MicroRNAs (miRs) are small non-coding RNAs implicated mainly in post-transcriptional gene silencing by interacting with the unstranslated region of the transcript. miR-210 represents a major hypoxia-inducible miRs, also known as hypoxamirs, which is ubiquitously expressed in a wide range of cells, serving versatile functions. This review article summarizes the current progress on biogenesis of miR-210 and its physiological roles including arrest of cell proliferation, repression of mitochondrial respiration, arrest of DNA repair, vascular biology, and angiogenesis. Given the fact that miR-210 is aberrantly expressed in a number of diseases such as tumor progression, myocardial infarction and cutaneous ischemic wounds, miR-210 could serve as an excellent candidate for prognostic purposes and therapeutic intervention. With the advancement of computational prediction, high-throughput target validation methodology, sequencing, proteomic analysis and microarray, it is anticipated that more down-stream targets of miR-210 and its-associated biological consequences under hypoxia will be unveiled establishing miR-210 as a major hub in the biology of hypoxia-response.

Micro-RNAs (miRs)2 are small non-coding RNAs consisting of ϳ22 nucleotide base pairs. These small nucleic acids could regulate gene expression by binding to the 3Ј untranslated region (3Ј UTR) of mRNA, resulting in either translational repression or transcript degradation. Around 30% of the genes in the whole genome are subjected to regulation by miRs (1). Because of the short sequence requirement for binding the target 3Ј UTR, a single miR could interact with a wide range of target transcripts, which could substantially alter gene expression and dictate cell fate such as proliferation, apoptosis, and cell migration.Angiogenesis, the formation of vessels from the existing vascular structure, is a crucial biological response in wound healing, menstrual cycle, tumor aggression, and diabetic retinopathy. Endothelial sprouting, which requires extracellular matrix remodeling and endothelial cell migration, is the prerequisite process of angiogenic response. Such biological response relies on highly coordinated gene expression in a temporal and spatial manner. Increasing evidence revealed that miRs play a pivotal role in the angiogenic process. Our group and others reported that dicer, a ribonuclease III catalyzing miR maturation, is involved in the angiogenic process in human endothelial cells (2-4). Endothelial-specific dicer knockout mice exhibited an impaired angiogenic response (5). Certain miRs such as miR-126 and miR-296 have been shown to exert pro-angiogenic effects, whereas other reports indicated that miR-130a, -221, and -222 inhibited angiogenesis (6). Recently, the miR-200 family has been shown to arrest cell migration and modulate epithelial-mesenchymal transition in a wide range of epithelial cancer cells (7-12). We hypothesized that miR-200b, one member in miR-200 family, regulates endothelial cell migration and angiogenic responses. In this study, we present the first evidence demonstrating that miR200b is hypoxia-inducible and down-regulates v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets-1), a novel direct target of miR-200b, subsequently promoting angiogenic response of HMEC. EXPERIMENTAL PROCEDURESCells, Cell Culture, and Hypoxic Treatment-Human dermal microvascular endothelial cells (HMECs) were cultured in a humidified chamber (37°C, 20% O 2 and 5% CO 2 ) in MCDB-131 medium supplemented with 10% FBS, 10 mM Lglutamine, and 100 IU/ml of penicillin, 0.1 mg/ml of streptomycin (Invitrogen), as described previously (3). Primary adult human dermal microvascular endothelial cells were cultured at 37°C (20% O 2 and 5% CO 2 ) in EBM-2 medium (Lonza) supplemented with EGM-2MV single quotes (Lonza) as described by the manufacturer. HEK-293 cells were grown at standard cell culture conditions (37°C, 20% O 2 and 5% CO 2 ) with DMEM supplemented with 10% FBS and 100 IU/ml of penicillin, 0.1 mg/ml of streptomycin. For hypoxic treatment, cells were seeded on a 35-mm dish at 0.5 ϫ 10 6 cells/plate 1 * This work was supported, in whole or in part, by National Institutes of Health Grants GM077185 and GM069...

Reactive oxygen and reactive nitrogen species (ROS/RNS) have been implicated in the pathogenesis of acute and chronic pancreatitis. Clinical and basic science studies have indicated that ROS/RNS formation processes are intimately linked to the development of the inflammatory disorders. The detrimental effects of highly reactive ROS/RNS are mediated by their direct actions on biomolecules (lipids, proteins, and nucleic acids) and activation of proinflammatory signal cascades, which subsequently lead to activation of immune responses. The present article summarizes the possible sources of ROS/RNS formation and the detailed signaling cascades implicated in the pathogenesis of pancreatic inflammation, as observed in acute and chronic pancreatitis. A therapeutic ROS/RNS-scavenging strategy has been advocated for decades; however, clinical studies examining such approaches have been inconsistent in their results. Emerging evidence indicates that pancreatitis-inducing ROS/RNS generation may be attenuated by targeting ROS/RNS-generating enzymes and upstream mediators.

Objective MicroRNAs (miRs) regulate angiogenesis by posttranscriptional silencing of target genes. The significance of angiostatic miR-200b in switching on skin wound angiogenesis was tested. Methods and Results Wounding caused imminent and transient downregulation of miR-200b in dermal wound-edge endothelial cells. Derailing this injury response by lentiviral delivery of miR-200b in vivo impaired wound angiogenesis. Computational prediction, target reporter luciferase assay, and Western blot analysis provided first evidence that miR-200b targets globin transcription factor binding protein 2 (GATA2) and vascular endothelial growth factor receptor 2 (VEGFR2). Overexpression of GATA2 or VEGFR2 in endothelial cells rescued the angiostatic effect of miR-200b in vitro. Downregulation of miR-200b derepressed GATA2 and VEGFR2 expression to switch on wound angiogenesis, which was disrupted in diabetic wounds. Treatment of endothelial cells with tumor necrosis factor-α, a proinflammatory cytokine abundant in diabetic wounds, induced miR-200b expression, silenced GATA2 and VEGFR2, and suppressed angiogenesis. These outcomes were attenuated using anti-miR-200b strategy. Neutralization of tumor necrosis factor-α in the diabetic wounds improved wound angiogenesis and closure, which was accompanied by downregulation of miR-200b expression and desilencing of GATA2 and VEGFR2. Conclusion Injury-induced repression of miR-200b turned on wound angiogenesis. In mice with diabetes mellitus, excessive tumor necrosis factor-α induced miR-200b blunting proangiogenic functions of GATA2 and VEGFR2.

Glutathione depletion and 12-lipoxygenase-dependent metabolism of arachidonic acid are known to be implicated in neurodegeneration associated with acute ischemic stroke. The objective of this study was to investigate the significance of miR-29 in neurodegeneration associated with acute ischemic stroke. Neural cell death caused by arachidonic acid insult of glutathionedeficient cells was preceded by a 12-lipoxygenase-dependent loss of miR-29b. Delivery of miR-29b mimic to blunt such loss was neuroprotective. miR-29b inhibition potentiated such neural cell death. 12-Lipoxygenase knockdown and inhibitors attenuated the loss of miR-29b in challenged cells. In vivo, stroke caused by middle-cerebral artery occlusion was followed by higher 12-lipoxygenase activity and loss of miR-29b as detected in laser-captured infarct site tissue. 12-Lipoxygenase knockout mice demonstrated protection against such miR loss. miR-29b gene delivery markedly attenuated stroke-induced brain lesion. Oral supplementation of a-tocotrienol, a vitamin E 12-lipoxygenase inhibitor, rescued stroke-induced loss of miR-29b and minimized lesion size. This work provides the first evidence demonstrating that loss of miR-29b at the infarct site is a key contributor to stroke lesion. Such loss is contributed by activity of the 12-lipoxygenase pathway providing maiden evidence linking arachidonic acid metabolism to miR-dependent mechanisms in stroke.