Proteomics Analysis of Skeletal Muscle from Leptin‐Deficient ob/ob Mice Reveals Adaptive Remodeling of Metabolic Characteristics and Fiber Type Composition

Abstract

Skeletal muscle insulin resistance, an early metabolic defect in the pathogenesis of type 2 diabetes (T2D), may be a cause or consequence of altered protein expression profiles. Proteomics technology offers enormous promise to investigate molecular mechanisms underlying pathologies, however, the analysis of skeletal muscle is challenging. Using state-of-the-art multienzyme digestion and filter-aided sample preparation (MED-FASP) and a mass spectrometry (MS)-based workflow, we performed a global proteomics analysis of skeletal muscle from leptin-deficient, obese, insulin resistant (ob/ob) and lean mice in mere two fractions in a short time (8 h per sample). We identified more than 6000 proteins with 118 proteins differentially regulated in obesity. This included protein kinases, phosphatases, and secreted and fiber type associated proteins. Enzymes involved in lipid metabolism in skeletal muscle from ob/ob mice were increased, providing evidence against reduced fatty acid oxidation in lipid-induced insulin resistance. Mitochondrial and peroxisomal proteins, as well as components of pyruvate and lactate metabolism, were increased. Finally, the skeletal muscle proteome from ob/ob mice displayed a shift toward the "slow fiber type." This detailed characterization of an obese rodent model of T2D demonstrates an efficient workflow for skeletal muscle proteomics, which may easily be adapted to other complex tissues.

Obesity modifies the stoichiometry of mitochondrial proteins in a way that is distinct to the subcellular localization of the mitochondria in skeletal muscle

“…In SS mitochondria, we found an 80% increase in ECHS1 (i.e., enoyl-CoA hydratase) in subjects with obesity, and in association with differential regulation of the fatty acid β-oxidation pathway. These findings are comparable to that in rodents showing increased expression of proteins participating in the β-oxidation of fatty acids in SS mitochondria after high-fat feeding [40], or proteins involved in overall lipid metabolism in muscle of obese animal models [41]. In IMF mitochondria, we found an even greater increase (126%) in ACADM (i.e., acyl-CoA dehydrogenase) in subjects with obesity, an enzyme also involved in the β-oxidation of fatty acids.…”

Trans-omic analysis reveals obesity-associated dysregulation of inter-organ metabolic cycles between the liver and skeletal muscle

“…In skeletal muscle of ob / ob mice, TAG was also identified as the increased DEM ( Figure 7 B), consistent with the previous finding ( Mastrocola et al., 2015 ). All eight DEMEs increased in skeletal muscle of ob / ob mice ( Figures 7 B and S12 D), and of these increased DEMEs, Cpt2, Acadm, Acadl, Acadvl, and Ecsh1 have been previously reported to increase ( Schönke et al., 2018 ). Expression of Hadhb and Acaa2 was regulated at the transcript level by the increased DRTFs such as Nfatc2 and Egr1 ( Figure 7 B).…”

Diabetes Induced Alterations in Murine Vitreous Proteome Are Mitigated by IL-6 Trans-Signaling Inhibition

“…MUPs are part of the lipocalin family, which are involved in communication and regulate glucose and lipid metabolism. Others have reported decreased Mup4 expression in diabetes, 44 while Mup8 levels are reportedly decreased 45 or unchanged. 46 Despite significant changes in the abundance of these proteins in diabetic mouse vitreous, their significance to DR pathology remains unclear.…”