beta-Arrestin1 mediates nicotinic acid-induced flushing, but not its antilipolytic effect, in mice.
Nicotinic acid is one of the most effective agents for both lowering triglycerides and raising HDL. However, the side effect of cutaneous flushing severely limits patient compliance. As nicotinic acid stimulates the GPCR GPR109A and Gi/Go proteins, here we dissected the roles of G proteins and the adaptor proteins, beta-arrestins, in nicotinic acid-induced signaling and physiological responses. In a human cell line-based signaling assay, nicotinic acid stimulation led to pertussis toxin-sensitive lowering of cAMP, recruitment of beta-arrestins to the cell membrane, an activating conformational change in beta-arrestin, and beta-arrestin-dependent signaling to ERK MAPK. In addition, we found that nicotinic acid promoted the binding of beta-arrestin1 to activated cytosolic phospholipase A2 as well as beta-arrestin1-dependent activation of cytosolic phospholipase A2 and release of arachidonate, the precursor of prostaglandin D2 and the vasodilator responsible for the flushing response. Moreover, beta-arrestin1-null mice displayed reduced cutaneous flushing in response to nicotinic acid, although the improvement in serum free fatty acid levels was similar to that observed in wild-type mice. These data suggest that the adverse side effect of cutaneous flushing is mediated by beta-arrestin1, but lowering of serum free fatty acid levels is not. Furthermore, G protein-biased ligands that activate GPR109A in a beta-arrestin-independent fashion may represent an improved therapeutic option for the treatment of dyslipidemia.
Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.
Robert W
RW
Walters
Arun K
AK
Shukla
Jeffrey J
JJ
Kovacs
Jonathan D
JD
Violin
Scott M
SM
DeWire
Christopher M
CM
Lam
J Ruthie
JR
Chen
Michael J
MJ
Muehlbauer
Erin J
EJ
Whalen
Robert J
RJ
Lefkowitz
D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D019390:Arrestins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D004423:Ear / Q000098:blood supply; D015777:Eicosanoids / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005483:Flushing / Q000139:chemically induced / Q000378:metabolism*; D006801:Humans; D007801:Langerhans Cells / Q000187:drug effects / Q000378:metabolism; D008066:Lipolysis / Q000187:drug effects* / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009525:Niacin / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D011720:Pyrazoles / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects; D013777:Tetrazoles / Q000494:pharmacology; D000071557:beta-Arrestins
C531233:3-(1H-tetrazol-5-yl)-1,4,5,6-tetrahydrocyclopentapyrazole; D019390:Arrestins; D015777:Eicosanoids; D005230:Fatty Acids, Nonesterified; D018722:Nicotinic Agonists; D011720:Pyrazoles; D043562:Receptors, G-Protein-Coupled; D011978:Receptors, Nicotinic; D013777:Tetrazoles; D000071557:beta-Arrestins; D009525:Niacin; D000242:Cyclic AMP; D048049:Extracellular Signal-Regulated MAP Kinases; D054510:Phospholipases A2, Cytosolic