G-protein estrogen receptor as a regulator of low-density lipoprotein cholesterol metabolism: cellular and population genetic studies.
OBJECTIVE
Estrogen deficiency is linked with increased low-density lipoprotein (LDL) cholesterol. The hormone receptor mediating this effect is unknown. G-protein estrogen receptor (GPER) is a recently recognized G-protein-coupled receptor that is activated by estrogens. We recently identified a common hypofunctional missense variant of GPER, namely P16L. However, the role of GPER in LDL metabolism is unknown. Therefore, we examined the association of the P16L genotype with plasma LDL cholesterol level. Furthermore, we studied the role of GPER in regulating expression of the LDL receptor and proprotein convertase subtilisin kexin type 9.


RESULTS
Our discovery cohort was a genetically isolated population of Northern European descent, and our validation cohort consisted of normal, healthy women aged 18 to 56 years from London, Ontario. In addition, we examined the effect of GPER on the regulation of proprotein convertase subtilisin kexin type 9 and LDL receptor expression by the treatment with the GPER agonist, G1. In the discovery cohort, GPER P16L genotype was associated with a significant increase in LDL cholesterol (mean±SEM): 3.18±0.05, 3.25±0.08, and 4.25±0.33 mmol/L, respectively, in subjects with CC (homozygous for P16), CT (heterozygotes), and TT (homozygous for L16) genotypes (P<0.05). In the validation cohort (n=339), the GPER P16L genotype was associated with a similar increase in LDL cholesterol: 2.17±0.05, 2.34±0.06, and 2.42±0.16 mmol/L, respectively, in subjects with CC, CT, and TT genotypes (P<0.05). In the human hepatic carcinoma cell line, the GPER agonist, G1, mediated a concentration-dependent increase in LDL receptor expression, blocked by either pretreatment with the GPER antagonist G15 or by shRNA-mediated GPER downregulation. G1 also mediated a GPER- and concentration-dependent decrease in proprotein convertase subtilisin kexin type 9 expression.


CONCLUSIONS
GPER activation upregulates LDL receptor expression, probably at least, in part, via proprotein convertase subtilisin kexin type 9 downregulation. Furthermore, humans carrying the hypofunctional P16L genetic variant of GPER have increased plasma LDL cholesterol. In aggregate, these data suggest an important role of GPER in the regulation of LDL receptor expression and consequently LDL metabolism.
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Yasin
Y
Hussain
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Qingming
Q
Ding
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Philip W
PW
Connelly
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
J Howard
JH
Brunt
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Matthew R
MR
Ban
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Adam D
AD
McIntyre
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Murray W
MW
Huff
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Robert
R
Gros
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.).
Robert A
RA
Hegele
From the Robarts Research Institute (Y.H., Q.D., M.R.B., A.D.M., M.W.H., R.G., R.A.H., R.D.F.) and Departments of Medicine (M.W.H., R.G., R.A.H., R.D.F.), Physiology and Pharmacology (R.G., R.A.H., R.D.F.), and Biochemistry (M.W.H.), Western University, London, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada (P.W.C.); and Department of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada (J.H.B.). feldmanr@lhsc.on.ca.
Ross D
RD
Feldman
D000293:Adolescent; D000328:Adult; D000368:Aged; D002170:Canada; D008078:Cholesterol, LDL / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005786:Gene Expression Regulation; D005787:Gene Frequency; D005828:Genetics, Population; D056945:Hep G2 Cells; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D010641:Phenotype; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D011960:Receptors, Estrogen / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D044465:White People / Q000235:genetics; D055815:Young Adult
D008078:Cholesterol, LDL; C109584:GPER1 protein, human; C573412:LDLR protein, human; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D011973:Receptors, LDL; C472125:PCSK9 protein, human; D000071449:Proprotein Convertase 9; D043484:Proprotein Convertases; D012697:Serine Endopeptidases
GPER protein, human; PCSK9 protein, human; cholesterol, LDL; receptors, LDL