Duchenne muscular dystrophy (DMD) is a serious genetic neuromuscular rare disease that is prevalent and caused by the mutation/deletion of the X-linked DMD gene that encodes dystrophin. Utrophin is a dystrophin homologous protein on human chromosome 6. Dystrophin and utrophin are highly homologous. They can recruit many dystrophin-glycoprotein complex (DGC)-related proteins and co-localize at the sarcolemma in the early stage of human embryonic development. Moreover, utrophin is overexpressed naturally at the mature myofiber sarcolemma in DMD patients. Therefore, utrophin is considered the most promising homologous protein to replace dystrophin. This review summarizes various modulating drugs and gene therapy approaches for utrophin replacement. As a universal method to treat DMD disease, utrophin has a promising therapeutic prospect and deserves further investigation.

Utrophin (UTRN), known as a tumor suppressor, potentially regulates tumor development and the immune microenvironment. However, its impact on breast cancer\'s development and treatment remains unstudied. We conducted a thorough examination of UTRN using both bioinformatic and in vitro experiments in this study. We discovered UTRN expression decreased in breast cancer compared to standard samples. High UTRN expression correlated with better prognosis. Drug sensitivity tests and RT-qPCR assays revealed UTRN\'s pivotal role in tamoxifen resistance. Furthermore, the Kruskal-Wallis rank test indicated UTRN\'s potential as a valuable diagnostic biomarker for breast cancer and its utility in detecting T stage of breast cancer. Additionally, our results demonstrated UTRN\'s close association with immune cells, inhibitors, stimulators, receptors, and chemokines in breast cancer (BRCA). This research provides a novel perspective on UTRN\'s role in breast cancer\'s prognostic and therapeutic value. Low UTRN expression may contribute to tamoxifen resistance and a poor prognosis. Specifically, UTRN can improve clinical decision-making and raise the diagnosis accuracy of breast cancer.

Regular exercise training benefits cardiovascular health and effectively reduces the risk for cardiovascular disease. Circular RNAs (circRNAs) play important roles in cardiac pathophysiology. However, the role of circRNAs in response to exercise training and biological mechanisms responsible for exercise-induced cardiac protection remain largely unknown.
RNA sequencing was used to profile circRNA expression in adult mouse cardiomyocytes that were isolated from mice with or without exercise training. Exercise-induced circRNA circUtrn was significantly increased in swimming-trained adult mouse cardiomyocytes. In vivo, circUtrn was found to be required for exercise-induced physiological cardiac hypertrophy. circUtrn inhibition abolished the protective effects of exercise on myocardial ischaemia-reperfusion remodelling. circUtrn overexpression prevented myocardial ischaemia-reperfusion-induced acute injury and pathological cardiac remodelling. In vitro, overexpression of circUtrn promoted H9 human embryonic stem cell-induced cardiomyocyte growth and survival via protein phosphatase 5 (PP5). Mechanistically, circUtrn directly bound to PP5 and regulated the stability of PP5 in a ubiquitin-proteasome-dependent manner. Hypoxia-inducible factor 1α-dependent splicing factor SF3B1 acted as an upstream regulator of circUtrn in cardiomyocytes.
The circRNA circUtrn is upregulated upon exercise training in the heart. Overexpression of circUtrn can prevent myocardial I/R-induced injury and pathological cardiac remodelling.

DRP1 and OPA1 play important roles in mitochondrial fusion and fission. However, the role of DRP1 and OPA1 amplification in mitochondrial cognitive impairment has not been reported. This study aimed to investigate the relationship between DRP1 and OPA1 and the risk of cognitive impairment.
In this study, 45 elderly patients with diabetes admitted to the Lianyungang Second People\'s Hospital from September 2020 to January 2021 were included. The patients were divided into normal group, mild cognitive impairment group and dementia group by using MMSE score, and the clinical characteristics of the three groups were compared. The amplification multiples of the two genes\' DNA were calculated by ΔΔCT and defined as 2- K. Spearman rank correlation was used to analyze the correlation between the DNA amplification multiples of patients\' DRP1 and OPA1 and AD8 and MoCA scores. The sensitivity and specificity of DNA amplification multiples of DRP1 and OPA1 to predict clinical outcomes of diabetic cognitive impairment were evaluated using Receiver operator characteristic (ROC) curves. Multiple logistic regression was used to evaluate the relationship between DNA amplification factor of DRP1 and OPA1 and cognitive function.
DRP1(2- K) and OPA1(2- K) significantly increased and decreased in dementia and MCI groups compared with the normal group (P ≤ 0.001). The DNA amplification factor of DRP1 was positively correlated with AD8 score and negatively correlated with MoCA score (P < 0.001). The DNA amplification factor of OPA1 was positively correlated with the MoCA score (P = 0.0002). Analysis of ROCs showed that the DNA amplification factor of OPA1 had a higher predictive value for dementia (P < 0.0001), and that it had a higher predictive value when used in combination with DRP1. Multiple logistic regression results showed that increased DNA amplification in DRP1 was associated with increased risk of dementia (OR 1.149;95%CI,1.035-1.275), and increased DNA amplification in OPA1 was associated with decreased risk of MCI (OR 0.004;95%CI,0.000-0.251) and dementia (OR 0.000;95%CI,0.000-0.134).
DNA amplification multiples of DRP1 and OPA1 are associated with the risk of dementia in elderly patients and may serve as potential biomarkers.

Gene therapy using the adeno-associated virus (rAAV) to deliver mini/micro- dystrophin is the current promising strategy for Duchenne Muscular Dystrophy (DMD). However, the further transformation of this strategy still faces many \"bottlenecks\". Most gene therapies are only suitable for infants with strong muscle cell regeneration and immature immune system, and the treatment depends heavily on the high dose of rAAV. However, high-dose rAAV inevitably causes side effects such as immune response and acute liver toxicity. Therefore, how to reduce the degree of fibrosis and excessive immune response in older patients and uncouple the dependence association between therapeutic effect and high dose rAAV are crucial steps for the transformation of rAAV-based gene therapy. The article analyzes the latest research and finds that the application of utrophin, the homologous protein of dystrophin, could avoid the immune response associated with dystrophin, and the exploration of methods to improve the expression level of mini/micro-utrophin in striated muscle, combined with the novel MyoAAV with high efficiency and specific infection of striated muscle, is expected to achieve the same therapeutic efficacy under the condition of reducing the dose of rAAV. Furthermore, the delivery of allogeneic cardio sphere-derived cells (CDCs) with anti-inflammatory and anti-fibrotic characteristics combined with immune suppression can provide a continuous and appropriate \"window period\" for gene therapy. This strategy can expand the number of patients who could benefit from gene therapy.

Duchenne muscular dystrophy (DMD) is a systemic progressive muscular disease caused by frame-disrupting mutations in the DMD gene. Although exon-skipping antisense oligonucleotides (AOs) are clinically approved and can correct DMD, insufficient muscle delivery limits efficacy. If AO activity can be enhanced by safe dietary supplements, clinical trials for efficacy can be undertaken rapidly to benefit patients. We showed previously that intravenous glycine enhanced phosphorodiamidate morpholino oligomer (PMO) delivery to peripheral muscles in mdx mice. Here, we demonstrate that the combination of oral glycine and metformin with intravenous PMO enhances PMO activity, dystrophin restoration, extends lifespan, and improves body-wide function and phenotypic rescue of dystrophin /utrophin double knock-out (DKO) mice without any overt adverse effects. The DKO mice treated with the combination without altering the approved administration protocol of PMO show improved cardio-respiratory and behavioral functions. Metformin and glycine individually are ineffective in DMD patients, but the combination of PMO with clinically-approved oral glycine and metformin might improve the efficacy of the treatment also in DMD patients. Our data suggest that this combination therapy might be an attractive therapy for DMD and potentially other muscle diseases requiring systemic treatment with AOs.

Duchenne Muscular Dystrophy (DMD) patients often suffer from both muscle wasting and osteoporosis. Our previous studies have revealed reduced regeneration potential in skeletal muscle and bone, concomitant with ectopic calcification of soft tissues in double knockout (dKO, dystrophin-/-; utrophin-/-) mice, a severe murine model for DMD. We found significant involvement of RhoA/ROCK (Rho-Associated Protein Kinase) signaling in mediating ectopic calcification of muscles in dKO mice. However, the cellular identity of these RhoA+ cells, and the role that RhoA plays in the chronic inflammation-associated pathologies has not been elucidated. Here, we report that CD68+ macrophages are highly prevalent at the sites of ectopic calcification of dKO mice, and that these macrophages highly express RhoA. Macrophages from dKO mice feature a shift towards a more pro-inflammatory M1 polarization and an increased expression of various senescence-associated secretory phenotype (SASP) factors that was reduced with the RhoA/ROCK inhibitor Y-27632. Further, systemic inhibition of RhoA activity in dKO mice led to reduced number of RhoA+/CD68+ cells, as well as a reduction in fibrosis and ectopic calcification. Together, these data revealed that RhoA signaling may be a key regulator of imbalanced mineralization in the dystrophic musculoskeletal system and consequently a therapeutic target for the treatment of DMD or other related muscle dystrophies.

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy seen in children. In addition to skeletal muscle, DMD also has a significant impact on bone. The pathogenesis of bone abnormalities in DMD is still unknown. Recently, we have identified a novel bone-regulating cytokine, fibroblast growth factor-21 (FGF-21), which is dramatically upregulated in skeletal muscles from DMD animal models. We hypothesize that muscle-derived FGF-21 negatively affects bone homeostasis in DMD. Dystrophin/utrophin double-knockout (dKO) mice were used in this study. We found that the levels of circulating FGF-21 were significantly higher in dKO mice than in age-matched WT controls. Further tests on FGF-21 expressing tissues revealed that both FGF-21 mRNA and protein expression were dramatically upregulated in dystrophic skeletal muscles, whereas FGF-21 mRNA expression was downregulated in liver and white adipose tissue (WAT) compared to WT controls. Neutralization of circulating FGF-21 by i.p. injection of anti-FGF-21 antibody significantly alleviated progressive bone loss in weight-bearing (vertebra, femur, and tibia) and non-weight bearing bones (parietal bones) in dKO mice. We also found that FGF-21 directly promoted RANKL-induced osteoclastogenesis from bone marrow macrophages (BMMs), as well as promoted adipogenesis while concomitantly inhibiting osteogenesis of bone marrow mesenchymal stem cells (BMMSCs). Furthermore, fibroblast growth factor receptors (FGFRs) and co-receptor β-klotho (KLB) were expressed in bone cells (BMM-derived osteoclasts and BMMSCs) and bone tissues. KLB knockdown by small interfering RNAs (siRNAs) significantly inhibited the effects of FGF21 on osteoclast formation of BMMs and on adipogenic differentiation of BMMSCs, indicating that FGF-21 may directly affect dystrophic bone via the FGFRs-β-klotho complex. In conclusion, this study shows that dystrophic skeletal muscles express and secrete significant levels of FGF-21, which negatively regulates bone homeostasis and represents an important pathological factor for the development of bone abnormalities in DMD. The current study highlights the importance of muscle/bone cross-talk via muscle-derived factors (myokines) in the pathogenesis of bone abnormalities in DMD. © 2019 American Society for Bone and Mineral Research.

In the present study, we were to screen the specific microRNA (miRNA) of exercise-induced muscle damage (EIMD) and assess the EIMD-specific miRNAs-regulated target of sarcolemmal damage in rats. Twenty-four male Sprague-Dawley (SD) rats were randomly divided into 3 groups, which included sedentary (C), 24 h post-exercise (E24) and 48 h post-exercise (E48) groups. Rat EIMD model was established by an acute eccentric exercise, i.e., a downhill running treatment at -16º gradient. EIMD characteristics were verified by Evans blue dye staining, differentially expressed miRNAs were detected by microarray assay, EIMD-specific miRNAs expressions were further validated by real-time quantitative RT-PCR (RT-qPCR), and targets of the miRNAs were predicted based on mRNA expressions of associated proteins and related pathway core molecules of sarcolemmal damage. Two EIMD-specific expressed miRNAs, including miR-206-3p and miR-139-3p, were found in the study. There was a significantly negative correlation (P < 0.05) between miR-206-3p expression and dystrophin (r = -0.68), utrophin (r = -0.64), JNK (r = -0.62) or ERK1 (r = -0.68) respectively, but no correlation was found between miR-139-3p and these biomolecules. The results suggest that: i) the expression profile of miRNAs in rat is significantly affected by EIMD, ii) miR-206-3p and miR-139-3p are the EIMD-specific miRNAs, and iii) miR-206-3p may control sarcolemmal damage by regulating dystrophin, utrophin, JNK and ERK1.

Glucocorticoid treatment represents a standard palliative treatment for Duchenne muscular dystrophy (DMD) patients, but various adverse effects have limited this treatment. In an effort to understand the mechanism(s) by which glucocorticoids impart their effects on the dystrophic muscle, and potentially reduce the adverse effects, we have studied the effect of prednisolone treatment in dystrophin/utrophin double knockout (dKO) mice, which exhibit a severe dystrophic phenotype due to rapid muscle stem cell depletion. Our results indicate that muscle stem cell depletion in dKO muscle is related to upregulation of mTOR, and that prednisolone treatment reduces the expression of mTOR and other pro-inflammatory mediators, consequently slowing down muscle stem cell depletion. However, prednisolone treatment was unable to improve the myogenesis of stem cells and reduce fibrosis in dKO muscle. We then studied whether glucocorticoid treatment can be improved by co-administration of an inhibitor of RhoA/ROCK signaling, which can be activated by glucocorticoids and was found in our previous work to be over-activated in dystrophic muscle. Our results indicate that the combination of RhoA/ROCK inhibition and glucocorticoid treatment in dystrophic muscle have a synergistic effect in alleviating the dystrophic phenotype. Taken together, our study not only shed light on the mechanism by which glucocorticoid imparts its beneficial effect on dystrophic muscle, but also revealed the synergistic effect of RhoA/ROCK inhibition and glucocorticoid treatment, which could lead to the development of more efficient therapeutic approaches for treating DMD patients.