Dicer1 Ablation Impairs Responsiveness of Cerebellar Granule Neuron Precursors to Sonic Hedgehog and Disrupts Expression of Distinct Cell Cycle Regulator Genes.
Granule neuron precursors (GNPs) proliferate under the influence of Sonic hedgehog (Shh) that is secreted by Purkinje neurons during early postnatal cerebellar development. To investigate microRNA (miRNA) function in this developmental process, we conditionally deleted the Dicer1 gene under the activity of human glial fibrillary acidic protein (hGFAP) promoter. We report that Dicer1-ablated GNPs display decreased proliferation and survival at early postnatal stages and that the proliferation defect of mutant GNPs cannot be rescued by treatment of an Shh agonist in vitro as assayed by 5-bromo-2'-deoxyuridine (BrdU) pulse labeling and Shh target gene expression detection. Further analysis reveals that the expression of distinct cell cycle regulator genes including cell cycle inhibitor, CDKN1a (p21), selectively increases in Dicer1-ablated GNPs. Subsequently, we demonstrate that miR-17-5p exhibits high expression level in the developing cerebellum and that transfection of a synthetic miR-17-5p mimic downregulates p21 protein expression in GNPs and promotes proliferation of GNPs in culture. Therefore, Dicer1 ablation impairs Shh-induced GNP proliferation by disrupting the expression of distinct cell cycle regulator genes that are targets of miR-17∼92 cluster members. This study establishes a molecular link between miRNAs and cell cycle progression in the proliferating GNPs during normal cerebellar development and may facilitate miRNA application in treating medulloblastoma.
West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
Qian
Q
Liu
West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
Mei
M
Jiang
West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.|School of Life Science, Sichuan University, Chengdu, 610041, People's Republic of China.
Yi
Y
Kuang
West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
Xiaoqiong
X
Shu
West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
Jun
J
Li
QSI International School of Chengdu, Chengdu, 610041, People's Republic of China.
Matthew W
MW
Li
West China Developmental & Stem Cell Institute, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China. hedongli@scu.edu.cn.|Department of Obstetric & Gynecologic and Pediatric, West China Second University Hospital, Sichuan University, Chengdu, 610041, People's Republic of China. hedongli@scu.edu.cn.|Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, 610041, People's Republic of China. hedongli@scu.edu.cn.
Hedong
H
Li
D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002531:Cerebellum / Q000254:growth & development* / Q000378:metabolism* / Q000473:pathology; D053487:DEAD-box RNA Helicases / Q000172:deficiency* / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D053823:Hedgehog Proteins / Q000819:agonists / Q000378:metabolism*; D006801:Humans; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000378:metabolism; D058953:Neural Stem Cells / Q000378:metabolism* / Q000473:pathology; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic; D043244:Ribonuclease III / Q000172:deficiency* / Q000235:genetics
D005904:Glial Fibrillary Acidic Protein; D053823:Hedgehog Proteins; D035683:MicroRNAs; C465570:Shh protein, mouse; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases
CDKN1a (p21); Cerebellum; Dicer (Dicer1); miR-17∼92; miRNA-sensitive (MRS) target gene; microRNA