Kim Jinny J, Jiwani Tayyaba, Erwood Steven, Loree Jillian, Rosenblum Norman D
Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada.
Department of Physiology, University of Toronto, Medical Sciences Building, Toronto, ON, Canada.
Dev Dyn. 2018 Jan;247(1):156-169. doi: 10.1002/dvdy.24526. Epub 2017 Jun 15.
Deficiency of Suppressor of Fused (SuFu), an intracellular mediator of Hedgehog signaling, in the murine mid-hindbrain disrupts cerebellar morphogenesis and cell differentiation in a manner that is rescued by constitutive expression of GLI3 transcriptional repressor (GLI3R). Here, we determined SuFu functions in cerebellar radial precursors following the stage of mid-hindbrain specification using a Blbp-Cre transgene.
SuFu-deficient cerebella were severely dysplastic, and characterized by laminar disorganization, and delayed differentiation of ventricular zone-derived precursors. In vitro analysis of cerebellar precursors isolated from control and mutant mice demonstrated an increased proportion of radial glial precursors vs. Tuj1-positive neurons in mutant cultures. Abnormal cell differentiation in SuFu-deficient precursors was rescued by a constitutively expressed GLI3R knock-in allele, albeit with variable penetrance. Using RNA expression analysis in control and SuFu-deficient cerebellar anlage, we identified up-regulation of Fgf15 in mutant tissue. Strikingly, exogenous hFGF19, a mFGF15 ortholog, inhibited neuronal differentiation in cultures of wild-type cerebellar precursors. Moreover, siRNA-mediated knockdown of Fgf15 in SuFu-deficient cerebellar precursors rescued their delayed differentiation to neurons.
Together, our results show that SuFu promotes cerebellar radial precursor differentiation to neurons. SuFu function is mediated in part by GLI3R and down-regulation of Fgf15 expression. Developmental Dynamics 247:156-169, 2018. © 2017 Wiley Periodicals, Inc.
在小鼠中脑-后脑，作为Hedgehog信号通路细胞内介质的融合抑制因子（SuFu）的缺失会以一种可被GLI3转录抑制因子（GLI3R）的组成型表达所挽救的方式破坏小脑形态发生和细胞分化。在此，我们使用Blbp-Cre转基因确定了SuFu在中脑-后脑特化阶段之后的小脑放射状前体细胞中的功能。
SuFu缺陷型小脑严重发育异常，其特征为层状结构紊乱以及脑室区来源的前体细胞分化延迟。对从对照小鼠和突变小鼠分离出的小脑前体细胞进行的体外分析表明，在突变培养物中，放射状胶质前体细胞与Tuj1阳性神经元的比例增加。尽管具有可变的外显率，但组成型表达的GLI3R敲入等位基因挽救了SuFu缺陷型前体细胞中的异常细胞分化。通过对对照和SuFu缺陷型小脑原基进行RNA表达分析，我们在突变组织中鉴定出Fgf15上调。引人注目的是，外源性人FGF19（小鼠FGF15的直系同源物）抑制了野生型小脑前体细胞培养物中的神经元分化。此外，在SuFu缺陷型小脑前体细胞中，siRNA介导的Fgf15敲低挽救了它们向神经元的延迟分化。
总之，我们的结果表明SuFu促进小脑放射状前体细胞向神经元分化。SuFu的功能部分由GLI3R介导，并通过下调Fgf15表达来实现。《发育动力学》247:156 - 169，2018年。© 2017威利期刊公司。
