UTS2R

UTS2R (GPR14) is the class A GPCR for urotensin-II (UII) - the cyclic undecapeptide that is the most potent vasoconstrictor discovered to date, surpassing endothelin-1 in isolated vessel preparations. The receptor is structurally related to the somatostatin receptor family and is expressed in vascular smooth muscle, heart, kidney, and CNS. UTS2R activation drives endothelium-independent vasoconstriction, cardiac hypertrophy, and fibrosis; elevated UII levels are found in heart failure, hypertension, pulmonary arterial hypertension, chronic kidney disease, and diabetes. No UTS2R antagonist is approved, but the target has generated extensive clinical-phase development for cardiovascular disease. Every scaffold targeting vasomotor tone, cardiac remodeling, or urotensin biology routes through this card.

UTS2R (chromosome 17q25.3, ~386 aa) is a Gq/11-primary class A GPCR with high structural homology to SSTR2/3. UII (cyclic: Glu-Thr-Pro-Asp-cyclo[Cys-Phe-Trp-Lys-Tyr-Cys]-Val-OH, positions 1–7 with 2–7 disulfide ring) binds with pKd ~9.2 (~0.6 nM). The cyclic hexapeptide core Cys-Phe-Trp-Lys-Tyr-Cys is the minimal pharmacophore for UTS2R activation; the ring is essential - linear UII has ~1000-fold lower affinity. Urotensin-II related peptide (URP, 8 aa) shares the same cyclic core and activates UTS2R with comparable affinity. Signaling: Gq/11 → PLC-β → IP3/Ca²⁺ → PKC → vasoconstriction, cardiac hypertrophy gene programs; Gi/o in some cell types → ↓cAMP; β-arrestin → ERK/p38 MAPK → profibrotic signaling; Rho/ROCK → myosin light chain phosphorylation → vascular smooth muscle contraction. In endothelial cells, UTS2R couples to Gq and eNOS pathway → NO → vasodilation, explaining the paradoxical vasodilatory effect in some vascular beds. UTS2R is upregulated in vascular smooth muscle in atherosclerosis, in cardiomyocytes in heart failure, and in glomeruli in diabetic nephropathy. Plasma UII levels correlate with cardiac output and pulmonary artery pressure in heart failure patients.

No UTS2R antagonist is approved. SB-611812 (palosuran, AC-7954) is a selective UTS2R antagonist that improved renal function in diabetic nephropathy Phase 2 trials but failed Phase 3 primary endpoints. GSK1440115 (selective UTS2R antagonist) showed cardiovascular safety but did not advance beyond Phase 2. For peptide research, the tractable recipes are: UII cyclic hexapeptide core analogs ([D-Trp³]-UII and related position-3 D-amino acid substitutions) with N-terminal truncations to generate UTS2R antagonists from the agonist scaffold - position 3 D-amino acid converts the hexapeptide from partial agonist to antagonist; UII analogs with Cys→Pen (penicillamine) ring constraint for enhanced metabolic stability of the critical disulfide; cyclic UII fragments with fatty acid conjugation for extended half-life in PAH/HF models; and biased UTS2R agonists that preferentially activate eNOS/NO vasodilation over Rho/ROCK-mediated vasoconstriction, targeting the favorable endothelial component of UTS2R pharmacology.