title: MicroRNA-30 inhibits antiapoptotic factor Mcl-1 in mouse and human hematopoietic cells after radiation exposure.
abstract: We previously reported that microRNA-30 (miR-30) expression was initiated by radiation-induced proinflammatory factor IL-1β and NFkB activation in mouse and human hematopoietic cells. However, the downstream effectors of miR-30 and its specific role in radiation-induced cell death are not well understood. In the present study, we evaluated effects of radiation on miR-30 expression and activation of intrinsic apoptotic pathway Bcl-2 family factors in in vivo mouse and in vitro human hematopoietic cells. CD2F1 mice and human CD34+ cells were exposed to different doses of gamma-radiation. In addition to survival studies, mouse blood, bone marrow (BM) and spleen cells and human CD34+ cells were collected at 4 h, and 1, 3 and 4 days after irradiation to determine apoptotic and stress response signals. Our results showed that mouse serum miR-30, DNA damage marker γ-H2AX in BM, and Bim, Bax and Bak expression, cytochrome c release, and caspase-3 and -7 activation in BM and/or spleen cells were upregulated in a radiation dose-dependent manner. Antiapoptotic factor Mcl-1 was significantly downregulated, whereas Bcl-2 was less changed or unaltered in the irradiated mouse cells and human CD34+ cells. Furthermore, a putative miR-30 binding site was found in the 3' UTR of Mcl-1 mRNA. miR-30 directly inhibits the expression of Mcl-1 through binding to its target sequence, which was demonstrated by a luciferase reporter assay, and the finding that Mcl-1 was uninhibited by irradiation in miR-30 knockdown CD34+ cells. Bcl-2 expression was not affected by miR-30. Our data suggest miR-30 plays a key role in radiation-induced apoptosis through directly targeting Mcl-1in hematopoietic cells.
authors.affiliation: Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
authors.forename: Xiang Hong
authors.initials: XH
authors.lastname: Li
authors.affiliation: Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
authors.forename: Cam T
authors.initials: CT
authors.lastname: Ha
authors.affiliation: Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, MD, USA. mang.xiao@usuhs.edu.
authors.forename: Mang
authors.initials: M
authors.lastname: Xiao
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D001853:Bone Marrow / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects; D053148:Caspase 3 / Q000378:metabolism; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D003037:Cobalt Radioisotopes; D045304:Cytochromes c / Q000378:metabolism; D005720:Gamma Rays; D005786:Gene Expression Regulation / Q000528:radiation effects*; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects; D006801:Humans; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000235:genetics / Q000378:metabolism*; D000069079:Radiation Exposure; D015398:Signal Transduction / Q000528:radiation effects
chemical_list: D020413:3' Untranslated Regions; D003037:Cobalt Radioisotopes; C579095:MCL1 protein, human; C546086:MIRN30b microRNA, human; C579094:Mcl1 protein, mouse; D035683:MicroRNAs; C534715:Mirn30d microRNA, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D045304:Cytochromes c; D053148:Caspase 3
keywords: Apoptosis; Hematopoietic cells; Human CD34+ cells; Mcl-1; MiR-30; Mice; Radiation-injury