微小RNA-129在肿瘤发生中的作用机制

微小RNA-129（microRNA-129, miR-129）是一种能产生miR-129-5p、miR-129-1-3p和miR-129-2-3p等3种成熟产物的miRNA,它们在细胞生长、发育、癌变等生命过程中有重要作用. miR-129在多种常见肿瘤中呈现高表达（如：胃癌和肺癌）或低表达（如：乳腺癌和食管鳞状细胞癌）的多样现象,而且这种异常表达与肿瘤的发生发展有密切联系. miR-129通过作用于性别决定区Y框蛋白4（sex-determining-region Y-box 4, SOX4）、细胞周期蛋白依赖激酶6（cyclin-dependent kinase 6, Cdk6）、含缬酪肽蛋白（valosin containing protein, VCP）和磷脂酰肌醇蛋白聚糖-3（glypican-3, GP3）等多种靶基因而在肿瘤发生、发展过程中起着重要作用.     

Highly automated nano-LC/MS-based approach for thousand cell-scale quantification of side chain-hydroxylated oxysterols

Iso-octyl chain-hydroxylated oxysterols were determined in attomoles per 10,000 cells concentrations in 10,000–80,000 cultured pancreatic adenocarcinoma cells, using a sensitive, highly automated nano-LC-ESI-MS-based method. Identified oxysterols included 24S hydroxycholesterol (24S-OHC), 25 hydroxycholesterol (25-OHC), and 27 hydroxycholesterol (27-OHC), while 20S hydroxycholesterol and 22S hydroxycholesterol were not detected. Lower mass limit of quantification was 23 fg (65 amol) for 25-OHC and 27-OHC (100 times lower than our previous method) and 54 fg (135 amol) for 24S-OHC, after derivatization into Girard T hydrazones and online sample cleanup using simplified and robust automatic filtration and filter back flushing solid phase extraction LC/MS/MS. The instrument configuration was easily installed using a commercial nano-LC/MS system. Recoveries in spiked sample were 96, 97, and 77% for 24S-OHC, 25-OHC, and 27-OHC, with within- and between-day repeatabilities of 1–21% and 2–20% relative SD, respectively. The study demonstrates the potential of nano-LC in lipidomics/sterolomics.     

Amyloid-beta peptide enhances tumor necrosis factor-alpha-induced iNOS through neutral sphingomyelinase/ceramide pathway in oligodendrocytes

Although accumulating evidence demonstrates that white matter degeneration contributes to pathology in Alzheimer's disease (AD), the underlying mechanisms are unknown. In order to study the roles of the amyloid-beta peptide in inducing oxidative stress damage in white matter of AD, we investigated the effects of amyloid-beta peptide 25-35 (Abeta) on proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha)-induced inducible nitric oxide synthase (iNOS) in cultured oligodendrocytes (OLGs). Although Abeta 25-35 by itself had little effect on iNOS mRNA, protein, and nitrite production, it enhanced TNF-alpha-induced iNOS expression and nitrite generation in OLGs. Abeta, TNF-alpha, or the combination of both, increased neutral sphingomyelinase (nSMase) activity, but not acidic sphingomyelinase (aSMase) activity, leading to ceramide accumulation. Cell permeable C2-ceramide enhanced TNF-alpha-induced iNOS expression and nitrite generation. Moreover, the specific nSMase inhibitor, 3-O-methyl-sphingomyelin (3-OMS), inhibited iNOS expression and nitrite production induced by TNF-alpha or by the combination of TNF-alpha and Abeta. Overexpression of a truncated mutant of nSMase with a dominant negative function inhibited iNOS mRNA production. 3-OMS also inhibited nuclear factor kappaB (NF-kappaB) binding activity induced by TNF-alpha or by the combination of TNF-alpha and Abeta. These results suggest that neutral sphingomyelinase/ceramide pathway is required but may not be sufficient for iNOS expression induced by TNF-alpha and the combination of TNF-alpha and Abeta.     

Network of three specific microRNAs influence type 2 diabetes through inducing insulin resistance in muscle cell lines

Insulin resistance has been implicated as one of the best predictors for type 2 diabetes. Growing evidence propose the involvement of microRNAs (miRNAs) as short regulatory molecules in modulating and inducing resistance. In this regard, we have investigated the role of three selected miRNAs in insulin resistance development (miR-135, miR-202, and miR-214), via assessing glucose uptake levels in C2C12 and L6 muscle cell lines. Interestingly, miRNA-transfected cells demonstrated a significantly different glucose uptake compared to the positive control cells. In addition, we evaluated the expression levels of three putative miRNA target genes (Rho-associated coiled-coil containing protein kinase 1, serine/threonine kinase 2, and vesicle-associated membrane protein 2) in transfected cells, recruiting luciferase assay. Our results indicated the targeting and downregulation of Rho-associated coiled-coil containing protein kinase 1 and serine/threonine kinase 2 genes in all miR-transfected cell lines ( P ≤ 0.05), but not for vesicle-associated membrane protein 2. MiRNA upregulation led to the poor stimulation of glucose uptake through insulin and developed insulin-resistant phenotype in both muscle cell lines. Our study showed the role of three miRNAs in the induction of insulin resistance in cell lines and making them prone to type 2 diabetes development.     

Long noncoding RNA NEAT1 sponges miR-495-3p to enhance myocardial ischemia-reperfusion injury via MAPK6 activation

The biological function of long noncoding RNA NEAT1 has been revealed in a lot of diseases. Nevertheless, it is still not yet clear whether NEAT1 can modulate the process of myocardial ischemia–reperfusion injury (M-I/R). Here, we reported that NEAT1 was able to sponge miR-495-3p to contribute to M-I/R injury through activating mitogen-activated protein kinase 6 (MAPK6). First, elevated expression of NEAT1 was revealed in M-I/R injury mice, meanwhile, lactate dehydrogenase (LDH) and creatine kinase-muscle/brain (CK-MB) were also upregulated in the serum. Meanwhile, as previously reported, miR-495 serves as a tumor suppressor or an oncogenic miRNA in different types of cancer. Currently, we found miR-495-3p was remarkably reduced in M-I/R mice. Additionally, NEAT1 was significantly induced whereas miR-495-3p was greatly reduced by H₂O₂ treatment in H9C2 cells. Moreover, loss of NEAT1 in H9C2 cells could repress the viability and proliferation of cells. For another, overexpression of NEAT1 exhibited an opposite phenomenon. Furthermore, LDH release and caspase-3 activity were obviously triggered by upregulation of NEAT1 while suppressed by NEAT1 knockdown. miR-495-3p was indicated and validated as a target of NEAT1 using the analysis of bioinformatics. Interestingly, we observed that miR-495-3p mimics repressed tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-18 protein expression while their levels were enhanced by the inhibition of miR-495-3p in H9c2 cells. Subsequently, it was manifested that MAPK6 was a target of miR-495-3p, which could exert a lot in the NEAT1/miR-495-3p-mediated M-I/R injury. Overall, our results implied that NEAT1 contributed to M-I/R injury via the modulation of miR-495-3p and MAPK6.     

miR-29b inhibits TGF-β1-induced cell proliferation in articular chondrocytes

Transforming growth factor β1 (TGF-β1) is a known regulator of chondrocyte proliferation and promotes cartilage repair in osteoarthritis (OA). microRNA-29b-3p (miR-29b-3p) is downregulated by TGF-β1 and overexpressed in OA cartilage. However, the ability of miR-29b-3p to mediate the chondrocyte pro-proliferative effects of TGF-β1 is not yet understood. This current study aimed to investigate the effect of miR-29b-3p on TGF-β1-induced cell proliferation in murine articular chondrocytes. The stimulation of chondrocytes by TGF-β1 for 24 h resulted in the downregulation of miR-29b-3p expression. The ratio of G0/G1 phase cells decreased in response to TGF-β1 whereas the ratio of S phase cells was increased. Consistent with this observation, miR-29b-3p overexpression inhibited TGF-β1’s ability to promote the ratio of S phase cells and downregulate the ratio of G0/G1 phase cells. These findings suggest that the downregulation of miR-29b-3p is a likely requirement for TGF-β1-mediated proliferation of murine articular chondrocytes. Furthermore, implying that miR-29b-3p expression may be involved in reduced chondrocyte proliferation in OA.