Figure 6. SMRT^mRID1 inhibits mitochondrial function.

(A) Assessment of fatty acid β-oxidation in brown fat (BAT) organ culture, primary hepatocytes and pre-adipocytes/fibroblasts. The rate of fatty acid oxidation was determined by ³H-palmitate breakdown to ³H₂O. (B) Assessment of mitochondrial DNA content in BAT and muscle. Mitochondrial DNA was quantified by real-time PCR and normalized to nuclear DNA content. (C) SMRT^mRID1 MEFs have reduced mitochondrial content. MitoTracker staining (green fluorescence) was conducted to determine mitochondrial content. (D) SMRT^mRID1 mice show reduced O₂ consumption and lowered body temperature. O₂ consumption, activity and food intake were determined by metabolic cages. (E) Histological analyses of BAT and liver sections (H & E staining) to examine lipid accumulation (see also Figure S3). Tissue triglyceride (TG) content was measured by enzymatic assays. Muscle, BAT and pre-adipocytes were isolated from 6-month old mice. Primary hepatocytes were from 2.5-month old mice. Values are expressed as means±SEM. *p<0.05, comparing wt to SMRT^mRID1 mice/cells.