This article is intended for research purposes only. MOTS-c is a research compound and is not intended for human or animal use.
Introduction: A Signaling Peptide Encoded in the Mitochondrial Genome
Among the growing family of mitochondrial-derived peptides (MDPs), MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) has emerged as one of the most extensively characterized retrograde signaling molecules linking mitochondrial function to nuclear gene regulation. First identified in 2015 by Lee et al. at the University of Southern California, MOTS-c is a 16-amino-acid peptide encoded by a short open reading frame (sORF) within the MT-RNR1 gene of the mitochondrial 12S ribosomal RNA (Lee et al., 2015). Unlike conventional mitochondrial proteins that function within the organelle, MOTS-c acts as a diffusible endocrine factor—detectable in plasma, skeletal muscle, and multiple organ systems—that exerts systemic metabolic effects primarily through activation of the 5′-AMP-activated protein kinase (AMPK) signaling cascade.
The discovery that a mitochondrially encoded peptide could translocate to the nucleus and directly regulate nuclear gene expression challenged longstanding assumptions about mitochondrial-nuclear communication. This review examines the molecular mechanisms by which MOTS-c engages AMPK-dependent signaling pathways, with emphasis on data generated in murine experimental models.
MOTS-c is translated from a 51-base-pair sORF embedded within the mitochondrial 12S rRNA gene, yielding a 16-amino-acid peptide with the sequence MRWQEMGYIFYPRKLR. The discovery team confirmed its mitochondrial origin by depleting mitochondrial DNA (mtDNA) in HeLa cells using ethidium bromide to generate rho-zero (ρ0) cells, which abolished both 12S rRNA and MOTS-c transcripts (Lee et al., 2015). This verification excluded the possibility that MOTS-c was encoded by nuclear mitochondrial DNA transfer sequences (NUMTs).
MOTS-c belongs to a broader class of MDPs that includes humanin and small humanin-like peptides (SHLPs), all of which are encoded within mitochondrial ribosomal RNA genes. However, MOTS-c is unique in its capacity to regulate the folate-methionine cycle and its downstream purine biosynthesis pathway—a mechanism that directly converges on AMPK activation (Zheng et al., 2023).
The Folate-AICAR-AMPK Signaling Axis
The primary intracellular mechanism through which MOTS-c activates AMPK was elucidated through global unbiased metabolomic profiling. Lee and colleagues demonstrated that MOTS-c treatment inhibits the folate cycle by reducing levels of 5-methyltetrahydrofolate (5Me-THF) and methionine while simultaneously increasing homocysteine concentrations (Lee et al., 2015). This inhibition of the folate cycle disrupts de novo purine biosynthesis, leading to intracellular accumulation of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)—a well-established endogenous AMPK activator.
AICAR is converted to ZMP (AICAR monophosphate), which mimics AMP and binds to the gamma subunit of AMPK, promoting its phosphorylation at Thr172 by upstream kinases including liver kinase B1 (LKB1). In murine skeletal muscle, this cascade results in increased phosphorylation of AMPK and its downstream target acetyl-CoA carboxylase (ACC), enhanced GLUT4 translocation to the plasma membrane, and increased glucose uptake independent of insulin signaling (Yang et al., 2021).
MOTS-c is sold strictly as a research compound. It is not approved for human or animal use by any regulatory agency.
This folate-AICAR-AMPK axis distinguishes MOTS-c from other AMPK activators. While pharmacological agents such as metformin activate AMPK through inhibition of mitochondrial complex I and alteration of the AMP:ATP ratio, MOTS-c operates through a metabolically distinct upstream mechanism that intersects one-carbon metabolism—a pathway central to nucleotide synthesis, methylation reactions, and redox homeostasis (Wan et al., 2023).
AMPK-Dependent Nuclear Translocation in Murine Models
A landmark finding by Kim et al. (2018) demonstrated that MOTS-c undergoes stress-induced nuclear translocation, representing a novel form of mitochondrial-to-nuclear retrograde signaling. Using murine cell lines and in vivo models, the investigators showed that metabolic stressors—including glucose restriction, serum deprivation, and oxidative stress agents such as tert-butyl hydroperoxide (tBHP)—trigger rapid nuclear accumulation of MOTS-c within 30 minutes, with return to baseline within 24 hours.
Critically, this nuclear translocation was AMPK-dependent. Both pharmacological AMPK activation (via metformin and AICAR) and genetic manipulation confirmed that AMPK activity is required for MOTS-c to access the nuclear compartment. Once in the nucleus, MOTS-c regulated expression of genes containing antioxidant response elements (AREs), interacting with stress-responsive transcription factors including nuclear factor erythroid 2-related factor 2 (NFE2L2/NRF2) and activating transcription factors ATF1 and ATF7 (Kim et al., 2018). These findings established that mitochondrial-derived peptides can function as direct nuclear gene regulators—not merely as cytoplasmic signaling intermediates.
Metabolic Phenotyping in High-Fat Diet Murine Models
The metabolic consequences of MOTS-c administration have been most thoroughly characterized in diet-induced obesity (DIO) murine models. In the foundational study by Lee et al. (2015), C57BL/6 mice fed a high-fat diet (HFD) and treated with MOTS-c demonstrated significant reductions in body weight gain, improved glucose tolerance, and enhanced insulin sensitivity compared to vehicle-treated controls. Skeletal muscle from MOTS-c-treated mice exhibited increased AMPK phosphorylation and elevated GLUT4 expression.
Subsequent work by Yang et al. (2021) demonstrated synergistic effects between MOTS-c administration and exercise intervention in HFD-fed mice. Combined treatment upregulated PGC-1alpha protein levels—a master regulator of mitochondrial biogenesis—along with GLUT4 expression and phosphorylation of both AMPK and ACC in skeletal muscle. These data suggest that MOTS-c amplifies the metabolic benefits of physical activity through convergent AMPK-dependent pathways.
Notably, endogenous MOTS-c levels are markedly reduced in both the skeletal muscle and plasma of HFD-induced obese mice, suggesting that obesity-associated mitochondrial dysfunction may impair MDP production—a finding with implications for understanding metabolic disease progression (Kim et al., 2019).
Cardiac Tissue: MOTS-c and Type 2 Diabetic Cardiomyopathy
Recent work by Pham et al. (2025) extended MOTS-c research into cardiac tissue using Zucker Diabetic Fatty (ZDF) rats as a type 2 diabetes model. MOTS-c-treated diabetic animals showed decreased fasting glucose levels, improved glucose homeostasis, and reduced left ventricular hypertrophy. At the mitochondrial level, treated cardiac tissue demonstrated increased oxidative phosphorylation (OXPHOS) respiration and decreased ATP hydrolysis rates under anoxic conditions, indicating restoration of mitochondrial coupling efficiency.
MOTS-c, CK2, and AMPK-Independent Skeletal Muscle Signaling
While AMPK activation represents the canonical MOTS-c signaling pathway, Kumagai et al. (2024) identified a parallel mechanism involving casein kinase 2 (CK2). Using in vitro binding assays and in vivo murine experiments, the investigators demonstrated that MOTS-c directly binds to and activates CK2. This interaction prevents skeletal muscle atrophy and enhances glucose uptake through the AKT signaling pathway. A naturally occurring human variant, K14Q MOTS-c, showed reduced CK2 binding affinity and failed to activate downstream effects—providing genetic evidence for the functional significance of this interaction (Kumagai et al., 2024).
Earlier work by the same group demonstrated that MOTS-c reduces myostatin levels and attenuates muscle atrophy signaling in diet-induced obese mice. The mechanism involves CK2-mediated PTEN inhibition, leading to increased AKT phosphorylation and suppression of FOXO1—a transcription factor that drives expression of myostatin and other muscle wasting genes (Kumagai et al., 2021). These AMPK-independent pathways broaden the understanding of how MOTS-c exerts protective effects on skeletal muscle.
Exercise Mimetic Properties and Age-Dependent Decline
Reynolds et al. (2021) published a comprehensive study in Nature Communications establishing MOTS-c as an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline. The study demonstrated that endogenous MOTS-c expression increases nearly 12-fold in human skeletal muscle following acute exercise, with plasma levels rising approximately 50% during and after physical activity.
In murine models, exogenous MOTS-c administration improved physical performance across young (2 months), middle-aged (12 months), and old (22 months) mice. Most remarkably, late-life initiated intermittent MOTS-c treatment (3 times per week, beginning at 23.5 months) was sufficient to increase physical capacity and extend healthspan. Treated mice showed a 6.4% increase in median lifespan (970 vs. 912 days) and a 7% increase in maximum lifespan (1,120 vs. 1,047 days) compared to controls (Reynolds et al., 2021).
These findings position MOTS-c alongside other mitochondria-targeted compounds such as SS-31 (Elamipretide) and NAD+ precursors as research tools for investigating mitochondrial contributions to aging. The telomere-maintenance peptide Epithalon and the lipolytic fragment AOD9604 represent additional research compounds being investigated in the context of age-related metabolic decline.
Pancreatic Islet Cell Senescence
A 2025 study by Kong et al. extended MOTS-c research into beta-cell biology using both type 1 (NOD mice) and type 2 (S961-treated mice) diabetes models. Systemic MOTS-c treatment reduced blood glucose levels, decreased immune cell infiltration in NOD mice, and lowered diabetes incidence in the S961 model. Mechanistically, MOTS-c downregulated glutaminolysis-dependent senescence through modulation of mTORC1 signaling, reducing the frequency of senescent beta cells in aged pancreatic islets (Kong et al., 2025). Circulating MOTS-c levels were also found to be significantly lower in human type 2 diabetes cohorts relative to healthy controls.
All compounds discussed in this article are intended for laboratory research only. None are approved for human consumption or therapeutic use.
MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) is a 16-amino-acid peptide encoded by a short open reading frame within the mitochondrial MT-RNR1 gene. It was first identified in 2015 and belongs to the mitochondrial-derived peptide (MDP) family, which includes humanin and SHLPs (Lee et al., 2015).
How does MOTS-c activate AMPK in murine models?
MOTS-c inhibits the folate cycle, reducing 5-methyltetrahydrofolate and methionine levels while blocking de novo purine biosynthesis. This leads to intracellular accumulation of AICAR, which is converted to ZMP—an AMP mimetic that directly activates AMPK by promoting Thr172 phosphorylation. In murine skeletal muscle, this results in increased GLUT4 expression and glucose uptake (Lee et al., 2015; Yang et al., 2021).
What is the significance of MOTS-c nuclear translocation?
Kim et al. (2018) demonstrated that MOTS-c translocates to the nucleus in an AMPK-dependent manner following metabolic stress. Once nuclear, it regulates genes containing antioxidant response elements (AREs) by interacting with transcription factors NRF2, ATF1, and ATF7. This represents a novel mitochondrial-to-nuclear retrograde signaling mechanism.
Does MOTS-c have AMPK-independent effects?
Yes. Kumagai et al. (2024) identified a parallel pathway in which MOTS-c directly binds and activates casein kinase 2 (CK2), leading to PTEN inhibition, increased AKT phosphorylation, and suppression of the atrophy-promoting transcription factor FOXO1. This pathway mediates anti-atrophic and glucose uptake effects independent of AMPK.
What metabolic effects have been observed in high-fat diet murine models?
In HFD-fed C57BL/6 mice, MOTS-c administration reduced body weight gain, improved glucose tolerance and insulin sensitivity, increased skeletal muscle AMPK phosphorylation, and elevated GLUT4 expression. Endogenous MOTS-c levels are markedly reduced in obese mice, suggesting impaired mitochondrial peptide production in metabolic disease states (Lee et al., 2015; Kim et al., 2019).
How does MOTS-c relate to exercise physiology research?
Reynolds et al. (2021) demonstrated that acute exercise induces a nearly 12-fold increase in skeletal muscle MOTS-c levels in humans. In aged mice, intermittent MOTS-c treatment improved physical capacity and was associated with a 6.4% increase in median lifespan. These data position MOTS-c as a critical exercise-responsive mitokine in aging research.
What are the implications of MOTS-c research for understanding mitochondrial signaling?
MOTS-c research has fundamentally expanded the understanding of mitochondrial-nuclear communication. The demonstration that a mitochondrially encoded peptide can enter the nucleus and directly regulate nuclear gene expression via AMPK-dependent mechanisms establishes a paradigm for retrograde signaling that extends beyond canonical ROS and metabolite-based models (Kim et al., 2018; Wan et al., 2023).
References
Lee C, Zeng J, Drew BG, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism. 2015;21(3):443-454. PubMed
Kim KH, Son JM, Benayoun BA, Lee C. The mitochondrial-encoded peptide MOTS-c translocates to the nucleus to regulate nuclear gene expression in response to metabolic stress. Cell Metabolism. 2018;28(3):516-524.e7. PubMed
Yang B, Yu Q, Chang B, et al. MOTS-c interacts synergistically with exercise intervention to regulate PGC-1alpha expression, attenuate insulin resistance and enhance glucose metabolism in mice via AMPK signaling pathway. Biochim Biophys Acta Mol Basis Dis. 2021;1867(6):166126. PubMed
Reynolds JC, Lai RW, Woodhead JST, et al. MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nature Communications. 2021;12(1):470. PubMed
Kumagai H, Coelho AR, Wan J, et al. MOTS-c reduces myostatin and muscle atrophy signaling. Am J Physiol Endocrinol Metab. 2021;320(4):E680-E690. PubMed
Zheng Y, Wei Z, Wang T. MOTS-c: A promising mitochondrial-derived peptide for therapeutic exploitation. Front Endocrinol. 2023;14:1120533. PubMed
Wan W, Zhang L, Lin Y, et al. Mitochondria-derived peptide MOTS-c: effects and mechanisms related to stress, metabolism and aging. J Transl Med. 2023;21(1):36. PubMed
Kong BS, Lee C, Cho YM. Mitochondrial-encoded peptide MOTS-c, diabetes, and aging-related diseases. Diabetes Metab J. 2023;47(3):315-324. PubMed
Kim SJ, Miller B, Kumagai H, Yen K, Cohen P. MOTS-c: an equal opportunity insulin sensitizer. J Mol Med. 2019;97(4):487-490. PubMed
Mohtashami Z, Singh MK, Thomaz Neto F, et al. Mitochondrial open reading frame of the 12S rRNA type-c: potential therapeutic candidate in retinal diseases. Antioxidants. 2023;12(2):518. PubMed
Kumagai H, Kim SJ, Miller B, et al. MOTS-c modulates skeletal muscle function by directly binding and activating CK2. iScience. 2024;27(11):111212. PubMed
Kong BS, Lee H, L’Yi SH, Hong S, Cho YM. Mitochondrial-encoded peptide MOTS-c prevents pancreatic islet cell senescence to delay diabetes. Exp Mol Med. 2025. PubMed
Pham T, Taberner A, Hickey A, Han JC. Mitochondria-derived peptide MOTS-c restores mitochondrial respiration in type 2 diabetic heart. Front Physiol. 2025;16:1602271. PubMed
All research compounds referenced in this article, including MOTS-c, are available with third-party certificates of analysis verifying purity and identity.
An analysis of cagrilintide (AM833) receptor pharmacology at the amylin receptor system. Covers amylin receptor subtype selectivity, RAMP protein interactions, receptor trafficking dynamics, and the structural basis of dual agonism at calcitonin-family receptors.
Curious about how mitochondrial health, metabolic-health, and MOTS-c peptide team up for better insulin-sensitivity, energy, and even the perks of exercise and longevity? Discover why tuning up your mitochondria isn’t always a straightforward win—and what you need to know before revving your cellular engines.
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MOTS-c as a Mitochondrial-Derived Peptide: AMPK Signaling Pathways in Murine Models
This article is intended for research purposes only. MOTS-c is a research compound and is not intended for human or animal use.
Introduction: A Signaling Peptide Encoded in the Mitochondrial Genome
Among the growing family of mitochondrial-derived peptides (MDPs), MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) has emerged as one of the most extensively characterized retrograde signaling molecules linking mitochondrial function to nuclear gene regulation. First identified in 2015 by Lee et al. at the University of Southern California, MOTS-c is a 16-amino-acid peptide encoded by a short open reading frame (sORF) within the MT-RNR1 gene of the mitochondrial 12S ribosomal RNA (Lee et al., 2015). Unlike conventional mitochondrial proteins that function within the organelle, MOTS-c acts as a diffusible endocrine factor—detectable in plasma, skeletal muscle, and multiple organ systems—that exerts systemic metabolic effects primarily through activation of the 5′-AMP-activated protein kinase (AMPK) signaling cascade.
The discovery that a mitochondrially encoded peptide could translocate to the nucleus and directly regulate nuclear gene expression challenged longstanding assumptions about mitochondrial-nuclear communication. This review examines the molecular mechanisms by which MOTS-c engages AMPK-dependent signaling pathways, with emphasis on data generated in murine experimental models.
Molecular Identity and Biosynthesis of MOTS-c
MOTS-c is translated from a 51-base-pair sORF embedded within the mitochondrial 12S rRNA gene, yielding a 16-amino-acid peptide with the sequence MRWQEMGYIFYPRKLR. The discovery team confirmed its mitochondrial origin by depleting mitochondrial DNA (mtDNA) in HeLa cells using ethidium bromide to generate rho-zero (ρ0) cells, which abolished both 12S rRNA and MOTS-c transcripts (Lee et al., 2015). This verification excluded the possibility that MOTS-c was encoded by nuclear mitochondrial DNA transfer sequences (NUMTs).
MOTS-c belongs to a broader class of MDPs that includes humanin and small humanin-like peptides (SHLPs), all of which are encoded within mitochondrial ribosomal RNA genes. However, MOTS-c is unique in its capacity to regulate the folate-methionine cycle and its downstream purine biosynthesis pathway—a mechanism that directly converges on AMPK activation (Zheng et al., 2023).
The Folate-AICAR-AMPK Signaling Axis
The primary intracellular mechanism through which MOTS-c activates AMPK was elucidated through global unbiased metabolomic profiling. Lee and colleagues demonstrated that MOTS-c treatment inhibits the folate cycle by reducing levels of 5-methyltetrahydrofolate (5Me-THF) and methionine while simultaneously increasing homocysteine concentrations (Lee et al., 2015). This inhibition of the folate cycle disrupts de novo purine biosynthesis, leading to intracellular accumulation of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)—a well-established endogenous AMPK activator.
AICAR is converted to ZMP (AICAR monophosphate), which mimics AMP and binds to the gamma subunit of AMPK, promoting its phosphorylation at Thr172 by upstream kinases including liver kinase B1 (LKB1). In murine skeletal muscle, this cascade results in increased phosphorylation of AMPK and its downstream target acetyl-CoA carboxylase (ACC), enhanced GLUT4 translocation to the plasma membrane, and increased glucose uptake independent of insulin signaling (Yang et al., 2021).
MOTS-c is sold strictly as a research compound. It is not approved for human or animal use by any regulatory agency.
This folate-AICAR-AMPK axis distinguishes MOTS-c from other AMPK activators. While pharmacological agents such as metformin activate AMPK through inhibition of mitochondrial complex I and alteration of the AMP:ATP ratio, MOTS-c operates through a metabolically distinct upstream mechanism that intersects one-carbon metabolism—a pathway central to nucleotide synthesis, methylation reactions, and redox homeostasis (Wan et al., 2023).
AMPK-Dependent Nuclear Translocation in Murine Models
A landmark finding by Kim et al. (2018) demonstrated that MOTS-c undergoes stress-induced nuclear translocation, representing a novel form of mitochondrial-to-nuclear retrograde signaling. Using murine cell lines and in vivo models, the investigators showed that metabolic stressors—including glucose restriction, serum deprivation, and oxidative stress agents such as tert-butyl hydroperoxide (tBHP)—trigger rapid nuclear accumulation of MOTS-c within 30 minutes, with return to baseline within 24 hours.
Critically, this nuclear translocation was AMPK-dependent. Both pharmacological AMPK activation (via metformin and AICAR) and genetic manipulation confirmed that AMPK activity is required for MOTS-c to access the nuclear compartment. Once in the nucleus, MOTS-c regulated expression of genes containing antioxidant response elements (AREs), interacting with stress-responsive transcription factors including nuclear factor erythroid 2-related factor 2 (NFE2L2/NRF2) and activating transcription factors ATF1 and ATF7 (Kim et al., 2018). These findings established that mitochondrial-derived peptides can function as direct nuclear gene regulators—not merely as cytoplasmic signaling intermediates.
Metabolic Phenotyping in High-Fat Diet Murine Models
The metabolic consequences of MOTS-c administration have been most thoroughly characterized in diet-induced obesity (DIO) murine models. In the foundational study by Lee et al. (2015), C57BL/6 mice fed a high-fat diet (HFD) and treated with MOTS-c demonstrated significant reductions in body weight gain, improved glucose tolerance, and enhanced insulin sensitivity compared to vehicle-treated controls. Skeletal muscle from MOTS-c-treated mice exhibited increased AMPK phosphorylation and elevated GLUT4 expression.
Subsequent work by Yang et al. (2021) demonstrated synergistic effects between MOTS-c administration and exercise intervention in HFD-fed mice. Combined treatment upregulated PGC-1alpha protein levels—a master regulator of mitochondrial biogenesis—along with GLUT4 expression and phosphorylation of both AMPK and ACC in skeletal muscle. These data suggest that MOTS-c amplifies the metabolic benefits of physical activity through convergent AMPK-dependent pathways.
Notably, endogenous MOTS-c levels are markedly reduced in both the skeletal muscle and plasma of HFD-induced obese mice, suggesting that obesity-associated mitochondrial dysfunction may impair MDP production—a finding with implications for understanding metabolic disease progression (Kim et al., 2019).
Cardiac Tissue: MOTS-c and Type 2 Diabetic Cardiomyopathy
Recent work by Pham et al. (2025) extended MOTS-c research into cardiac tissue using Zucker Diabetic Fatty (ZDF) rats as a type 2 diabetes model. MOTS-c-treated diabetic animals showed decreased fasting glucose levels, improved glucose homeostasis, and reduced left ventricular hypertrophy. At the mitochondrial level, treated cardiac tissue demonstrated increased oxidative phosphorylation (OXPHOS) respiration and decreased ATP hydrolysis rates under anoxic conditions, indicating restoration of mitochondrial coupling efficiency.
MOTS-c, CK2, and AMPK-Independent Skeletal Muscle Signaling
While AMPK activation represents the canonical MOTS-c signaling pathway, Kumagai et al. (2024) identified a parallel mechanism involving casein kinase 2 (CK2). Using in vitro binding assays and in vivo murine experiments, the investigators demonstrated that MOTS-c directly binds to and activates CK2. This interaction prevents skeletal muscle atrophy and enhances glucose uptake through the AKT signaling pathway. A naturally occurring human variant, K14Q MOTS-c, showed reduced CK2 binding affinity and failed to activate downstream effects—providing genetic evidence for the functional significance of this interaction (Kumagai et al., 2024).
Earlier work by the same group demonstrated that MOTS-c reduces myostatin levels and attenuates muscle atrophy signaling in diet-induced obese mice. The mechanism involves CK2-mediated PTEN inhibition, leading to increased AKT phosphorylation and suppression of FOXO1—a transcription factor that drives expression of myostatin and other muscle wasting genes (Kumagai et al., 2021). These AMPK-independent pathways broaden the understanding of how MOTS-c exerts protective effects on skeletal muscle.
Exercise Mimetic Properties and Age-Dependent Decline
Reynolds et al. (2021) published a comprehensive study in Nature Communications establishing MOTS-c as an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline. The study demonstrated that endogenous MOTS-c expression increases nearly 12-fold in human skeletal muscle following acute exercise, with plasma levels rising approximately 50% during and after physical activity.
In murine models, exogenous MOTS-c administration improved physical performance across young (2 months), middle-aged (12 months), and old (22 months) mice. Most remarkably, late-life initiated intermittent MOTS-c treatment (3 times per week, beginning at 23.5 months) was sufficient to increase physical capacity and extend healthspan. Treated mice showed a 6.4% increase in median lifespan (970 vs. 912 days) and a 7% increase in maximum lifespan (1,120 vs. 1,047 days) compared to controls (Reynolds et al., 2021).
These findings position MOTS-c alongside other mitochondria-targeted compounds such as SS-31 (Elamipretide) and NAD+ precursors as research tools for investigating mitochondrial contributions to aging. The telomere-maintenance peptide Epithalon and the lipolytic fragment AOD9604 represent additional research compounds being investigated in the context of age-related metabolic decline.
Pancreatic Islet Cell Senescence
A 2025 study by Kong et al. extended MOTS-c research into beta-cell biology using both type 1 (NOD mice) and type 2 (S961-treated mice) diabetes models. Systemic MOTS-c treatment reduced blood glucose levels, decreased immune cell infiltration in NOD mice, and lowered diabetes incidence in the S961 model. Mechanistically, MOTS-c downregulated glutaminolysis-dependent senescence through modulation of mTORC1 signaling, reducing the frequency of senescent beta cells in aged pancreatic islets (Kong et al., 2025). Circulating MOTS-c levels were also found to be significantly lower in human type 2 diabetes cohorts relative to healthy controls.
All compounds discussed in this article are intended for laboratory research only. None are approved for human consumption or therapeutic use.
Frequently Asked Questions
What is MOTS-c and where is it encoded?
MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) is a 16-amino-acid peptide encoded by a short open reading frame within the mitochondrial MT-RNR1 gene. It was first identified in 2015 and belongs to the mitochondrial-derived peptide (MDP) family, which includes humanin and SHLPs (Lee et al., 2015).
How does MOTS-c activate AMPK in murine models?
MOTS-c inhibits the folate cycle, reducing 5-methyltetrahydrofolate and methionine levels while blocking de novo purine biosynthesis. This leads to intracellular accumulation of AICAR, which is converted to ZMP—an AMP mimetic that directly activates AMPK by promoting Thr172 phosphorylation. In murine skeletal muscle, this results in increased GLUT4 expression and glucose uptake (Lee et al., 2015; Yang et al., 2021).
What is the significance of MOTS-c nuclear translocation?
Kim et al. (2018) demonstrated that MOTS-c translocates to the nucleus in an AMPK-dependent manner following metabolic stress. Once nuclear, it regulates genes containing antioxidant response elements (AREs) by interacting with transcription factors NRF2, ATF1, and ATF7. This represents a novel mitochondrial-to-nuclear retrograde signaling mechanism.
Does MOTS-c have AMPK-independent effects?
Yes. Kumagai et al. (2024) identified a parallel pathway in which MOTS-c directly binds and activates casein kinase 2 (CK2), leading to PTEN inhibition, increased AKT phosphorylation, and suppression of the atrophy-promoting transcription factor FOXO1. This pathway mediates anti-atrophic and glucose uptake effects independent of AMPK.
What metabolic effects have been observed in high-fat diet murine models?
In HFD-fed C57BL/6 mice, MOTS-c administration reduced body weight gain, improved glucose tolerance and insulin sensitivity, increased skeletal muscle AMPK phosphorylation, and elevated GLUT4 expression. Endogenous MOTS-c levels are markedly reduced in obese mice, suggesting impaired mitochondrial peptide production in metabolic disease states (Lee et al., 2015; Kim et al., 2019).
How does MOTS-c relate to exercise physiology research?
Reynolds et al. (2021) demonstrated that acute exercise induces a nearly 12-fold increase in skeletal muscle MOTS-c levels in humans. In aged mice, intermittent MOTS-c treatment improved physical capacity and was associated with a 6.4% increase in median lifespan. These data position MOTS-c as a critical exercise-responsive mitokine in aging research.
What are the implications of MOTS-c research for understanding mitochondrial signaling?
MOTS-c research has fundamentally expanded the understanding of mitochondrial-nuclear communication. The demonstration that a mitochondrially encoded peptide can enter the nucleus and directly regulate nuclear gene expression via AMPK-dependent mechanisms establishes a paradigm for retrograde signaling that extends beyond canonical ROS and metabolite-based models (Kim et al., 2018; Wan et al., 2023).
References
All research compounds referenced in this article, including MOTS-c, are available with third-party certificates of analysis verifying purity and identity.
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