Regulation of the Uncoupling Protein Gene (Ucp) by β1, β2, and β3-Adrenergic Receptor Subtypes in Immortalized Brown Adipose Cell Lines *

摘要: Abstract Immortalized brown adipocyte cell lines derived from a mouse hibernoma express all three β-adrenergic receptor subtypes, including β3-adrenergic (AR). In response to norepinephrine, cAMP production by plasma membranes four clonal was stimulated levels comparable with adipocytes isolated interscapular adipose tissue (72.8-89.6 versus 97.8 pmol cAMP/min/mg of protein, respectively). All responded the highly selective agonist CL316,243 stimulating adenylyl cyclase activity (3-10-fold over basal). β1-, β2-, and mRNA detected Northern blotting and/or reverse transcriptase-polymerase chain reaction. Competition binding assays antagonists CGP20712A I-cyanopindolol showed proportions β1AR β2AR in immortalized cells be similar (cells: 35% β1AR, 65% β2AR; tissue: 41%, 59% β2AR). Expression fat-specific mitochondrial uncoupling protein (Ucp) agonists two lines. The ability individual βAR subtypes regulate Ucp expression examined combinations antagonists. could induced any subtypes. However, greatest obtained simultaneously (100 μM isoproterenol). Incubation cultured or at an optimal concentration (5 μM) did not prevent norepinephrine further activity, suggesting that combined activation β1AR/β2AR, plus β3AR, together produced additive response. Multiple forms were identified white tissues. blot analysis types 5, 6, 10. Screening transcriptase-PCR products DNA sequencing confirmed identities these lower additional isoforms, raising possibility couple distinct cyclases. Because display functional phenotypic similarities adipocytes, they will useful model study regulation function, control activity.