Targeting NAT10 protects against sepsis-induced skeletal muscle atrophy by inhibiting ROS/NLRP3

Identification of VDAC1 as a mitochondria-related target of Duchenne muscular dystrophy based on bioinformatics analysis and in vitro experiments

BACKGROUND

Mitochondrial dysfunction is a well-recognized pathological feature of Duchenne Muscular Dystrophy (DMD). The potential regulatory role of mitochondria-related genes (MRGs) in DMD remains to be further explored.

METHODS

GEO datasets and MRGs were used to analysis mitochondrial scores and evaluate patients' immunological characteristics. Weighted gene co-expression network analysis, differentially expressed genes (DEGs) and MRGs were used to identify hub genes. A specific hub gene was selected, and the effects of this gene overexpression on a horse serum (HS) treated C2C12 cell in vitro model were investigated.

RESULTS

Mitochondrial score was decreased in DMD group. Significant differences were observed in 12 immune cell types in normal/DMD and high/low mitochondrial score groups. 9 hub genes were identified, with 7 validated. Among them, VDAC1 was selected for further study. Overexpression of VDAC1 in HS C2C12 myoblasts promoted cell proliferation, reduced apoptosis rate and the Bax expression (with concurrent Bcl2 upregulation), diminished LDH release to reduce cytotoxicity, decreased intracellular ROS levels to alleviate oxidative stress, inhibited the expression of autophagy (LC3) and atrophy (Atrogin-1 and MuRF-1) markers, and promoted differentiation.

CONCLUSION

In conclusion, VDAC1 may participate in the myoblast proliferation and myotube atrophy by influencing mitochondrial function, which may serve as a new target for DMD treatment.

NAT10 Regulates LPS-Induced Inflammation via Stabilization of N4-Acetylated PTX3 mRNA in Human Dental Pulp Stem Cells

Severe dental pulp inflammation can lead to tissue lysis and destruction, underscoring the necessity for effective treatment of pulpitis. N-acetyltransferase 10 (NAT10)-mediated N4-acetylcytidine (ac4C) modification has recently emerged as a key regulator in inflammatory processes. However, whether NAT10 affects the inflammatory response in human dental pulp stem cells (hDPSCs) remains unelucidated. In this study, elevated NAT10 expression was observed in pulpitis tissues and LPS-stimulated hDPSCs. Knockdown of NAT10 led to reduced inflammatory gene expression and lower reactive oxygen species (ROS) production in LPS-stimulated hDPSCs, while the chemotactic migration of macrophages was also suppressed. Similar results were observed when hDPSCs were treated with Remodelin, an inhibitor of NAT10. Differentially expressed genes identified through RNA sequencing were significantly enriched in inflammatory signaling pathways after NAT10 depletion. Among the differential genes, pentraxins 3 (PTX3) was identified as the potential target gene due to the presence of the ac4C modification site and its known ability to regulate dental pulp inflammation. The mRNA and protein levels of PTX3 were reduced in NAT10-deficient cells, along with a decrease in its mRNA stability. Exogenous PTX3 supplementation partially reversed the inflammatory inhibition induced by NAT10 knockdown. Further evidence in vivo revealed that Remodelin treatment attenuated the severity of dental pulp inflammation in rats with pulpitis. In summary, these data indicated that NAT10 deficiency inhibited the stability of PTX3 mRNA and further inhibited hDPSC inflammation, while Remodelin might be a potential therapeutic agent for pulp capping.

Identification and mechanistic analysis of shared biomarkers and pathogenesis in acute pancreatitis and sepsis based on differential gene expression and protein interaction networks

Acute pancreatitis (AP) is a common gastrointestinal inflammatory disease that requires hospitalization, with 40-70% of patients in moderate to severe stages potentially developing sepsis, which is closely related to high mortality rates and poor prognosis. Therefore, early identification of AP patients at risk of developing sepsis is crucial for reducing mortality. This study aims to identify core genes associated with sepsis to provide new core genes for early warning and management of patients with acute pancreatitis. The study utilized the GSE54514, GSE57065, GSE95233, and GSE194331 datasets for analysis, employing weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) network construction. Six core genes were identified using two machine learning methods and validated with the GSE3644 and GSE28750 datasets. The analysis revealed that the identified core genes (NDUFA1, COX7A2, COX7B, UQCRQ, SNRPG, and NDUFA4) are related to the oxidative phosphorylation (OxPhos) pathway, and significant differences were observed in the immune cell composition between AP and sepsis patients. SNRPG may play a role in the progression from AP to sepsis by regulating NDUFA4, linking it to cellular metabolism and redox balance. The newly identified core genes and their associated molecular mechanisms provide important clinical insights into the progression of acute pancreatitis to sepsis, potentially offering new research directions for future therapeutic strategies. Clinical trial number: This study was approved by the Ethics Committee of (Municipal Hospital affiliated to Taizhou University), in accordance with the Declaration of Helsinki. Approval number: LWSL202400220.

Emerging Role of NAT10 as ac4C Writer in Inflammatory Diseases: Mechanisms and Therapeutic Applications

The incidence of inflammatory diseases, including infections, autoimmune disorders, and tumors, is consistently increasing year by year, posing a significant and growing threat to human health on a global scale. Recent research has indicated that RNA acetylation modification, a specific type of post-transcriptional modification, may play a critical role in the pathogenesis of these diseases. Among the various mechanisms of RNA modification, N-acetyltransferase 10 (NAT10) has been identified as the sole cytidine acetyltransferase in eukaryotes. NAT10 is responsible for acetylating mRNA cytosine, which leads to the formation of N4-acetylcytidine (ac4C), a modification that subsequently influences mRNA stability and translation efficiency. Despite these insights, the specific roles and underlying mechanisms by which RNA acetylation contributes to the onset and progression of inflammatory diseases remain largely unclear. This review aimed to elucidate the alterations in NAT10 expression, the modifications it induces in target genes, and its overall contribution to the pathogenesis of various inflammatory conditions. It has been observed that NAT10 expression tends to increase in most inflammatory conditions, thereby affecting the expression and function of target genes through the formation of ac4C. Furthermore, inhibitors targeting NAT10 present promising therapeutic avenues for treating inflammatory diseases by selectively blocking NAT10 activity, thereby preventing the modification of target genes and suppressing immune cell activation and inflammatory responses. This potential for therapeutic intervention underscores the critical importance of further research on NAT10's role in inflammatory disease pathogenesis, as understanding these mechanisms could lead to significant advancements in treatment strategies, potentially transforming the therapeutic landscape for these conditions.

Polygonatum sibiricum polysaccharide ameliorates skeletal muscle aging and mitochondrial dysfunction via PI3K/Akt/mTOR signaling pathway

BACKGROUND

Sarcopenia is currently a life-threatening disease for the elderly. Polygonatum sibiricum polysaccharide (PSP) has anti-oxidative stress and anti-inflammatory effects. However, the effects of PSP on skeletal muscle aging, myoblast differentiation and mitochondrial dysfunction through PI3K/Akt/mTOR signaling pathway has not been explored.

PURPOSE

To explore the effects and related mechanisms of PSP on muscle aging, myoblast differentiation and mitochondrial dysfunction.

METHODS

The chemical components of Polygonatum sibiricum were determined using the UHPLC-MS/MS method. The common targets and biological pathways between PSP and sarcopenia were investigated by network pharmacology analysis. In vitro C2C12 cells experiments were performed to reveal the effects of PSP on muscle aging, myotube differentiation, and mitochondrial damage. In addition, in vivo experiments were designed with the mouse model of D-gal-induced aging to evaluate the ameliorative impact of PSP on the skeletal muscle mass and function.

RESULTS

Polygonatum sibiricum mainly included 466 bioactive components. Polygonatum sibiricum and sarcopenia had 278 common targets by network pharmacology analysis, which were associated with mitochondrial function and PI3K/Akt/mTOR pathway. In vitro experiment indicated that PSP significantly enhanced the viability of C2C12 cells and myotube differentiation by down-regulating p21, p53, p16, MuRF1 and Atrogin-1and up-regulating MyoD, Myogenin, and MyHC. However, the addition of LY294002, PI3K/Akt/mTOR pathway inhibitor, partially reversed the anti-aging and anti-oxidative stress effects of PSP. PSP also significantly improved mitochondrial membrane potential and decreased mitochondrial ROS levels by upregulating the phosphorylation of the PI3K/Akt/mTOR pathway. In vivo experimental data indicated that PSP significantly enhanced muscle strength, endurance, mass of skeletal muscle (quadriceps and gastrocnemius) and cross-sectional area (CSA) of skeletal muscle in D-gal induced aging mice.

CONCLUSION

PSP exhibits significant ameliorative effects on skeletal muscle aging and atrophy, as well as mitochondrial dysfunction by activating the PI3K/Akt/mTOR signaling pathway. Our study uniquely investigates the effects of PSP on skeletal muscle aging and mitochondrial dysfunction with a specific focus on the PI3K/Akt/mTOR signaling pathway, which highlights the potential of PSP as a novel therapeutic agent for sarcopenia, offering an alternative to current treatment strategies.

Impact of Alpha-Ketoglutarate on Skeletal Muscle Health and Exercise Performance: A Narrative Review

AKG, a central metabolite in the Krebs cycle, plays a vital role in cellular energy production and nitrogen metabolism. This review explores AKG's potential therapeutic applications in skeletal muscle health and exercise performance, focusing on its mechanisms for promoting muscle regeneration and counteracting muscle atrophy. A literature search was conducted using the PubMed, Web of Science, and Scopus databases, yielding 945 articles published up to 31 October 2024. Of these, 112 peer-reviewed articles met the inclusion criteria and formed the basis of this review. AKG supports muscle recovery by stimulating muscle satellite cells (MuSCs) and macrophage polarization, aiding muscle repair and reducing fibrosis. Additionally, AKG shows promise in preventing muscle atrophy by enhancing protein synthesis, inhibiting degradation pathways, and modulating inflammatory responses, making it relevant in conditions like sarcopenia, cachexia, and injury recovery. For athletes and active individuals, AKG supplementation has enhanced endurance, reduced fatigue, and supported faster post-exercise recovery. Despite promising preliminary findings, research gaps remain in understanding AKG's long-term effects, optimal dosage, and specific pathways, particularly across diverse populations. Further research, including large-scale clinical trials, is essential to clarify AKG's role in muscle health and to optimize its application as a therapeutic agent for skeletal muscle diseases and an enhancer of physical performance. This review aims to provide a comprehensive overview of AKG's benefits and identify future directions for research in both clinical and sports settings.

A scoping review of preclinical intensive care unit-acquired weakness models

Background

Animal models focusing on neuromuscular outcomes are crucial for understanding the mechanisms of intensive care unit-acquired weakness (ICU-AW) and exploring potential innovative prevention and treatment strategies.

Aim

To analyse and evaluate preclinical ICU-AW models.

Methods

We manually searched five English and four Chinese databases from 1 January 2002, to 1 February 2024, and reviewed related study references. Full-text publications describing animal models of muscle weakness and atrophy in critical illness were included. Detailed information about model types, animal species, sex, age, induction methods, outcome measures, drawbacks and strengths was extracted from each included study.

Results

A total of 3,451 citations were initially retrieved, with 84 studies included in the final analysis. The most frequently studied animal model included rodents (86.9%), 64.3% of which were male animals. ICU-AW animal models were mostly induced by comprehensive intensive care unit (ICU) interventions (38.1%) and sepsis (51.2%). Most studies focused on limb muscles (66.7%), diaphragm muscles (21.4%) or both (9.5%). Reported outcomes primarily included muscular pathological changes (83.3%), electrophysiological examinations of muscles (57.1%) and animal grip strength (16.6%). However, details such as animal age, mortality data, experimental design, randomisation, blinding, sample size and interventions for the experimental group and/or control group were inadequately reported.

Conclusion

Many preclinical models are used to study ICU-AW, but the reporting of methodological details is often incomplete. Although current ICU animal models can mimic the characteristics of human ICU-AW, there is no standard model. Future preclinical studies should develop a standard ICU-AW animal model to enhance reproducibility and improve scientific rigor in exploring the mechanisms and potential treatment of ICU-AW.

GSDMD KNOCKOUT ALLEVIATES SEPSIS-ASSOCIATED SKELETAL MUSCLE ATROPHY BY INHIBITING IL18/AMPK SIGNALING

ABSTRACT

Background: Sepsis commonly leads to skeletal muscle atrophy, characterized by substantial muscle weakness and degeneration, ultimately contributing to an adverse prognosis. Studies have shown that programmed cell death is an important factor in the progression of muscle loss in sepsis. However, the precise role and mechanism of pyroptosis in skeletal muscle atrophy are not yet fully comprehended. Therefore, we aimed to examine the role and mechanism of action of the pyroptosis effector protein GSDMD in recognized cellular and mouse models of sepsis. Methods: The levels of GSDMD and N-GSDMD in skeletal muscle were evaluated 2, 4, and 8 days after cecal ligation and puncture. Sepsis was produced in mice that lacked the Gsdmd gene (Gsdmd knockout) and in mice with the normal Gsdmd gene (wild-type) using a procedure called cecal ligation and puncture. The degree of muscular atrophy in the gastrocnemius and tibialis anterior muscles was assessed 72 h after surgery in the septic mouse model. In addition, the architecture of skeletal muscles, protein expression, and markers associated with pathways leading to muscle atrophy were examined in mice from various groups 72 h after surgery. The in vitro investigations entailed the use of siRNA to suppress Gsdmd expression in C2C12 cells, followed by stimulation of these cells with lipopolysaccharide to evaluate the impact of Gsdmd downregulation on muscle atrophy and the related signaling cascades. Results: This study has demonstrated that the GSDMD protein, known as the "executive" protein of pyroptosis, plays a crucial role in the advancement of skeletal muscle atrophy in septic mice. The expression of N-GSDMD in the skeletal muscle of septic mice was markedly higher compared with the control group. The Gsdmd knockout mice exhibited notable enhancements in survival, muscle strength, and body weight compared with the septic mice. Deletion of the Gsdmd gene reduced muscular wasting in the gastrocnemius and tibialis anterior muscles caused by sepsis. Studies conducted in living organisms ( in vivo ) and in laboratory conditions ( in vitro ) have shown that the absence of the Gsdmd gene decreases indicators of muscle loss associated with sepsis by blocking the IL18/AMPK signaling pathway. Conclusion: The results of this study demonstrate that the lack of Gsdmd has a beneficial effect on septic skeletal muscle atrophy by reducing the activation of IL18/AMPK and inhibiting the ubiquitin-proteasome system and autophagy pathways. Therefore, our research provides vital insights into the role of pyroptosis in sepsis-related skeletal muscle wasting, which could potentially lead to the development of therapeutic and interventional approaches for preventing septic skeletal muscle atrophy.

NAT10-mediated ac4C acetylation of TFRC promotes sepsis-induced pulmonary injury through regulating ferroptosis

BACKGROUND

Sepsis-induced pulmonary injury (SPI) is a common complication of sepsis with a high rate of mortality. N4-acetylcytidine (ac4C) is mediated by the ac4C "writer", N-acetyltransferase (NAT)10, to regulate the stabilization of mRNA. This study aimed to investigate the role of NAT10 in SPI and the underlying mechanism.

METHODS

Twenty-three acute respiratory distress syndrome (ARDS) patients and 27 non-ARDS volunteers were recruited. A sepsis rat model was established. Reverse transcription-quantitative polymerase chain reaction was used to detect the expression of NAT10 and transferrin receptor (TFRC). Cell viability was detected by cell counting kit-8. The levels of Fe2+, glutathione, and malondialdehyde were assessed by commercial kits. Lipid reactive oxygen species production was measured by flow cytometric analysis. Western blot was used to detect ferroptosis-related protein levels. Haematoxylin & eosin staining was performed to observe the pulmonary pathological symptoms.

RESULTS

The results showed that NAT10 was increased in ARDS patients and lipopolysaccharide-treated human lung microvascular endothelial cell line-5a (HULEC-5a) cells. NAT10 inhibition increased cell viability and decreased ferroptosis in HULEC-5a cells. TFRC was a downstream regulatory target of NAT10-mediated ac4C acetylation. Overexpression of TFRC decreased cell viability and promoted ferroptosis. In in vivo study, NAT10 inhibition alleviated SPI.

CONCLUSION

NAT10-mediated ac4C acetylation of TFRC aggravated SPI through promoting ferroptosis.

Molecular mechanisms of Sepsis attacking the immune system and solid organs

Remarkable progress has been achieved in sepsis treatment in recent times, the mortality rate of sepsis has experienced a gradual decline as a result of the prompt administration of antibiotics, fluid resuscitation, and the implementation of various therapies aimed at supporting multiple organ functions. However, there is still significant mortality and room for improvement. The mortality rate for septic patients, 22.5%, is still unacceptably high, accounting for 19.7% of all global deaths. Therefore, it is crucial to thoroughly comprehend the pathogenesis of sepsis in order to enhance clinical diagnosis and treatment methods. Here, we summarized classic mechanisms of sepsis progression, activation of signal pathways, mitochondrial quality control, imbalance of pro-and anti- inflammation response, diseminated intravascular coagulation (DIC), cell death, presented the latest research findings for each mechanism and identify potential therapeutic targets within each mechanism.

The possible mechanisms of ferroptosis in sepsis-associated acquired weakness

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection, and its morbidity and mortality rates are increasing annually. It is an independent risk factor for intensive care unit-acquired weakness (ICU-AW), which is a common complication of patients in ICU. This situation is also known as sepsis-associated acquired weakness (SAW), and it can be a complication in more than 60% of patients with sepsis. The outcomes of SAW are often prolonged mechanical ventilation, extended hospital stays, and increased morbidity and mortality of patients in ICUs. The pathogenesis of SAW is unclear, and an effective clinical treatment is not available. Ferroptosis is an iron-dependent type of cell death with unique morphological, biochemical, and genetic features. Unlike other forms of cell death such as autophagy, apoptosis, and necrosis, ferroptosis is primarily driven by lipid peroxidation. Cells undergo ferroptosis during sepsis, which further enhances the inflammatory response. This process leads to increased cell death, as well as multi-organ dysfunction and failure. Recently, there have been sporadic reports suggesting that SAW is associated with ferroptosis, but the exact pathophysiological mechanisms remain unclear. Therefore, we reviewed the possible pathogenesis of ferroptosis that leads to SAW and offer new strategies to prevent and treat SAW.