The Signature of MicroRNA Dysregulation in Muscle Paralyzed by Spinal Cord Injury Includes Downregulation of MicroRNAs that Target Myostatin Signaling

MiR-145 suppresses the motility of prostate cancer cells by targeting cadherin-2

Metastasis is the main cause of poor prognosis in the advanced prostate cancer in clinic. Accumulating evidences have proposed that cell motility greatly contributes to the multiple steps of the metastatic process. MicroRNA-145 (miR-145) has been found to be downregulated in prostate cancer and serve as a putative tumor suppressor via decrease of cell growth and augmentation of cell death; however, the effects and the underlying mechanisms of miR-145 in prostate cancer cell motility have not been completely clarified. In the current study, we first demonstrated that miR-145 exerted inhibitory effects on the aggressive phenotype of the prostate cancer cells. Based on the bioinformatics analysis of the putative target genes of miR-145, we further experimentally identified a novel mechanism of miR-145 suppressing the aggressive phenotype of prostate cancer cells via directly targeting cadherin-2 (CDH2) protein translation. Re-expression of CDH2 could rescue miR-145-triggered cell migration and invasion defects. Our results suggested that miR-145 suppressed the motility of prostate cancer cells via post-transcriptional downregulation of CDH2 expression, and miR-145-CDH2 pair might serve as a potential target for intervention of prostate cancer metastasis.

MicroRNA-145-Mediated KDM6A Downregulation Enhances Neural Repair after Spinal Cord Injury via the NOTCH2/Abcb1a Axis

Spinal cord injury (SCI) causes a significant physical, emotional, social, and economic burden to millions of people. MicroRNAs are known players in the regulatory circuitry of the neural repair in SCI. However, most microRNAs remain uncharacterized. Here, we demonstrate the neuroprotection of microRNA-145 (miR-145) after SCI in vivo and in vitro. In silico analysis predicted the target gene KDM6A of miR-145. The rat SCI model was developed by weight drop, and lipopolysaccharide- (LPS-) induced PC12 cell inflammatory injury model was also established. We manipulated the expression of miR-145 and/or KDM6A both in vivo and in vitro to explain their roles in rat neurological functional recovery as well as PC12 cell activities and inflammation. Furthermore, we delineated the mechanistic involvement of NOTCH2 and Abcb1a in the neuroprotection of miR-145. According to the results, miR-145 was poorly expressed and KDM6A was highly expressed in the spinal cord tissue of the SCI rat model and LPS-induced PC12 cells. Overexpression of miR-145 protects PC12 cells from LPS-induced cell damage and expedites neurological functional recovery of SCI in rats. miR-145 was validated to target and downregulate the demethylase KDM6A expression, thus abrogating the expression of Abcb1a by promoting the methylation of NOTCH2. Additionally, in vivo findings verified that miR-145 expedites neuroprotection after SCI by regulating the KDM6A/NOTCH2/Abcb1a axis. Taken together, miR-145 confers neuroprotective effects and enhances neural repair after SCI through the KDM6A-mediated NOTCH2/Abcb1a axis.

Mesenchymal stem cell-derived exosomes containing miR-145-5p reduce inflammation in spinal cord injury by regulating the TLR4/NF-κB signaling pathway

EXs (Exosomes) secreted by mesenchymal stem cells (MSCs) have the potential to treat spinal cord injury (SCI), this study aimed to further explore the therapeutic effect of EXs on SCI. Firstly, EXs were extracted from MSCs and analyzed with a transmission electron microscope. Next, MSCs with or without the miR-145-5p plasmid were injected into the SCI rat model, and then rat damage was evaluated by BBB score, HE staining and Nissl staining. And then Luciferase experiment verified the targeting relationship between miR-145-5p and TLR4. Furthermore, LPS-induced PC12 cells were established and incubated with Dil-labeled MSC-EXs to explore their effects on cell viability, apoptosis and inflammation through MTT, flow cytometry and ELISA, respectively. In addition, expressions of TLR4/NF-κB signaling pathway related factors were measured by qRT-PCR and Western blot. The results showed that after MSCs were successfully isolated, the existence of EXs in MSCs was confirmed. Moreover, MSC-EXs containing miR-145-5p improved functional recovery and reduced histopathological injury and inflammation in SCI rats. And MSC-EXs promoted miR-145-5p expression in spinal cord tissue and inhibited TLR4/NF-κB pathway activation in SCI rats. MSC-EXs inhibited LPS-induced inflammatory response and activation of the TLR4/NF-κB pathway in PC12 cells. In addition, we also found that miR-145-5p specifically targeted TLR4. TLR4 overexpression significantly reversed the effect of EX-miR-145-5p on maintaining PC12 cell viability, inhibiting apoptosis and inflammatory response, and activating TLR4/NF- κB pathway. In conclusion, mesenchymal stem cell-derived EXs containing miR-145-5p reduce inflammation in spinal cord injury by regulating the TLR4/NF-κB signaling pathway.

Myokines in skeletal muscle physiology and metabolism: Recent advances and future perspectives

Myokines are molecules produced and secreted by skeletal muscle to act in an auto-, para- and endocrine manner to alter physiological function of target tissues. The growing number of effects of myokines on metabolism of distant tissues provides a compelling case for crosstalk between skeletal muscle and other tissues and organs to regulate metabolic homoeostasis. In this review, we summarize and discuss the current knowledge regarding the impact on metabolism of several canonical and recently identified myokines. We focus specifically on myostatin, β-aminoisobutyric acid, interleukin-15, meteorin-like and myonectin, and discuss how these myokines are induced and regulated as well as their overall function. We also review how these myokines may serve as potential prognostic biomarkers that reflect whole-body metabolism and how they may be attractive therapeutic targets for treating muscle and metabolic diseases.

Geniposide protects PC12 cells from lipopolysaccharide-evoked inflammatory injury via up-regulation of miR-145-5p

Geniposide is an active ingredient with anti-apoptotic and anti-inflammatory properties. This study was to examine the effects of geniposide on a cell model of spinal cord injury (SCI). PC12 cells were administrated with geniposide before subjected to LPS. The effects of geniposide were analyzed by utilizing CCK-8 assay, apoptosis assay, ELISA, RT-qPCR and Western blot. We found that PC12 cells viability was unchanged by treating with geniposide. However, geniposide with concentrations of 200 or 300 μg/mL significantly mitigated LPS-evoked viability loss. Meanwhile, apoptosis driven by LPS was mitigated by geniposide, which accompanied with p53, Bax and cleaved caspase-3 down-regulation, and Bcl-2 up-regulation. Besides this, the expression and release of IL-1β, IL-6, IL-8 and TNF-α evoked by LPS were mitigated by geniposide. miR-145-5p was a target of geniposide. miR-145-5p expression was up-regulated by geniposide, and geniposide did not protect PC12 cells against LPS injury when miR-145-5p was silenced. Moreover, geniposide inhibited NF-κB and JNK pathways via up-regulating miR-145-5p. In short, the present work described the neuroprotective effects of geniposide by targeting miR-145-5p. Further mechanisms involved in geniposide's beneficial effects are correlated with the inhibited NF-κB and JNK pathways. Highlights Geniposide prevents LPS-induced injury in PC12 cells; Geniposide up-regulates miR-145-5p; Geniposide protects PC12 cells via up-regulation of miR-145-5p; Geniposide inhibits NF-κB and JNK pathways via up-regulation of miR-145-5p.

Protective Effects of MiR-129-5p on Acute Spinal Cord Injury Rats

BACKGROUND Spinal cord injury (SCI) is a severe devastating condition associated with serious disability and neurologic deficits. Aberrant micro RNA (miRNA) expression has been related to a variety of central nervous system diseases including SCI. In the present study, we aimed to discover the role of miR-129-5p on SCI. MATERIAL AND METHODS An acute SCI rat model was induced, following the modified Allen method. A total of 36 rats were randomly assigned into 4 groups (n=9 in every group): Sham group; Model group (SCI+saline); SCI+NC group; and SCI+miR-129-5p group (100 nm solution, every 2 days). Basso-Beattie-Bresnahan (BBB) locomotor rating score was carried out to determine functional recovery. TUNEL (terminal dUTP nick-end labeling) staining was used to evaluate cell apoptosis. Hematoxylin and eosin staining was performed to assess the pathological state of spinal cord. Furthermore, western blot assay was conducted to measure the calpain1 and calpain2 expression. RESULTS Our data suggested that the expression level of miR-129-5p was markedly reduced in rats after SCI. Then miR-129-5p mimic was injected into the vertebral canal. We found that the SCI+miR-129-5p group had a high score in the BBB test compared with the SCI+NC group and the Model group. The overexpression of miR-129-5p obviously reduced tissue loss, damaged cells, and the number of TUNEL positive cells. Moreover, western blot assay exhibited that overexpression of miR-129-5p decreased calpain1, calpain2, and cleaved caspase-3 expression. CONCLUSIONS Our findings suggested that overexpression of miR-129-5p improved neurological function by promoting functional recovery, reducing tissue loss and cell apoptosis in rats in an SCI model, possibly through downregulation of calpain1 and calpain2.

β2-adrenergic receptor-mediated mitochondrial biogenesis improves skeletal muscle recovery following spinal cord injury

In addition to local spinal cord dysfunction, spinal cord injury (SCI) can result in decreased skeletal muscle mitochondrial activity and muscle atrophy. Treatment with the FDA-approved β₂-adrenergic receptor (ADRB2) agonist formoterol has been shown to induce mitochondrial biogenesis (MB) in both the spinal cord and skeletal muscle and, therefore, has the potential to address comprehensive mitochondrial and organ dysfunction following SCI. Female C57BL/6 mice were subjected to moderate contusion SCI (80 Kdyn) followed by daily administration of vehicle or formoterol beginning 8 h after injury, a clinically relevant time-point characterized by a 50% decrease in mtDNA content in the injury site. As measured by the Basso Mouse Scale, formoterol treatment improved locomotor recovery in SCI mice compared to vehicle treatment by 7 DPI, with continued recovery observed through 21 DPI (3.5 v. 2). SCI resulted in 15% body weight loss in all mice by 3 DPI. Mice treated with formoterol returned to pre-surgery weight by 13 DPI, while no weight gain occurred in vehicle-treated SCI mice. Remarkably, formoterol-treated mice exhibited a 30% increase in skeletal muscle mass compared to those treated with vehicle 21 DPI (0.93 v. 0.72% BW), corresponding with increased MB and decreased skeletal muscle atrophy. These effects were not observed in ADRB2 knockout mice subjected to SCI, indicating that formoterol is acting via the ADRB2 receptor. Furthermore, knockout mice exhibited decreased basal spinal cord and skeletal muscle PGC-1α expression, suggesting that ADRB2 may play a role in mitochondrial homeostasis under physiological conditions. These data provide evidence for systemic ADRB2-mediated MB as a therapeutic avenue for the treatment of SCI.

Genomic regions and enrichment analyses associated with carcass composition indicator traits in Nellore cattle

The aim of this study was to estimate genetic parameters and identify genomic regions associated with carcass traits obtained by ultrasound and visual scores in Nellore cattle. Data from ~66,000 animals from the National Association of Breeders and Researchers (ANCP) were used. The variance components for backfat thickness, rump fat thickness and Longissimus muscle area (LMA) were estimated considering a linear model whereas a threshold model for body structure (BS), finishing precocity (FP) and musculature (MS) traits. The SNP solutions were estimated using the ssGBLUP approach by considering windows of 10 consecutive SNPs. Regions that accounted for more than 1.0% of the additive genetic variance were used. Genes identified within the significant windows, such as FOXA3, AP2S1, FKRP, NPASI and ATP6V1G1, were found to be related with MS, while OMA1 and FFGY with BS and FP traits. The PLTP, TNNC2 and GPAT2 genes were found in the regions associated with LMA, as well as TKT, FNDC5 and CHRND can strongly be related with fat deposition. Gene enrichment analysis revealed processes that might be directly influenced the organism growth and development. These results should help to better understand the genetic and physiological mechanisms regulating growth and body composition, muscle tissue development and subcutaneous fat expression, and this information might be useful for future genomic studies in Nellore cattle.

Murine intestinal organoids resemble intestinal epithelium in their microRNA profiles

Intestinal organoids were established as an ex vivo model of the intestinal epithelium. We investigated whether organoids resemble the intestinal epithelium in their microRNA (miRNA) profiles. Total RNA samples were obtained from crypt and villus fractions in murine intestine and from cultured organoids. Microarray analysis showed that organoids largely resembled intestinal epithelial cells in their miRNA profiles. In silico prediction followed by qRT-PCR suggested that six genes are regulated by corresponding miRNAs along the crypt-villus axis, suggesting miRNA regulation of epithelial cell renewal in the intestine. However, such expression patterns of miRNAs and their target mRNAs were not reproduced during organoids maturation. This might be due to lack of luminal factors and endocrine, nervous, and immune systems in organoids and different cell populations between in vivo epithelium and organoids. Nevertheless, we propose that intestinal organoids provide a useful in vitro model to investigate miRNA expression in intestinal epithelial cells.

miR-29b affects neurocyte apoptosis by targeting MCL-1 during cerebral ischemia/reperfusion injury

The present study aimed to determine whether an miRNA (miR)-29b inhibitor protected against cerebral ischemia/reperfusion (I/R) injury in vitro and to investigate the underlying mechanisms. As a model for induced cerebral IR injury, N2a cells were exposed to an oxygen-glucose deprivation/reoxygenation (OGD/R) environment. Using this model, it was demonstrated that miR-29b was significantly upregulated compared with cells in a normal environment. The interactions between miR-29b and myeloid cell leukemia sequence (MCL)-1 were then investigated using dual-luciferase assays, revealing a strong regulation of MCL-1 through the 3'untranslated region. Using the OGD/R model, the present study additionally examined the effects of miR-29b and miR-29b inhibitor on cell viability and apoptosis using Cell Counting kit 8 and flow cytometry assays, respectively. miR-29b transfection led to increased N2a cell apoptosis and reduced cell viability under an OGD/R environment. However, this effect was reversed by the miR-29b inhibitor. Finally, the effects of miR-29b on the expression of several Wnt-associating proteins were examined. It was observed that B cell lymphoma-2 was inhibited by miR-29b, as was MCL-1, whereas caspase-3 expression was promoted. The miR-29b inhibitor demonstrated the opposite effect. Overall, miR-29b promoted neurocyte apoptosis by targeting MCL-1 during cerebral I/R injury. The results of the present study suggest a potential novel therapeutic target for the treatment of ischemic stroke.

MiR-302 enhances the viability and stemness of male germline stem cells

MicroRNAs were reported to be able to regulate mGSCs' self-renewal through post-transcriptional inhibition of gene expression. miR-302 worked as one important microRNA family existed mainly in human ESCs, and its role in mGSCs has not been reported yet. To elucidate the role of miR-302 in dairy goat mGSCs, the expression profile of miR-302 was explored through qPCR and FISH. Furthermore, to detect the function of miR-302, the expression vector containing miR-302 was transfected into mGSCs, and then, the cell cycle, the cell apoptosis and the genes associated with mGSCs' self-renewal and differentiation were examined. The results showed that miR-302 expressed in testis moderately and located on the basement of seminiferous tubes which shared the same location as mGSCs. Transfection of the vector containing miR-302 fragment into the immortalized mGSCs obviously enhanced the cell proliferation ability and the attachment ability, also, promoted the expression level of CD49f and OCT4. Also, miR-302 reduced the cell apoptosis and downregulated the expression of P21. miR-302 sustained mGSCs' proliferation in vitro.

miR-411 suppresses acute spinal cord injury via downregulation of Fas ligand in rats

OBJECTIVE

To explore the role of miR-411/FasL in acute spinal cord injury (ASCI).

METHODS

The ASCI rat model was established, and expression of miR-411 and Fas ligand (FasL) was examined. Basso, Beattie and Bresnahan (BBB) score was used to evaluate the rats' neurological function. PC12 oxygen-glucose deprivation (OGD) model was also established. Gene manipulation (including miR-411 mimic or inhibitor) was used to modulate gene expression. Luciferase reporter assay was conducted to confirm the targeting relationship between miR-411 and FasL. Flow cytometry was applied in the measurement of PC12 cell apoptosis. Finally, the miR-411 mimic was injected into the vertebral canal of ASCI rats to determine the effects of miR-411 in vivo.

RESULTS

Compared with sham group, the expression of miR-411 and FasL was significantly decreased and increased in ASCI group, respectively (P < 0.05). Similarly, the expression of miR-411 and FasL was significantly lower and higher in OGD group than that in control group, respectively (P < 0.05). miR-411 directly controlled the FasL expression. miR-411 mimic can dramatically reduce the increased percentage of apoptosis cells caused by OGD when comparing to mimic control, which was greatly reversed by the overexpression of FasL (P < 0.05). Further, the BBB score was significantly elevated in the miR-411 mimic group when comparing to mimic control group, with decreased FasL expression (P < 0.05).

CONCLUSION

miR-411 mimic suppressed PC12 cell apoptosis via FasL, and relieved ASCI in rats.

Spinal Cord Injury Leads to Hyperoxidation and Nitrosylation of Skeletal Muscle Ryanodine Receptor-1 Associated with Upregulation of Nicotinamide Adenine Dinucleotide Phosphate Oxidase 4

Spinal cord injury (SCI) results in marked atrophy and dysfunction of skeletal muscle. There are currently no effective treatments for SCI-induced muscle atrophy or the dysfunction of the remaining muscle tissue. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-4 (Nox4) produces reactive oxygen species (ROS) in sarcoplasmic reticulum (SR) and has been identified as an important O2 sensor in skeletal muscle. Ryanodine receptors (RyRs) are calcium (Ca2+) channels that are responsible for Ca2+ release from SR. In skeletal muscle, type1 RyR (RyR1) is predominantly functional. RyR1 is regulated by multiple proteins, including calstabin1, which assures that they close appropriately once contraction has ceased. RyR1 function is also regulated by oxidation and redox-dependent cysteine nitrosylation. Excessive oxidation/nitrosylation of RyR1 is associated with dissociation of calstabin1 and reduced muscle force generation. However, whether Nox4 levels in skeletal muscle are elevated or whether RyR1 is oxidized or nitrosylated after SCI has not been determined. In this study, we examined Nox4 expression, oxidation/nitrolysation status, and association of calstabin1 with RyR1 in skeletal muscle derived from rats that were subjected to T4 complete transection (SCI), and observed elevated expression of Nox4 messenger RNA and protein in muscle after SCI associated with enhanced binding of Nox4 to RyR1, increased oxidation and nitrosylation of RyR1, and dissociation of calstabin1 from RyR1 in SCI rat muscle. Our data suggest that RyR1 dysfunction resulting from excessive oxidation/nitrosylation may contribute to reduced specific force after SCI and suggest that Nox4 may be the source of ROS responsible for increased oxidation and nitrosylation of RyR1.

Recombinant myostatin reduces highly expressed microRNAs in differentiating C2C12 cells

Myostatin is small glycopeptide that is produced and secreted by skeletal muscle. It is a potent negative regulator of muscle growth that has been associated with conditions of frailty. In C2C12 cells, myostatin limits cell differentiation. Myostatin acts through activin receptor IIB, activin receptor-like kinase (ALK) and Smad transcription factors. microRNAs (miRNA) are short, 22 base pair nucleotides that bind to the 3' UTR of target mRNA to repress translation or reduce mRNA stability. In the present study, expression in differentiating C2C12 cells of the myomiRs miR-1 and 133a were down-regulated following treatment with 1 μg of recombinant myostatin at 1 d post-induction of differentiation while all myomiRs (miR-1, 133a/b and 206) were upregulated by SB431542, a potent ALK4/5/7 inhibitor which reduces Smad2 signaling, at 1 d and all, with the exception of miR-206, were upregulated by SB431542 at 3 d. The expression of the muscle-enriched miR-486 was greater following treatment with SB431542 but not altered by myostatin. Other highly expressed miRNAs in skeletal muscle, miR-23a/b and 145, were altered only at 1 d post-induction of differentiation. miR-27b responded differently to treatments at 1 d, where it was upregulated, as compared to 3 d, where it was downregulated. Neither myostatin nor SB431542 altered cell size or cell morphology. The data indicate that myostatin represses myomiR expression in differentiating C2C12 cells and that inhibition of Smad signaling with SB431542 can result in large changes in highly expressed miRNAs in differentiating myoblasts.