title: MicroRNA-21 protects neurons from ischemic death.
abstract: MicroRNAs are small RNAs that attenuate protein expression by complementary binding to the 3'-UTR of a target mRNA. Currently, very little is known about microRNAs after cerebral ischemia. In particular, microRNA-21 (miR-21) is a strong antiapoptotic factor in some biological systems. We investigated the role of miR-21 after stroke in the rat. We employed in situ hybridization and laser capture microdissection in combination with real-time RT-PCR to investigate the expression of miR-21 after stroke. In situ hybridization revealed that miR-21 expression was upregulated in neurons of the ischemic boundary zone, and quantitative real-time RT-PCR analysis revealed that stroke increased mature miR-21 levels by approximately threefold in neurons isolated from the ischemic boundary zone by laser capture microdissection as compared with homologous contralateral neurons 2 days (n = 4; P < 0.05) and 7 days (n = 3; P < 0.05) after stroke. In vitro, overexpression of miR-21 in cultured cortical neurons substantially suppressed oxygen and glucose deprivation-induced apoptotic cell death, whereas attenuation of endogenous miR-21 by antisense inhibition exacerbated cell death after oxygen and glucose deprivation. Moreover, overexpression of miR-21 in neurons significantly reduced FASLG levels, and introduction of an miR-21 mimic into 293-HEK cells substantially reduced luciferase activity in a reporter system containing the 3'-UTR of Faslg. Our data indicate that overexpression of miR-21 protects against ischemic neuronal death, and that downregulation of FASLG, a tumor necrosis factor-α family member and an important cell death-inducing ligand whose gene is targeted by miR-21, probably mediates the neuroprotective effect. These novel findings suggest that miR-21 may be an attractive therapeutic molecule for treatment of stroke.
authors.affiliation: Department of Neurology, Henry Ford Hospital, Detroit, MI, USA.
authors.forename: Ben
authors.initials: B
authors.lastname: Buller
authors.forename: Xianshuang
authors.initials: X
authors.lastname: Liu
authors.forename: Xinli
authors.initials: X
authors.lastname: Wang
authors.forename: Rui L
authors.initials: RL
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Ann
authors.initials: A
authors.lastname: Hozeska-Solgot
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
authors.forename: Zheng G
authors.initials: ZG
authors.lastname: Zhang
mesh_terms: D000818:Animals; D016923:Cell Death; D053222:Fas Ligand Protein / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D007511:Ischemia / Q000473:pathology*; D035683:MicroRNAs / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000473:pathology*; D020011:Protective Agents; D051381:Rats; D017208:Rats, Wistar; D020521:Stroke
chemical_list: D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D035683:MicroRNAs; D020011:Protective Agents; C546082:mirn21 microRNA, rat