Download MicroRNA ablation affects Bergmann glial morphology and disrupts

Title: MicroRNA ablation affects Bergmann glial morphology and disrupts tissue
morphogenesis in the developing mouse cerebellum
Yi Kuang1, 4, 6, Qian Liu1, 6, Ning Huang1, 4, Jun Li1, Xiaoqiong Shu1, Chi Zhang1, 4, Mei
Jiang1, Q. Richard Lu5 and Hedong Li1, 2, 3, *
1
West China Developmental & Stem Cell Institute, 2Department of Pediatrics, 3Key
Laboratory of Obstetric＆Gynecologic and Pediatric Diseases and Birth Defects,
Ministry of Education, West China Second University Hospital, 4School of Life Science,
Sichuan University, Chengdu 610041, P.R. China
5
Department of Developmental Biology, University of Texas Southwestern Medical
Center, Dallas, TX 75390, USA
6
These authors contributed equally to this work
*Correspondence should be addressed to:
Dr. Hedong Li
Tel. 86-28-85501982
E-mail: [email protected]
Keywords: hGFAP, miR-9, Dicer, Cre-flox, Bergmann glia.
Abstract:
MicroRNAs (miRNAs) play important roles during development of the central nervous
system (CNS). Several reports indicate that tissue development and cellular
differentiation in the developing forebrains are disrupted in the absence of miRNAs.
However, miRNA functions during cerebellar development have not been systematically
characterized. Here we conditionally knockout Dicer gene under the activity of human
glial fibrillary acidic protein (hGFAP) promoter to examine the effect of miRNAs in the
developing cerebellum. We found that ablation of miRNAs resulted in a smaller
cerebellum, mis-positioned Purkinje neurons, decreased proliferation and increased
apoptosis in granule neuron precursors, decreased number of basket and stellate
interneurons and aberrant morphology of Bergmann glia. In addition, Notch1 signaling
appears to be blocked in miRNA-ablated Bergmann glia. We further identified miR-9 as
differentially expressed in Bergmann glial cells, and its expression was promoted by
Notch1 activation. We also demonstrated that cortical radial glia exhibited normal
morphology in the absence of miRNAs and yet reduced radial glial marker expression at
embryonic stage, and that the postnatal radial glial transition to astrocytes was promoted
in miRNA-ablated forebrains. These results further stressed the critical involvement of
miRNAs in the developing CNS including cerebellum and provided first evidence of
differential miRNA function in regulating radial glial phenotype in different regions of
the developing CNS.