title: Stat3 and C/EBPβ synergize to induce miR-21 and miR-181b expression during sepsis.
abstract: Myeloid-derived suppressor cells (MDSCs) increase late sepsis immunosuppression and mortality in mice. We reported that microRNA (miR) 21 and miR-181b expression in Gr1+CD11b+myeloid progenitors increase septic MDSCs in mice by arresting macrophage and dendritic cell differentiation. Here, we report how sepsis regulates miR-21 and miR-181b transcription. In vivo and in vitro binding studies have shown that C/EBPα transcription factor, which promotes normal myeloid cell differentiation, binds both miRNA promoters in Gr1+CD11b+cells from sham mice. In contrast, in sepsis Gr1+CD11b+MDSCs miR-21 and miR-181b promoters bind both transcription factors Stat3 and C/EBPβ, which co-imunoprecipitate as a single complex. Mechanistically, transcription factor Rb phosphorylation supports Stat3 and C/EBPβ accumulation at both miRNA promoters, and C/EBPβ or Stat3 depletion by siRNA in sepsis Gr1+CD11b+MDSCs inhibits miR-21 and miR-181b expression. To further support this molecular path for MDSC accumulation, we found that Stat3 and C/EBP binding at miR-21 or miR-181b promoter was induced by IL-6, using a luciferase reporter gene transfection into naive Gr1+CD11b+cells. Identifying how sepsis MDSCs are generated may inform new treatments to reverse sepsis immunosuppression.
authors.affiliation: Department of Internal Medicine, East Tennessee State University College of Medicine, Johnson City, TN, USA.
authors.forename: Clara
authors.initials: C
authors.lastname: McClure
authors.affiliation: Department of Internal Medicine, East Tennessee State University College of Medicine, Johnson City, TN, USA.
authors.forename: Melissa B
authors.initials: MB
authors.lastname: McPeak
authors.affiliation: Department of Internal Medicine, East Tennessee State University College of Medicine, Johnson City, TN, USA.
authors.forename: Dima
authors.initials: D
authors.lastname: Youssef
authors.affiliation: Department of Internal Medicine, East Tennessee State University College of Medicine, Johnson City, TN, USA.
authors.forename: Zhi Q
authors.initials: ZQ
authors.lastname: Yao
authors.affiliation: Department of Internal Medicine, Section of Molecular Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCall
authors.affiliation: Department of Internal Medicine, East Tennessee State University College of Medicine, Johnson City, TN, USA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Gazzar
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001665:Binding Sites; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D008297:Male; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008954:Models, Biological; D000072737:Myeloid-Derived Suppressor Cells / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D016160:Retinoblastoma Protein / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D018805:Sepsis / Q000235:genetics*
chemical_list: D015703:Antigens, CD; D022782:CCAAT-Enhancer-Binding Protein-beta; C531950:MIRN21 microRNA, mouse; D035683:MicroRNAs; D016160:Retinoblastoma Protein; D050796:STAT3 Transcription Factor; C529100:mirn181 microRNA, mouse