Adiponectin regulates MOTS-c production through the APPL1-SIRT1-PGC-1α pathway, and exercise restores this connection disrupted by obesity.
APPL1-SIRT1-PGC-1αthe complete signaling pathway connecting adiponectin to MOTS-c mitochondrial peptide production
What the researchers found
In mice lacking the adiponectin gene (Adipoq-/- knockouts), MOTS-c levels in blood and muscle were significantly lower than normal. This directly links adiponectin to MOTS-c production.
In muscle cells (C2C12 myotubes), adiponectin treatment increased MOTS-c gene expression. The researchers traced the signaling chain: adiponectin activates APPL1, which activates SIRT1, which activates PGC-1alpha, which drives MOTS-c production. Blocking any step in this chain (with inhibitors or siRNA) stopped the MOTS-c increase.
In mice on a high-fat diet, both exercise and injected adiponectin or MOTS-c raised MOTS-c levels in blood and muscle. This was accompanied by improved insulin sensitivity, suggesting MOTS-c is a key mediator of adiponectin's metabolic benefits.
Overexpressing SIRT1 amplified the adiponectin effect on MOTS-c, while blocking PGC-1alpha eliminated it. This establishes the APPL1-SIRT1-PGC-1alpha pathway as the mechanism.
Why it matters
MOTS-c is a relatively new discovery: a peptide encoded by mitochondrial DNA that influences metabolism. This study reveals how the body naturally regulates MOTS-c production through adiponectin signaling. It positions MOTS-c as a potential drug target for type 2 diabetes and explains part of why exercise improves insulin sensitivity.
The numbers in context
Adipoq-/- mice: lower MOTS-c; HFD: reduced MOTS-c; exercise and Acrp30 injection: restored MOTS-c; APPL1-SIRT1-PGC-1α pathway confirmed
How the study worked
Tested in mice and cell cultures. Used wild-type C57BL/6 mice on high-fat diet, adiponectin knockout mice, and C2C12 muscle cell cultures. Interventions included exercise, injected adiponectin (Acrp30), injected MOTS-c, gene overexpression, siRNA knockdown, and pharmacological inhibitors. Measured MOTS-c mRNA and protein levels, insulin sensitivity markers, and pathway components.
Who was studied
C57BL/6 mice (wild-type and adiponectin knockout) on high-fat diet; C2C12 myotubes
What this study cannot tell us
Tested in mice, not people. Mouse metabolism differs from human metabolism, and the APPL1-SIRT1-PGC-1alpha pathway may not work identically in humans. The adiponectin knockout model eliminates all adiponectin, which is more extreme than the reduced levels seen in human obesity. Cell culture experiments used C2C12 mouse myotubes, which may not perfectly replicate human muscle biology.
How to read the evidence
Moderate evidence from mouse and cell culture studies. The pathway is well-mapped mechanistically but not yet confirmed in humans.
When this study was published
Published in 2020. MOTS-c research has expanded significantly, with human studies beginning to explore therapeutic applications.
The bigger picture
MOTS-c is generating excitement as a potential anti-aging and metabolic therapy. This study reveals how the body naturally regulates MOTS-c production, connecting the adiponectin-exercise-mitochondria axis. Understanding this regulation is essential for developing MOTS-c-based treatments.
Questions still open
- Can MOTS-c supplementation bypass the need for adiponectin signaling?
- Does this pathway work the same way in humans?
- Could MOTS-c levels serve as a biomarker for metabolic health?
Common questions
What is MOTS-c and why is it important?
Does this mean exercise boosts MOTS-c through adiponectin?
Read the original research
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.
Diabetologia, 63(12), 2675-2688
Citation
Guo, Qi; Chang, Bo; Yu, Qiong-Li; Xu, Si-Tong; Yi, Xue-Jie; Cao, Shi-Cheng. (2020). 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.. Diabetologia, 63(12), 2675-2688. https://doi.org/10.1007/s00125-020-05269-3