Fig. 2: Metabolic derangements in GPR180 knockout mice are caused by dysfunctional BAT.

UCP1 protein in a iBAT (p = 0.0425) and b iWAT (p = 0.0027) of GPR180 global knockout mice and their wild-type littermates (n = 7) fed chow diet and housed at room temperature (RT). c Energy expenditure in male mice with deleted GPR180 (n = 6) on chow diet and housed at RT (AUC p < 0.0001). d Representative images including rainbow scale bar indicating temperature range with min 28 °C and max 36 °C and e quantification of surface temperature in male GPR180 global knockout mice and wild-type littermates (n = 6; p = 0.0065). f Intraperitoneal glucose tolerance test in 12-weeks-old male mice housed at RT and fed chow diet (WT n = 6, GPR180^−/− n = 7; p = 0.047 at 15 min, p = 0.0001 at 30 min and p < 0.0001 at 60 min). g Body weight gain (p = 0.0212 at 6 weeks, p = 0.0036 at 7 weeks, p = 0.0006 at 8 weeks, p = 0.0003 at 9 weeks, p = 0.0004 at 10 weeks, p < 0.0001 at 11 and 12 weeks), and h hepatic lipid accumulation (p = 0.008856) in male mice housed RT and fed HFD for 12 weeks (WT n = 11, GPR180^−/− n = 12). i Glucose tolerance test in 12-weeks-old male mice housed at thermoneutrality (TN) for 8 weeks prior the test and fed chow diet (n = 5). j Body weight gain and k hepatic lipid accumulation in animals housed at TN and fed HFD (n = 5). Representative blots and quantification of the UCP1 protein levels in l iBAT and m iWAT (p = 0.0473) of male adipocyte-specific GPR180 (aGPR180) knockout mice and fl/fl controls (fl/fl control n = 11, aGPR180 knockout n = 10). n Energy expenditure in male aGPR180 knockout mice and fl/fl controls (fl/fl control n = 6, aGPR180 knockout n = 5; p = 0.0473; 0.0051; 0.0450; 0.0098; 0.0139; 0.0412; 0.0277; 0.0212; 0.0278). o Representative images including rainbow scale bar indicating temperature range with min 28 °C and max 36 °C and p quantification of surface temperature (p = 0.0255 for basal and p = 0.0086 for post CL-316,423) in male aGPR180 knockout mice and fl/fl controls (fl/fl control n = 9, aGPR180 n = 8). q Glucose tolerance test in male aGPR180 knockouts and fl/fl controls (n = 4; p = 0.0002 at 15 min and p = 0.0243 at 30 min) 2 weeks after tamoxifen (TAM) gavage (2 mg/animal) in two consecutive days while mice were housed at RT and fed chow diet. r Body weight gain in aGPR180 knockout mice fed HFD housed at RT (fl/fl control n = 6, aGPR180 knockout n = 7; p = 0.0419 at 11 weeks and p = 0.0011 at 12 weeks). Data are presented as mean ± SEM. Statistical significance was calculated using two-sided (a–c, h, k) and one-sided Student´s t-test (l, m) or two-way ANOVA with repeated measurements followed by Sidak post-hoc test (e–g, i, j, p–r) and Fisher’ LSD multiple comparison test (n). Area under the curve was calculated to compare energy expenditure in the global knockout mice (c). Statistical differences are indicated as *p < 0.05, **p < 0.01 and ***p < 0.001. AUC area under the curve, CL CL-316,243, GPR180, G protein-coupled receptor 180, HFD high-fat diet, HSP90 Heat shock protein 90, iBAT interscapular brown adipose tissue, iWAT inguinal white adipose tissue, RT room temperature, TAM tamoxifen, UCP1 Uncoupling protein 1, WT wild-type.