Muscle atrophy induced by overexpression of ALAS2 is related to muscle mitochondrial dysfunction

Dehydroandrographolide succinate attenuates dexamethasone-induced skeletal muscle atrophy by regulating Akt/GSK3β and MuRF-1 pathways

Andrographis paniculata (AGPA) is known for its wide-ranging biological activities, including antiviral, antipyretic, and anticancer properties. However, its effects on muscle atrophy have not been well understood. This study investigates the impact of andrographolide (AD) and dehydroandrographolide succinate (DAS), key components of AGPA, on skeletal muscle atrophy using in vitro and in vivo models. We employed dexamethasone (DEX)-treated mice and C2C12 myotubes as models of skeletal muscle atrophy. While DAS and AD did not reverse the DEX-induced reduction in body weight, both compounds significantly restored grip strength in DEX-treated mice. Notably, DAS treatment, but not AD, markedly improved running speed, endurance time, and distance. Both DAS and AD enhanced lean muscle mass in the whole body, tibialis anterior (TA), and gastrocnemius (GS) muscles, as well as increased TA thickness, with DAS demonstrating superior efficacy compared to AD. In C2C12 myotubes treated with DEX, DAS and AD increased ATP production and myotube diameter. Mechanistically, both compounds upregulated phosphorylation of Akt and GSK3β and downregulated MuRF-1 expression. These results indicate that DAS and AD mitigate muscle atrophy via the Akt/GSK3β and MuRF-1 pathways, with DAS showing greater anti-atrophy efficiency. Thus, DAS emerges as a promising therapeutic candidate for the prevention of skeletal muscle atrophy.

Astragaloside IV Improves Muscle Atrophy by Modulating the Activity of UPS and ALP via Suppressing Oxidative Stress and Inflammation in Denervated Mice

Peripheral nerve injury is common clinically and can lead to neuronal degeneration and atrophy and fibrosis of the target muscle. The molecular mechanisms of muscle atrophy induced by denervation are complex and not fully understood. Inflammation and oxidative stress play an important triggering role in denervated muscle atrophy. Astragaloside IV (ASIV), a monomeric compound purified from astragalus membranaceus, has antioxidant and anti-inflammatory properties. The aim of this study was to investigate the effect of ASIV on denervated muscle atrophy and its molecular mechanism, so as to provide a new potential therapeutic target for the prevention and treatment of denervated muscle atrophy. In this study, an ICR mouse model of muscle atrophy was generated through sciatic nerve dissection. We found that ASIV significantly inhibited the reduction of tibialis anterior muscle mass and muscle fiber cross-sectional area in denervated mice, reducing ROS and oxidative stress-related protein levels. Furthermore, ASIV inhibits the increase in inflammation-associated proteins and infiltration of inflammatory cells, protecting the denervated microvessels in skeletal muscle. We also found that ASIV reduced the expression levels of MAFbx, MuRF1 and FoxO3a, while decreasing the expression levels of autophagy-related proteins, it inhibited the activation of ubiquitin-proteasome and autophagy-lysosome hydrolysis systems and the slow-to-fast myofiber shift. Our results show that ASIV inhibits oxidative stress and inflammatory responses in skeletal muscle due to denervation, inhibits mitophagy and proteolysis, improves microvascular circulation and reverses the transition of muscle fiber types; Therefore, the process of skeletal muscle atrophy caused by denervation can be effectively delayed.

ALAS2 overexpression alleviates oxidative stress-induced ferroptosis in aortic aneurysms via GATA1 activation

Background

Aortic aneurysm, characterized by abnormal dilation of the aorta, poses significant health risks. This study aims to investigate the interaction between 5-aminolevulinate synthase 2 (ALAS2) and GATA-binding protein 1 (GATA1) in ferroptosis and oxidative stress responses in aortic aneurysm.

Methods

A weighted gene co-expression network analysis (WGCNA) was performed on the differentially expressed genes (DEGs) within the GSE9106 dataset to identify the key module. Subsequently, protein-protein interaction (PPI) network analysis was performed on the key module. Mouse aortic vascular smooth muscle cells (MOVAS) were treated with hydrogen peroxide (H2O2) to induce oxidative stress, and ferroptosis inducers and inhibitors were added to evaluate their effects on iron content and oxidative stress markers. Through a series of in vitro cellular experiments, we assessed cell viability, expression levels of GATA1 and iron mutation-associated proteins, as well as cellular phenotypes such as inflammatory responses and apoptosis rates.

Results

Three candidate genes (ALAS2, GYPA, and GYPB) were upregulated in the thoracic aortic aneurysm (TAA) samples of the GSE9106 dataset. The H2O2 treatment increased the MOVAS cells' iron content and oxidative stress, upregulated ALAS2 protein levels, and decreased the ferroptosis-related protein levels. ALAS2 overexpression reversed H2O2-induced apoptosis and increased the inflammatory cytokine levels. Additionally, the knockdown of GATA1 partially reversed the protective mechanism of overexpressed ALAS2 on H2O2-induced ferroptosis.

Conclusions

ALAS2 overexpression reduced H2O2-induced oxidative damage and iron-induced apoptosis in MOVAS cells, and GATA1 knockdown partially reversed this protective effect. These findings suggested that the ALAS2 and GATA1 regulatory pathways may be potential therapeutic targets in aortic aneurysms.

Use of Transcriptome Sequencing to Analyze the Effects of Different Doses of an Astragalus-Rhubarb-Saffron Mixture in Mice with Diabetic Kidney Disease

Purpose

To investigate the therapeutic effect and underlying mechanism of a traditional Chinese medicine (TCM) mixture consisting of Astragalus, rhubarb, and saffron in a mouse model of diabetic kidney disease (DKD).

Methods

Forty-eight db/db mice received no TCM (DKD model), low-dose TCM, medium-dose TCM, or high-dose TCM, and an additional 12 db/m mice received no TCM (normal control). Intragastric TCM or saline (controls) was administered daily for 24 weeks. Blood glucose, body weight, serum creatinine (SCr), blood urea nitrogen (BUN), blood lipids, and urinary microalbumin were measured every four weeks, and the urinary albumin excretion rate (UAER) was calculated. After 24 weeks, kidney tissues were collected for transcriptome sequencing, and the main functions of these genes were determined via functional enrichment analysis.

Results

Compared with the DKD model group, the medium-dose and high-dose TCM groups had significantly decreased levels of SCr, BUN, total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and UAER (all p<0.05). We identified 42 genes that potentially functioned in this therapeutic response, and the greatest effect on gene expression was in the high-dose TCM group. We also performed functional enrichment analysis to explore the potential mechanisms of action of these different genes.

Conclusion

A high-dose of the Astragalus-rhubarb-saffron TCM provided the best prevention of DKD. Analysis of the kidney transcriptome suggested that this TCM mixture may prevent DKD by altering immune responses and oxygen delivery by hemoglobin.

MCC950 Ameliorates Diabetic Muscle Atrophy in Mice by Inhibition of Pyroptosis and Its Synergistic Effect with Aerobic Exercise

Diabetic muscle atrophy is an inflammation-related complication of type-2 diabetes mellitus (T2DM). Even though regular exercise prevents further deterioration of atrophic status, there is no effective mediator available for treatment and the underlying cellular mechanisms are less explored. In this study, we investigated the therapeutic potential of MCC950, a specific, small-molecule inhibitor of NLRP3, to treat pyroptosis and diabetic muscle atrophy in mice. Furthermore, we used MCC950 to intervene in the protective effects of aerobic exercise against muscle atrophy in diabetic mice. Blood and gastrocnemius muscle (GAS) samples were collected after 12 weeks of intervention and the atrophic state was assessed. We initially corroborated a diabetic muscle atrophy phenotype in db/db mice (D) by comparison with control m/m mice (W) by examining parameters such as fasting blood glucose (D vs. W: 24.47 ± 0.45 mmol L-1 vs. 4.26 ± 0.6 mmol L-1, p < 0.05), grip strength (D vs. W: 166.87 ± 15.19 g vs. 191.76 ± 14.13 g, p < 0.05), exercise time (D vs. W: 1082.38 ± 104.67 s vs. 1716 ± 168.55 s, p < 0.05) and exercise speed to exhaustion (D vs. W: 24.25 ± 2.12 m min-1 vs. 34.75 ± 2.66 m min-1, p < 0.05), GAS wet weight (D vs. W: 0.07 ± 0.01 g vs. 0.13 ± 0.01 g, p < 0.05), the ratio of GAS wet weight to body weight (D vs. W: 0.18 ± 0.01% vs. 0.54 ± 0.02%, p < 0.05), and muscle fiber cross-sectional area (FCSA) (D vs. W: 1875 ± 368.19 µm2 vs. 2747.83 ± 406.44 µm2, p < 0.05). We found that both MCC950 (10 mg kg-1) treatment and exercise improved the atrophic parameters that had deteriorated in the db/db mice, inhibited serum inflammatory markers and significantly attenuated pyroptosis in atrophic GAS. In addition, a combined MCC950 treatment with exercise (DEI) exhibited a further improvement in glucose uptake capacity and muscle performance. This combined treatment also improved the FCSA of GAS muscle indicated by Laminin immunofluorescence compared to the group with the inhibitor treatment alone (DI) (DEI vs. DI: 2597 ± 310.97 vs. 1974.67 ± 326.15 µm2, p < 0.05) or exercise only (DE) (DEI vs. DE: 2597 ± 310.97 vs. 2006.33 ± 263.468 µm2, p < 0.05). Intriguingly, the combination of MCC950 treatment and exercise significantly reduced NLRP3-mediated inflammatory factors such as cleaved-Caspase-1, GSDMD-N and prevented apoptosis and pyroptosis in atrophic GAS. These findings for the first time demonstrate that targeting NLRP3-mediated pyroptosis with MCC950 improves diabetic muscle homeostasis and muscle function. We also report that inhibiting pyroptosis by MCC950 can enhance the beneficial effects of aerobic exercise on diabetic muscle atrophy. Since T2DM and muscle atrophy are age-related diseases, the young mice used in the current study do not seem to fully reflect the characteristics of diabetic muscle atrophy. Considering the fragile nature of db/db mice and for the complete implementation of the exercise intervention, we used relatively young db/db mice and the atrophic state in the mice was thoroughly confirmed. Taken together, the current study comprehensively investigated the therapeutic effect of NLRP3-mediated pyroptosis inhibited by MCC950 on diabetic muscle mass, strength and exercise performance, as well as the synergistic effects of MCC950 and exercise intervention, therefore providing a novel strategy for the treatment of the disease.

Differences in Leukocyte Transcriptomes of Morbidly Obese Patients With High Output Heart Failure: A Pilot Study

Background and Objectives

Heart failure is characterized by alterations of gene expression that provide insight into the underlying pathophysiologic mechanisms. However, obesity-related high output heart failure (HOHF) is a specific phenotype of heart failure that has not been studied using gene expression. Our aim in this study was to examine the variances in leukocyte transcriptomes of morbidly obese patients with HOHF.

Methods

In this cross-sectional study, we applied stranded total RNA-sequencing to six patients with morbid obesity and HOHF and 6 patients with morbid obesity and non-HOHF. Differential gene expression was calculated, and Ingenuity Pathway Analysis software was used to interpret the canonical pathways, functional changes, upstream regulators, and networks in these patients.

Results

We found in patients with HOHF that there were 116 differentially expressed genes with upregulation of 114 genes and downregulation of 2 genes. The differentially expressed genes were involved with cell proliferation, mitochondrial function, erythropoiesis, erythrocyte stability, and apoptosis. The top upregulated canonical pathways associated with differentially expressed genes were autophagy, adenosine monophosphate-activated protein kinase signaling, and senescence pathways. We identified GATA binding protein 1 as an upstream regulator and nuclear factor kappa-light-chain-enhancer of activated B cells associated network.

Conclusions

We are the first to report the differential gene expression in patients with obesity-related HOHF and reveal the various pathophysiologic mechanisms underlying the disease. Further research is needed to determine the role of cellular function and maintenance, inflammation, and iron homeostasis in obesity-related HOHF.

Microarray analysis of hub genes, non-coding RNAs and pathways in lung after whole body irradiation in a mouse model

PURPOSE

Previous research has highlighted the impact of radiation damage, with cancer patients developing acute disorders including radiation induced pneumonitis or chronic disorders including pulmonary fibrosis months after radiation therapy ends. We sought to discover biomarkers that predict these injuries and develop treatments that mitigate this damage and improve quality of life.

MATERIALS AND METHODS

Six- to eight-week-old female C57BL/6 mice received 1, 2, 4, 8, 12 Gy or sham whole body irradiation. Animals were euthanized 48 h post exposure and lungs removed, snap frozen and underwent RNA isolation. Microarray analysis was performed to determine dysregulation of messenger RNA (mRNA), microRNA (miRNA), and long non-coding RNA (lncRNA) after radiation injury.

RESULTS

We observed sustained dysregulation of specific RNA markers including: mRNAs, lncRNAs, and miRNAs across all doses. We also identified significantly upregulated genes that can indicate high dose exposure, including Cpt1c, Pdk4, Gdf15, and Eda2r, which are markers of senescence and fibrosis. Only three miRNAs were significantly dysregulated across all radiation doses: miRNA-142-3p and miRNA-142-5p were downregulated and miRNA-34a-5p was upregulated. IPA analysis predicted inhibition of several molecular pathways with increasing doses of radiation, including: T cell development, Quantity of leukocytes, Quantity of lymphocytes, and Cell viability.

CONCLUSIONS

These RNA biomarkers might be highly relevant in the development of treatments and in predicting normal tissue injury in patients undergoing radiation treatment. We are conducting further experiments in our laboratory, which includes a human lung-on-a-chip model, to develop a decision tree model using RNA biomarkers.

Protective effects of electroacupuncture on polycystic ovary syndrome in rats: Down-regulating Alas2 to inhibit apoptosis, oxidative stress, and mitochondrial dysfunction in ovarian granulosa cells

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder affecting women at reproductive age. The therapeutic effect of electroacupuncture (EA) on PCOS has been revealed, while the anti-PCOS mechanisms of EA have not been fully explored. In this study, PCOS were induced in rats by daily injection with dehydroepiandrosterone (DHEA) for 20 days and EA treatment was performed for 5 weeks. The mRNA expression profiles in ovarian tissues from control, PCOS, and EA-treated rats were examined by high-throughput mRNA sequencing. 5'-aminolevulinate synthase 2 (Alas2), a vital rate-limiting enzyme of the heme synthesis pathway, was selected to be further studied. PCOS led to the upregulation of Alas2 mRNA, whereas EA treatment restored this change. In vitro, primary ovarian granulosa cells (GCs) were challenged with H₂O₂ to mimic the oxidative stress (OS) state in PCOS. H₂O₂ induced apoptosis, OS, mitochondrial dysfunction, as well as Alas2 overexpression in GCs, while lentivirus-mediated Alas2 knockdown evidently restrained the above impairments. In summary, this study highlights the crucial role of Alas2 in cell apoptosis, OS, and mitochondrial dysfunction of PCOS GCs and provides potential therapeutic candidates for further investigation on PCOS treatment.

microRNA-181a Promotes Mitochondrial Dysfunction and Inflammatory Reaction in a Rat Model of Intensive Care Unit-Acquired Weakness by Inhibiting IGFBP5 Expression

This study investigated mechanisms by which microRNA (miR)-181a orchestrates mitochondrial dysfunction and inflammation in a rat model of intensive care unit-acquired weakness (ICU-AW). Expression of miR-181a and insulin-like growth factor binding protein 5 (IGFBP5) was detected and then miR-181a was overexpressed or inhibited and IGFBP5 was overexpressed in the ICU-AW rats. The expression of UCP-3, metaphase chromosome protein 1 (MCP1), mitochondrial DNA (mtDNA), inflammatory factors, phosphorylation (p)-JAK1, p-STAT1, and p-STAT2 were measured in skeletal muscle tissues; binding of miR-181a to IGFBP5 was evaluated by a dual-luciferase reporter assay. The results demonstrated high expression of miR-181a and low expression of IGFBP5 in ICU-AW versus control rats; IGFBP5 was identified as a target gene of miR-181a. Further experiments demonstrated that ICU-AW rats suffered from marked loss of grip strength and decreased adenosine triphosphate production, mtDNA content, and UCP-3 mRNA expression in skeletal muscles; this was accompanied by elevated TNF-α, IL-6, IL-1β, MCP1, p-JAK1, p-STAT1, and p-STAT2 levels. Importantly, miR-181a suppression alleviated strength loss, inflammatory reaction, and mitochondrial dysfunction and diminished the phosphorylation levels of JAK1, STAT1, and STAT2 whereas IGFBP5 upregulation rescued the effect of miR-181a overexpression in ICU-AW rats. These results indicate that miR-181a promotes mitochondrial dysfunction and inflammation by activating the JAK/STAT pathway via IGFBP5 in ICU-AW model rats.

Iron supplementation is sufficient to rescue skeletal muscle mass and function in cancer cachexia

Cachexia is a wasting syndrome characterized by devastating skeletal muscle atrophy that dramatically increases mortality in various diseases, most notably in cancer patients with a penetrance of up to 80%. Knowledge regarding the mechanism of cancer-induced cachexia remains very scarce, making cachexia an unmet medical need. In this study, we discovered strong alterations of iron metabolism in the skeletal muscle of both cancer patients and tumor-bearing mice, characterized by decreased iron availability in mitochondria. We found that modulation of iron levels directly influences myotube size in vitro and muscle mass in otherwise healthy mice. Furthermore, iron supplementation was sufficient to preserve both muscle function and mass, prolong survival in tumor-bearing mice, and even rescues strength in human subjects within an unexpectedly short time frame. Importantly, iron supplementation refuels mitochondrial oxidative metabolism and energy production. Overall, our findings provide new mechanistic insights in cancer-induced skeletal muscle wasting, and support targeting iron metabolism as a potential therapeutic option for muscle wasting diseases.

Acute Hepatic Porphyria: Pathophysiological Basis of Neuromuscular Manifestations

Acute hepatic porphyria represents a rare, underdiagnosed group of inherited metabolic disorders due to hereditary defects of heme group biosynthesis pathway. Most patients have their definite diagnosis after several years of complex and disabling clinical manifestations and commonly after life-threatening acute neurovisceral episodes or severe motor handicap. Many key studies in the last two decades have been performed and led to the discovery of novel possible diagnostic and prognostic biomarkers and to the development of new therapeutic purposes, including small interfering RNA-based therapy, specifically driven to inhibit selectively delta-aminolevulinic acid synthase production and decrease the recurrence number of severe acute presentation for most patients. Several distinct mechanisms have been identified to contribute to the several neuromuscular signs and symptoms. This review article aims to present the current knowledge regarding the main pathophysiological mechanisms involved with the acute and chronic presentation of acute hepatic porphyria and to highlight the relevance of such content for clinical practice and in decision making about therapeutic options.