miR‑760 regulates skeletal muscle proliferation in rheumatoid arthritis by targeting Myo18b

Astragalus polysaccharide promotes osteogenic differentiation of human bone marrow derived mesenchymal stem cells by facilitating ANKFY1 expression through miR-760 inhibition

Aims

Astragalus polysaccharide (APS) participates in various processes, such as the enhancement of immunity and inhibition of tumours. APS can affect osteoporosis (OP) by regulating the osteogenic differentiation of human bone mesenchymal stem cells (hBMSCs). This study was designed to elucidate the mechanism of APS in hBMSC proliferation and osteoblast differentiation.

Methods

Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting were performed to determine the expression of microRNA (miR)-760 and ankyrin repeat and FYVE domain containing 1 (ANKFY1) in OP tissues and hBMSCs. Cell viability was measured using the Cell Counting Kit-8 assay. The expression of cyclin D1 and osteogenic marker genes (osteocalcin (OCN), alkaline phosphatase (ALP), and runt-related transcription factor 2 (RUNX2)) was evaluated using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Mineral deposits were detected through Alizarin Red S staining. In addition, Western blotting was performed to detect the ANKFY1 protein levels following the regulation of miR-760. The relationship between miR-760 and ANKFY1 was determined using a luciferase reporter assay.

Results

The expression of miR-760 was upregulated in OP tissues, whereas ANKFY1 expression was downregulated. APS stimulated the differentiation and proliferation of hBMSCs by: increasing their viability; upregulating the expression levels of cyclin D1, ALP, OCN, and RUNX2; and inducing osteoblast mineralization. Moreover, APS downregulated the expression of miR-760. Overexpression of miR-760 was found to inhibit the promotive effect of APS on hBMSC differentiation and proliferation, while knockdown of miR-760 had the opposite effect. ANKFY1 was found to be the direct target of miR-760. Additionally, ANKFY1 participated in the APS-mediated regulation of miR-760 function in hBMSCs.

Conclusion

APS promotes the osteogenic differentiation and proliferation of hBMSCs. Moreover, APS alleviates the effects of OP by downregulating miR-760 and upregulating ANKFY1 expression.

MiR-760 targets HBEGF to control cartilage extracellular matrix degradation in osteoarthritis

The present study was developed to explore whether microRNA (miR)-760 targets heparin-binding EGF-like growth factor (HBEGF) to control cartilage extracellular matrix degradation in osteoarthritis. Both miR-760 and HBEGF expression levels were analysed in human degenerative cartilage tissues and in interleukin (IL)-1β/tumour necrosis factor (TNF)-α-treated chondrocytes in vitro. A series of knockdown and overexpression assays were then used to gauge the functional importance of miR-760 and HBEGF in OA, with qPCR and western immunoblotting analyses. Bioinformatics assays were used to identify putative miR-760 target genes, with these predictions then being validated through RNA pulldown and luciferase reporter assays. A murine anterior cruciate ligament transection model of OA was then established to prove the in vivo relevance of these findings. These experiments revealed that human degenerative cartilage tissues exhibited significant increases in miR-760 expression with a concomitant drop in HBEGF levels. IL-1β/TNF-α-treated chondrocytes also exhibited significant increases in miR-760 expression with a concomitant drop in HBEGF expression. When chondrocytes were transfected with either miR-760 inhibitor or HBEGF overexpression constructs, this was sufficient to interfere with degradation of the extracellular matrix (ECM). Moreover, miR-760 was confirmed to control chondrocyte matrix homeostasis by targeting HBEGF, and the overexpression of HBEGF partially reversed the effects of miR-760 mimic treatment on the degradation of the cartilage ECM. When OA model mice were administered an intra-articular knee injection of an adenoviral vector encoding a miR-760 mimic construct, cartilage ECM degradation was aggravated. Conversely, the overexpression of HBEGF in OA model mice partially reversed the effects of miR-760 overexpression, restoring appropriate ECM homeostasis. In summary, these data indicated that the miR-760/HBEGF axis plays a central role in orchestrating the pathogenesis of OA, making it a candidate target for therapeutic efforts in OA.

Effect of Er Miao San on peritoneal macrophage polarisation through the miRNA-33/NLRP3 signalling pathway in a rat model of adjuvant arthritis

CONTEXT

Er Miao San (EMS) is a formulation that contains Atractylodis Rhizoma and Phellodendri Cortex in 1:1 ratio, and is commonly used to treat rheumatoid arthritis (RA) and other inflammatory diseases.

OBJECTIVE

We investigated the mechanism of action and effects of EMS on peritoneal macrophage differentiation in a rat model of adjuvant arthritis (AA).

MATERIALS AND METHODS

EMS (3, 1.5 and 0.75 g/kg; once daily) and methotrexate (0.5 mg/kg; once every 3 days) were administered orally from days 21 to 35 after immunisation. Paw swelling and arthritis index were measured; pathological changes in the ankle joint were observed using x-ray and haematoxylin eosin staining. The ratio of CD86/CD206 in macrophages was detected by flow cytometry. Examination of the miRNA-33/NLRP3 signalling pathway was examined by RT-qPCR and western blotting. The levels of cytokines in the serum and cell supernatants were tested by ELISA.

RESULTS

EMS significantly reduced the AA index in rats (from 11.0 to 9.3) and pathological changes in the ankle joint (from 3.8 to 1.4). The ratio of CD86/CD206 was reduced, and polarisation to M1 improved (from 0.9 to 0.6) in macrophages of EMS-treated rats. EMS downregulated the miRNA-33/NLRP3 pathway. Furthermore, EMS treatment increased IL-10 and TGF-β levels in the serum and supernatant of macrophages of AA rats and simultaneously decreased the levels of IL-1β and TNF-α.

DISCUSSION AND CONCLUSIONS

Our results suggest that EMS may reduce macrophage polarisation to the M1 inflammatory phenotype by downregulating the miRNA-33/NLRP3 pathway in AA rats. These findings may provide new insights into the treatment of RA.

Genome-Wide Identification of RNA Editing Sites Affecting Muscle Development in Yak

Skeletal muscle growth and development is a complicated process that is regulated at multiple steps and by numerous myogenesis genes. RNA editing represents one of the events at the post-transcriptional level, which contributes to the diversity of transcriptome and proteome by altering the nucleotides of RNAs. However, RNA editing events in the skeletal muscle of yaks are still not well defined. This study conducted whole-genome RNA-editing identification in skeletal muscle of yaks at embryonic stage (ES) and adult stage (AS). We found a total of 11,168 unique RNA editing sites, most of which were detected in the intergenic region. After annotation, we totally identified 2,718 editing sites within coding regions, among which 858 were missense changes. Moreover, totally 322 editing sites in the 3′ untranslated regions (UTR) were also predicted to alter the set of miRNA target sites, indicating that RNA editing may be involved in translational repression or mRNA degradation. We found 838 RNA editing sites (involving 244 common genes) that are edited differentially in ES as compared to AS. According to the KEGG enrichment analysis, these differentially edited genes were mainly involved in pathways highly related to skeletal muscle development and myogenesis, including MAPK, AMPK, Wnt, and PI3K-Akt signaling pathways. Altogether, our work presents the first characterization of RNA editing sites within yak skeletal muscles on a genome-wide scale and enhances our understanding of the mechanism of skeletal muscle development and myogenesis.

Frailty in Aging and the Search for the Optimal Biomarker: A Review

In the context of accelerated aging of the population worldwide, frailty has emerged as one of the main risk factors that can lead to loss of self-sufficiency in older people. This syndrome is defined as a reduced state of physiological reserve and functional capacity. The main diagnostic tools for frailty are based on scales that show deficits compared to their clinical application, such as the Fried frailty phenotype, among others. In this context, it is important to have one or more biomarkers with clinical applicability that can objectively and precisely determine the degree or risk of frailty in older people. The objective of this review was to analyze the biomarkers associated with frailty, classified according to the pathophysiological components of this syndrome (inflammation, coagulation, antioxidants, and liver function, among others). The evidence demonstrates that biomarkers associated with inflammation, oxidative stress, skeletal/cardiac muscle function, and platelet function represent the most promising markers of frailty due to their pathophysiological association with this syndrome. To a lesser extent but with the possibility of greater innovation, biomarkers associated with growth factors, vitamins, amino acids, and miRNAs represent alternatives as markers of this geriatric syndrome. Likewise, the incorporation of artificial intelligence represents an interesting approach to strengthening the diagnosis of frailty by biomarkers.

miR760 regulates ATXN1 levels via interaction with its 5' untranslated region

Identifying modifiers of dosage-sensitive genes involved in neurodegenerative disorders is imperative to discover novel genetic risk factors and potential therapeutic entry points. In this study, we focus on Ataxin-1 (ATXN1), a dosage-sensitive gene involved in the neurodegenerative disease spinocerebellar ataxia type 1 (SCA1). While the precise maintenance of ATXN1 levels is essential to prevent disease, the mechanisms that regulate ATXN1 expression remain largely unknown. We demonstrate that ATXN1's unusually long 5' untranslated region (5' UTR) negatively regulates its expression via posttranscriptional mechanisms. Based on recent reports that microRNAs (miRNAs) can interact with both 3' and 5' UTRs to regulate their target genes, we identify miR760 as a negative regulator that binds to a conserved site in ATXN1's 5' UTR to induce RNA degradation and translational inhibition. We found that delivery of Adeno-associated virus (AAV)-expressing miR760 in the cerebellum reduces ATXN1 levels in vivo and mitigates motor coordination deficits in a mouse model of SCA1. These findings provide new insights into the regulation of ATXN1 levels, present additional evidence for miRNA-mediated gene regulation via 5' UTR binding, and raise the possibility that noncoding mutations in the ATXN1 locus may act as risk factors for yet to be discovered progressive ataxias.

Regulation of MYO18B mRNA by a network of C19MC miRNA-520G, IFN-γ, CEBPB, p53 and bFGF in hepatocellular carcinoma

MYO18B has been proposed to contribute to the progression of hepatocellular carcinoma (HCC). However, the signals that govern MYO18B transcription are not known. Here we show that, a network of C19MC miRNA-520G, IFN-γ, CEBPB and p53 transcriptional-defects promote MYO18B mRNA expression in HCCs. IFN-γ by itself suppresses MYO18B transcription, but promotes it when miRNA-520G is stably overexpressed. Similarly, CEBPB-liver-enriched activator protein (LAP) isoform overexpression suppresses MYO18B transcription but promotes transcription when the cells are treated with IFN-γ. Furthermore, miR-520G together with mutant-p53 promotes MYO18B transcription. Conversely, bFGF suppresses MYO18B mRNA irrespective of CEBPB, miR-520G overexpression or IFN-γ treatment. Finally high MYO18B expression reflects poor prognosis while high MYL5 or MYO1B expression reflects better survival of HCC patients. Thus, we identified a network of positive and negative regulators of MYO18B mRNA expression which reflects the survival of HCC patients.