Loss of EMILIN-1 Enhances Arteriolar Myogenic Tone Through TGF- (Transforming Growth Factor-)-Dependent Transactivation of EGFR (Epidermal Growth Factor Receptor) and Is Relevant for Hypertension in Mice and Humans

Objective EMILIN-1 (elastin microfibrils interface located protein-1) protein inhibits pro-TGF- (transforming growth factor-) proteolysis and limits TGF- bioavailability in vascular extracellular matrix. Emilin1(-/-) null mice display increased vascular TGF- signaling and are hypertensive. Because EMILIN-1 is expressed in vessels from embryonic life to adulthood, we aimed at unravelling whether the hypertensive phenotype of Emilin1(-/-) null mice results from a developmental defect or lack of homeostatic role in the adult. Approach and Results By using a conditional gene targeting inactivating EMILIN-1 in smooth muscle cells of adult mice, we show that increased blood pressure in mice with selective smooth muscle cell ablation of EMILIN-1 depends on enhanced myogenic tone. Mechanistically, we unveil that higher TGF- signaling in smooth muscle cells stimulates HB-EGF (heparin-binding epidermal growth factor) expression and subsequent transactivation of EGFR (epidermal growth factor receptor). With increasing intraluminal pressure in resistance arteries, the cross talk established by TGF- and EGFR signals recruits TRPC6 (TRP [transient receptor potential] classical type 6) and TRPM4 (TRP melastatin type 4) channels, lastly stimulating voltage-dependent calcium channels and potentiating myogenic tone. We found reduced EMILIN-1 and enhanced myogenic tone, dependent on increased TGF--EGFR signaling, in resistance arteries from hypertensive patients. Conclusions Taken together, our findings implicate an unexpected role of the TGF--EGFR pathway in hypertension with current translational perspectives.