Introduction

Mitochondrial dysfunction contributes to the pathogenesis of metabolic disorders such as obesity1. Mitochondria are highly dynamic organelles that play essential roles in energy metabolism, heat production, generation of oxygen radicals, calcium signaling, and apoptosis2,3,4,5,6. To maintain metabolic health, mitochondrial selective autophagy (mitophagy), mitochondrial biogenesis, and various mitochondrial protein degradation processes coordinately control the quality of mitochondria6,7.

Mitophagy involves the recognition of damaged mitochondria by the autophagosome through microtubule-associated protein 1 light chain 3 (LC3) adapters in ubiquitin-dependent and independent mechanisms8,9. PTEN-induced putative kinase 1 (Pink1, encoded by Park6) and E3 ubiquitin-protein ligase Parkin are known to function in ubiquitin-dependent mitophagy, while other proteins such as TBC1 domain family member 15 (Tbc1d15) and Nip3-like protein X (Nix) contribute to ubiquitin-independent mitophagy9,10,11,12.

Emerging evidence has shown that low mitochondrial content and activity contribute to adipocyte hypertrophy and metabolic disorders13,14,15,S1 for a list of the primers used.

RNA sequencing and analysis

A homogenous portion of frozen adipose samples were homogenized using a tissue homogenizer in Trizol. RNA was isolated using the Qiagen RNeasy Mini QIAcube Kit following the manufacturer’s instructions. Isolated RNA was checked for concentration using a NanoDrop and purity using the Agilent TapeStation. Only samples with RIN > 7.0 were used. Libraries were prepared using the KAPA mRNA HyperPrep Kit following the manufacturer’s instructions. The resulting libraries were combined into two pools and sequenced on an Illumina HiSeq 3000 within the UCLA TCGB core facility following in-house established protocols. Raw reads were checked for quality using FastQC, aligned to the Mus musculus GRCm38, and then counted using Mus musculus GRCm38 version 97. Alignment and counting occurred using Rsubread v 2.4.263. Raw counts were then analyzed for differential gene expression using the DESeq2 v1.30.064.

Statistics

Values presented are expressed as means ± SEM unless otherwise indicated. Statistical analyses were performed using Student’s t test when comparing two groups of samples or Two-way analysis of variance (ANOVA) for identification of significance within and between groups using GraphPad Prism9.4.1 (GraphPad Software). Significance was set a priori at P < 0.05. For RNA Sequencing analysis, the significance was set as FDR < 0.05.

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.