Ablation of adipose Atg7 tunes down mitochondrial turnover and impairs metabolism in mice.

(A,B) Western blotting (A) and densitometric (B) analyses of autophagy proteins in control (Ctrl) and adipocyte Atg7 knockout (ad7KO) mice; n=6. (C) Transmission electron microscopic view of inguinal adipose tissue sections. The arrows point to mitochondria engulfed by autophagosome for clearance, and the asterisks mark the mitochondria not engulfed by autophagosome. (D) Counts of mitochondria inside autophagosome (MiA, marked by arrows) and mitochondria outside autophagosome (MoA, marked by asterisks) under the transmission electron microscope (area of 35 μm2); n=6–8. (E) Western blotting (upper panel) and densitometric (lower panel) analyses of adipose browning maker UCP1 in inguinal adipose tissues; n=6. (F) RNAseq analysis of Atg7, mitochondrial genes (mt-Nd1, mt-Nd2, mt-Nd3, mt-Nd4, mt-cytb), fatty acid metabolism related genes (Fasn, Acaca, and Acsm3), browning marker (Cidea), and iron status marker (Fth1) in Ctrl and ad7KO mice. (G) Measurement of body temperatures; n=6. (H,I) Glucose tolerance test (H) and calculation of area under the curve (AUC, I); n=6–8. (J) Measurement of HOMA-IR; n=6–10. (K) Knockdown of Atg7 (Atg7-KD) in 3T3L1 cells; n=4–6. (L–N) Measurement of basal respiration (BR, L), maximal respiration (MR, M), and spare respiration capacity (SRC, N) of 3T3L1 adipocytes; n=3–4. (O) Schematic view of how blockage of autophagy via Atg7 impaired mitochondrial turnover and metabolic function; QC, quality control. *P<0.05, **P<0.01, ***P<0.001.