The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance

The Warburg effect: The hacked mitochondrial-nuclear communication in cancer

Mitochondrial-nuclear communication is vital for maintaining cellular homeostasis. This communication begins with mitochondria sensing environmental cues and transmitting signals to the nucleus through the retrograde cascade, involving metabolic signals such as substrates for epigenetic modifications, ATP and AMP levels, calcium flux, etc. These signals inform the nucleus about the cell's metabolic state, remodel epigenome and regulate gene expression, and modulate mitochondrial function and dynamics through the anterograde feedback cascade to control cell fate and physiology. Disruption of this communication can lead to cellular dysfunction and disease progression, particularly in cancer. The Warburg effect is the metabolic hallmark of cancer, characterized by disruption of mitochondrial respiration and increased lactate generation from glycolysis. This metabolic reprogramming rewires retrograde signaling, leading to epigenetic changes and dedifferentiation, further reprogramming mitochondrial function and promoting carcinogenesis. Understanding these processes and their link to tumorigenesis is crucial for uncovering tumorigenesis mechanisms. Therapeutic strategies targeting these disrupted pathways, including metabolic and epigenetic components, provide promising avenues for cancer treatment.

Reduced serum levels of mitochondria-derived peptide MOTS-c in patients with obstructive sleep apnea

Recent research has identified the mitochondrial open reading frame of the 12S rRNA-c (MOTS-c) as a crucial mitochondrial peptide that significantly influences metabolic regulation, mimics the effects of exercise, and mitigates oxidative stress. This study aims to investigate the relationship between serum MOTS-c levels and obstructive sleep apnea (OSA) to enhance our understanding of the disease's pathophysiology. By elucidating this relationship, we hope to uncover new insights into the mechanisms underlying OSA and its associated metabolic complications. Seventy-seven participants were enrolled in this study, including 53 patients with OSA and 24 controls. We measured serum MOTS-c levels and collected participants' demographic characteristics, polysomnography (PSG) data, complete blood count (CBC) data, and sleep-related questionnaires. The study included 77 participants, consisting of 8 patients with mild OSA, 16 with moderate OSA, 29 with severe OSA, and 24 controls. The cohort comprised 26 women and 51 men. Analysis revealed that serum MOTS-c levels were significantly correlated with BMI, AHI (Apnea-Hypopnea Index), and ODI (Oxygen Desaturation Index), independent of age. Additionally, the severity of OSA was inversely related to serum MOTS-c levels, with lower levels observed in patients with more severe OSA. Variations in serum MOTS-c levels were also noted across different BMI classifications. Analysis of covariance (ANCOVA), with BMI as a covariate, demonstrated that the severity of OSA was an independent factor influencing serum MOTS-c levels. Serum MOTS-c levels correlate with both severity of OSA and BMI classification, suggesting that MOTS-c may have significant therapeutic potential for treating OSA.

Microproteins in Metabolism

Metabolism is a complex network of biochemical pathways that break down macromolecules to produce energy essential for cellular function. Disruptions in metabolic homeostasis are closely linked to noncommunicable diseases (NCDs) such as cardiovascular disease, type 2 diabetes, and cancer, which are leading causes of death worldwide. Many NCD-associated conditions, including obesity and insulin resistance, stem from metabolic dysfunction, and current therapies often fall short in preventing disease progression, highlighting the need for novel therapeutic targets. Microproteins, small proteins of ≤100-150 amino acids, have recently emerged as important regulators of metabolism. Encoded by short open reading frames (sORFs), many of these proteins were historically overlooked due to their small size and misclassification as noncoding RNAs. Advances in genomics and proteomics have revealed that these sORFs can encode functional proteins with critical roles in metabolic pathways. In this review, we highlight the microproteins involved in energy metabolism, mitochondrial function, and nutrient signaling. We discuss their emerging roles in the pathogenesis of NCDs and explore their potential as novel therapeutic targets. As microprotein biology continues to evolve, these small but powerful regulators may offer new strategies for treating metabolic dysfunction and reducing the global burden of NCDs.

Eukaryotic Microproteins

Microproteins are polypeptides of 100-150 amino acids or fewer that have not been annotated by genome annotation consortia, given their small size and other noncanonical properties. Translated microproteins are now known to number in the thousands in the human genome, to function in critical cellular and physiological processes, and to be dysregulated or mutated in diseases including neurodegeneration and cancer. Knowledge about microproteins has rapidly accumulated since the advent of ribosome profiling enabled their global discovery 15 years ago. In this review, we summarize what is known about eukaryotic microprotein discovery, the sequences and expression mechanisms of small open reading frames, and microprotein functions from yeast to human.

MOTS-c Peptide Attenuated Diabetic Cardiomyopathy in STZ-Induced Type 1 Diabetic Mouse Model

BACKGROUND

Diabetic cardiomyopathy (DCM) pathogenesis is a common complication of diabetes, but effective treatments remain limited. Mitochondrial-derived peptide MOTS-c has shown therapeutic promise in animal models of various heart diseases, but its efficacy in DCM is unknown. This study investigates the effects of MOTS-c treatment in a mouse model of type 1 diabetes-induced DCM.

METHODS

Type 1 diabetes (T1DM) was induced in mice by streptozotocin (STZ) injection. After diabetes establishment, the mice were randomly dividend into two groups treated with or without MOTS-c peptide, which was administered subcutaneously by osmotic pump for 12 weeks. At the end of the experiment, cardiac function, histology, and molecular changes were determined.

RESULTS

The results showed that diabetic mice exhibited significant cardiac dysfunction, dilatation, and adverse cardiac remodeling. MOTS-c treatment markedly ameliorated these diabetes-associated myocardial function and structure abnormalities. Additionally, MOTS-c reversed AMPK signaling deactivation and inhibited inflammation in the diabetic heart.

CONCLUSIONS

Our data demonstrated a protective effect of MOTS-c against diabetic cardiomyopathy potentially by activating the AMPK pathway and inhibiting inflammation. These findings demonstrate the therapeutic efficacy of MOTS-c for diabetic cardiomyopathy and warrant further investigation into its clinical potential.

MOTS-c mimics exercise to combat diabetic liver fibrosis by targeting Keap1-Nrf2-Smad2/3

Liver fibrosis is a common complication of T2DM(Type 2 diabetes mellitus). Appropriate intervention (exercise or drugs) in the early stage of liver fibrosis can slow down or even reverse liver fibrosis. MOTS-c (Mitochondrial open reading frame of the 12 S r RNA type-c ) has been described as an exercise-mimicking substance, and its effects are similar to those achieved by aerobic exercise; however, the exact mechanism remains to be elucidated. In this study, liver function was impaired in a T2DM rat model, leading to the aggravation of liver fibrosis. T2DM rats with liver fibrosis were subjected to MOTS-c, aerobic exercise therapy, or their combination. HE staining, Masson's trichrome staining and immunohistochemistry were used for histopathological examination. Transcriptome sequencing, q-PCR and WB were used to detect the expression of Keap1 (Kelch-like ECH-associated protein 1), Nrf2 (Nuclear factor erythroid 2-related factor 2 ), Smad2/3/4 and other genes. MOTS-c and aerobic exercise therapy improved T2DM-induced liver fibrosis. Additionally, cells were transfected with MOTS-c overexpression or interference plasmids or MOTS-c was added to the culture medium. MOTS-c overexpression or MOTS-c addition to the culture medium inhibited ROS levels, increased the mRNA and protein expression of Keap1-Nrf2 pathway genes and decreased the expression of TGF-β1(Transforming growth factor-beta1)/Smad pathway genes. Our findings demonstrate that MOTS-c modulates the progression of T2DM complicated by liver fibrosis through a Keap1-Nrf2-Smad2/3 signaling pathway-dependent mechanism.

Could MOTS-c Levels in Children with Type 1 Diabetes Mellitus Be an Indicator for Early Diabetic Kidney Disease?

Objective

To compare serum mitochondrial open reading frame of 12S rRNA-c (MOTS-c) levels, a new potential biomarker for oxidative stress, in children with type 1 diabetes mellitus (T1DM) and healthy children. A further aim was to investigate serum MOTS-c levels as a potential early indicator of diabetic kidney disease (DKD) by correlating levels with changes in glomerular filtration and microalbuminuria.

Methods

Patients with a diagnosis of T1DM and healthy controls were recruited. MOTS-c, urinary albumin excretion, estimated glomerular filtration rate (eGFR), and hemoglobin A1c (HbA1c) were evaluated and clinical features and anthropometric measurements were collected. Patients were stratified according to diabetes duration, presence of albuminuria, glomerular hyperfiltration, eGFR decline and metabolic control.

Results

The T1DM group included 82 [female:male (F:M) 1:1.64] patients while the controls numbered 61 (F:M 1:0.97), with respective mean ages of 14.3±3.3 and 10.6±4.2 years (p<0.01). MOTS-c levels were significantly lower in the T1DM group than controls (76.2±1.3 vs 105.2±7.0, p<0.001). No difference was found in MOTS-c levels between patient subgroups categorized by diabetes duration, obesity, metabolic control, hypertension, hyperlipidemia, glomerular hyperfiltration, decline in eGFR, and presence of microalbuminuria. Simple linear regression indicated that MOTS-c was not predictive for DKD.

Conclusion

MOTS-c levels were lower in children with T1DM than in healthy children. However, the lack of association of MOTS-c with renal biomarkers suggested that it is not an effective early marker for DKD. However, this finding suggests that the onset of oxidative damage and mitochondrial dysfunction in T1DM is independent of DKD. In addition, the results suggests that HbA1c and duration of diabetes are significant risk factors for development of microalbuminuria, while changes in eGFR and microalbuminuria continue to serve as indicators of DKD.

Extrachromosomal circular DNA drives dynamic genome plasticity: emerging roles in disease progression and clinical potential

Extrachromosomal circular DNA (eccDNA) has emerged as a dynamic and versatile genomic element with key roles in physiological regulation and disease pathology. This review synthesizes current knowledge on eccDNA, covering its classification, biogenesis, detection methods, biological functions, and clinical implications. Once considered rare anomalies, eccDNAs are now recognized as major drivers of oncogene amplification, genomic plasticity, and therapeutic resistance, particularly in cancer. EccDNA subtypes such as microDNA, double minutes, and ecDNA are defined by their structural, genomic, and pathological features. EccDNAs originate through diverse mechanisms including DNA repair, chromothripsis, breakage fusion bridge cycles, and apoptosis, occurring in both normal and stressed cells. Advances in long-read and single-cell sequencing, CRISPR-based synthesis, and computational tools have improved detection and functional analysis. Functionally, eccDNAs contribute to transcriptional amplification, activate immune responses through cGAS-STING signaling, and facilitate intercellular communication. They are found across a range of tissues and disease states-including cancer, cardiovascular, neurological, autoimmune, and metabolic disorders-and serve as both biomarkers and regulatory elements. We introduce the concept of the stress selection theory, which proposes eccDNA as an adaptive reservoir that enhances cellular fitness in response to environmental and therapeutic pressures. Despite growing insights, challenges remain in understanding tissue-specific roles, achieving clinical translation, and standardizing methodologies. Emerging tools in multi-omics, spatial biology, and artificial intelligence are expected to drive future breakthroughs in precision medicine.

Mitochondrial Dysfunction in the Development and Progression of Cardiometabolic Diseases: A Narrative Review

Mitochondria play a central role in energy metabolism and continuously adapt through dynamic processes such as fusion and fission. When the balance between these processes is disrupted, it can lead to mitochondrial dysfunction and increased oxidative stress, contributing to the development and progression of various cardiometabolic diseases (CMDs). Their role is crucial in diabetes mellitus (DM), since their dysfunction drives β-cell apoptosis, immune activation, and chronic inflammation through excessive ROS production, worsening endogenous insulin secretion. Moreover, sympathetic nervous system activation and altered dynamics, contribute to hypertension through oxidative stress, impaired mitophagy, endothelial dysfunction, and cardiomyocyte hypertrophy. Furthermore, the role of mitochondria is catalytic in endothelial dysfunction through excessive reactive oxygen species (ROS) production, disrupting the vascular tone, permeability, and apoptosis, while impairing antioxidant defense and promoting inflammatory processes. Mitochondrial oxidative stress, resulting from an imbalance between ROS/Reactive nitrogen species (RNS) imbalance, promotes atherosclerotic alterations and oxidative modification of oxidizing low-density lipoprotein (LDL). Mitochondrial DNA (mtDNA), situated in close proximity to the inner mitochondrial membrane where ROS are generated, is particularly susceptible to oxidative damage. ROS activate redox-sensitive inflammatory signaling pathways, notably the nuclear factor kappa B (NF-κB) pathway, leading to the transcriptional upregulation of proinflammatory cytokines, chemokines, and adhesion molecules. This proinflammatory milieu promotes endothelial activation and monocyte recruitment, thereby perpetuating local inflammation and enhancing atherogenesis. Additionally, mitochondrial disruptions in heart failure promote further ischemic injury and excessive oxidative stress release and impair ATP production and Ca2⁺ dysregulation, contributing to cell death, fibrosis, and decreased cardiac performance. This narrative review aims to investigate the intricate relationship between mitochondrial dysfunction and CMDs.

Skeletal Muscle as a Mediator of Interorgan Crosstalk During Exercise: Implications for Aging and Obesity

Physical exercise is critical for preventing and managing chronic conditions, such as cardiovascular disease, type 2 diabetes, hypertension, and sarcopenia. Regular physical activity significantly reduces cardiovascular and all-cause mortality. Exercise also enhances metabolic health by promoting muscle growth, mitochondrial biogenesis, and improved nutrient storage while preventing age-related muscle dysfunction. Key metabolic benefits include increased glucose uptake, enhanced fat oxidation, and the release of exercise-induced molecules called myokines, which mediate interorgan communication and improve overall metabolic function. These myokines and other exercise-induced signaling molecules hold promise as therapeutic targets for aging and obesity-related conditions.

MOTS-c attenuates lung ischemia-reperfusion injury via MYH9-Dependent nuclear translocation and transcriptional activation of antioxidant genes

Acute respiratory distress syndrome (ARDS) following cardiopulmonary bypass (CPB) is driven by oxidative stress during lung ischemia-reperfusion injury (LIRI). Mitochondrial-derived peptide MOTS-c has emerged as a regulator of mitochondrial-nuclear communication, yet its role in CPB-induced ARDS remains unclear. Here, we identify MOTS-c as a critical mediator of endothelial protection against LIRI through MYH9-dependent nuclear translocation and transcriptional activation of antioxidant genes. In rat LIRI models, endothelial cells exhibited the most significant MOTS-c upregulation, correlating with barrier preservation and reduced oxidative stress. Mechanistically, hypoxia-reoxygenation (HR) triggered reactive oxygen species (ROS)-dependent phosphorylation of MYH9 at Ser1943 via casein kinase II subunit alpha (CK2A), enabling MOTS-c binding to MYH9-γ-Actin complexes for nuclear transport. RNA sequencing (RNA-seq) combined with chromatin immunoprecipitation sequencing (ChIP-seq) revealed direct MOTS-c interaction with promoters of antioxidant genes (e.g., HMOX1, NQO1), which harbor antioxidant response elements (AREs). Clinically, serum MOTS-c increments within 24 h post-CPB (ΔMOTS-c) outperformed traditional biomarkers in predicting ARDS incidence, with multivariate models incorporating ΔMOTS-c achieving superior discriminative power (AUC = 0.885). Exogenous MOTS-c administration in rats attenuated lung injury by reducing oxidative damage, inflammation, and mortality, recapitulating endogenous protective mechanisms. Our findings establish MOTS-c as a dual-function molecule-acting via ROS-CK2A-MYH9 signaling to activate nuclear antioxidant defenses and serving as a prognostic biomarker for CPB-related complications. This study bridges mitochondrial dynamics, nuclear transcriptional regulation, and clinical outcomes, offering novel preventive avenues for IRI-associated pathologies.

Effects of metformin on transcriptomic and metabolomic profiles in breast cancer survivors enrolled in the randomized placebo-controlled MetBreCS trial

Metformin reduces the incidence of breast cancer in patients with obesity and type 2 diabetes. However, our knowledge of the effects of metformin on breast cancer recurrence is limited. Within the randomized double-blind placebo-controlled phase II trial MetBreCS, we examined changes in breast tissue from breast cancer survivors with BMI > 25 kg/m2 after treatment with metformin. To identify metformin-regulated signaling pathways, we integrated the transcriptomic, metabolomic and steroid hormone profiles using bivariate and functional analyses. We identified MS4A1, HBA2, MT-RNR1, MT-RNR2, EGFL6 and FDCSP expression to be differentially expressed in breast tissues from metformin-treated postmenopausal women. The integration of transcriptomic and metabolomic profiles revealed down-regulation of immune response genes associated with reduced levels of arginine and citrulline in the metformin-treated group. The integration of transcriptomic and steroid hormone profiles showed an enrichment of steroid hormone biosynthesis and metabolism pathways with highly negatively correlated CYP11A1 and CYP1B1 expression in breast tissue from postmenopausal metformin-treated women. Our results indicate that postmenopausal breast cancer survivors treated with metformin have specific changes in breast tissue gene expression that may prevent the development of new tumors.Trial registration: MetBreCs trial is registered at European Union Clinical Trials Register (EudraCT Protocol # 2015-001001-14) on 07/10/2015.

Mitochondria‑derived peptides: Promising microproteins in cardiovascular diseases (Review)

Mitochondria‑derived peptides (MDPs) are a unique class of peptides encoded by short open reading frames in mitochondrial DNA, including the mitochondrial open reading frame of the 12S ribosomal RNA type‑c (MOTS‑c). Recent studies suggest that MDPs offer therapeutic benefits in various diseases, including neurodegenerative disorders and types of cancer, due to their ability to increase cellular resilience. Mitochondrial dysfunction is a key factor in the onset and progression of cardiovascular diseases (CVDs), such as atherosclerosis and heart failure, as it disrupts energy metabolism, increases oxidative stress and promotes inflammation. MDPs such as humanin and MOTS‑c have emerged as important regulators of mitochondrial health, as they show protective effects against these processes. Recent studies have shown that MDPs can restore mitochondrial function, reduce oxidative damage and alleviate inflammation, thus counteracting the pathological mechanisms that drive CVDs. Therefore, MDPs hold promise as therapeutic agents that are capable of slowing, stopping, or even reversing CVD progression and their use presents a promising strategy for future treatments. However, the clinical application of MDPs remains challenging due to their low bioavailability, poor stability and high synthesis costs. Thus, it is necessary to improve drug delivery systems to enhance the bioavailability of MDPs. Moreover, integrating basic research with clinical trials is essential to bridge the gap between experimental findings and clinical applications.

Current Perspectives on Functional Involvement of Micropeptides in Virus-Host Interactions

Micropeptides (miPEPs), encoded by short open reading frames (sORFs) within various genomic regions, have recently emerged as critical regulators of multiple biological processes. In particular, these small molecules are now increasingly being recognized for their role in modulating viral replication, pathogenesis, and host immune responses. Both host miPEPs and virus-derived miPEPs have been noted for their ability to regulate virus-host interactions through diversified mechanisms such as altering protein stability and modulating protein-protein interactions. Although thousands of sORFs have been annotated as having the potential to encode miPEPs, only a small number have been experimentally validated so far, with some directly linked to virus-host interactions and a small subset associated with immune modulation, indicating that the investigation of miPEPs is still in its infancy. The systematic identification, translational status assessment, in-depth characterization, and functional analysis of a substantial fraction of sORFs encoding miPEPs remain largely underexplored. Further studies are anticipated to uncover the intricate mechanisms underlying virus-host interactions, host immune modulation, and the broader biological functions of miPEPs. This article will review the emerging roles of miPEPs in virus-host interactions and host immunity, and discuss the challenges and future perspectives of miPEP studies.

Endogenous micropeptides as potential diagnostic biomarkers and therapeutic drugs

Micropeptides, these small proteins derived from non-coding RNA, typically consist of no more than 100 amino acids in length. Despite the challenges in analysis and identification, their various critical functions within organisms cannot be overlooked. They play a significant role in maintaining energy metabolism balance, regulating the immune system, and influencing the development of tumors, which also gives them a decisive impact on the occurrence and development of various diseases. This review aims to outline the role and potential value of micropeptides, introducing their tissue classification and distribution, biological functions, and mechanisms, with a focus on their potential as diagnostic markers and therapeutic drugs.

A large-scale sORF screen identifies putative microproteins involved in cancer cell fitness

The human genome contains thousands of potentially coding short open reading frames (sORFs). While a growing set of microproteins translated from these sORFs have been demonstrated to mediate important cellular functions, the majority remains uncharacterized. In our study, we performed a high-throughput CRISPR-Cas9 knock-out screen targeting 11,776 sORFs to identify microproteins essential for cancer cell line growth. We show that the CENPBD2P gene encodes a translated sORF and promotes cell fitness. We selected five additional candidate sORFs encoding microproteins between 11 and 63 amino acids in length for further functional assessment. Green fluorescent protein fusion constructs of these microproteins localized to distinct subcellular compartments, and the majority showed reproducible biochemical interaction partners. Studying the fitness and transcriptome of sORF knock-outs and complementation with the corresponding microprotein, we identify rescuable phenotypes while also illustrating the limitations and caveats of our pipeline for sORF functional screening and characterization.

Exercise Mimetics in Aging: Suggestions from a Systematic Review

Background/Objectives: Growth in the aging world population is accompanied by an increase in comorbidities, profoundly impacting the quality of life of older people. This development has motivated a large effort to investigate the mechanisms underlying aging and the search for countermeasures. The most investigated strategies envisage the control of diet and physical exercise, which exploit both common and distinct mechanisms to promote health. Since the application of nutritional and exercise protocols to aged persons introduces several issues due to their disabled state, some strategies have been developed. The nutritional approach exploits a wide range of compounds, including calorie restriction mimetics, supplements, antioxidants, and others. In the context of exercise, in recent years, molecules able to provide similar effects to exercise, the so-called exercise mimetics, have been developed. Methods: To have a better perspective on exercise mimetics and their connection with nutrition, we performed a systematic search of the PubMed and Scopus databases using the term "exercise mimetics". Results: In total, 97 research articles were selected and discussed. The present review provides evidence of the presence of multiple exercise-mimetic compounds and physical strategies that can target metabolic pathways, oxidative stress defense mechanisms, or myokine modulation. Conclusions: Interestingly, this review highlights that an important number of exercise mimetics are represented by products of natural origin and supplements assimilable with diet. This evidence provides a further link between exercise and nutrition and confers a central role on nutrition in the context of exercise mimetics.

Effects of Glucagon-Like Peptide-1 Receptor Agonists, Sodium-Glucose Cotransporter-2 Inhibitors, and Their Combination on Neurohumoral and Mitochondrial Activation in Patients With Diabetes

BACKGROUND

We investigated the effects of the combined treatment with glucagon like peptide-1 receptor agonists (GLP-1RA) and sodium-glucose cotransporter-2 inhibitors (SGLT-2i) on NT-proBNP (N-terminal pro-brain natriuretic peptide), GDF-15 (growth differentiation factor 15), and MOTS-c (mitochondrial-derived peptide-c) in patients with type 2 diabetes (T2D) and high or very high cardiovascular risk.

METHODS

We studied 163 consecutive patients with type 2 diabetes who were treated with insulin (n=40), liraglutide (n=41), empagliflozin (n=42), or their combination (GLP-1RA+SGLT-2i) (n=40) and were matched using propensity score analysis. We measured the following at baseline and 4 and 12 months of treatment: (1) NT-proBNP, GDF-15, and MOTS-c; (2) 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and (3) left ventricular global longitudinal strain, left atrial strain during atrial reservoir phase, and global work index using speckle-tracking imaging.

RESULTS

At 12 months, GLP-1RA, SGLT-2i, and their combination showed a greater reduction of NT-proBNP (-43.1% versus -54.2% versus -56.9% versus -14.7%) and GDF-15 than insulin. Only treatment with SGLT-2i and GLP-1RA+SGLT-2i improved MOTS-c. GLP-1RA, SGLT-2i, or GLP-1RA+SGLT-2i provided an increase of global longitudinal strain, left atrial strain, and global work index compared with insulin. In all patients, the reduction of NT-proBNP was associated with the improvement of global longitudinal strain, left atrial strain during atrial reservoir phase, and global work index; the decrease of GDF-15 with the increase of ABTS and MOTS-c; and the increase of MOTs-c with improved global longitudinal strain and constructive myocardial work at 12 months (P<0.05).

CONCLUSIONS

Twelve-month treatment with combination of GLP-1RA+SGLT-2i was associated with a greater reduction of neurohumoral markers and increase of antioxidant ability than each treatment alone and insulin. SGLT-2i appear more effective in the improvement of neurohumoral and mitochondrial activation.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03878706.

Comprehensive discovery and functional characterization of the noncanonical proteome

The systematic identification and functional characterization of noncanonical translation products, such as novel peptides, will facilitate the understanding of the human genome and provide new insights into cell biology. Here, we constructed a high-coverage peptide sequencing reference library with 11,668,944 open reading frames and employed an ultrafiltration tandem mass spectrometry assay to identify novel peptides. Through these methods, we discovered 8945 previously unannotated peptides from normal gastric tissues, gastric cancer tissues and cell lines, nearly half of which were derived from noncoding RNAs. Moreover, our CRISPR screening revealed that 1161 peptides are involved in tumor cell proliferation. The presence and physiological function of a subset of these peptides, selected based on screening scores, amino acid length, and various indicators, were verified through Flag-knockin and multiple other methods. To further characterize the potential regulatory mechanisms involved, we constructed a framework based on artificial intelligence structure prediction and peptide‒protein interaction network analysis for the top 100 candidates and revealed that these cancer-related peptides have diverse subcellular locations and participate in organelle-specific processes. Further investigation verified the interacting partners of pep1-nc-OLMALINC, pep5-nc-TRHDE-AS1, pep-nc-ZNF436-AS1 and pep2-nc-AC027045.3, and the functions of these peptides in mitochondrial complex assembly, energy metabolism, and cholesterol metabolism, respectively. We showed that pep5-nc-TRHDE-AS1 and pep2-nc-AC027045.3 had substantial impacts on tumor growth in xenograft models. Furthermore, the dysregulation of these four peptides is closely correlated with clinical prognosis. Taken together, our study provides a comprehensive characterization of the noncanonical proteome, and highlights critical roles of these previously unannotated peptides in cancer biology.

Non-canonical ORFs-derived protein products in mitochondria: A multifaceted exploration of their functions in health and disease

Traditionally, eukaryotic mRNAs were perceived as inherently monocistronic. However, recent insights from ribosome profiling (Ribo-seq) and proteomics studies challenge this paradigm. These investigations reveal that, beyond the currently annotated reference proteins (RefProts), there exist additional proteins known as alternative proteins (AltProts) and small open reading frames derived microproteins encoded in regions of mRNAs previously considered untranslated or in non-coding transcripts. This experimental evidence broadens the spectrum of functional proteins within cells, tissues, and organs, potentially offering crucial insights into biological processes. Notably, a significant proportion of these newly identified AltProts and microproteins demonstrates localization in mitochondria, contributing to the functions of mitochondrial complexes. This review delves into the overlooked realm of the alternative proteome within mitochondria, exploring the role of nuclear or mitochondrial-genome-encoded AltProts and microproteins in physiological and pathological cellular processes.

MOTS-c mimics remote ischemic preconditioning in protecting against lung ischemia-reperfusion injury by alleviating endothelial barrier dysfunction

Remote ischemic preconditioning (RIPC) induces the expression of unidentified protective cytokines that mitigate lung ischemia-reperfusion injury (LIRI). This study hypothesizes that MOTS-c, a mitokine with potent protective effects against mitochondrial damage, contributes to RIPC-mediated protection by alleviating endothelial barrier dysfunction. In human lung transplantation patients, serum levels of MOTS-c significantly decreased following IR injury but were markedly increased when RIPC was performed prior to transplantation. Similarly, in a mouse model of LIRI, RIPC restored serum MOTS-c levels and improved lung injury outcomes. Intravenous administration of MOTS-c in mice replicated the protective effects observed with RIPC. Mechanistic studies demonstrated that repeated hypoxia in human primary skeletal muscle immortalized cells (HPSMIC) led to the secretion of conditioned media that protected HUVECs from OGD/R-induced injury; silencing MOTS-c abolished these protective effects. Further investigations using nuclear factor erythroid 2-related factor 2 (Nrf2) knockout mice and the Nrf2 inhibitor ML385 revealed that MOTS-c exerts its protective function by increasing Nrf2 protein levels, thereby maintaining endothelial barrier integrity. In conclusion, this study identifies MOTS-c as a novel mediator of RIPC's protective effects against LIRI and highlights its potential as a therapeutic alternative for preventing lung injury and preserving vascular endothelial function.

Mitochondrial genetics, signalling and stress responses

Mitochondria are multifaceted organelles with crucial roles in energy generation, cellular signalling and a range of synthesis pathways. The study of mitochondrial biology is complicated by its own small genome, which is matrilineally inherited and not subject to recombination, and present in multiple, possibly different, copies. Recent methodological developments have enabled the analysis of mitochondrial DNA (mtDNA) in large-scale cohorts and highlight the far-reaching impact of mitochondrial genetic variation. Genome-editing techniques have been adapted to target mtDNA, further propelling the functional analysis of mitochondrial genes. Mitochondria are finely tuned signalling hubs, a concept that has been expanded by advances in methodologies for studying the function of mitochondrial proteins and protein complexes. Mitochondrial respiratory complexes are of dual genetic origin, requiring close coordination between mitochondrial and nuclear gene-expression systems (transcription and translation) for proper assembly and function, and recent findings highlight the importance of the mitochondria in this bidirectional signalling.

Are Mitochondria a Potential Target for Treating β-Thalassemia?

The inherited genetic disorder β-thalassemia affects the hematopoietic system and is caused by the low production or absence of adult hemoglobin (HbA). Ineffective erythropoiesis is the hallmark of β-thalassemia pathophysiology and is characterized by an erythropoietin-driven substantial increase in erythroblast proliferation, coupled with an increase in late-stage precursor apoptosis, which results in low levels of circulating mature red blood cells (RBCs) and chronic anemia. Mitochondrial dysfunction commonly occurs in these cells because of the increased demand for energy production and the need to manage abnormal hemoglobin chain synthesis. Moreover, several studies have highlighted the importance of gradual mitochondrial clearance for mature erythroid cell production. This review offers an overview of the mitochondrial role in essential cellular processes, particularly those crucial for maintaining RBC health and function. Additionally, recent evidence regarding the contribution of mitochondrial dysfunction to the pathophysiology and severity of β-thalassemia is discussed, along with updated insights into indirect mitochondria-targeting treatments, which present potential pharmacological targets.

Mitochondrial-derived microproteins: from discovery to function

Given the uniqueness of the mitochondria, and the fact that they have their own genome, mitochondrial-derived microproteins (MDPs) are similar to, but different from, nuclear-encoded microproteins. The discovery of an increasing number of microproteins from this organelle and the importance of mitochondria to cellular and organismal health make it a priority to study this novel class of proteins in search of possible therapeutic targets and cures. In this review, we discuss the history of MDP discovery, describe the function of each MDP, and conclude with future goals and techniques to help discover more MDPs.

Endurance training enhances skeletal muscle mitochondrial respiration by promoting MOTS-c secretion

The mitochondrial open reading frame of 12S rRNA-c (MOTS-c) is a biologically active mitochondria-derived peptide. However, the relationship between MOTS-c, skeletal muscle mitochondrial function, and endurance exercise adaptations is unknown. Here, we tested indices such as maximal oxygen uptake and serum MOTS-c levels in marathon runners and sedentary subjects. In addition, we tested aerobic exercise capacity, skeletal muscle mitochondrial respiration rate, and serum MOTS-c levels in mice subjected to long-term endurance training groups and sedentary groups. Our results indicated a close association between serum MOTS-c levels and aerobic exercise capacity. Circulating MOTS-c levels are expected to be an important indicator for predicting aerobic exercise capacity and assessing body fat status, endurance training load, and physical function. More importantly, we found that endurance training may enhance the mitochondrial respiratory function of skeletal muscle by promoting the secretion of MOTS-c and activating the AMPK/PGC-1α pathway.

MDPAO1 peptide from human milk enhances brown adipose tissue thermogenesis and mitigates obesity

The regulatory effect of breastfeeding on offspring metabolism has garnered significant attention as an effective strategy in combating childhood obesity. However, the underlying mechanism remains largely unknown. Through integrated analysis of multiple human milk peptide databases and functional screening, MDPAO1 (milk-derived peptide associated with obesity 1) was identified as having potential activity in promoting the expression of thermogenic genes. In lactating mice, intervention with MDPAO1 enhanced the thermogenic phenotype of brown adipose tissue (BAT) and overall metabolic activity. Moreover, MDPAO1 intervention led to reduced body weight gain, increased brown fat mass, and improved glucose tolerance and insulin sensitivity in a mouse model of high-fat diet (HFD)-induced obesity. RNA-seq analysis of BAT post-MDPAO1 intervention revealed close association with mitochondrial oxidative respiratory chain and mitophagy. Subsequent in vitro experiments conducted on primary brown adipocytes confirmed that MDPAO1 inhibited mitophagy, increased mitochondrial mass, and elevated levels of mitochondrial respiratory chain complexes. In conclusion, this study underscores the potential of MDPAO1, a peptide enriched in breast milk, in activating the thermogenic phenotype of brown adipose tissue and mitigating obesity, thus offering novel insights into the mechanisms underlying breastfeeding's role in preventing childhood obesity.

The Role of Mitokines in Diabetic Nephropathy

Diabetic nephropathy (DN) has gradually become one of the main causes of end-stage renal disease (ESRD). However, there is still a lack of effective preventive measures to delay its progression. As the energy factory in the cell, mitochondria play an irreplaceable role in maintaining cell homeostasis. Interestingly, recent studies have shown that in addition to maintaining homeostasis in cells in which mitochondria reside, when mitochondrial perturbations occur in one tissue, distal tissues can also sense and act through mitochondrial stress response pathways through a group of proteins or peptides called "mitokines". Here, we reviewed the mitokines that have been found thus far and summarized their research progress in DN. Finally, we explored the possibility of mitokines as potential therapeutic targets for DN.

Mitochondrial mechanisms in Treg cell regulation: Implications for immunotherapy and disease treatment

Regulatory T cells (Tregs) play a critical role in maintaining immune homeostasis and preventing autoimmune diseases. Recent advances in immunometabolism have revealed the pivotal role of mitochondrial dynamics and metabolism in shaping Treg functionality. Tregs depend on oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) to support their suppressive functions and long-term survival. Mitochondrial processes such as fusion and fission significantly influence Treg activity, with mitochondrial fusion enhancing bioenergetic efficiency and reducing reactive oxygen species (ROS) production, thereby promoting Treg stability. In contrast, excessive mitochondrial fission disrupts ATP synthesis and elevates ROS levels, impairing Treg suppressive capacity. Furthermore, mitochondrial ROS act as critical signaling molecules in Treg regulation, where controlled levels stabilize FoxP3 expression, but excessive ROS leads to mitochondrial dysfunction and immune dysregulation. Mitophagy, as part of mitochondrial quality control, also plays an essential role in preserving Treg function. Understanding the intricate interplay between mitochondrial dynamics and Treg metabolism provides valuable insights for developing novel therapeutic strategies to treat autoimmune disorders and enhance immunotherapy in cancer.

MOTS-c relieves hepatocellular carcinoma resistance to TRAIL-induced apoptosis under hypoxic conditions by activating MEF2A

BACKGROUND

Mitochondrial ORF of the 12S rRNA type-c (MOTS-c) as an AMPK agonist can regulate the expression of adaptive nuclear genes to promote cell homeostasis. However, the investigation of MOTS-c in hepatocellular carcinoma (HCC) is insufficient. This study aims to reveal the role of MOTS-c on HCC cell apoptosis.

METHODS

Huh7 and HCCLM3 cells were incubated with MOTS-c under a hypoxic condition. MOTS-c levels were quantified by enzyme-linked immunosorbent assay in the peripheral blood of HCC patients and healthy controls. Cell viability was detected by 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell apoptosis was investigated by flow cytometry and Tunel assay. Protein expression was detected by western blotting or immunohistochemistry assay. Dual-luciferase reporter assay and chromatin immunoprecipitation assay were performed to identify the association among myocyte enhancer factor 2A (MEF2A), death receptor 4 (DR4) and DR5. A tumor-bearing nude mouse model was conducted to assess the effect of MOTS-c on HCC tumor formation in vivo.

RESULTS

MOTS-c levels in the peripheral blood of HCC patients were significantly lower compared to healthy individuals. MOTS-c promoted HCC cell apoptosis under hypoxia conditions. Hypoxia stimulation decreased the protein expression of MEF2A, DR4, DR5, fas-associating via death domain (FADD) and caspase-8, while these effects were attenuated after MOTS-c treatment. MOTS-c induced TRAIL-induced apoptosis of HCC cells by activating MEF2A through the phosphorylation of AMPK under hypoxia treatment. In addition, MEF2A transcriptionally up-regulated DR4 and DR5. MOTS-c activated MEF2A to regulate DR4 and DR5 expression, further mediating TRAIL-induced apoptosis. Further, MOTS-c treatment relieved hypoxia-induced tumor growth in vivo.

CONCLUSION

MOTS-c relieved hypoxia-induced HCC cell resistance to TRAIL-caused apoptosis by activating MEF2A.

MOTS-c regulates the ROS/TXNIP/NLRP3 pathway to alleviate diabetic cardiomyopathy

Chronic low-grade inflammation is a characteristic of diabetes, which often culminates in cardiovascular events including myocardial damage, thereby increasing the risk of debilitating cardiac complications. The mitochondria-derived peptide MOTS-c regulates glucose and lipid metabolism while improving insulin resistance, making it a potential candidate for the treatment of diabetes and cardiovascular diseases. We investigated the impact of MOTS-c on cardiac structure and inflammation in diabetic rats induced by a high-sugar-fat diet combined with low-dose streptozotocin (30 mg/kg, i.p.). Our results confirm that high glucose levels activate the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome and increase reactive oxygen species (ROS), ultimately leading to myocardial injury. Furthermore, treatment with MOTS-c (0.5 mg/kg/day, i.p.) for 8 weeks reduced the expression of ROS/TXNIP/NLRP3 pathway proteins to inhibit the diabetic myocardial inflammatory response. These findings suggested that MOTS-c alleviates myocardial damage by inhibiting the ROS/TXNIP/NLRP3 pathway.

[Gly14]-Humanin ameliorates high glucose-induced endothelial senescence via SIRT6

High glucose (HG) induced endothelial senescence is related to endothelial dysfunction and cardiovascular complications in diabetic patients. Humanin, a member of mitochondrial derived peptides (MDPs), is thought to contribute to aging-related cardiovascular protection. The goal of the study is to explore the pathogenesis of HG-induced endothelial senescence and potential anti-senescent effects of Humanin. Human umbilical vein endothelial cells (HUVECs) were exposed to glucose to induce senescence, determined by β-galactosidase staining and the expressions of p21, p53, and p16. A clinically relevant dose of HG (15 mM, HG) induced endothelial senescence after 72 h incubation without elevated apoptosis. HG-induced senescence was attributed to the induction of reactive oxygen species (ROS) caused by SIRT6 downregulation, as ROS inhibitor N-acetyl cysteine blocked HG-induced senescence, while inactivation of SIRT6 increased ROS levels and promoted senescence. Strikingly. pretreatment with [Gly14]-Humanin (HNG) antagonized the downregulation of SIRT6 in response to HG and alleviated ROS production and cell senescence. HG-induced reduction of SIRT6 results in ROS overproduction and endothelial senescence. Humanin protects against HG-induced endothelial senescence via SIRT6. This study provides new directions for biological products related to Humanin to be a potential candidate for the prevention of vascular aging in diabetes.

Evaluation of vascular peroxidase 1, humanin, MOTS-c and miR-200c expression levels in untreated preeclampsia patients

BACKGROUND

The objective of this study was to evaluate the levels of Vascular Peroxidase 1 (VPO1), humanin, and MOTS-c in relation to miR-200c expression in untreated preeclamptic pregnancies, and to compare these findings with endoglin levels.

METHODS AND RESULTS

In this study, blood samples were collected from preeclamptic patients presenting to the clinic prior to the initiation of treatment. The levels of endoglin, VPO1, humanin, and MOTS-c were measured using enzyme-linked immunosorbent assay (ELISA), while miR-200c expression was quantified using reverse transcription polymerase chain reaction (RT-PCR). Receiver operating characteristic (ROC) analysis was performed to assess diagnostic accuracy. Statistical significance was determined at p < 0.05. The levels of endoglin, VPO1, and miR-200c were found to be significantly elevated in the preeclampsia group compared to the control group (p < 0.05), whereas MOTS-c levels were significantly reduced (p < 0.05). No significant difference was observed in humanin levels between the two groups. A positive correlation was identified between endoglin levels and VPO1 (r = 0.943, p < 0.001), humanin (r = 0.421, p < 0.01), and uric acid (r = 0.314, p = 0.02) in the preeclamptic group.

CONCLUSIONS

Our findings suggest that the elevation of VPO1 and miR-200c levels, along with the reduction of humanin and MOTS-c levels, may contribute to the increased endoglin levels and subsequent endothelial dysfunction observed in preeclampsia. These changes may be associated with the pathogenesis and severity of the disease.

Inter- and intracellular mitochondrial communication: signaling hubs in aging and age-related diseases

Mitochondria are versatile and complex organelles that can continuously communicate and interact with the cellular milieu. Deregulated communication between mitochondria and host cells/organelles has significant consequences and is an underlying factor of many pathophysiological conditions, including the process of aging. During aging, mitochondria lose function, and mitocellular communication pathways break down; mitochondrial dysfunction interacts with mitochondrial dyscommunication, forming a vicious circle. Therefore, strategies to protect mitochondrial function and promote effective communication of mitochondria can increase healthy lifespan and longevity, which might be a new treatment paradigm for age-related disorders. In this review, we comprehensively discuss the signal transduction mechanisms of inter- and intracellular mitochondrial communication, as well as the interactions between mitochondrial communication and the hallmarks of aging. This review emphasizes the indispensable position of inter- and intracellular mitochondrial communication in the aging process of organisms, which is crucial as the cellular signaling hubs. In addition, we also specifically focus on the status of mitochondria-targeted interventions to provide potential therapeutic targets for age-related diseases.

In-silico identification of putatively functional intergenic small open reading frames in the cucumber genome and their predicted response to biotic and abiotic stresses

The availability of high-throughput sequencing technologies increased our understanding of different genomes. However, the genomes of all living organisms still have many unidentified coding sequences. The increased number of missing small open reading frames (sORFs) is due to the length threshold used in most gene identification tools, which is true in the genic and, more importantly and surprisingly, in the intergenic regions. Scanning the cucumber genome intergenic regions revealed 420 723 sORF. We excluded 3850 sORF with similarities to annotated cucumber proteins. To propose the functionality of the remaining 416 873 sORF, we calculated their codon adaptation index (CAI). We found 398 937 novel sORF (nsORF) with CAI ≥ 0.7 that were further used for downstream analysis. Searching against the Rfam database revealed 109 nsORFs similar to multiple RNA families. Using SignalP-5.0 and NLS, identified 11 592 signal peptides. Five predicted proteins interacting with Meloidogyne incognita and Powdery mildew proteins were selected using published transcriptome data of host-pathogen interactions. Gene ontology enrichment interpreted the function of those proteins, illustrating that nsORFs' expression could contribute to the cucumber's response to biotic and abiotic stresses. This research highlights the importance of previously overlooked nsORFs in the cucumber genome and provides novel insights into their potential functions.

Transcriptional analysis of cancer cachexia: conserved and unique features across preclinical models and biological sex

Studies suggest heterogeneity in cancer cachexia (CC) among models and biological sexes, yet examinations comparing models and sexes are scarce. We compared the transcriptional landscape of skeletal muscle across murine CC models and biological sexes during early and late CC. Global gene expression analyses were performed on gastrocnemius [Lewis lung carcinoma (LLC)], quadriceps (KPC-pancreatic), and tibialis anterior [Colon-26 (C26)-colorectal and ApcMin/+] muscles across biological sexes. Differentially expressed genes (DEGs) were identified using an adj-P value of <0.05, followed by pathway and computational cistrome analyses. Integrating all controls, early and late stages of all models and sexes revealed up to 68% of DEGs and pathways were enriched at early and late CC, indicating a conserved transcriptional profile during CC development. Comparing DEGs and pathways within sexes and across models, in early CC, the transcriptional response was highly heterogeneous. At late stage, 11.5% of upregulated and 10% of downregulated genes were shared between models in males, whereas 18.9% of upregulated and 7% of downregulated DEGs were shared in females. Shared DEGs were enriched in proteasome and mitophagy/autophagy pathways (upregulated), and downregulation of energy metabolism pathways in males only. Between sexes, though the proportion of shared DEGs was low (<16%), similar pathway enrichment was observed, including proteasome and mitophagy at late-stage CC. In early CC, oncostatin M receptor (Osmr) upregulation was the only commonality across all models and sexes, whereas CLOCK and ARNTL/BMAL1 were predicted transcriptional factors associated with dysregulations in all three male models. This study highlights sex and model differences in CC progression and suggests conserved transcriptional changes as potential therapeutic targets.NEW & NOTEWORTHY This study is among the first to integrate and compare the skeletal muscle transcriptional landscape across multiple preclinical models and biological sexes. We highlight that 1) early CC transcriptional changes are two-thirds conserved at late stages, 2) DEGs are largely model and sex specific, and 3) transcriptional factors including CLOCK and ARNTL/BMAL1, which influence early CC gene expression, might represent a global therapeutic target with a chance of efficacy across various cancer types.

Microproteins encoded by short open reading frames: Vital regulators in neurological diseases

Short open reading frames (sORFs) are frequently overlooked because of their historical classification as non-coding elements or dismissed as "transcriptional noise". However, advanced genomic and proteomic technologies have allowed for screening and validating sORFs-encoded peptides, revealing their fundamental regulatory roles in cellular processes and sparking a growing interest in microprotein biology. In neuroscience, microproteins serve as neurotransmitters in signal transmission and regulate metabolism and emotions, exerting pivotal effects on neurological conditions such as nerve injury, neurogenic tumors, inflammation, and neurodegenerative diseases. This review summarizes the origins, characteristics, classifications, and functions of microproteins, focusing on their molecular mechanisms in neurological disorders. Potential applications, future perspectives, and challenges are discussed.

Micropeptide MPM regulates cardiomyocyte proliferation and heart growth via the AKT pathway

The role of micropeptide in cardiomyocyte proliferation remains unknown. We found that MPM (micropeptide in mitochondria) was highly expressed in cardiomyocytes. Compared to MPM+/+ mice, MPM knockout (MPM-/-) mice exhibited reduction in left ventricular (LV) mass, myocardial thickness and LV fractional shortening. RNA-sequencing analysis in H9c2, a rat cardiomyocyte cell line, identified downregulation of cell cycle-promoting genes as the most significant alteration in MPM-silencing cells. Consistently, gain- and loss-of-function analyses in H9c2 cells revealed that cardiomyocyte proliferation was repressed by silencing MPM but was promoted by overexpressing MPM. Moreover, the cardiomyocytes in the hearts of MPM-/- mice displayed reduced proliferation rates. Mechanism investigations disclosed that MPM is crucial for AKT activation in cardiomyocytes. We also identified an interaction between MPM and PTPMT1, and found that silencing PTPMT1 attenuated the effect of MPM in activating the AKT pathway, whereas inhibition of the AKT pathway abrogated the role of MPM in promoting cardiomyocyte proliferation. Collectively, these results indicate that MPM may promote cardiomyocyte proliferation and thus heart growth by interacting with PTPMT1 to activate the AKT pathway. Our findings identify the novel function and regulatory network of MPM and highlight the importance of micropeptides in cardiomyocyte proliferation and heart growth.

MOTS-c modulates skeletal muscle function by directly binding and activating CK2

MOTS-c is a mitochondrial microprotein that improves metabolism. Here, we demonstrate CK2 is a direct and functional target of MOTS-c. MOTS-c directly binds to CK2 and activates it in cell-free systems. MOTS-c administration to mice prevented skeletal muscle atrophy and enhanced muscle glucose uptake, which were blunted by suppressing CK2 activity. Interestingly, the effects of MOTS-c are tissue-specific. Systemically administered MOTS-c binds to CK2 in fat and muscle, yet stimulates CK2 activity in muscle while suppressing it in fat by differentially modifying CK2-interacting proteins. Notably, a naturally occurring MOTS-c variant, K14Q MOTS-c, has reduced binding to CK2 and does not activate it or elicit its effects. Male K14Q MOTS-c carriers exhibited a higher risk of sarcopenia and type 2 diabetes (T2D) in an age- and physical-activity-dependent manner, whereas females had an age-specific reduced risk of T2D. Altogether, these findings provide evidence that CK2 is required for MOTS-c effects.

Effects of empagliflozin and dapagliflozin on serum humanin, MOTS-c levels, nitrosative stress, and ferroptosis parameters in diabetic patients with heart failure

Sodium-glucose cotransporter 2 (SGLT2) inhibitors produce cardioprotective effects on heart failure (HF), even in the absence of diabetes. However, the underlying mechanisms of this cardioprotective effect remain unexplored. The purpose of this study was to examine the effects of SGLT2 inhibitors on serum MOTS-c, humanin levels, nitrosative stress, and ferroptosis parameters in diabetic patients with HF with reduced ejection fraction (HFrEF). A total of 74 adult diabetic patients with HFrEF and 37 healthy controls were included in this prospective study. Half of the patients were using SGLT2 inhibitors (empagliflozin or dapagliflozin) for at least two months. Serum nitric oxide and 3-nitrotyrosine levels were markedly higher in diabetic patients with HFrEF than the control (P < 0.001), but these elevations were inhibited with SGLT2 inhibitors. Although SGLT2 inhibitors had no marked effect on humanin levels, they significantly augmented MOTS-c levels when compared to the control. SGLT2 inhibitors augmented GPX4 but inhibited ACSL4 levels when compared to diabetic patients with HF. However, TFRC levels were increased in the patient group (P < 0.001 for all) but not modified with SGLT2 inhibitors. Our results suggest that increased nitrosative stress is significantly depressed by SGLT2 inhibitors. This study was the first to show that SGLT2 inhibitors can stimulate MOTS-c, but not humanin, in diabetic patients with HFrEF. SGLT2 inhibitors reduced ferroptosis through elevation of GPX4 and suppression of ACSL4 levels. Our data suggest that SGLT2 inhibitors could produce cardioprotective effects through relieving ferroptosis, inhibiting nitosative stress, and stimulating mitochondrial MOTS-c release.

The Human Mitochondrial Genome Encodes for an Interferon-Responsive Host Defense Peptide

The mitochondrial DNA (mtDNA) can trigger immune responses and directly entrap pathogens, but it is not known to encode for active immune factors. The immune system is traditionally thought to be exclusively nuclear-encoded. Here, we report the identification of a mitochondrial-encoded host defense peptide (HDP) that presumably derives from the primordial proto-mitochondrial bacteria. We demonstrate that MOTS-c (mitochondrial open reading frame from the twelve S rRNA type-c) is a mitochondrial-encoded amphipathic and cationic peptide with direct antibacterial and immunomodulatory functions, consistent with the peptide chemistry and functions of known HDPs. MOTS-c targeted E. coli and methicillin-resistant S. aureus (MRSA), in part, by targeting their membranes using its hydrophobic and cationic domains. In monocytes, IFNγ, LPS, and differentiation signals each induced the expression of endogenous MOTS-c. Notably, MOTS-c translocated to the nucleus to regulate gene expression during monocyte differentiation and programmed them into macrophages with unique transcriptomic signatures related to antigen presentation and IFN signaling. MOTS-c-programmed macrophages exhibited enhanced bacterial clearance and shifted metabolism. Our findings support MOTS-c as a first-in-class mitochondrial-encoded HDP and indicates that our immune system is not only encoded by the nuclear genome, but also by the co-evolved mitochondrial genome.

Mitochondrial-Derived Peptide MOTS-c Suppresses Ovarian Cancer Progression by Attenuating USP7-Mediated LARS1 Deubiquitination

Mitochondrial-nuclear communication plays a vital role in maintaining cellular homeostasis. MOTS-c, a short peptide derived from the 12S rRNA of mitochondrial DNA, has been suggested as a retrograde mitochondrial signal. Although recent clinical studies have suggested a possible link between MOTS-c and human cancer, the role of MOTS-c in tumorigenesis has yet to be investigated. Here, MOTS-c levels are found to be reduced in both serum and tumor tissues from ovarian cancer (OC) patients, which are associated with poor patients' prognosis. Exogenous MOTS-c inhibits the proliferation, migration and invasion of OC cells, and induces cell cycle arrest and apoptosis. Mechanistically, MOTS-c interacts with LARS1 and promotes its ubiquitination and proteasomal degradation. In addition, USP7 was identified as a deubiquitinase of LARS1, and MOTS-c can attenuates USP7-mediated LARS1 deubiquitination by competing with USP7 for binding to LARS1. Besides, LARS1 was found to be increased and play an important oncogenic function in OC. More importantly, MOTS-c displays a marked anti-tumor effect on OC growth without systemic toxicity in vivo. In conclusion, this study reveals a crucial role of MOTS-c in OC and provides a possibility for MOTS-c as a therapeutic target for the treatment of this manlignacy.

The Relationship Between MOTS-c K14Q Polymorphism and Sarcopenia, Blood Lipids, and Mental Health in Older Korean Adults

Background/objectives: An East Asian-specific 1382A>C polymorphism in the mitochondrial open reading frame of the 12S rRNA type-c results in an amino acid substitution from Lys (K) to Gln (Q) at the 14th amino acid residue. This study investigated the association between m.1382A>C polymorphism and sarcopenia, blood lipids, and mental health in older Korean adults. Methods: The study included 683 community-dwelling Korean adults (345 men and 338 women) aged 65 years and older. The m.1382A>C polymorphism was genotyped with a 7500 real-time PCR system. Handgrip strength (HGS) was measured, and appendicular skeletal muscle (ASM) mass was calculated. Demographics, blood lipids, falling risk, nutritional intake, cognition function, and depression were additionally measured. Results: Men carrying the C allele had significantly higher ASM (21.6 ± 3.0 vs. 19.5 ± 2.2 kg, p = 0.018), ASM/height2 (7.76 ± 0.76 vs. 7.14 ± 0.62 kg/m2, p = 0.012), lean mass (53.3 ± 6.2 vs. 46.5 ± 4.0 kg, p < 0.001), left HGS (33.3 ± 5.0 vs. 28.9 ± 4.0 kg, p = 0.010), and right HGS (35.6 ± 5.3 vs. 30.9 ± 4.3 kg, p = 0.009) than men carrying the A allele. The genotype differences in ASM (p = 0.017), ASM/height2 (p = 0.011), lean mass (p < 0.001), left HGS (p = 0.010), and right HGS (p = 0.009) remained significant even after adjusting for all measured covariates. By contrast, no significant differences in other measured parameters were found between women carrying the A and C alleles. Conclusions: Our study findings indicate that the m.1382A>C polymorphism may be used as a genetic biomarker of age-related sarcopenia in older Korean men.

Mitochondrial haplogroup R offers protection against obesity in Kuwaiti and Qatari populations

Background

The Kuwaiti and Qatari populations have a high prevalence of obesity, a major risk factor for various metabolic disorders. Previous studies have independently explored mitochondrial DNA (mtDNA) variations and their association with obesity in these populations. This study aims to investigate the role of mtDNA haplogroups and variants in obesity risk among these Gulf populations.

Methods

Whole exome sequencing data from 1,112 participants (348 Kuwaitis and 764 Qataris) were analyzed for mtDNA variants. Participants were classified as obese or non-obese based on body mass index (BMI). Association analyses were performed to examine the relationship between mtDNA haplogroups and obesity, adjusting for covariates such as age and sex.

Results

Haplogroup R was found to be protective against obesity, with an odds ratio (OR) of 0.69 (p = 0.045). This association remained significant after adjusting for age and sex (OR = 0.694; 95% CI: 0.482-0.997; p = 0.048). Several mtDNA variants, particularly those involved in mitochondrial energy metabolism, showed nominal associations with obesity, but these did not remain significant after correcting for multiple testing.

Conclusion

Haplogroup R consistently demonstrates a protective association against obesity in both Kuwaiti and Qatari populations, highlighting its potential as a biomarker for obesity risk in the Gulf region. However, further research with larger sample sizes is needed to validate these findings and clarify the role of mtDNA variants in obesity.

Mitochondrial Function and Dysfunction in White Adipocytes and Therapeutic Implications

For a long time, white adipocytes were thought to function as lipid storages due to the sizeable unilocular lipid droplet that occupies most of their space. However, recent discoveries have highlighted the critical role of white adipocytes in maintaining energy homeostasis and contributing to obesity and related metabolic diseases. These physiological and pathological functions depend heavily on the mitochondria that reside in white adipocytes. This article aims to provide an up-to-date overview of the recent research on the function and dysfunction of white adipocyte mitochondria. After briefly summarizing the fundamental aspects of mitochondrial biology, the article describes the protective role of functional mitochondria in white adipocyte and white adipose tissue health and various roles of dysfunctional mitochondria in unhealthy white adipocytes and obesity. Finally, the article emphasizes the importance of enhancing mitochondrial quantity and quality as a therapeutic avenue to correct mitochondrial dysfunction, promote white adipocyte browning, and ultimately improve obesity and its associated metabolic diseases. © 2024 American Physiological Society. Compr Physiol 14:5581-5640, 2024.

Network-based modelling reveals cell-type enriched patterns of non-coding RNA regulation during human skeletal muscle remodelling

A majority of human genes produce non-protein-coding RNA (ncRNA), and some have roles in development and disease. Neither ncRNA nor human skeletal muscle is ideally studied using short-read sequencing, so we used a customised RNA pipeline and network modelling to study cell-type specific ncRNA responses during muscle growth at scale. We completed five human resistance-training studies (n=144 subjects), identifying 61% who successfully accrued muscle-mass. We produced 288 transcriptome-wide profiles and found 110 ncRNAs linked to muscle growth in vivo, while a transcriptome-driven network model demonstrated interactions via a number of discrete functional pathways and single-cell types. This analysis included established hypertrophy-related ncRNAs, including CYTOR - which was leukocyte-associated (FDR = 4.9 ×10-7). Novel hypertrophy-linked ncRNAs included PPP1CB-DT (myofibril assembly genes, FDR = 8.15 × 10-8), and EEF1A1P24 and TMSB4XP8 (vascular remodelling and angiogenesis genes, FDR = 2.77 × 10-5). We also discovered that hypertrophy lncRNA MYREM shows a specific myonuclear expression pattern in vivo. Our multi-layered analyses established that single-cell-associated ncRNA are identifiable from bulk muscle transcriptomic data and that hypertrophy-linked ncRNA genes mediate their association with muscle growth via multiple cell types and a set of interacting pathways.

Detection of host cell microprotein impurities in antibody drug products

Chinese hamster ovary (CHO) cells are used to produce almost 90% of therapeutic monoclonal antibodies (mAbs) and antibody fusion proteins (Fc-fusion). The annotation of non-canonical translation events in these cellular factories remains incomplete, limiting our ability to study CHO cell biology and detect host cell protein (HCP) impurities in the final antibody drug product. We utilised ribosome footprint profiling (Ribo-seq) to identify novel open reading frames (ORFs) including N-terminal extensions and thousands of short ORFs (sORFs) predicted to encode microproteins. Mass spectrometry-based HCP analysis of eight commercial antibody drug products (7 mAbs and 1 Fc-fusion protein) using the extended protein sequence database revealed the presence of microprotein impurities. We present evidence that microprotein abundance varies with growth phase and can be affected by the cell culture environment. In addition, our work provides a vital resource to facilitate future studies of non-canonical translation and the regulation of protein synthesis in CHO cell lines.

Mitochondrial-derived peptides in cardiovascular disease: Novel insights and therapeutic opportunities

BACKGROUND

Mitochondria-derived peptides (MDPs) represent a recently discovered family of peptides encoded by short open reading frames (ORFs) found within mitochondrial genes. This group includes notable members including humanin (HN), mitochondrial ORF of the 12S rDNA type-c (MOTS-c), and small humanin-like peptides 1-6 (SHLP1-6). MDPs assume pivotal roles in the regulation of diverse cellular processes, encompassing apoptosis, inflammation, and oxidative stress, which are all essential for sustaining cellular viability and normal physiological functions. Their emerging significance extends beyond this, prompting a deeper exploration into their multifaceted roles and potential applications.

AIM OF REVIEW

This review aims to comprehensively explore the biogenesis, various types, and diverse functions of MDPs. It seeks to elucidate the central roles and underlying mechanisms by which MDPs participate in the onset and development of cardiovascular diseases (CVDs), bridging the connections between cell apoptosis, inflammation, and oxidative stress. Furthermore, the review highlights recent advancements in clinical research related to the utilization of MDPs in CVD diagnosis and treatment.

KEY SCIENTIFIC CONCEPTS OF REVIEW

MDPs levels are diminished with aging and in the presence of CVDs, rendering them potential new indicators for the diagnosis of CVDs. Also, MDPs may represent a novel and promising strategy for CVD therapy. In this review, we delve into the biogenesis, various types, and diverse functions of MDPs. We aim to shed light on the pivotal roles and the underlying mechanisms through which MDPs contribute to the onset and advancement of CVDs connecting cell apoptosis, inflammation, and oxidative stress. We also provide insights into the current advancements in clinical research related to the utilization of MDPs in the treatment of CVDs. This review may provide valuable information with MDPs for CVD diagnosis and treatment.

Network-based modelling reveals cell-type enriched patterns of non-coding RNA regulation during human skeletal muscle remodelling

A majority of human genes produce non-protein-coding RNA (ncRNA), and some have roles in development and disease. Neither ncRNA nor human skeletal muscle is ideally studied using short-read sequencing, so we used a customized RNA pipeline and network modelling to study cell-type specific ncRNA responses during muscle growth at scale. We completed five human resistance-training studies (n = 144 subjects), identifying 61% who successfully accrued muscle-mass. We produced 288 transcriptome-wide profiles and found 110 ncRNAs linked to muscle growth in vivo, while a transcriptome-driven network model demonstrated interactions via a number of discrete functional pathways and single-cell types. This analysis included established hypertrophy-related ncRNAs, including CYTOR-which was leukocyte-associated (false discovery rate [FDR] = 4.9 × 10-7). Novel hypertrophy-linked ncRNAs included PPP1CB-DT (myofibril assembly genes, FDR = 8.15 × 10-8), and EEF1A1P24 and TMSB4XP8 (vascular remodelling and angiogenesis genes, FDR = 2.77 × 10-5). We also discovered that hypertrophy lncRNA MYREM shows a specific myonuclear expression pattern in vivo. Our multi-layered analyses established that single-cell-associated ncRNA are identifiable from bulk muscle transcriptomic data and that hypertrophy-linked ncRNA genes mediate their association with muscle growth via multiple cell types and a set of interacting pathways.