Inhibition Of miR-494 Research Articles

MicroRNA-494, Upregulated by Tumor Necrosis Factor-α, Desensitizes Insulin Effect in C2C12 Muscle Cells

Chronic inflammation is fundamental for the induction of insulin resistance in the muscle tissue of vertebrates. Although several miRNAs are thought to be involved in the development of insulin resistance, the role of miRNAs in the association between inflammation and insulin resistance in muscle tissue is poorly understood. Herein, we investigated the aberrant expression of miRNAs by conducting miRNA microarray analysis of TNF-α-treated mouse C2C12 myotubes. We identified two miRNAs that were upregulated and six that were downregulated by a >1.5-fold change compared to normal cells. Among the findings, qRT-PCR analysis confirmed that miR-494 is consistently upregulated by TNF-α-induced inflammation. Overexpression of miR-494 in CHOIR/IRS1 and C2C12 myoblasts suppressed insulin action by down-regulating phosphorylations of GSK-3α/β, AS160 and p70S6K, downstream of Akt. Moreover, overexpression of miR-494 did not regulate TNF-α-mediated inflammation . Among genes bearing the seed site for miR-494, RT-PCR analysis showed that the expression of Stxbp5, an inhibitor of glucose transport, was downregulated following miR-494 inhibition. In contrast, the expression of PTEN decreased in the cells analyzed, thus showing that both positive and negative regulators of insulin action may be simultaneously controlled by miR-494. To investigate the overall effect of miR-494 on insulin signaling, we performed a PCR array analysis containing 84 genes related to the insulin signaling pathway, and we observed that 25% of genes were downregulated (P<0.05) and 11% were upregulated (P<0.05). These results confirm that miR-494 might contribute to insulin sensitivity by positive and negative regulation of the expression of diverse genes. Of note, PCR array data showed downregulation of Slc2A4, a coding gene for Glut4. Altogether, the present study concludes that the upregulation of miR-494 expression by TNF-α-mediated inflammation exacerbates insulin resistance. Therefore, we suggest that miR-494 could prove an important target for the diagnosis and therapy of inflammation-mediated insulin resistance in muscle.

MicroRNA‐494 within an oncogenic microRNA megacluster regulates G 1 /S transition in liver tumorigenesis through suppression of mutated in colorectal cancer

Hepatocellular carcinoma (HCC) is associated with poor survival for patients and few effective treatment options, raising the need for novel therapeutic strategies. MicroRNAs (miRNAs) play important roles in tumor development and show deregulated patterns of expression in HCC. Because of the liver’s unique affinity for small nucleic acids, miRNA-based therapy has been proposed in the treatment of liver disease. Thus, there is an urgent need to identify and characterize aberrantly expressed miRNAs in HCC. In our study, we profiled miRNA expression changes in de novo liver tumors driven by MYC and/or RAS, two canonical oncogenes activated in a majority of human HCCs. We identified an up-regulated miRNA megacluster comprised of 53 miRNAs on mouse chromosome 12qF1 (human homolog 14q32). This miRNA megacluster is up-regulated in all three transgenic liver models and in a subset of human HCCs. An unbiased functional analysis of all miRNAs within this cluster was performed. We found that miR-494 is overexpressed in human HCC and aids in transformation by regulating the G1/S cell cycle transition through targeting of the Mutated in Colorectal Cancer tumor suppressor. miR-494 inhibition in human HCC cell lines decreases cellular transformation, and anti-miR-494 treatment of primary MYC-driven liver tumor formation significantly diminishes tumor size. Conclusion: Our findings identify a new therapeutic target (miR-494) for the treatment of HCC. (Hepatology 2014;58:202–215)

Overexpressed miR-494 down-regulates PTEN gene expression in cells transformed by anti-benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide

Aims We investigated the functionality of miR-494 in anti-benzo(a)pyrene-trans-7,8-dihydrodiol-9,10-epoxide (anti-BPDE)-transformed human bronchial epithelial cell 16HBE to reveal its potential target coding-gene. Main methods The expression of mature miR-494 in cells was detected by miRNA-specific quantitative real-time polymerase chain reaction (QRT-PCR). QRT-PCR and Western blot were used to identify the expression of phosphatase and tensin homolog (PTEN) mRNA and protein. Following activation or inhibition of mature miRNA expression with precursors or antisense inhibitors, PTEN expression, luciferase activities, cell apoptosis, cell growth in soft agar and cell motility were analyzed. Key findings The expression of miR-494 increased while PTEN protein appeared to be lower in malignant transformed 16HBE cells. Enforced miR-494 level decreased PTEN protein expression compared to a negative precursor control group. Inhibition of miR-494 expression increased PTEN protein expression compared to negative inhibitor control group. Decreased expression of miR-494 increased caspase-3/7 activities in transformed 16HBE cells, and increased expression of miR-494 decreased this activity. Inhibition of miR-494 also decreased the malignancy of transformed cells. Significance MiR-494 regulates the expression of PTEN post-transcriptionally and functions as a micro-oncogene in carcinogenesis induced by anti-BPDE. MiR-494 may be a useful target for gene therapy.

Neutralizing antibodies to interferon beta: Assessment of their clinical and radiographic impact: An evidence report: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

<h3>Abstract</h3> Defects in stress responses are important contributors in many chronic conditions including cancer, cardiovascular disease, diabetes, and obesity-driven pathologies like non-alcoholic steatohepatitis (NASH). Specifically, endoplasmic reticulum (ER) stress is linked with these pathologies and control of ER stress can ameliorate tissue damage. MicroRNAs have a critical role in regulating diverse stress responses including ER stress. Here we show that miR-494 plays a functional role during ER stress. ER stress inducers (tunicamycin &amp; thapsigargin) robustly increase the expression of miR-494 <i>in vitro</i> in an ATF6 dependent manner. Surprisingly, miR-494 pretreatment dampens the induction and magnitude of ER stress in response to tunicamycin in endothelial cells. Conversely, inhibition of miR-494 increases ER stress <i>de novo</i> and amplifies the effects of ER stress inducers. Using Mass Spectrometry (TMT-MS) we identified 23 proteins that are downregulated by both tunicamycin and miR-494. Among these, we found 6 transcripts which harbor a putative miR-494 binding site. We validated the anti-apoptotic gene <i>BIRC5</i> (survivin) as one of the targets of miR-494 during ER stress. Finally, induction of ER stress <i>in vivo</i> increases miR-494 expression in the liver. Pretreatment of mice with a miR-494 plasmid via hydrodynamic injection decreased ER stress in response to tunicamycin in part by decreasing inflammatory chemokines and cytokines. In summary, our data indicates that ER stress driven miR-494 may act in a feedback inhibitory loop to dampen downstream ER stress signaling. We propose that RNA-based approaches targeting miR-494 or its targets may be attractive candidates for inhibiting ER stress dependent pathologies in human disease.