title: MicroRNAs Promote Granule Cell Expansion in the Cerebellum Through Gli2.
abstract: MicroRNAs (miRNAs) are important regulators of cerebellar function and homeostasis. Their deregulation results in cerebellar neuronal degeneration and spinocerebellar ataxia type 1 and contributes to medulloblastoma. Canonical miRNA processing involves Dicer, which cleaves precursor miRNAs into mature double-stranded RNA duplexes. In order to address the role of miRNAs in cerebellar granule cell precursor development, loxP-flanked exons of Dicer1 were conditionally inactivated using the granule cell precursor-specific Atoh1-Cre recombinase. A reduction of 87% in Dicer1 transcript was achieved in this conditional Dicer knockdown model. Although knockdown resulted in normal survival, mice had disruptions to the cortical layering of the anterior cerebellum, which resulted from the premature differentiation of granule cell precursors in this region during neonatal development. This defect manifested as a thinner external granular layer with ectopic mature granule cells, and a depleted internal granular layer. We found that expression of the activator components of the Hedgehog-Patched pathway, the Gli family of transcription factors, was perturbed in conditional Dicer knockdown mice. We propose that loss of Gli2 mRNA mediated the anterior-restricted defect in conditional Dicer knockdown mice and, as proof of principle, were able to show that miR-106b positively regulated Gli2 mRNA expression. These findings confirm the importance of miRNAs as positive mediators of Hedgehog-Patched signalling during granule cell precursor development.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St Lucia, Queensland, 4072, Australia. l.constantin@uq.edu.au.
authors.forename: Lena
authors.identifier: http://orcid.org/0000-0003-1492-3845
authors.initials: L
authors.lastname: Constantin
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, St Lucia, Queensland, 4072, Australia.
authors.forename: Brandon J
authors.initials: BJ
authors.lastname: Wainwright
mesh_terms: D000818:Animals; D002531:Cerebellum / Q000254:growth & development* / Q000473:pathology / Q000502:physiology*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000378:metabolism*; D058953:Neural Stem Cells / Q000473:pathology / Q000502:physiology; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000473:pathology / Q000502:physiology*; D009929:Organ Size; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism*; D000075746:Zinc Finger Protein Gli2
chemical_list: C000618551:Gli2 protein, mouse; D051741:Kruppel-Like Transcription Factors; D035683:MicroRNAs; C543896:Mirn106 microRNA, mouse; D012333:RNA, Messenger; D000075746:Zinc Finger Protein Gli2; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases
keywords: Cerebellum; Dicer1 protein; Gli2 protein; Growth and development; Mirn106 microRNA; Mouse