title: Influence of miR-155 on Cell Apoptosis in Rats with Ischemic Stroke: Role of the Ras Homolog Enriched in Brain (Rheb)/mTOR Pathway.
abstract: BACKGROUND We designed and carried out this study to examine the role of miR-155 and the Rheb/mTOR pathway in ischemic stroke. We also investigated how these two elements interact with each other and contribute to injuries resulting from ischemic stroke. MATERIAL AND METHODS We used both a middle cerebral artery occlusion rat model in vivo and an oxygen-glucose deprivation cell model in vitro to simulate the onset of ischemic stroke. miR-155 mimics, miR-155 inhibitors, and Rheb siRNA were transfected to alter the expression of miR-155 and Rheb. Infarct sizes were measured using magnetic resonance imaging (MRI) and triphenyltetrazolium chloride (TTC) staining; cell apoptosis rates were calculated using Annexin V-FITC/PI staining and flow cytometry. Levels of miR-155, Rheb, mTOR, and S6K were examined by RT-PCR, immunofluorescence, and western blot. We performed a luciferase activity assay so that the association between miR-155 and Rheb could be fully assessed. RESULTS We demonstrated that miR-155 bound the 3'-UTR of Rheb and suppressed Rheb expression. As suggested by animal models, significant cerebral infarct volumes and cell apoptosis were induced by increased expression of miR-155 and decreased expression of Rheb, mTOR, and p-S6K (P<0.05). miR-155 inhibitors exhibited protective effects on ischemic stroke, including down-regulation of infarction size in cerebral tissues in vivo and reduced apoptosis of BV2 cells in vitro with increased expression of Rheb, mTOR and p-S6K (P<0.05). These protective effects could be substantially antagonized by the transfection of Rheb siRNA (P<0.05). CONCLUSIONS Inhibition of miR-155 may play protective roles in ischemic stroke by phosphorylating S6K through the Rheb/mTOR pathway.
authors.affiliation: Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China (mainland).|Department of Neurology, Weifang People's Hospital, Weifang, Shandong, China (mainland).
authors.forename: Guoping
authors.initials: G
authors.lastname: Xing
authors.affiliation: Department of Dermatology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, China (mainland).
authors.forename: Zengxiang
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Department of Neurology, Weifang People's Hospital, Weifang, Shandong, China (mainland).
authors.forename: Chi
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China (mainland).
authors.forename: Xudong
authors.initials: X
authors.lastname: Pan
authors.affiliation: Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China (mainland).
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Xu
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002545:Brain Ischemia / Q000150:complications / Q000235:genetics* / Q000473:pathology; D002460:Cell Line; D004195:Disease Models, Animal; D005434:Flow Cytometry; D007150:Immunohistochemistry; D008156:Luciferases / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D010766:Phosphorylation; D000076205:Ras Homolog Enriched in Brain Protein; D017207:Rats, Sprague-Dawley; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D015398:Signal Transduction; D013194:Staining and Labeling; D020521:Stroke / Q000150:complications / Q000235:genetics* / Q000473:pathology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; C580597:MIRN155 microRNA, rat; D035683:MicroRNAs; D009479:Neuropeptides; D000076205:Ras Homolog Enriched in Brain Protein; C087693:Rheb protein, rat; D008156:Luciferases; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D058570:TOR Serine-Threonine Kinases; D020559:Monomeric GTP-Binding Proteins