The Succinate Receptor SUCNR1 Resides at the Endoplasmic Reticulum and Relocates to the Plasma Membrane in Hypoxic Conditions

The Study of the Effectiveness of Ethylmethylhydroxypyridine Succinate in Acute Alcohol Intoxication

The effectiveness of ethylmethylhydroxypyridine succinate (EMHPS) in acute alcohol intoxication was tested in a study on SPF male outbred ICR mice. Ethanol (concentration 40%) was administered to animals once intraperitoneally at a dose of 4 g/kg. Control animals were injected with saline in an equivalent volume. In 15 min after the administration of alcohol, the animals were injected intravenously or intramuscularly with EMHPS at a dose of 50 or 100 mg/kg or with saline via the same route in an equivalent volume. Animal behavior was tested 3 and 24 h later after administration of the substances. After 3 and 24 h, mice in the pathological control groups developed semiptosis, the gait and the turning over reflex were impaired, the strength of the hind limbs decreased and the distance between the hind limbs increased when landing; in the open-field test, the latency of the first movement increased, and the number of rearing postures decreased. Intravenous and intramuscular administration of EMHPS in doses of 50 and 100 mg/kg had a pronounced antitoxic and neuroprotective effect in acute alcohol intoxication: all studied parameters did not differ significantly from the control.

Versatile lactate signaling via HCAR1: a multifaceted GPCR involved in many biological processes

G-coupled protein receptors (GPCRs) are the ultimate refuge of pharmacology and medicine as more than 40% of all marketed drugs are directly targeting these receptors. Through cell surface expression, they are at the forefront of cellular communication with the outside world. Metabolites among the conveyors of this communication are becoming more prominent with the recognition of them as ligands for GPCRs. HCAR1 is a GPCR conveyor of lactate. It is a class A GPCR coupled to Gαi which reduces cellular cAMP along with the downstream Gβγ signaling. It was first found to inhibit lipolysis, and lately has been implicated in diverse cellular processes, including neural activities, angiogenesis, inflammation, vision, cardiovascular function, stem cell proliferation, and involved in promoting pathogenesis for different conditions, such as cancer. Other than signaling from the plasma membrane, HCAR1 shows nuclear localization with different location-biased activities therein. Although different functions for HCAR1 are being discovered, its cell and molecular mechanisms are yet ill understood. Here, we provide a comprehensive review on HCAR1, which covers the literature on the subject, and discusses its importance and relevance in various biological phenomena.

Succinate at the Crossroad of Metabolism and Angiogenesis: Roles of SDH, HIF1α and SUCNR1

Angiogenesis is an essential process by which new blood vessels develop from existing ones. While adequate angiogenesis is a physiological process during, for example, tissue repair, insufficient and excessive angiogenesis stands on the pathological side. Fine balance between pro- and anti-angiogenic factors in the tissue environment regulates angiogenesis. Identification of these factors and how they function is a pressing topic to develop angiogenesis-targeted therapeutics. During the last decade, exciting data highlighted non-metabolic functions of intermediates of the mitochondrial Krebs cycle including succinate. Among these functions is the contribution of succinate to angiogenesis in various contexts and through different mechanisms. As the concept of targeting metabolism to treat a wide range of diseases is rising, in this review we summarize the mechanisms by which succinate regulates angiogenesis in normal and pathological settings. Gaining a comprehensive insight into how this metabolite functions as an angiogenic signal will provide a useful approach to understand diseases with aberrant or excessive angiogenic background, and may provide strategies to tackle them.