG1 controls eNOS activity to prevent endothelial dysfunction, hypertension, and atherosclerosis

Hypertension (HTN), the chronic elevation of blood pressure, accounts for more atherosclerotic cardiovascular disease deaths than any other modifiable risk factor. ¹ In the arteries, stable blood flow (s-flow) drives healthy, atheroprotective endothelial cell (EC) functions including nitric oxide (NO) production, barrier function, and anti-inflammatory programs via the action of flow-sensitive proteins. We showed that s-flow stimulates Heart-of-Glass 1 (HEG1) protein expression, localization to cell-cell junctions, and secretion from ECs. ² We found that conditional, endothelial cell-specific knockout of ( Heg1 ^ECKO ) exacerbates atherosclerosis ² , however the mechanism was unknown. Here, we report a new role of HEG1 in controlling EC dysfunction, hypertension and atherosclerosis. We discover a novel mechanism: HEG1 regulates NO bioavailability via a flow-dependent HEG1-eNOS interaction (endothelial nitric oxide synthase, NOS3). Heg1 ^ECKO develops spontaneous hypertension and severe atherosclerosis, both of which are effectively treated by Angiotensin-Converting Enzyme inhibition (ACEi). UK BioBank and Swedish cohort studies reveal that plasma HEG1 levels are associated with hypertension and cardiovascular disease risk. ^3,4 Our findings suggest HEG1 may serve as a biomarker to advance personalized therapies for EC dysfunction, hypertension, and atherosclerosis.