Atypical beta-adrenergic receptor in 3T3-F442A adipocytes. Pharmacological and molecular relationship with the human beta 3-adrenergic receptor.
Expression of ligand binding properties for an atypical beta-adrenergic receptor (beta-AR) subtype was studied during the adipose differentiation of murine 3T3-F442A cells and compared with that of the human beta 3-AR expressed in Chinese hamster ovary cells stably transfected with the human beta 3-AR gene (CHO-beta 3 cells) Emorine, L. J., Marullo, S., Briend-Sutren, M. M., Patey, G., Tate, K., Delavier-Klutchko, C., and Strosberg, A. D. (1989) Science 245, 1118-1121). 3T3-F442A adipocytes exhibited high and low affinity binding sites for (-)-4-(3-t-butylamino-2-hydroxypropoxy) [5,7-3H]benzimidazole-2-one ((-)-[3H]CGP-12177) (KD = 1.2 and 38.3 nM) and (-)-[125I]iodocyanopindolol ([125I]CYP) (KD = 47 and 1,510 pM). The high affinity sites corresponded to the classical beta 1- and beta 2-AR subtypes whereas the KD values of the low affinity sites for the radioligands were similar to those measured in CHO-beta 3 cells (KD = 28 nM and 1,890 pM for (-)-[3H]CGP12177 and [125I]CYP, respectively). These low affinity sites were undetectable in preadipocytes but represented about 90% of total beta-ARs in adipocytes. The atypical beta-AR and the human beta 3-AR add similarly low affinities (Ki = 3-5 microM) for (+/-)-(2-(3-carbamoyl-4-hydroxyphenoxy)ethylamino-3)-(4-(1-methyl- 4- trifluormethyl-2-imidazolyl)-phenoxy)-2-propanol methane sulfonate (CGP20712A) or erythro-(+/-)-1-(7-methylindan-4-yloxy)-3-isopropylaminob utan-2-ol (ICI118551), highly selective beta 1- and beta 2-AR antagonists, respectively, in agreement with the poor inhibitory effect of the compounds on (-)-isoproterenol (IPR)-stimulated adenylate cyclase activity. Atypical beta-AR and beta 3-AR had an affinity about 10-50 times higher for sodium-4-(2-[2-hydroxy-2-(3-chlorophenyl)ethylamino]propyl)phenoxyace tate sesquihydrate (BRL37344) than the beta 1-AR subtype. This correlates with the potent lipolytic effect of BRL37344 in adipocytes. The rank order of potency of agonists in functional and binding studies was BRL37344 greater than IPR less than (-)-norepinephrine greater than (-)-epinephrine both in 3T3 adipocytes and CHO-beta 3 cells. As in CHO-beta 3 cells, the classical beta 1- and beta 2-antagonists CGP12177, oxprenolol, and pindolol were partial agonists in adipocytes. Although undetectable in preadipocytes, a major mRNA species of 2.3 kilobases (kb) and a minor one of 2.8 kb were observed in adipocytes by hybridization to a human beta 3-AR specific probe.(ABSTRACT TRUNCATED AT 400 WORDS)
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Unité 282 Institut National de la Santé et de la Recherche Médicale-Centre National de la Recherche Scientifique, Hôpital Henri Mondor, Créteil, France.
Emorine
L J
LJ
Lasnier
F
F
Blin
N
N
Baude
B
B
Nahmias
C
C
Strosberg
A D
AD
Pairault
J
J
D016475:3T3 Cells; D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D000319:Adrenergic beta-Antagonists; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D015152:Blotting, Northern; D004247:DNA / Q000235:genetics; D004983:Ethanolamines / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D010096:Oxprenolol / Q000494:pharmacology; D010869:Pindolol / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011412:Propanolamines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D004983:Ethanolamines; D007093:Imidazoles; D011412:Propanolamines; D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D010096:Oxprenolol; C057368:BRL 37344; D004247:DNA; D010869:Pindolol; C049763:CGP 20712A; C033394:CGP 12177