Roux-en-Y gastric bypass surgery restores insulin-mediated glucose partitioning and mitochondrial dynamics in primary myotubes from severely obese humans

Abstract

Background/Objectives: Impaired insulin-mediated glucose partitioning is an intrinsic metabolic defect in skeletal muscle from severely obese humans (BMI ≥ 40 kg/m 2). Roux-en-Y gastric bypass (RYGB) surgery has been shown to improve glucose metabolism in severely obese humans. The purpose of the study was to determine the effects of RYGB surgery on glucose partitioning, mitochondrial network morphology, and markers of mitochondrial dynamics skeletal muscle from severely obese humans. Subject/Methods: Human skeletal muscle cells were isolated from muscle biopsies obtained from RYGB patients (BMI = 48.0 ± 2.1, n=7) prior to, 1-month and 7-months following surgery and lean control subjects (BMI = 22.4 ± 1.1, n=7). Complete glucose oxidation, non-oxidized glycolysis rates, mitochondrial respiratory capacity, mitochondrial network morphology and regulatory proteins of mitochondrial dynamics were determined in differentiated human myotubes. Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Pharmacological inhibition of dynamin‐related protein 1 attenuates skeletal muscle insulin resistance in obesity

“…The primary finding of our study was that Drp1 inhibition in vivo using the pharmacological inhibitor Mdivi-1 attenuated skeletal muscle insulin resistance at the early stage in the development of diet-induced obesity. The beneficial effects of Drp1 inhibition are in line with previous work, including ours that demonstrated the inverse relationship between Drp1 activity and skeletal muscle insulin sensitivity (Fealy et al, 2014;Kugler et al, 2020), as well as a study showing that single Mdivi-1 injection transiently (i.e., 1 h prior to sacrifice) enhanced insulin signaling in a genetic model of obesity (Jheng et al, 2012). Our results extended these findings by demonstrating the short-term efficacy of Drp1 inhibitor administration in vivo in the setting of obesity-induced insulin resistance.…”

“…Previously isolated human skeletal muscle cells (HSkMCs) from severely obese, insulin-resistant women (BMI ≥40 kg/ | 3 of 18 KUGLER Et aL. m 2 , HOMA-IR ≥2.5, n = 6) and lean insulin-sensitive women (BMI < 25 kg/m 2 , HOMA-IR < 2.5, n = 6) were used in this study (Kugler et al, 2020). In brief, human skeletal muscle cells (Passage 3) were thawed, pooled together, and grown in a humidified environment with 5% CO 2 at 37°C on a type-I collagen-coated flask (Greiner Bio-one).…”

“…Gastrocnemius muscles were mechanically homogenized in ice-cold homogenization buffer supplemented with protease and phosphatase inhibitors and centrifuged at 12,000 rpm for 15 min at 4°C. Cell lysates were homogenized, as previously described (Kugler et al, 2020…”

“…While Drp1-mediated mitochondrial fission is essential in maintaining mitochondrial function and overall skeletal muscle health (Dulac et al, 2020;Favaro et al, 2019), excessive activation/upregulation of Drp1 leads to aberrant mitochondrial fission causing imbalanced mitochondrial dynamics and mitochondrial fragmentation (Giovarelli et al, 2020;Touvier et al, 2015). We and others recently reported that Drp1 is hyperactivated in skeletal muscle from obese insulin-resistant humans, and this hyperactivation is strongly correlated with impaired skeletal muscle insulin signaling and glucose metabolism (Fealy et al, 2014;Kugler et al, 2020). Additionally, Jheng et al demonstrated that a Drp1 knockdown provided protection from palmitate-induced mitochondrial fragmentation and insulin resistance in the C 2 C 12 cell culture model (Jheng et al, 2012).…”

Characterization of Skeletal Muscle Endocrine Control in an In Vitro Model of Myogenesis

“…The last decade has been an exciting period for the study of the biology of skeletal muscle stem cells and tissue regeneration and the development of novel human in vitro cell models can contribute to the identification of new mechanisms that control myogenesis [14][15][16][17][18][19][20]. These human cell cultures appear more suitable for predictive screening strategies when compared to rodent cell lines, such as C2C12 or rat L6 myoblasts [21,22].…”