Adiponectin treatment improves insulin resistance in mice by regulating the expression of the mitochondrial-derived peptide MOTS-c and its response to exercise via APPL1–SIRT1–PGC-1α

Abstract

Aims/hypothesis Adiponectin stimulates mitochondrial biogenesis through peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), a major regulator of mitochondrial biogenesis. MOTS-c (mitochondrial open reading frame of the 12S rRNA) is a biologically active mitochondrial-derived peptide encoded by mitochondrial DNA. It influences the mechanisms of obesity and diabetes. We hypothesised that the adiponectin pathway may regulate the production and/or secretion of MOTS-c in skeletal muscle. We aimed to determine whether exercise and adiponectin affect MOTS-c to improve insulin resistance in mice. Methods To investigate this hypothesis, we used wild-type C57BL/6 mice subjected to high-fat diet, an exercise regimen, and i.p. injection of recombinant mouse adiponectin (Acrp30) or MOTS-c, and adiponectin knockout (Adipoq −/− ) mice (C57BL/6 background) subjected to i.p. injection of Acrp30. C2C12 myotubes were also treated with sirtuin 1 (SIRT1) inhibitor, PGC-1α inhibitor, SIRT1 activator, plasmid-expressed active APPL1 (adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper), pcDNA-SIRT1, or siRNA against APPL1, SIRT1 or PGC-1α. Results In Adipoq -/mice, MOTS-c levels in the plasma and skeletal muscle were downregulated. In C2C12 myotubes, adiponectin increased the mRNA expression of MOTS-c. APPL1 protein level following adiponectin treatment positively correlated with MOTS-c protein and mRNA levels in C2C12 myotubes. SIRT1 overexpression increased the adiponectininduced mRNA and protein expression of MOTS-c, SIRT1 and PGC-1α. Pharmacologic and genetic inhibition of PGC-1α suppressed the increases in MOTS-c mRNA and protein levels induced by SIRT1 overexpression. In mice, plasma and skeletal muscle MOTS-c levels were significantly downregulated following high-fat-diet. Exercise and i.p. Acrp30 or MOTS-c increased MOTS-c levels and adiponectin mRNA and protein expression in the plasma and skeletal muscle. Conclusions/interpretation Our findings showed that the APPL1-SIRT1-PGC-1α pathway regulates the production and/or secretion of skeletal muscle MOTS-c by mediating adiponectin signalling. Our study provides an insight into the cellular and molecular pathways underlying the pathogenesis of diabetes and shows that MOTS-c is a potential novel therapeutic target in the treatment of diabetes. Keywords Adiponectin . Diabetes . Exercise-mediated signalling . Mitochondrial biogenesis . MOTS-c . Skeletal muscle Abbreviations Acrp30 Recombinant mouse adiponectin AMPK AMP-activated protein kinase APPL1 Adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1 HFD High-fat diet KO Knockout MOTS-c Mitochondrial open reading frame of the 12S rRNA-c mtDNA Mitochondrial DNA PGC-1α Peroxisome proliferator-activated receptor-γ coactivator 1α Electronic supplementary material The online version of this article (

The mitochondrial signaling peptide MOTS-c improves myocardial performance during exercise training in rats

“…We assessed the effects of aerobic exercise combined with MOTS-c treatment on myocardial structure using HE staining and transmission electron microscopy. Aerobic exercise (12 weeks) reversed collagen deposition, reduced the number of disordered cells, and restored myocardial cell structure in rats fed a high-fat diet 35 , 36 . We demonstrate that exercise widened intercellular myocardial cell spaces and caused myocardial fibers to be thickened and more closely arranged.…”

“…For example, 8 weeks of aerobic exercise decreased body weight and increased HWI in rats 31 , while rats exposed to swimming training for 12 weeks had decreased body weights and increased heart weight and HWI 32 . Supplementation with MOTS-c induces hypoglycemia and a reduction in lipid levels 33 – 35 . We reported that exercised rats reduced body weights and increased HWI, consistent with other reports that aerobic exercise induced myocardial hypertrophy.…”

Mitochondrial-derived peptides as a novel intervention for obesity and cardiac diseases: bench evidence for potential bedside application

“…In addition to AMPK, adiponectin is an adipose-derived adipokine associated with obesity-related diseases. It increases glucose sensitivity and fat metabolism, improves mitochondrial function and exerts anti-inflammatory properties to combat obesity by modulating MDPs,22–25 suggesting MDPs could be a potential governor of the metabolic pathways associated with obesity.…”

“…The mechanism used by MOTS-c was associated with the adiponectin pathway in a C2C12 skeletal muscle cell line (table 1). 25 Activation of the adiponectin receptor also promoted insulin secretion via triggering multiple downstream signals, including the adaptor protein, phosphotyrosine interaction, PH domain and leucine zipper containing 1 (APPL1) 25 28. Moreover, C2C12 cells treated with adiponectin were associated with increased MOTS-c levels along with increased activation of APPL1, sirtuin 1 (SIRT 1) and PGC-1α expression 25.…”

Mediating Roles of hsCRP, TNF-α and Adiponectin on the Associations between Body Fat and Fatty Liver Disease among Overweight and Obese Adults

“…In the liver, adiponectin acts by activating 5-AMP-activated protein kinases and peroxisome proliferator-activated receptor-α pathways, as well as inhibiting Toll-like receptor-4 mediated signaling [30]. There is evidence that adiponectin decreases hepatic and systemic IR and attenuates liver inflammation and fibrosis [31,32].…”