Intestinal epithelial dopamine receptor signaling drives sex-specific disease exacerbation in a mouse model of multiple sclerosis.

Although the gut microbiota can influence central nervous system (CNS) autoimmune diseases, the contribution of the intestinal epithelium to CNS autoimmunity is less clear. Here, we showed that intestinal epithelial dopamine D2 receptors (IEC DRD2) promoted sex-specific disease progression in an animal model of multiple sclerosis. Female mice lacking Drd2 selectively in intestinal epithelial cells showed a blunted inflammatory response in the CNS and reduced disease progression. In contrast, overexpression or activation of IEC DRD2 by phenylethylamine administration exacerbated disease severity. This was accompanied by altered lysozyme expression and gut microbiota composition, including reduced abundance of Lactobacillus species. Furthermore, treatment with N2-acetyl-L-lysine, a metabolite derived from Lactobacillus, suppressed microglial activation and neurodegeneration. Taken together, our study indicates that IEC DRD2 hyperactivity impacts gut microbial abundances and increases susceptibility to CNS autoimmune diseases in a female-biased manner, opening up future avenues for sex-specific interventions of CNS autoimmune diseases.

Gut microbial fatty acid isomerization modulates intraepithelial T cells.

The human gut microbiome constantly converts natural products derived from the host and diet into numerous bioactive metabolites1-3. Dietary fats are essential micronutrients that undergo lipolysis to release free fatty acids (FAs) for absorption in the small intestine4. Gut commensal bacteria modify some unsaturated FAs-for example, linoleic acid (LA)-into various intestinal FA isomers that regulate host metabolism and have anticarcinogenic properties5. However, little is known about how this diet-microorganism FA isomerization network affects the mucosal immune system of the host. Here we report that both dietary factors and microbial factors influence the level of gut LA isomers (conjugated LAs (CLAs)) and that CLAs in turn modulate a distinct population of CD4+ intraepithelial lymphocytes (IELs) that express CD8αα in the small intestine. Genetic abolition of FA isomerization pathways in individual gut symbionts significantly decreases the number of CD4+CD8αα+ IELs in gnotobiotic mice. Restoration of CLAs increases CD4+CD8αα+ IEL levels in the presence of the transcription factor hepatocyte nuclear factor 4γ (HNF4γ). Mechanistically, HNF4γ facilitates CD4+CD8αα+ IEL development by modulating interleukin-18 signalling. In mice, specific deletion of HNF4γ in T cells leads to early mortality from infection by intestinal pathogens. Our data reveal a new role for bacterial FA metabolic pathways in the control of host intraepithelial immunological homeostasis by modulating the relative number of CD4+ T cells that were CD4+CD8αα+.

Development and application of an efficient genomic mating method to maximize the production performances of three-way crossbred pigs.

Creating synthetic lines is the standard mating mode for commercial pig production. Traditional mating performance was evaluated through a strictly designed cross-combination test at the 'breed level' to maximize the benefits of production. The Duroc-Landrace-Yorkshire (DLY) three-way crossbred production system became the most widely used breeding scheme for pigs. Here, we proposed an 'individual level' genomic mating procedure that can be applied to commercial pig production with efficient algorithms for estimating marker effects and for allocating the appropriate boar-sow pairs, which can be freely accessed to public in our developed HIBLUP software at https://www.hiblup.com/tutorials#genomic-mating. A total of 875 Duroc boars, 350 Landrace-Yorkshire sows and 3573 DLY pigs were used to carry out the genomic mating to assess the production benefits theoretically. The results showed that genomic mating significantly improved the performances of progeny across different traits compared with random mating, such as the feed conversion rate, days from 30 to 120 kg and eye muscle area could be improved by -0.12, -4.64 d and 2.65 cm2, respectively, which were consistent with the real experimental validations. Overall, our findings indicated that genomic mating is an effective strategy to improve the performances of progeny by maximizing their total genetic merit with consideration of both additive and dominant effects. Also, a herd of boars from a richer genetic source will increase the effectiveness of genomic mating further.

HIBLUP: an integration of statistical models on the BLUP framework for efficient genetic evaluation using big genomic data.

Human diseases and agricultural traits can be predicted by modeling a genetic random polygenic effect in linear mixed models. To estimate variance components and predict random effects of the model efficiently with limited computational resources has always been of primary concern, especially when it involves increasing the genotype data scale in the current genomic era. Here, we thoroughly reviewed the development history of statistical algorithms used in genetic evaluation and theoretically compared their computational complexity and applicability for different data scenarios. Most importantly, we presented a computationally efficient, functionally enriched, multi-platform and user-friendly software package named 'HIBLUP' to address the challenges that are faced currently using big genomic data. Powered by advanced algorithms, elaborate design and efficient programming, HIBLUP computed fastest while using the lowest memory in analyses, and the greater the number of individuals that are genotyped, the greater the computational benefits from HIBLUP. We also demonstrated that HIBLUP is the only tool which can accomplish the analyses for a UK Biobank-scale dataset within 1 h using the proposed efficient 'HE + PCG' strategy. It is foreseeable that HIBLUP will facilitate genetic research for human, plants and animals. The HIBLUP software and user manual can be accessed freely at https://www.hiblup.com.

Both human diseases and agricultural traits can be predicted by incorporating phenotypic observations and a relationship matrix among individuals in a linear mixed model. Due to the great demand for processing massive data of genotyped individuals, the existing algorithms that require several repetitions of inverse computing on increasingly big dense matrices (e.g. the relationship matrix and the coefficient matrix of mixed model equations) have encountered a bottleneck. Here, we presented a software tool named 'HIBLUP' to address the challenges. Powered by our advanced algorithms (e.g. HE + PCG), elaborate design and efficient programming, HIBLUP can successfully avoid the inverse computing for any big matrix and compute fastest under the lowest memory, which makes it very promising for genetic evaluation using big genomic data.

IAnimal: a cross-species omics knowledgebase for animals.

With the exponential growth of multi-omics data, its integration and utilization have brought unprecedented opportunities for the interpretation of gene regulation mechanisms and the comprehensive analyses of biological systems. IAnimal (https://ianimal.pro/), a cross-species, multi-omics knowledgebase, was developed to improve the utilization of massive public data and simplify the integration of multi-omics information to mine the genetic mechanisms of objective traits. Currently, IAnimal provides 61 191 individual omics data of genome (WGS), transcriptome (RNA-Seq), epigenome (ChIP-Seq, ATAC-Seq) and genome annotation information for 21 species, such as mice, pigs, cattle, chickens, and macaques. The scale of its total clean data has reached 846.46 TB. To better understand the biological significance of omics information, a deep learning model for IAnimal was built based on BioBERT and AutoNER to mine 'gene' and 'trait' entities from 2 794 237 abstracts, which has practical significance for comprehending how each omics layer regulates genes to affect traits. By means of user-friendly web interfaces, flexible data application programming interfaces, and abundant functional modules, IAnimal enables users to easily query, mine, and visualize characteristics in various omics, and to infer how genes play biological roles under the influence of various omics layers.

Adipocyte-derived exosomal miR-22-3p modulated by circadian rhythm disruption regulates insulin sensitivity in skeletal muscle cells.

Circadian rhythm disruption leads to dysregulation of lipid metabolism, which further drive the occurrence of insulin resistance (IR). Exosomes are natural carrier systems that advantageous for cell communication. In the present study, we aimed to explore whether and how the exosomal microRNAs (miRNAs) in circulation participate in modulating skeletal muscle IR induced by circadian rhythm disruption. In the present study, 24-h constant light (12-h light/12-h light, LL) was used to establish the mouse model of circadian rhythm disruption. Bmal1 interference was used to establish the cell model of circadian rhythm disruption. And in clinical experiments, we chose a relatively large group of rhythm disturbance-shift nurses. We showed that LL-induced circadian rhythm disruption led to increased body weight and visceral fat volume, as well as occurrence of IR in vivo. Furthermore, exosomal miR-22-3p derived from adipocytes in the context of circadian rhythm disruption induced by Bmal1 interference could be uptaken by skeletal muscle cells to promote IR occurrence in vitro. Moreover, miR-22-3p in circulation was positively correlated with the clinical IR-associated factors. Collectively, these data showed that exosomal miR-22-3p in circulation may act as potential biomarker and therapeutic target for skeletal muscle IR, contributing to the prevention of diabetes in the context of rhythm disturbance.

Integrated metabolomic and transcriptomic analysis reveals biosynthesis mechanism of flavone and caffeoylquinic acid in chrysanthemum.

BACKGROUND: Chrysanthemum morifolium 'HangBaiJu', a popular medicinal and edible plant, exerts its biological activities primarily through the presence of flavones and caffeoylquinic acids (CQAs). However, the regulatory mechanism of flavone and CQA biosynthesis in the chrysanthemum capitulum remains unclear. RESULTS: In this study, the content of flavones and CQAs during the development of chrysanthemum capitulum was determined by HPLC, revealing an accumulation pattern with higher levels at S1 and S2 and a gradual decrease at S3 to S5. Transcriptomic analysis revealed that CmPAL1/2, CmCHS1/2, CmFNS, CmHQT, and CmHCT were key structural genes in flavones and CQAs biosynthesis. Furthermore, weighted gene co-expression correlation network analysis (WGCNA), k-means clustering, correlation analysis and protein interaction prediction were carried out in this study to identify transcription factors (TFs) associated with flavone and CQA biosynthesis, including MYB, bHLH, AP2/ERF, and MADS-box families. The TFs CmERF/PTI6 and CmCMD77 were proposed to act as upstream regulators of CmMYB3 and CmbHLH143, while CmMYB3 and CmbHLH143 might form a complex to directly regulate the structural genes CmPAL1/2, CmCHS1/2, CmFNS, CmHQT, and CmHCT, thereby controlling flavone and CQA biosynthesis. CONCLUSIONS: Overall, these findings provide initial insights into the TF regulatory network underlying flavones and CQAs accumulation in the chrysanthemum capitulum, which laid a theoretical foundation for the quality improvement of C. morifolium 'HangBaiJu' and the high-quality development of the industry.

Hypothalamic POMC neuron-specific knockout of MC4R affects insulin sensitivity by regulating Kir2.1.

BACKGROUND: Imbalance in energy regulation is a major cause of insulin resistance and diabetes. Melanocortin-4 receptor (MC4R) signaling at specific sites in the central nervous system has synergistic but non-overlapping functions. However, the mechanism by which MC4R in the arcuate nucleus (ARC) region regulates energy balance and insulin resistance remains unclear. METHODS: The MC4Rflox/flox mice with proopiomelanocortin (POMC) -Cre mice were crossed to generate the POMC-MC4Rflox/+ mice. Then POMC-MC4Rflox/+ mice were further mated with MC4Rflox/flox mice to generate the POMC-MC4Rflox/flox mice in which MC4R is selectively deleted in POMC neurons. Bilateral injections of 200 nl of AAV-sh-Kir2.1 (AAV-sh-NC was used as control) were made into the ARC of the hypothalamus. Oxygen consumption, carbon dioxide production, respiratory exchange ratio and energy expenditure were measured by using the CLAMS; Total, visceral and subcutaneous fat was analyzed using micro-CT. Co-immunoprecipitation assays (Co-IP) were used to analyze the interaction between MC4R and Kir2.1 in GT1-7 cells. RESULTS: POMC neuron-specific ablation of MC4R in the ARC region promoted food intake, impaired energy expenditure, leading to increased weight gain and impaired systemic glucose homeostasis. Additionally, MC4R ablation reduced the activation of POMC neuron, and is not tissue-specific for peripheral regulation, suggesting the importance of its central regulation. Mechanistically, sequencing analysis and Co-IP assay demonstrated a direct interaction of MC4R with Kir2.1. Knockdown of Kir2.1 in POMC neuron-specific ablation of MC4R restored the effect of MC4R ablation on energy expenditure and systemic glucose homeostasis, indicating by reduced body weight and ameliorated insulin resistance. CONCLUSION: Hypothalamic POMC neuron-specific knockout of MC4R affects energy balance and insulin sensitivity by regulating Kir2.1. Kir2.1 represents a new target and pathway that could be targeted in obesity.

Water Adsorption on Kaolinite Basal and Edge Surfaces.

The sequence of water adsorption is significant to understand the mechanism of clay-water interactions on clay mineral surfaces. Kaolinite is a typical non-expansive phyllosilicate clay, and its water adsorption is generally recognized to occur on the basal surfaces of aluminum-silicate particles, whereas edge surface adsorption is prevalently overlooked due to its complexity despite its potential large surface area available for adsorption. In this study, we used molecular dynamics and metadynamics simulation to quantitatively assess the free energy of water adsorption, viz., matric potential, on kaolinite for four types of external surfaces, namely, a basal silicon-oxygen (Si-O) surface, a basal aluminum-oxygen (Al-O) surface, and edge surfaces with deprotonation and protonation. The results show that edge surfaces exhibit adsorption sites that are more active with the lowest matric potential of -1.86 GPa, lower than that of basal surfaces (-0.92 GPa), due to protonation and deprotonation processes of the dangling oxygen. The adsorption isotherm from 0.2% of relative humidity (RH) was measured and analyzed using an augmented Brunauer-Emmet-Teller model to separate the edge and basal surface adsorption, further verifying that edge surface adsorption may prevail in kaolinite and occur earlier than base surface adsorption in RH less than 5%.

Synthesis of Nanostructured Bismuth Sulfide with Controllable Morphology for Advanced Lithium/Sodium-Ion Storage.

Rational design of electrode materials with an excellent structure and morphology is crucial for improving electrochemical properties. Herein, various unique nanostructured Bi2S3 materials with controllable morphology were obtained through a simple and efficient oil bath reaction strategy. Bi2S3 with different morphologies can be obtained by regulating the polarity of solvent, and the lattice spacing can also be adjusted. The Bi2S3 nanomaterials obtained with ethanol as solvent (BS-3) show a three-dimensional nanoflower-like structure assembled with porous layers. The unique structure facilitates the transport of ions and accommodates the volume variation of Bi2S3 during energy storage. Consequently, BS-3 nanoflowers exhibited superior cycling stability and excellent high-rate capability for lithium storage (maintained a high capacity of 923.8 mA h g-1 after 950 cycles at 1.0 A g-1) and excellent sodium storage. We provide guidance for precise synthesis and energy storage application of Bi2S3 nanomaterials.

Exosome-like nanovesicles derived from Phellinus linteus inhibit Mical2 expression through cross-kingdom regulation and inhibit ultraviolet-induced skin aging.

BACKGROUND: Phellinus linteus (PL), which is a typical medicinal fungus, has been shown to have antitumor and anti-inflammatory activities. However, studies on the effect of anti-photoaging are limited. Studies have shown that exosome-like nanovesicles are functional components of many medicinal plants, and miRNAs in exosome-like nanovesicles play a cross-kingdom regulatory role. At present, research on fungi exosome-like nanovesicles (FELNVs) is few. RESULTS: We systematically evaluated the anti-aging effects of PL. FELNVs of PL were isolated, and the functional molecular mechanisms were evaluated. The results of volunteer testing showed that PL had anti-aging activity. The results of component analysis showed that FELNVs were the important components of PL function. FELNVs are nanoparticles (100-260 nm) with a double shell structure. Molecular mechanism research results showed that miR-CM1 in FELNVs could inhibit Mical2 expression in HaCaT cells through cross-kingdom regulation, thereby promoting COL1A2 expression; inhibiting MMP1 expression in skin cells; decreasing the levels of ROS, MDA, and SA-ß-Gal; and increasing SOD activity induced by ultraviolet (UV) rays. The above results indicated that miR-CM1 derived from PL inhibited the expression of Mical2 through cross-kingdom regulation and inhibited UV-induced skin aging. CONCLUSION: miR-CM1 plays an anti-aging role by inhibiting the expression of Mical2 in human skin cells through cross-species regulation.

[Clinical and genetic analysis of a child with disorder of sex development].

OBJECTIVE: To report on the diagnosis and treatment process and clinical characteristics of a child with disorder of sex development (DSD) and to conduct pathological, imaging and genetic analysis for the patient. METHODS: Clinical data of the patient were collected. Genetic testing including chromosomal karyotyping, fluorescence in situ hybridization (FISH), copy number variations (CNVs) analysis, SRY gene detection and multiple ligation-dependent probe amplification (MLPA) were carried out. RESULTS: The patient had a social gender of male, with a history of hypospadia and breast development. Sex hormone tests showed slightly raised prolactin. Imaging results showed bilateral breast hyperplasia, abnormal seminal vesicle glands, rudimentary uterus, and underdeveloped right testis. Intraoperative examination revealed that the child had an ovary on the left and a testis on the right. The pathological results showed fibroadenomatoid changes in the breast. The patient had a karyotype of 46,XX. FISH results showed 46,XX.ish(DXZ1x2, SRYx0). Molecular testing showed that NR0B1, PHEX, CXORF21, GJB1, PQBP1, and COL4A5 genes are duplicated. There was a presence of SRY gene and absence of UYT gene. CONCLUSION: DSD should be considered in patients with genital abnormality and male breast development. Ultrasound, sex hormone test and genetic testing should be performed to confirm the diagnosis of DSD, and molecular testing should be performed if necessary. Individualized treatment of DSD patient requires cooperation of multiple clinical disciplines.

RNA m6A methylation promotes the formation of vasculogenic mimicry in hepatocellular carcinoma via Hippo pathway.

Vasculogenic mimicry (VM) formed by aggressive tumor cells to mimic vasculogenic networks plays an important role in the tumor malignancy of HCC. However, the pathogenesis underlying VM is complex and has not been fully defined. m6A is a common mRNA modification and has many biological effects. However, the relationship between m6A and VM remains unclear. In this research, we found that m6A methyltransferase METTL3 in HCC tissues was positively correlated with VM. The m6A level of mRNA significantly increased in 3D cultured cells treated with VEGFa and was related to VM formation. Transcriptome sequencing analysis of 3D cultured cells with knockdown Mettl3 showed that the Hippo pathway was involved in m6A-mediated VM formation. Further mechanism research indicated that the m6A modification of YAP1 mRNA affected the translation of YAP1 mRNA. In conclusion, m6A methylation plays a key role in VM formation in HCC. METTL3 and YAP1 could be potential therapeutic targets via impairing VM formation in anti-metastatic strategies.

Long noncoding RNA Hotair facilitates retinal endothelial cell dysfunction in diabetic retinopathy.

BACKGROUND: Retinal endothelial cell (REC) dysfunction induced by diabetes mellitus (DM) is an important pathological step of diabetic retinopathy (DR). Long noncoding RNAs (lncRNAs) have emerged as novel modulators in DR. The present study aimed to investigate the role and mechanism of lncRNA Hotair in regulating DM-induced REC dysfunction. METHODS: The retinal vascular preparations and immunohistochemical staining assays were conducted to assess the role of Hotair in retinal vessel impairment in vivo. The EdU, transwell, cell permeability, CHIP, luciferase activity, RIP, RNA pull-down, and Co-IP assays were employed to investigate the underlying mechanism of Hotair-mediated REC dysfunction in vitro. RESULTS: Hotair expression was significantly increased in diabetic retinas and high glucose (HG)-stimulated REC. Hotair knockdown inhibited the proliferation, invasion, migration, and permeability of HG-stimulated REC in vitro and reduced the retinal acellular capillaries and vascular leakage in vivo. Mechanistically, Hotair bound to LSD1 to inhibit VE-cadherin transcription by reducing the H3K4me3 level on its promoter and to facilitate transcription factor HIF1α-mediated transcriptional activation of VEGFA. Furthermore, LSD1 mediated the effects of Hotair on REC function under HG condition. CONCLUSION: The Hotair exerts its role in DR by binding to LSD1, decreasing VE-cadherin transcription, and increasing VEGFA transcription, leading to REC dysfunction. These findings revealed that Hotair is a potential therapeutic target of DR.

Biosynthesis of selenium nanoparticles and their protective, antioxidative effects in streptozotocin induced diabetic rats.

Green synthesis of selenium nanoparticles (Se NPs) was performed by mixing Hibiscus sabdariffa (roselle plant) leaf extract with the solution of selenious acid (H2SeO3) under continuous stirring conditions resulting the roselle plant secondary metabolites conjugated Se NPs. The existence of functional groups of roselle plant secondary metabolites on the surface of prepared Se NPs was confirmed by Fourier transform infrared spectroscopy (FTIR). The formation of crystalline nanoparticles with anisotropic shape was confirmed by transmission electron microscopy (TEM) images. Furthermore, we also studied anti-oxidative and protective effects of Se NPs in streptozotocin (STZ) induced diabetes rats. These STZ induced diabetic rats were daily exposed to Se NPs or/and insulin treatment and the effect of Se NPs on the factors correlated to oxidative damage in the rat testes were evaluated. The biochemical studies showed that the Se NPs are capable to enhance the serum testosterone reduction caused due to STZ induced diabetes. In addition, Se NPs can significantly reduce the oxidative stress indicators of the testicular tissue such as nitric oxide and lipid peroxidation. However, the treatment of Se NPs on the STZ induced diabetic rats increased the activities of antioxidant enzyme as well as the glutathione content in testicular tissues. Furthermore, microscopic studies revealed that the Se NPs are capable of preventing the histological damage in the testes of STZ induced diabetic rats. Altogether, these results explained the possible effects of Se NPs in attenuating oxidative damage induced by diabetes, especially in the testicular tissue.

[Gene variant analysis of a child presented with neonatal diabetes and multiple organ malformations].

OBJECTIVE: To explore the genetic basis for an infant with neonatal diabetes (NDM) and multiple malformations. METHODS: Genetic variants were detected by next generation sequencing (NGS). Suspected variant was verified by Sanger sequencing. RESULTS: A de novo heterozygous variant, c.1454_1455del(p.K485Rfs), was detected in exon 5 of the GATA6 gene. The variant was undetected in his parents and unreported previously. Bioinformatic analysis predicted the variant to be pathogenic. CONCLUSION: The heterozygous variant of c.1454_1455del(p.K485Rfs) of the GATA6 gene probably underlies the disease in this child. Genetic testing can facilitate diagnosis and genetic counseling for NDM.

Fluoxetine ameliorates dysbiosis in a depression model induced by chronic unpredicted mild stress in mice.

Background: Accumulating evidence has shown that neuropsychiatric disorders are associated with gut microbiota through the gut-brain axis. However, the effects of antidepressant treatment on gut microbiota are rarely studied. Here, we investigated whether stress led to gut microbiota changes and whether fluoxetine plays a role in microbiota alteration. Methods: We investigated changes in gut microbiota in a depression model induced by chronic unpredicted mild stress (CUMS) and a restoration model by applying the classic antidepressant drug fluoxetine. Results: We found that stress led to low bacterial diversity, simpler bacterial network, and increased abundance of pathogens, such as Escherichia/Shigella, and conditional pathogens, such as Enterococcus, Vagococcus, and Aerococcus. However, these changes were attenuated by fluoxetine directly and indirectly. Furthermore, the correlation analysis indicated strong correlations between gut microbiota and anxiety- and depression-like behaviors. Conclusions: This study revealed that fluoxetine led to restoration of dysbiosis induced by stress stimulation, which may imply a possible pathway through which one CNS target drug plays its role in reshaping the gut microbiota.

Bcl-3 promotes proliferation and chemosensitivity in BL1 subtype of TNBC cells.

Bcl-3 is an established oncogene in diverse malignant tumors. In this study, we investigated a dual role of Bcl-3 in BL1-subtype triple-negative breast cancer (TNBC). The BL1-subtype TNBC is featured by increasing cell cycle gene expression and the highest sensitivity to chemotherapy among all subtypes. Bcl-3 is associated with a better prognosis in BL1 patients. Bcl-3 knockdown in BL1 cell MDA-MB-468 induces the inhibition of cell proliferation and the G1/S transition arrest by promoting p27 and reducing the expressions of c-Myc and skp2 at mRNA and protein levels. Meanwhile, Bcl-3 enhances the sensitivity of MDA-MB-468 to chemotherapeutics ABX and PTX. Furthermore, the regulation mechanisms are restricted to BL1 cell and do not occur in SUM159PT, a typical MSL subtype of TNBC cell. These data suggest that Bcl-3 may be a potential clinical biomarker for diagnosis, treatment, and prognosis of patients with BL1-subtype TNBC.

Melanocortin 4 Receptor Activation Attenuates Mitochondrial Dysfunction in Skeletal Muscle of Diabetic Rats.

A previous study has confirmed that the central melanocortin system was able to mediate skeletal muscle AMP-activated protein kinase (AMPK) activation in mice fed a high-fat diet, while activation of the AMPK signaling pathway significantly induced mitochondrial biogenesis. Our hypothesis was that melanocortin 4 receptor (MC4R) was involved in the development of skeletal muscle injury in diabetic rats. In this study, we treated diabetic rats intracerebroventricularly with MC4R agonist R027-3225 or antagonist SHU9119, respectively. Then, we measured the production of reactive oxygen species (ROS), the levels of malondialdehyde (MDA) and glutathione (GSH), the mitochondrial DNA (mtDNA) content and mitochondrial biogenesis, and the protein levels of p-AMPK, AMPK, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α), sirtuin 1 (SIRT1), and manganese superoxide dismutase (MnSOD) in the skeletal muscle of diabetic rats. The results showed that there was significant skeletal muscle injury in the diabetic rats along with serious oxidative stress and decreased mitochondrial biogenesis. Treatment with R027-3225 reduced oxidative stress and induced mitochondrial biogenesis in skeletal muscle, and also activated the AMPK-SIRT1-PGC-1α signaling pathway. However, diabetic rats injected with MC4R antagonist SHU9119 showed an aggravated oxidative stress and mitochondrial dysfunction in skeletal muscle. In conclusion, our results revealed that MC4R activation was able to attenuate oxidative stress and mitochondrial dysfunction in skeletal muscle induced by diabetes partially through activating the AMPK-SIRT1-PGC-1α signaling pathway. J. Cell. Biochem. 118: 4072-4079, 2017. © 2017 Wiley Periodicals, Inc.