title: Dicer deficiency reveals microRNAs predicted to control gene expression in the developing adrenal cortex.
abstract: MicroRNAs (miRNAs) are small, endogenous, non-protein-coding RNAs that are an important means of posttranscriptional gene regulation. Deletion of Dicer, a key miRNA processing enzyme, is embryonic lethal in mice, and tissue-specific Dicer deletion results in developmental defects. Using a conditional knockout model, we generated mice lacking Dicer in the adrenal cortex. These Dicer-knockout (KO) mice exhibited perinatal mortality and failure of the adrenal cortex during late gestation between embryonic day 16.5 (E16.5) and E18.5. Further study of Dicer-KO adrenals demonstrated a significant loss of steroidogenic factor 1-expressing cortical cells that was histologically evident as early as E16.5 coincident with an increase in p21 and cleaved-caspase 3 staining in the cortex. However, peripheral cortical proliferation persisted in KO adrenals as assessed by staining of proliferating cell nuclear antigen. To further characterize the embryonic adrenals from Dicer-KO mice, we performed microarray analyses for both gene and miRNA expression on purified RNA isolated from control and KO adrenals of E15.5 and E16.5 embryos. Consistent with the absence of Dicer and the associated loss of miRNA-mediated mRNA degradation, we observed an up-regulation of a small subset of adrenal transcripts in Dicer-KO mice, most notably the transcripts coded by the genes Nr6a1 and Acvr1c. Indeed, several miRNAs, including let-7, miR-34c, and miR-21, that are predicted to target these genes for degradation, were also markedly down-regulated in Dicer-KO adrenals. Together these data suggest a role for miRNA-mediated regulation of a subset of genes that are essential for normal adrenal growth and homeostasis.
authors.affiliation: Program in Cellular and Molecular Biology, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Krill
authors.forename: Katherine
authors.initials: K
authors.lastname: Gurdziel
authors.forename: Joanne H
authors.initials: JH
authors.lastname: Heaton
authors.forename: Derek P
authors.initials: DP
authors.lastname: Simon
authors.forename: Gary D
authors.initials: GD
authors.lastname: Hammer
mesh_terms: D000302:Adrenal Cortex / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D001483:Base Sequence; D017252:CD3 Complex / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D016923:Cell Death / Q000235:genetics; D049109:Cell Proliferation; D017124:Conserved Sequence / Q000235:genetics; D053487:DEAD-box RNA Helicases / Q000172:deficiency / Q000378:metabolism*; D004249:DNA Damage / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D047108:Embryonic Development / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D019426:Integrases / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D043244:Ribonuclease III / Q000172:deficiency / Q000378:metabolism*; D012984:Software; D016019:Survival Analysis; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D017252:CD3 Complex; D053487:DEAD-box RNA Helicases; D019426:Integrases; D035683:MicroRNAs; D012333:RNA, Messenger; D043244:Ribonuclease III; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C045073:Cre recombinase; C509781:Dicer1 protein, mouse