title: MiR-449a Affects Epithelial Proliferation during the Pseudoglandular and Canalicular Phases of Avian and Mammal Lung Development.
abstract: Congenital diaphragmatic hernia is associated with pulmonary hypoplasia and respiratory distress, which result in high mortality and morbidity. Although several transgenic mouse models of lung hypoplasia exist, the role of miRNAs in this phenotype is incompletely characterized. In this study, we assessed microRNA expression levels during the pseudoglandular to canalicular phase transition of normal human fetal lung development. At this critical time, when the distal respiratory portion of the airways begins to form, microarray analysis showed that the most significantly differentially expressed miRNA was miR-449a. Prediction algorithms determined that N-myc is a target of miR-449a and identified the likely miR-449a:N-myc binding sites, confirmed by luciferase assays and targeted mutagenesis. Functional ex vivo knock-down in organ cultures of murine embryonic lungs, as well as in ovo overexpression in avian embryonic lungs, suggested a role for miR-449a in distal epithelial proliferation. Finally, miR-449a expression was found to be abnormal in rare pulmonary specimens of human fetuses with Congenital Diaphragmatic Hernia in the pseudoglandular or canalicular phase. This study confirms the conserved role of miR-449a for proper pulmonary organogenesis, supporting the delicate balance between expansion of progenitor cells and their terminal differentiation, and proposes the potential involvement of this miRNA in human pulmonary hypoplasia.
authors.affiliation: Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Boston, MA, United States of America.|Health Sciences and Technology Medical Program, Harvard Medical School, Boston, MA, United States of America.|Department of Medicine, Boston Children's Hospital, Boston, MA, United States of America.
authors.forename: Ethan L
authors.initials: EL
authors.lastname: Sanford
authors.affiliation: Department of Obstetrics & Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Kwong W
authors.initials: KW
authors.lastname: Choy
authors.affiliation: Department of Surgery, Harvard Medical School, Boston, MA, United States of America.|Broad Institute of MIT and Harvard, Cambridge, MA, United States of America.
authors.forename: Patricia K
authors.initials: PK
authors.lastname: Donahoe
authors.affiliation: Department of Surgery, Harvard Medical School, Boston, MA, United States of America.|Broad Institute of MIT and Harvard, Cambridge, MA, United States of America.
authors.forename: Adam A
authors.initials: AA
authors.lastname: Tracy
authors.affiliation: Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Boston, MA, United States of America.
authors.forename: Regis
authors.initials: R
authors.lastname: Hila
authors.affiliation: Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Boston, MA, United States of America.|Department of Surgery, Harvard Medical School, Boston, MA, United States of America.
authors.forename: Maria
authors.initials: M
authors.lastname: Loscertales
authors.affiliation: Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Boston, MA, United States of America.|Department of Surgery, Harvard Medical School, Boston, MA, United States of America.
authors.forename: Mauro
authors.initials: M
authors.lastname: Longoni
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics; D049109:Cell Proliferation; D002645:Chickens; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008168:Lung / Q000196:embryology* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics*; D015513:Oncogene Proteins / Q000737:chemistry / Q000235:genetics; D038081:Organogenesis / Q000235:genetics*; D034622:RNA Interference; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D020413:3' Untranslated Regions; D035683:MicroRNAs; D015513:Oncogene Proteins; D012333:RNA, Messenger