MicroRNA suppression of stress-responsive NDRG2 during dexamethasone treatment in skeletal muscle cells

Circulating miR-28-5p is overexpressed in patients with sarcopenia despite long-term remission of Cushing's syndrome: a pilot study

Introduction

Patients with Cushing's syndrome (CS) in remission show sustained fatigue, myopathy, and an increased prevalence of sarcopenia. The mechanisms that determine these persistent muscle problems are not well known. We aimed to identify circulating microRNAs (miRNAs) with differential expression that could be potential biomarkers for the diagnosis and/or prognosis in CS.

Patients and methods

Thirty-six women in sustained remission for 13 ± 7 years (mean ± SD) from CS, with a median age (IQ range) of 51 (45.2-60) years and mean ± SD BMI of 27 ± 4 Kg/m2, and 36 matched healthy controls were investigated. In 7 patients sarcopenia was present according to the European Working Group on Sarcopenia in Older People (EWGSOP) criteria. Small RNA libraries were generated and indexed using a modified Illumina TruSeq small RNA-sequencing protocol. MiRNAs were identified in plasma using bioinformatic analysis, and validation was carried out using RT-qPCR. For the validation, Taqman probes were performed on QuantStudio 5 equipment (Applied Biosystems).

Results

In a first discovery group using RNA-sequencing, plasma samples of 18 CS patients and 18 healthy subjects were investigated; circulating miR-28-5p, miR-495-3p and miR-654-5p were upregulated in CS patients as compared with controls (p<0.05). In a validation study of the 3 upregulated miRNAs in 36 patients and 26 controls, no differences were observed by RT-qPCR; however, the expression of circulating miR-28-5p was upregulated in CS patients with sarcopenia as compared with those without (AUC for fold-change in the ROC analysis, 0.798; p=0.0156). The optimized cut-off value for miR-28-5p to identify CS patients with sarcopenia was 3.80, which yielded a sensitivity of 86% and a specificity of 69%.

Conclusion

MiR-28-5p, a muscle-specific microRNA involved in myotube proliferation and differentiation in vivo, may serve as an independent non-invasive biomarker for identifying CS patients at high-risk of sarcopenia despite biochemical remission.

MicroRNA-100 Reduced Fetal Bovine Muscle Satellite Cell Myogenesis and Augmented Intramuscular Lipid Deposition by Modulating IGF1R

Previously, microRNA-100 (miR-100) and its putative mRNA target, insulin-like growth factor receptor-1 (IGF1R) were identified as differentially and inversely expressed in bovine longissimus dorsi (LD) muscles with divergent intramuscular fat (IMF) content by our group. While IGF1R signaling is implicated in myogenesis and muscle lipid metabolism, the underlying regulatory mechanisms are poorly understood. In the present study, we aimed to investigate the regulation of IGF1R by miR-100 during bovine muscle satellite cell (BMSC) myogenesis and lipid deposition. MiR-100 was confirmed to target the IGF1R 3′-untranslated region (3′-UTR) by luciferase reporter assay. Furthermore, expression of miR-100 and IGF1R was reciprocal during BMSC differentiation, suggesting a crosstalk between the two. Correspondingly, miR-100 mimic (agomiR) suppressed the levels of IGF1R, PI3K/AKT pathway signaling, myogenic gene MYOG, muscle structural components MYH7 and MYH8, whereas the inhibitor (antagomiR) had no clear stimulating effects. The IGF1R inhibitor (BMS-754807) curtailed receptor levels and triggered atrophy in muscle myotubes but did not influence miR-100 expression. AgomiR increased oleic acid-induced lipid deposition in BMSC myotubes supporting its involvement in intramuscular fat deposition, while antagomiR had no effect. Moreover, mitochondrial beta-oxidation and long-chain fatty acid synthesis-related genes were modulated by agomiR addition. Our results demonstrate modulatory roles of miR-100 in BMSC development, lipid deposition, and metabolism and suggest a role of miR-100 in marbling characteristics of meat animals and fat oxidation in muscle.

Aerosol inhalation of edaravone can improve inflammation, oxidative stress and pulmonary function of rats with smoke inhalation injury by down-regulating miR-320

OBJECTIVE

To explore the protective effects and related mechanism of aerosol inhalation of edaravone on inflammation, oxidative stress and pulmonary function (PF) in rats with smoke inhalation injury.

METHODS

Twenty-four rats were stochastically and equally divided into four groups: group A (edaravone-preventing group), group B (model group), group C (low-dose group) and group D (high-dose group). The serum of rats was collected to determine the expression of miR-320, inflammatory mediators (TNF-α, IL-6, IL-10), oxidative stress indexes (MDA, SOD, MPO) and oxygenation index (OI). Pulmonary tissues of rats were collected to determine the total lung water (TLW), wet-to-dry ratio (W/D) and other parameters. HE staining was adopted for pathological evaluation.

RESULTS

Compared with group B, the levels of miR-320, TNF-α, IL-6, MDA, MPO, TLW and W/D in group A were significantly down-regulated, while IL-10, SOD and OI levels were significantly up-regulated, and the trend of this change was more obvious than that in group C and group D, with notably better improvement degree in group D than group C. In HE staining, the pulmonary tissue structure was basically normal in group A, and was better than that of the other three groups. In group B, the pulmonary tissue was seriously damaged, accompanied by a large number of inflammatory cells infiltration and alveolar wall thickening. The pathological condition of group C was notably ameliorated, the extent of this improvement was more pronounced in group D, and the degree of pathological improvement in group D was superior to that in group C.

CONCLUSION

Aerosol inhalation of edaravone in advance can reduce the levels of inflammatory factors and oxidative stress indexes in serum of smoke inhalation injury rats, thus protecting PF, which may be related to the down-regulation of miR-320 by edaravone.