Fig. 2: Prolonged maintenance of beige fat by deleting Cdkn2a prevents HFHS-induced obesity and glucose intolerance by enhancing energy expenditure.

a Experimental procedure. Two-month-old UCP1-RFP (control) and Cdkn2a^Ucp1 KO male mice were housed under cold conditions for 7 consecutive days to induce beige fat formation. Mice were then administered TAM and fed a HFHS diet at room temperature for 120 days. b Representative images of 6-month-old control or Cdkn2a^Ucp1 KO male mice under HFHS. c Body weight of control (n = 13) or Cdkn2a^Ucp1 KO male mice under HFHS (n = 10). d NMR analysis of fat (left panel) and lean masses (right panel) of body weight of control or Cdkn2a^Ucp1 KO male mice under HFHS (n = 7–15). e Tile scan of IGW from control or Cdkn2a^Ucp1 KO male mice under HFHS. Scale bar, 100 μM. f Quantification of adipocyte sizes in IGW from control (n = 4) or Cdkn2a^Ucp1 KO male mice (n = 3). g The blood glucose level of control (n = 13) or Cdkn2a^Ucp1 KO male mice (n = 10) ad libitum feeding with HFHS. h The serum insulin level of control (n = 14) or Cdkn2a^Ucp1 KO (n = 11) male mice under HFHS. i The blood glucose level of control (n = 14) or Cdkn2a^Ucp1 KO (n = 11) male mice under HFHS after intraperitoneal injection of glucose for glucose (GTT) tolerance tests. j Area under the curve (AUC) analyses of (i). k The blood glucose level of control or Cdkn2a^Ucp1 KO mice under HFHS after intraperitoneal injection of insulin for insulin (ITT) tolerance tests (n = 6). l Area under the curve (AUC) analyses of (k). m Energy expenditure of control (n = 5) or Cdkn2a^Ucp1 KO (n = 7) male mice fed a HFHS. n Body temperature of control or Cdkn2a^Ucp1 KO male mice during this experiment (n = 8). o Immunofluorescence staining of UCP1 and RFP in IGW from control or Cdkn2a^Ucp1 KO male mice. Scale bar, 50 μM. p Quantification of the percentage of RFP+ cells that express endogenous UCP1. q qPCR analysis of the mRNA expression of thermogenic genes in IGW from control or Cdkn2a^Ucp1 KO male mice (n = 6). r Western blot analysis of UCP1 in IGW from control or Cdkn2a^Ucp1 KO male mice (n = 3). p values were determined by two-tailed Student’s t test. Data are expressed as means ± SEM.