Differential mitochondrial gene expression in adipose tissue following weight loss induced by diet or bariatric surgery.

CONTEXT Mitochondria are essential for cellular energy homeostasis, yet their role in subcutaneous adipose tissue (SAT) during different types of weight-loss interventions remains unknown. OBJECTIVE Investigate how SAT mitochondria change following diet-induced and bariatric surgery-induced weight-loss interventions in four independent weight-loss studies. DESIGN/SETTING The DiOGenes study is a European multicenter dietary intervention with an 8-week low caloric diet (LCD; 800 kcal/d; n=261) and 6-month weight maintenance (n=121) period. The Kuopio Obesity Surgery study (KOBS) is a Roux-en-Y gastric bypass (RYGB) surgery study (n=172) with a 1-year follow-up. We associated weight-loss percentage with global and 2210 mitochondria-related RNA transcripts in linear regression analysis adjusted for age and sex. We repeated these analyses in two studies. The Finnish CRYO study has a 6-week LCD (800-1000 kcal/d; n=19) and a 10.5-month follow-up. The Swedish DEOSH study is a RYGB surgery study with a 2-year (n=49) and 5-year (n=37) follow-up. RESULTS Diet-induced weight loss led to a significant transcriptional downregulation of oxidative phosphorylation (DiOGenes; Ingenuity Pathway Analyses (IPA) z-scores: -8.7 following LCD, -4.4 following weight maintenance; CRYO: IPA z-score: -5.6, all p<0.001), while upregulation followed surgery-induced weight loss (KOBS: IPA z-score: 1.8, p<0.001; in DEOSH: IPA z-scores: 4.0 following 2 years, 0.0 following 5 years). We confirmed an upregulated oxidative phosphorylation at the proteomics level following surgery (IPA z-score: 3.2, p<0.001). CONCLUSIONS Differentially regulated SAT mitochondria-related gene expressions suggest qualitative alterations between weight-loss interventions, providing insights into the potential molecular mechanistic targets for weight-loss success.