Bioinformatics analysis in menopause transition promotes distinct modulation in calvaria and bone marrow osteoblastic cells

We read with great interest the recent report by Semeghini et al. (2017), Cell Biol Int, “Menopause transition promotes distinct modulation of mRNAs and miRNAs expression in calvaria and bone marrow osteoblastic cells,” which appeared on 24 May 2017 in Cell Biology International. The results of the report are very helpful for us; however, from our perspective, the author's method in bioinformatics analysis is inappropriate: Student's t‐test is an inappropriate statistical method for detecting differentially expressed mRNA or miRNA in osteoblastic cells from calvaria of ovariectomized rats compared to control or in osteoblastic cells from bone marrow of ovariectomized rats compared to control.     

MicroRNA‐31a‐5p from aging BMSCs links bone formation and resorption in the aged bone marrow microenvironment

The alteration of age‐related molecules in the bone marrow microenvironment is one of the driving forces in osteoporosis. These molecules inhibit bone formation and promote bone resorption by regulating osteoblastic and osteoclastic activity, contributing to age‐related bone loss. Here, we observed that the level of microRNA‐31a‐5p (miR‐31a‐5p) was significantly increased in bone marrow stromal cells (BMSCs) from aged rats, and these BMSCs demonstrated increased adipogenesis and aging phenotypes as well as decreased osteogenesis and stemness. We used the gain‐of‐function and knockdown approach to delineate the roles of miR‐31a‐5p in osteogenic differentiation by assessing the decrease of special AT‐rich sequence‐binding protein 2 (SATB2) levels and the aging of BMSCs by regulating the decline of E2F2 and recruiting senescence‐associated heterochromatin foci (SAHF). Notably, expression of miR‐31a‐5p, which promotes osteoclastogenesis and bone resorption, was markedly higher in BMSCs‐derived exosomes from aged rats compared to those from young rats, and suppression of exosomal miR‐31a‐5p inhibited the differentiation and function of osteoclasts, as shown by elevated RhoA activity. Moreover, using antagomiR‐31a‐5p, we observed that, in the bone marrow microenvironment, inhibition of miR‐31a‐5p prevented bone loss and decreased the osteoclastic activity of aged rats. Collectively, our results reveal that miR‐31a‐5p acts as a key modulator in the age‐related bone marrow microenvironment by influencing osteoblastic and osteoclastic differentiation and that it may be a potential therapeutic target for age‐related osteoporosis.     

In vitro proliferation and differentiation potential of bone marrow-derived mesenchymal stem cells from ovariectomized rats

Bone marrow-derived mesenchymal stem cells (BMMSCs) from the patients suffering from age-related osteoporosis were found to have numerous degeneration, such as decreased growth rate, impaired capacity of differentiating into local tissue, and repressed telomerase activity. However, it is not clear whether post-menopausal osteoporotic bone is either subject to such decline in cellular function. In the present study, bone marrow cells were harvested from ovariectomized (OVX) and Sham rats and cultured in vitro at 3 months post-surgery. MTT assay indicated that the proliferation potential of ^OVXBMMSCs was always higher than that of ^ShamBMMSCs, no matter cultured in basic, osteoblastic or adipogenic medium. Alkaline phosphatase activity assay, Alizarin red S staining, Oil red O staining and real-time RT-PCR analysis further demonstrated that bilateral ovariectomization positively influenced the osteoblastic and adipogenic differentiation potential of BMMSCs, this action may be partly mediated through up-regulation of osteoblastic special markers core binding factor a1, collagen type I and low-density lipoprotein receptor-related protein 5, as well as adipogenic special markers peroxisome proliferators activated receptor gamma, CCAAT/enhancer binding protein alpha and adipocyte lipid-binding protein 2. These results may hold great promise for using post-menopausal osteoporotic bone as an attractive autologous marrow source for tissue engineering and cell-based therapies.     

Serum miRNAs are potential biomarkers for the detection of disc degeneration,among which miR‐26a‐5p suppresses Smad1 to regulate disc homeostasis

Disc degeneration is a common clinical condition in which damaged discs cause chronic pain; however, a laboratory diagnosis method for its detection is not available. As circulating miRNAs have potential as biomarkers, their application in disc degeneration has not been explored. Here, we prepared serum miRNAs from a mouse disc degeneration model and performed miRNA‐Seq and quantitative PCR to characterize disc degeneration–associated miRNAs. We identified three miRNAs, including miR‐26a‐5p, miR‐122‐5p and miR‐215‐5p, undergoing perturbation during the pathogenesis of disc degeneration. Specifically, the levels of miR‐26a‐5p in the serum demonstrated steady increases in the model of disc degeneration, compared with those in the pre‐injury samples of younger age or compared with normal controls of the same age but without disc degeneration, whereas the miRNAs miR‐122‐5p and miR‐215‐5p exhibited lower expression in post‐injury samples than in their counterparts without the surgery. Moreover, we found that miR‐26a‐5p targets Smad1 expression, and Smad1 negatively regulates Vegfa expression in disc cells, and thus, miR‐26a‐5p promotes disc degeneration. In summary, we established a method that consistently profiles circulating miRNAs and identified multiple miRNAs as promising biomarkers for disc degeneration, among which miR‐26a‐5p enhances VEGF expression during disc degeneration through targeting Smad1 signalling.     

SLIT2/ROBO1‐miR‐218‐1‐RET/PLAG1: a new disease pathway involved in Hirschsprung's disease

Hirschsprung's disease (HSCR) is a rare congenital disease caused by impaired proliferation and migration of neural crest cells. We investigated changes in expression of microRNAs (miRNAs) and the genes they regulate in tissues of patients with HSCR. Quantitative real‐time PCR and immunoblot analyses were used to measure levels of miRNA, mRNAs, and proteins in colon tissues from 69 patients with HSCR and 49 individuals without HSCR (controls). Direct interactions between miRNAs and specific mRNAs were indentified in vitro, while the function role of miR‐218‐1 was investigated by using miR‐218 transgenic mice. An increased level of miR‐218‐1 correlated with increased levels of SLIT2 and decreased levels of RET and PLAG1 mRNA and protein. The reductions in RET and PLAG1 by miR‐218‐1 reduced proliferation and migration of SH‐SY5Y cells. Overexpression of the secreted form of SLIT2 inhibited cell migration via binding to its receptor ROBO1. Bowel tissues from miR‐218‐1 transgenic mice had nerve fibre hyperplasia and reduced numbers of gangliocytes, compared with wild‐type mice. Altered miR‐218‐1 regulation of SLIT2, RET and PLAG1 might be involved in the pathogenesis of HSCR.     

Hormone replacement therapy enhances IGF‐1 signaling in skeletal muscle by diminishing miR‐182 and miR‐223 expressions: a study on postmenopausal monozygotic twin pairs

MiRNAs are fine‐tuning modifiers of skeletal muscle regulation, but knowledge of their hormonal control is lacking. We used a co‐twin case–control study design, that is, monozygotic postmenopausal twin pairs discordant for estrogen‐based hormone replacement therapy (HRT) to explore estrogen‐dependent skeletal muscle regulation via miRNAs. MiRNA profiles were determined from vastus lateralis muscle of nine healthy 54–62‐years‐old monozygotic female twin pairs discordant for HRT (median 7 years). MCF‐7 cells, human myoblast cultures and mouse muscle experiments were used to confirm estrogen's causal role on the expression of specific miRNAs, their target mRNAs and proteins and finally the activation of related signaling pathway. Of the 230 miRNAs expressed at detectable levels in muscle samples, qPCR confirmed significantly lower miR‐182, miR‐223 and miR‐142‐3p expressions in HRT using than in their nonusing co‐twins. Insulin/IGF‐1 signaling emerged one common pathway targeted by these miRNAs. IGF‐1R and FOXO3A mRNA and protein were more abundantly expressed in muscle samples of HRT users than nonusers. In vitro assays confirmed effective targeting of miR‐182 and miR‐223 on IGF‐1R and FOXO3A mRNA as well as a dose‐dependent miR‐182 and miR‐223 down‐regulations concomitantly with up‐regulation of FOXO3A and IGF‐1R expression. Novel finding is the postmenopausal HRT‐reduced miRs‐182, miR‐223 and miR‐142‐3p expression in female skeletal muscle. The observed miRNA‐mediated enhancement of the target genes' IGF‐1R and FOXO3A expression as well as the activation of insulin/IGF‐1 pathway signaling via phosphorylation of AKT and mTOR is an important mechanism for positive estrogen impact on skeletal muscle of postmenopausal women.     

MicroRNA signatures associated with immortalization of EBV-transformed lymphoblastoid cell lines and their clinical traits

Objective: MicroRNAs (miRNAs) are negative regulators of gene expression that play important roles in cell processes such as proliferation, development and differentiation. Recently, it has been reported that miRNAs are related to development of carcinogenesis. The aim of this study was to identify miRNAs associated with terminal immortalization of Epstein–Barr virus (EBV)‐transformed lymphoblastoid cell line (LCL) and associated clinical traits. Material and Methods: Hence, we performed miRNA microarray approach with early‐ (p6) and late‐passage (p161) LCLs. Results and Conclusion: Microarray data showed that nine miRNAs (miR‐20b*, miR‐28‐5p, miR‐99a, miR‐125b, miR‐151‐3p, miR‐151:9.1, miR‐216a, miR‐223* and miR‐1296) were differentially expressed in most LCLs during long‐term culture. In particular, miR‐125b was up‐regulated in all the tested late‐passage LCLs. miR‐99a, miR‐125b, miR‐216a and miR‐1296 were putative negative regulators of RASGRP3, GPR160, PRKCH and XAF1, respectively, which were found to be differentially expressed in LCLs during long‐term culture in a previous study. Linear regression analysis showed that miR‐200a and miR‐296‐3p correlated with triglyceride and HbA1C levels, respectively, suggesting that miRNA signatures of LCLs could provide information on the donor’s health. In conclusion, our study suggests that expression changes of specific miRNAs may be required for terminal immortalization of LCLs. Thus, differentially expressed miRNAs would be a potential marker for completion of cell immortalization during EBV‐mediated tumorigenesis.     

Induced miR‐99a expression represses Mtor cooperatively with miR‐150 to promote regulatory T‐cell differentiation

Peripheral induction of regulatory T (Treg) cells provides essential protection from inappropriate immune responses. CD4⁺ T cells that lack endogenous miRNAs are impaired to differentiate into Treg cells, but the relevant miRNAs are unknown. We performed an overexpression screen with T‐cell‐expressed miRNAs in naive mouse CD4⁺ T cells undergoing Treg differentiation. Among 130 candidates, the screen identified 29 miRNAs with a negative and 10 miRNAs with a positive effect. Testing reciprocal Th17 differentiation revealed specific functions for miR‐100, miR‐99a and miR‐10b, since all of these promoted the Treg and inhibited the Th17 program without impacting on viability, proliferation and activation. miR‐99a cooperated with miR‐150 to repress the expression of the Th17‐promoting factor mTOR. The comparably low expression of miR‐99a was strongly increased by the Treg cell inducer “retinoic acid”, and the abundantly expressed miR‐150 could only repress Mtor in the presence of miR‐99a. Our data suggest that induction of Treg cell differentiation is regulated by a miRNA network, which involves cooperation of constitutively expressed as well as inducible miRNAs.     

Periostin表达上调对去势大鼠骨髓间充质干细胞生物学行为的作用

目的:探究Periostin(骨膜蛋白)表达上调对雌性去势大鼠骨髓间充质干细胞(BMSCs)成骨分化、细胞增殖与凋亡特性的作用。方法:通过去势手术建立雌性大鼠骨质疏松模型,待建模成功后分离培养并鉴定BMSCs,利用含有增强型绿色荧光蛋白(EGFP)和大鼠Periostin基因的重组慢病毒转染P3代BMSCs,成骨诱导后鉴定其成骨分化能力改变,流式细胞仪检测其细胞周期以及细胞凋亡率的变化。结果:成功建立骨质疏松模型;荧光显微镜下观察到绿色荧光提示慢病毒载体实现转染并表达目的蛋白;慢病毒转染组BMSCs成骨诱导后ALP及茜素红染色较去势组BMSCs染色加深;慢病毒转染组BMSCs的S期细胞比例为(17.07±0.56)%,显著高于去势组BMSCs的S期细胞比例(8.42±0.02)%,差异具有统计学意义(P0.05);慢病毒转染组BMSCs的细胞凋亡率为(7.3±0.1)%,显著低于去势组BMSCs的凋亡率(12.05±0.55)%,其差异具有统计学意义(P0.05)。结论:Periostin表达上调可提高去势骨髓间充质干细胞的成骨分化及细胞增殖能力,并对其凋亡有抑制作用。     

Identification of micro‐RNA networks in end‐stage heart failure because of dilated cardiomyopathy

Micro‐RNAs regulate gene expression by directly binding to the target mRNAs. The goal of the study was to examine the expression profiling of miRNAs in human failing hearts and identify the key miRNAs that regulate molecular signalling networks and thus contribute to this pathological process. The levels of miRNAs and expressed genes were analysed in myocardial biopsy samples from patients with end‐stage heart failure (n = 14) and those from normal heart samples (n = 8). Four networks were built including the Gene regulatory network, Signal‐Network, miRNA‐GO‐Network and miRNA‐Gene‐Network. According to the fold change in the network and probability values in the microarray cohort, RT‐PCR was performed to measure the expression of five of the 72 differentially regulated miRNAs. miR‐340 achieved statistically significant. miR‐340 was identified for the first time in cardiac pathophysiological condition. We overexpressed miR‐340 in cultured neonatal rat cardiomyocytes to identify whether miR‐340 plays a determining role in the progression of heart failure. ANP, BNP and caspase‐3 were significantly elevated in the miR‐340 transfected cells compared with controls (P < 0.05). The cross‐sectional area of overexpressing miR‐340 cardiomyocytes (1952.22 ± 106.59) was greater (P < 0.0001) than controls (1059.99 ± 45.59) documented by Laser Confocal Microscopy. The changes of cellular structure and the volume were statistical significance. Our study provided a comprehensive miRNA expression profiling in the end‐stage heart failure and identified miR‐340 as a key miRNA contributing to the occurrence and progression of heart failure. Our discoveries provide novel therapeutic targets for patients with heart failure.     

miRNA‐221 and miRNA‐222 synergistically function to promote vascular calcification

Vascular calcification shares many similarities with skeletal mineralisation and involves the phenotypic trans‐differentiation of vascular smooth muscle cells (VSMCs) to osteoblastic cells within a calcified environment. Various microRNAs (miRs) are known to regulate cell differentiation; however, their role in mediating VSMC calcification is not fully understood. miR‐microarray analysis revealed the significant down‐regulation of a range of miRs following nine days in culture, including miR‐199b, miR‐29a, miR‐221, miR‐222 and miR‐31 (p < 0.05). Subsequent studies investigated the specific role of the miR‐221/222 family in VSMC calcification. Real‐time quantitative polymerase chain reaction data confirmed the down‐regulation of miR‐221 (32.4%; p < 0.01) and miR‐222 (15.7%; p < 0.05). VSMCs were transfected with mimics of miR‐221 and miR‐222, individually and in combination. Increased calcium deposition was observed in the combined treatment (two‐fold; p < 0.05) but not in individual treatments. Runx2 and Msx2 expression was increased during calcification, but no difference in expression was observed following transfection with miR mimics. Interestingly, miR‐221 and miR‐222 mimics induced significant changes in ectonucleotide phosphodiesterase 1 (Enpp1) and Pit‐1 expression, suggesting that these miRs may modulate VSMC calcification through cellular inorganic phosphate and pyrophosphate levels. © 2013 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd.