Insight into SUCNR1 (GPR91) structure and function

SUCNR1 (or GPR91) belongs to the family of G protein-coupled receptors (GPCR), which represents the largest
group of membrane proteins in human genome. The majority of marketed drugs targets GPCRs, directly or
indirectly. SUCNR1 has been classified as an orphan receptor until a landmark study paired it with succinate, a
citric acid cycle intermediate.
According to the current paradigm, succinate triggers SUCNR1 signaling pathways to indicate local stress that
may affect cellular metabolism. SUCNR1 implication has been well documented in renin-induced hypertension,
ischemia/reperfusion injury, inflammation and immune response, platelet aggregation and retinal angiogenesis.
In addition, the SUCNR1-induced increase of blood pressure may contribute to diabetic nephropathy or cardiac
hypertrophy.
The understanding of SUCNR1 activation, signaling pathways and functions remains largely elusive, which calls
for deeper investigations. SUCNR1 shows a high potential as an innovative drug target and is probably an important
regulator of basic physiology. In order to achieve the full characterization of this receptor,more specific pharmacological
tools such as small-molecules modulators will represent an important asset. In this review, we
describe the structural features of SUCNR1, its current ligands and putative binding pocket. We give an exhaustive
overview of the known and hypothetical signaling partners of the receptor in different in vitro and in vivo
systems. The link between SUCNR1 intracellular pathways and its pathophysiological roles are also extensively
discussed.