ADAM17-Mediated Glypican-1 Shedding as a Putative Mechanism Contributing to Impaired Endothelial Shear Stress Mechanotransduction

Endothelial dysfunction, a hallmark of type 2 diabetes (T2D), precedes cardiovascular disease and is characterized by reduced arterial flow-mediated dilation (FMD). Typically, shear stress forces generated by blood flow are detected and transduced in an outside-in fashion by mechanosensitive structures that coat the luminal surface of endothelial cells. However, these mechanosensors are degraded in T2D. For example, we provide evidence that in mesenteric arteries of diabetic (db/db) mice, glypican-1 content on the luminal surface is reduced, and that this coincides with impaired FMD. Glypican-1 is a well-known mechanosensor, and new evidence from a proteomic analysis suggests that it is a substrate for the proinflammatory enzyme ADAM17. Our prior work demonstrates that ADAM17 and its activity are elevated in the vascular wall and in plasma samples of individuals with T2D, yet the mechanisms contributing to endothelial ADAM17 overactivity are not fully elucidated. Herein, we put forth the hypothesis that iRhom2, an enzyme responsible for ADAM17 trafficking, contributes to overactivation of the mature and active form of endothelial ADAM17, which in turn causes the shedding of glypican-1, leading to impaired shear stress mechanotransduction. In support of this hypothesis, we reveal that endothelial overexpression of iRhom2 causes an increased presence of mature ADAM17 in the cell membrane. Furthermore, overexpression of ADAM17 in endothelial cells leads to reduced glypican-1 content in the cell lysate, whereas, in the supernatant, its content is increased, suggestive of glypican-1 cleavage. Notably, using a cell-free based assay, we reveal the cleavage sites of glypican-1 when exposed to recombinant active ADAM17, and demonstrate that this cleavage is reduced in the presence of TAPI-0, an ADAM17 inhibitor. In support of the notion that ADAM17 overactivity impairs mechanotransduction of shear stress, we show that upregulation of eNOS in endothelial cells subjected to shear stress (15 dynes/cm 2 , 2 hr) is abrogated in ADAM17-overexpressing cells. Congruently, in human omental arteries, intraluminal exposure to recombinant active ADAM17 (1 µg/mL, 1 hr) reduces FMD, without affecting endothelium-independent vasodilation. Lastly, mesenteric arteries from Western diet-fed mice lacking ADAM17 in endothelial cells exhibit greater FMD than mesenteric arteries from wildtype counterparts, whereas the magnitude of endothelium-independent vasodilation remains similar. Taken together, these findings support the hypothesis that iRhom2 contributes to trafficking and maturation of ADAM17 in endothelial cells, and that ADAM17 overactivity causes an impairment in shear stress mechanotransduction, likely via the cleavage of glypican-1 and presumably other mechanosensors. Support: MU LSF (to MAA), 23PRE1020897 (to GP), 24EIA1248820 (to JP), MU Research Excellence Program (to FIR-P and LF-S), R01HL151384 and R01HL153264 (to LM-L and JP). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.