Role of neuraminidase in promoting the shedding of endothelial mechanosensing structures in type 2 diabetes

Endothelial dysfunction represents a causal factor in the pathogenesis of cardiovascular disease associated with type 2 diabetes (T2D). Previous work shows that endothelial mechanosensing structures are degraded in T2D, resulting in impaired shear stress mechanotransduction and decreased endothelial-derived nitic oxide (NO) bioavailability. Recent evidence suggests that glypican-1, a well-known mechanosensor, is a substrate of the proinflammatory enzyme a disintegrin and metalloproteinase-17 (ADAM17). A key step in ADAM17 activation is externalization of phosphatidylserine (PS) to the outer leaflet of the plasma membrane, which can be mediated by the phospholipid scramblase anoctamin-6 (ANO6). However, whether ANO6-mediated activation of ADAM17 leads to glypican-1 shedding in endothelial cells remains unknown. Also unknown are the mechanisms by which this pathway becomes overactive in T2D. We recently reported that T2D is associated with increased circulating levels of neuraminidase, a soluble enzyme that cleaves sialic acid residues. We also showed that intraluminal exposure of isolated arteries to neuraminidase impairs shear stress mechanotransduction. Herein, we tested the hypothesis that neuraminidase-induced impaired shear stress mechanotransduction is mediated by ANO6-induced ADAM17 activation and consequent shedding of glypican-1. All reported differences are significant at P<0.05. In support of our hypothesis, we show that neuraminidase and ADAM17 activities are increased, while nitrite (NO surrogate) is decreased, in plasma of men and women with T2D who also display evidence of impaired shear stress mechanotransduction ( i.e., diminished flow-mediated dilation). In cultured endothelial cells, we show that neuraminidase exposure decreases sialic acid content and increases intracellular Ca 2+ mobilization, adhesion of lactadherin (a peptide that binds externalized PS), ADAM17 activity, and shedding of glypican-1. Also in cultured endothelial cells, overexpression of ADAM17 increases shedding of glypican-1 and impairs shear stress-induced activation of endothelial NO synthase. Congruently, intraluminal exposure of human omental arteries to active ADAM17 recombinant protein impairs flow-mediated dilation. Furthermore, silencing of ANO6 reduces ADAM17 activity, leading to increased presence of glypican-1 on the endothelial cell surface. Taken together, we provide evidence that neuraminidase, an enzyme increased in the circulation of individuals with T2D, promotes ANO6-dependent externalization of PS in endothelial cells, which in turn leads to ADAM17 activation and consequent shedding of glypican-1. Thus, this work supports the idea that the neuraminidase-ANO6-ADAM17 axis should be considered as a potential target for restoring endothelial mechanosensation and improving NO bioavailability in T2D. R01HL151384 (to LAML and JP), R01HL153264 (to LAML and JP), R01HL137769 (to JP), and R21DK116081 (to CM-A). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.