Nomenclature: HCA1 receptor

Family: Hydroxycarboxylic acid receptors

Annotation status:  image of a green circle Annotated and expert reviewed. Please contact us if you can help with updates. 

Contents

Gene and Protein Information
class A G protein-coupled receptor
Species TM AA Chromosomal Location Gene Symbol Gene Name Reference
Human 7 346 12q24.3 HCAR1 hydroxycarboxylic acid receptor 1
Mouse 7 351 5 F Gpr81 G protein-coupled receptor 81
Rat 7 351 12q15 Hcar1 hydroxycarboxylic acid receptor 1
Previous and Unofficial Names
TA-GPCR
LACR
FKSG80
G-protein coupled receptor 81
LACR1
G-protein coupled receptor 104
T-cell activation G protein-coupled receptor
lactate receptor 1
GPR81
GPR104
HCA1
G protein-coupled receptor 104
G protein-coupled receptor 81
LOC689936
similar to G protein-coupled receptor 81
Database Links
Ensembl Gene
Entrez Gene
GPCRDB
GeneCards
GenitoUrinary Development Molecular Anatomy Project
HomoloGene
Human Protein Reference Database
InterPro
KEGG Gene
OMIM
PharmGKB Gene
PhosphoSitePlus
Protein Ontology (PRO)
RefSeq Nucleotide
RefSeq Protein
TreeFam
UniGene Hs.
UniProtKB
Wikipedia
Natural/Endogenous Ligands
L-lactic acid
Comments: Proposed ligand, two publications
Agonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Affinity Units Reference
3,5-dihydroxybenzoic acid Mm Full agonist 3.76 pEC50 10
pEC50 3.76 (EC50 1.72x10-4 M) [10]
3,5-dihydroxybenzoic acid Hs Full agonist 3.72 pEC50 10
pEC50 3.72 (EC50 1.91x10-4 M) [10]
D-lactic ​acid Hs Partial agonist 2.52 pEC50 2
pEC50 2.52 [2]
L-lactic acid Mm Full agonist 2.17 – 2.82 pEC50 1,11
pEC50 2.17 – 2.82 [1,11]
L-lactic acid Hs Full agonist 1.3 – 2.89 pEC50 1-2,11,15
pEC50 1.3 – 2.89 [1-2,11,15]
γ-hydroxybutyric acid Hs Full agonist 1.82 pEC50 11
pEC50 1.82 (EC50 1.53x10-2 M) [11]
nicotinic acid Hs Unknown - pEC50 16
pEC50 [16]
View species-specific agonist tables
Agonist Comments
Of all naturally occurring agonists only L-lactic acid reaches levels sufficient to activate the receptor. Although the basal plasma concentrations of L-lactate are in the range of 0.5 and 2 mM [6,12-13], up to at least seven-fold increases in physiological lactic acid concentractions have been reported under certain conditions [3,5,8,14].

Nicotinic acid is capable of stimulating HCA1 at high concentrations only (10mM), which precludes the determination of an EC50 value or the assessment of full verses partial agonism [16].
Antagonist Comments
Currently no antagonists are known for HCA1.
Allosteric Modulator Comments
Currently no allosteric regulators are known for HCA1.
Primary Transduction Mechanisms
Transducer Effector/Response
Gi/Go family
References: 
Tissue Distribution
Pituitary gland.
Species:  Human
Technique:  Northern blotting.
References:  9
Fetal liver, fetal heart.
Species:  Human
Technique:  RT-PCR.
References:  17
Adipose tissue- brown and white.
Species:  Human
Technique:  RT-PCR.
References:  11
Adipose tissue- brown and white.
Species:  Mouse
Technique:  Genetic reporter, RT-PCR.
References:  1,11
Adipose tissue- brown and white.
Species:  Rat
Technique:  RT-PCR.
References:  11
Expression Datasets

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Log average relative transcript abundance in mouse tissues measured by qPCR from Regard, J.B., Sato, I.T., and Coughlin, S.R. (2008). Anatomical profiling of G protein-coupled receptor expression. Cell, 135(3): 561-71. [PMID:18984166] [Raw data: website]

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Functional Assays
Measurement of GTPγS binding in HEK 293T cells transfected with the human HCA1 receptor and Gαo1.
Species:  Human
Tissue:  HEK 293T cells.
Response measured:  Stimulation of GTPγS binding.
References:  16
Physiological Functions
Mediation of inhibitory regulation of lipolysis by lactate.
Species:  Mouse
Tissue:  Adipose tissue.
References:  1-2,11
Inhibition of lipolysis in response to insulin. Insulin increases formation and release of lactate in adipocytes. Lactate then acts in an auto-/paracrine manner through HCA1 on adipocytes.
Species:  Mouse
Tissue:  Adipocytes.
References:  1
Physiological Consequences of Altering Gene Expression
Reduced insulin-induced antilipolysis: mice lacking HCA1 show reduced antilipolysis in response to insulin as well as a reduced weight gain under high fat diet.
Species:  Mouse
Tissue:  Adipose tissue.
Technique:  Gene knockouts.
References:  1
Phenotypes, Alleles and Disease Models Mouse data from MGI

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Allele Composition & genetic background Accession Phenotype Id Phenotype Reference
Gpr81tm1Dgen Gpr81tm1Dgen/Gpr81tm1Dgen
B6.Cg-Gpr81
MGI:2441671  MP:0008033 impaired lipolysis PMID: 18952058 
General Comments
Thiazolidinediones increase the expression of HCA1 via PPARγ [7], whereas LPS decreases expression of HCA1 via TLR4 [4].

REFERENCES

1. Ahmed K, Tunaru S, Tang C, Müller M, Gille A, Sassmann A, Hanson J, Offermanns S. (2010) An autocrine lactate loop mediates insulin-dependent inhibition of lipolysis through GPR81. Cell Metab.11 (4): 311-9. [PMID:20374963]

2. Cai TQ, Ren N, Jin L, Cheng K, Kash S, Chen R, Wright SD, Taggart AK, Waters MG. (2008) Role of GPR81 in lactate-mediated reduction of adipose lipolysis. Biochem Biophys Res Commun377 (3): 987-991. [PMID:18952058]

3. DiGirolamo M, Newby FD, Lovejoy J. (1992) Lactate production in adipose tissue: a regulated function with extra-adipose implications. FASEB J.6 (7): 2405-12. [PMID:1563593]

4. Feingold KR, Moser A, Shigenaga JK, Grunfeld C. (2011) Inflammation inhibits GPR81 expression in adipose tissue. Inflamm. Res.60 (10): 991-5. [PMID:21751047]

5. Hagström-Toft E, Enoksson S, Moberg E, Bolinder J, Arner P. (1997) Absolute concentrations of glycerol and lactate in human skeletal muscle, adipose tissue, and blood. Am. J. Physiol.273 (3 Pt 1): E584-92. [PMID:9316449]

6. HUCKABEE WE. (1958) Relationships of pyruvate and lactate during anaerobic metabolism. I. Effects of infusion of pyruvate or glucose and of hyperventilation. J. Clin. Invest.37 (2): 244-54. [PMID:13513755]

7. Jeninga EH, Bugge A, Nielsen R, Kersten S, Hamers N, Dani C, Wabitsch M, Berger R, Stunnenberg HG, Mandrup S et al.. (2009) Peroxisome proliferator-activated receptor gamma regulates expression of the anti-lipolytic G-protein-coupled receptor 81 (GPR81/Gpr81). J. Biol. Chem.284 (39): 26385-93. [PMID:19633298]

8. Kreisberg RA. (1980) Lactate homeostasis and lactic acidosis. Ann. Intern. Med.92 (2 Pt 1): 227-37. [PMID:6766289]

9. Lee DK, Nguyen T, Lynch KR, Cheng R, Vanti WB, Arkhitko O, Lewis T, Evans JF, George SR, O'Dowd BF. (2001) Discovery and mapping of ten novel G protein-coupled receptor genes. Gene275: 83-91. [PMID:11574155]

10. Liu C, Kuei C, Zhu J, Yu J, Zhang L, Shih A, Mirzadegan T, Shelton J, Sutton S, Connelly MA et al.. (2012) 3,5-Dihydroxybenzoic acid, a specific agonist for hydroxycarboxylic acid 1, inhibits lipolysis in adipocytes. J. Pharmacol. Exp. Ther.341 (3): 794-801. [PMID:22434674]

11. Liu C, Wu J, Zhu J, Kuei C, Yu J, Shelton J, Sutton SW, Li X, Yun SJ, Mirzadegan T, Mazur C, Kamme F, Lovenberg TW. (2009) Lactate Inhibits Lipolysis in Fat Cells through Activation of an Orphan G-protein-coupled Receptor, GPR81. J Biol Chem.284 (5): 2811-2822. [PMID:19047060]

12. Marbach EP, Weil MH. (1967) Rapid enzymatic measurement of blood lactate and pyruvate. Use and significance of metaphosphoric acid as a common precipitant. Clin. Chem.13 (4): 314-25. [PMID:6036716]

13. Niessner H, Beutler E. (1973) Fluorometric analysts of glycolytic intermediates in human red blood cells. Biochem Med8 (1): 123-34. [PMID:4744313]

14. Osnes JB, Hermansen L. (1972) Acid-base balance after maximal exercise of short duration. J Appl Physiol32 (1): 59-63. [PMID:5007019]

15. Southern C, Cook JM, Neetoo-Isseljee Z, Taylor DL, Kettleborough CA, Merritt A, Bassoni DL, Raab WJ, Quinn E, Wehrman TS et al.. (2013) Screening β-Arrestin Recruitment for the Identification of Natural Ligands for Orphan G-Protein-Coupled Receptors. J Biomol Screen18 (5): 599-609. [PMID:23396314]

16. Wise A, Foord SM, Fraser NJ, Barnes AA, Elshourbagy N, Eilert M, Ignar DM, Murdock PR, Steplewski K, Green A, Brown AJ, Dowell SJ, Szekeres PG, Hassall DG, Marshall FH, Wilson S, Pike NB. (2003) Molecular identification of high and low affinity receptors for nicotinic acid. J Biol Chem278: 9869-9874. [PMID:12522134]

17. Wu FM, Huang HG, Hu M, Gao Y, Liu YX. (2006) [Molecular cloning, tissue distribution and expression in engineered cells of human orphan receptor GPR81]. Sheng Wu Gong Cheng Xue Bao22: 408-412. [PMID:16755919]

To cite this database page, please use the following:

Stefan Offermanns, Steven L. Colletti, Adriaan P. Ijzerman, Timothy W. Lovenberg, Graeme Semple, Alan Wise.
Hydroxycarboxylic acid receptors: HCA1 receptor. Last modified on 12/12/2013. Accessed on 02/09/2014. IUPHAR database (IUPHAR-DB), http://www.iuphar-db.org/DATABASE/ObjectDisplayForward?objectId=311.

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