Figure 1. Optic atrophy 1 (OPA1) deficiency leads to mitochondrial dysfunction in brown adipose tissue (BAT), while improving energy balance and thermoregulation in mice.

(A, B) OPA1 expression in BAT of wild-type (WT) mice fed either control (10% fat) or a high-fat diet (HFD 60% fat) for 12 weeks. (A) Opa1 mRNA expression in BAT. (B) Representative immunoblot of OPA1 and densitometric analysis of OPA1 normalized by tubulin (images were cropped from the same membrane). (C, D) OPA1 expression in BAT of WT mice maintained at 30°C or 4°C for 3 days. (C) Opa1 mRNA expression in BAT. (D) Representative immunoblot of OPA1 and densitometric analysis of OPA1 (total levels and long/short isoforms – images were cropped from the same membrane). (E–J) Morphological and functional characterization of BAT from 8-week-old OPA1 BAT KO mice (KO). (E) Opa1 mRNA expression in BAT. (F) Representative immunoblot in BAT of OPA1 and UCP1 and densitometric analysis normalized to tubulin (dashed line separates genotypes). (G) Representative images of H&E-stained histological sections and electron micrographs of BAT from 8-week-old WT and KO mice (n = 3). Scale bar = 100 μm and 2 μm, respectively. (H, I) Functional analysis of mitochondria isolated from BAT of WT and KO mice. (H) Basal (state 2) and ADP-stimulated (state 3) pyruvate-malate-supported oxygen consumption rates (OCRs). (I) State 2 and state 3 palmitoyl-carnitine-supported OCR. (J) Palmitoyl-carnitine-supported ATP synthesis rates. (K–P) Body mass and body composition in 8- and 20 week-old WT and KO mice. (K) Body mass (8 and 20 weeks of age). (L) Body composition (8 weeks of age). (M) Body composition (20 weeks of age). (N) BAT mass. (O) Inguinal white adipose tissue (iWAT) mass. (P) Gonadal white adipose tissue mass (gWAT). (Q) Regression plot comparing oxygen consumption as a function of body mass in mice housed at 30°C. (R) Core body temperature in 8-week-old mice housed at 30°C. Data are expressed as means ± SEM. Significant differences were determined by Student's t‐test, using a significance level of p<0.05. *Significantly different vs. WT mice. VO₂ data was analyzed by ANCOVA.

Figure 1—figure supplement 1. Age-dependent changes in body composition and glucose homeostasis in optic atrophy 1 (OPA1) brown adipose tissue (BAT) knockout (KO) mice.

Related to Figure 1. (A–C) Representative immunoblot of OPA1 and densitometric analysis of OPA1 normalized by tubulin or GAPDH. (A) Inguinal white adipose tissue (iWAT) (dashed line separates genotypes). (B) Liver (images were cropped from the same membrane). (C) Skeletal muscle. (D–F) Body composition in 4-week-old females. (D) Body mass. (E) Percent fat mass to body weight. (F) Percent lean mass to body weight. (G) Regression plot comparing oxygen consumption as a function of body mass. (H) Percent fat mass to body weight in 8-week-old mice. (I) Percent lean mass to body weight in 8-week-old mice. (J) Percent fat mass to body weight in 20-week-old mice. (K) Percent lean mass to body weight in 20-week-old mice. (L) Glucose tolerance test (GTT) in 8-week-old mice. (M) Area under the curve for the GTT performed at 8 weeks. (N) GTT in 20-week-old mice. (O) Area under the curve for the GTT performed at 20 weeks. (P–T) Body composition and glucose homeostasis in 50-week-old female mice. (P) Body mass. (Q) Percent fat mass to body weight. (R) Percent lean mass to body weight. (S) GTT in 50-week-old mice. (T) Area under the curve for the GTT performed at 50 weeks. (U) Food intake measured in 8-week-old mice under thermoneutral conditions. (V) Locomotor activity measured in 8-week-old mice under thermoneutral conditions. Data are expressed as means ± SEM. Data are expressed as means ± SEM. Significant differences were determined by Student's t‐test, using a significance level of p<0.05. * Significantly different vs. wild-type (WT) mice. VO₂ data was analyzed by ANCOVA.

Figure 1—figure supplement 2. Data collected in 8-week-old optic atrophy 1 (OPA1) brown adipose tissue (BAT) knockout mice (KO) and their wild-type littermate controls (WT) reared at thermoneutrality.

Related to Figure 1. (A) Body mass. (B) Percent fat mass normalized to body weight. (C) Percent lean mass normalized to body weight. (D) BAT mass normalized by body weight. (E) Gonadal white adipose tissue (gWAT) mass normalized by body weight. (F) Inguinal white adipose tissue (iWAT) mass normalized to body weight. (G) Regression plot comparing oxygen consumption as a function of body mass. (H) Average food intake. (I) Locomotor activity. Data are expressed as means ± SEM. Significant differences were determined by Student's t‐test using a significance level of p<0.05. *Significantly different vs. WT mice. VO₂ data was analyzed by ANCOVA.