Mitochondrial Peptide MOTS-c Shields Pancreatic Cells From Aging to Block Diabetes
MOTS-c, a peptide encoded in mitochondrial DNA, declines with age and may prevent β-cell senescence to delay both type 1 and type 2 diabetes.
Summary
Researchers show that MOTS-c, a mitochondria-encoded peptide, decreases with aging in pancreatic islet cells and in the blood of type 2 diabetes patients. Treating aged C57BL/6 mice, insulin-receptor-antagonist (S961)-treated mice, and autoimmune NOD mice with MOTS-c reduced markers of β-cell senescence, improved glucose tolerance, and preserved insulin secretion. Mechanistically, MOTS-c modulates nuclear gene expression and metabolites involved in the aspartate–glutamate transport pathway, reducing glutaminolysis-dependent senescence. These findings identify MOTS-c as a potential senotherapeutic agent to preserve pancreatic β-cell health and slow diabetes progression.
Detailed Summary
Diabetes involves progressive loss of pancreatic β-cell mass and function, and cellular senescence—a state of irreversible growth arrest accompanied by a pro-inflammatory secretory phenotype—is now recognized as a shared mechanism driving both type 1 (T1D) and type 2 diabetes (T2D). Mitochondrial dysfunction is a hallmark of senescence, yet the role of mitochondria-encoded peptides in β-cell senescence had not been investigated.
This study focused on MOTS-c (mitochondrial ORF of the 12S rRNA type-c), a bioactive peptide encoded within the mitochondrial genome that regulates metabolic homeostasis via AMPK and mTOR pathways. The researchers first established that MOTS-c expression declines with age in pancreatic islets across multiple datasets from both humans and mice, and confirmed via in-house ELISA that circulating MOTS-c levels are significantly lower in T2D patients (n=45, mean age ~65) compared with healthy controls (n=19, mean age ~29).
Using three complementary mouse models—chronologically aged (60–90-week-old) C57BL/6 mice, S961-treated C57BL/6 mice (an acute β-cell-specific senescence and hyperglycemia model induced by the insulin-receptor antagonist S961 via osmotic pump), and NOD mice (a T1D autoimmune model)—the team demonstrated that intraperitoneal MOTS-c treatment (0.5 mg/kg/day) reduced canonical senescence markers including γ-H2AX, p16 (Cdkn2a), p21 (Cdkn1a), and the senescence-associated secretory phenotype (SASP) cytokines IL-1β and IL-6. MOTS-c treatment also improved glucose tolerance in intraperitoneal glucose tolerance tests and preserved insulin secretion across these models. In NOD mice, combining MOTS-c with exendin-4 (a GLP-1 receptor agonist) provided additive protection against autoimmune diabetes onset.
Mechanistically, transcriptomic and metabolomic analyses in pancreatic islets and Min6 β-cells revealed that MOTS-c modulates the aspartate–glutamate transport axis—specifically regulating Slc1a5 (ASCT2, a glutamine transporter), glutaminase isoforms (Gls1/Gls2), and malate-aspartate shuttle components (Got1, Got2, Mdh1, Mdh2)—to reduce glutaminolysis-dependent senescence. MOTS-c also exhibited non-cell-autonomous effects: conditioned media from MOTS-c-treated islets reduced senescence markers in naïve recipient islet cells, suggesting a paracrine mechanism.
These findings position MOTS-c as a promising senotherapeutic agent for both T1D and T2D, acting upstream of multiple senescence pathways by coordinating mitochondrial-nuclear communication through peptide signaling. The work opens a new conceptual framework: that declining mitochondrial peptide production with age may directly contribute to β-cell senescence and diabetes risk.
Key Findings
- Circulating MOTS-c levels are significantly lower in T2D patients versus healthy controls, declining with age.
- MOTS-c treatment reduced β-cell senescence markers (p16, p21, γ-H2AX, IL-1β) in three distinct mouse diabetes models.
- MOTS-c improved glucose tolerance and insulin secretion in aged, S961-treated, and NOD mice.
- MOTS-c suppresses glutaminolysis-dependent senescence by modulating the aspartate–glutamate transport pathway.
- Conditioned media from MOTS-c-treated islets protected naïve islet cells from senescence, indicating paracrine effects.
Methodology
The study used three in vivo mouse models (aged C57BL/6, S961-treated C57BL/6, and NOD mice) with intraperitoneal MOTS-c delivery, plus in vitro experiments in Min6 and NIT-1 β-cell lines. Human circulating MOTS-c was measured by in-house ELISA in 45 T2D patients and 19 healthy controls. Senescence was assessed via immunofluorescence, qPCR, western blotting, and metabolomic/transcriptomic profiling.
Study Limitations
The human cohort was small (n=64) and the T2D and control groups were substantially mismatched in age (65 vs. 29 years), confounding age versus disease comparisons. Long-term safety, optimal dosing, and delivery methods for MOTS-c in humans remain untested. Mechanistic studies relied partly on cell lines and ex vivo islets, which may not fully replicate in vivo β-cell biology.
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