MiR-204 regulates type 1 IP ₃ R to control vascular smooth muscle cell contractility and blood pressure

MiR-204 is expressed in vascular smooth muscle cells (VSMC). However, its role in VSMC contraction is not known. We determined if miR-204 controls VSMC contractility and blood pressure through regulation of sarcoplasmic reticulum (SR) calcium (Ca ²⁺ ) release. Systolic blood pressure (SBP) and vasoreactivity to VSMC contractile agonists (phenylephrine (PE), thromboxane analogue (U46619), endothelin-1 (ET-1), angiotensin-II (Ang II) and norepinephrine (NE) were compared in aortas and mesenteric resistance arteries (MRA) from miR-204 ^−/− mice and wildtype mice (WT). There was no difference in basal systolic blood pressure (SBP) between the two genotypes; however, hypertensive response to Ang II was significantly greater in miR-204 ^−/− mice compared to WT mice. Aortas and MRA of miR-204 ^−/− mice had heightened contractility to all VSMC agonists. In silico algorithms predicted the type 1 Inositol 1, 4, 5-trisphosphate receptor (IP ₃ R1) as a target of miR-204. Aortas and MRA of miR-204 ^−/− mice had higher expression of IP ₃ R1 compared to WT mice. Difference in agonist-induced vasoconstriction between miR-204 ^−/− and WT mice was abolished with pharmacologic inhibition of IP ₃ R1. Furthermore, Ang II-induced aortic IP ₃ R1 was greater in miR-204 ^−/− mice compared to WT mice. In addition, difference in aortic vasoconstriction to VSMC agonists between miR-204 ^−/− and WT mice persisted after Ang II infusion. Inhibition of miR-204 in VSMC in vitro increased IP ₃ R1, and boosted SR Ca ²⁺ release in response to PE, while overexpression of miR-204 downregulated IP ₃ R1. Finally, a sequence-specific nucleotide blocker that targets the miR-204-IP ₃ R1 interaction rescued miR-204-induced downregulation of IP ₃ R1. We conclude that miR-204 controls VSMC contractility and blood pressure through IP ₃ R1-dependent regulation of SR calcium release.