Zhou H, Hughes D E, Major M L, Yoo K, Pesold C, Costa R H
Department of Molecular Genetics, University of Illinois at Chicago, College of Medicine, 60607, USA.
Gene Expr. 2001;9(4-5):217-36. doi: 10.3727/000000001783992597.
To assess the role of hepatocyte nuclear factor-3beta (HNF-3beta) in hepatocyte-specific gene transcription, we reported the characterization of the liver phenotype with transgenic mice in which the -3-kb transthyretin (TTR) promoter functioned to increase HNF-3beta expression. During breeding of the TTR-HNF-3beta transgenic mice we noticed that they displayed severe ataxia. In this study, we describe the analysis of our transgenic cerebellar phenotype and demonstrate that ectopic expression of HNF-3beta disrupted cerebellar morphogenesis and caused reduction in cerebellar size. In postnatal cerebellum, the HNF-3beta transgene expression pattern is colocalized to glial fibrillary acidic protein-positive cerebellar astrocytes and Bergmann glial cells. As a result of protracted expression, the transgenic cerebella are impaired in terms of astrocyte dispersal and formation of Bergmann glial cell processes. This caused a disruption in neuronal cell migration to the cortical laminar layers and Purkinje dendritic arbor maturation, thus leading to diminished foliation. Differential hybridization of cDNA arrays was used to identify altered expression of cerebellar genes, which is consistent with the observed defect in transgenic cerebellar morphogenesis and size as well as glial maturation. These include diminished expression of the brain lipid-binding protein, which is required for glial morphological differentiation, and the basic helix-loop-helix NeuroD/Beta2 and homeodomain Engrailed-2 transcription factors, which are required for normal cerebellar morphogenesis and foliation. Undetectable levels of ataxia telangiectasia (ATM), which is required for proper development of the Purkinje dendritic arbor, were found in postnatal transgenic cerebella. Furthermore, the transgenic cerebella displayed levels of insulin-like growth factor binding protein-1 elevated to 22 times greater than those measured for wild-type cerebella, an elevation consistent with the reduction in transgenic cerebellar size.
为评估肝细胞核因子-3β（HNF-3β）在肝细胞特异性基因转录中的作用，我们报道了用转基因小鼠对肝脏表型的特征描述，其中-3 kb转甲状腺素蛋白（TTR）启动子发挥作用以增加HNF-3β的表达。在TTR-HNF-3β转基因小鼠的繁殖过程中，我们注意到它们表现出严重的共济失调。在本研究中，我们描述了对转基因小脑表型的分析，并证明HNF-3β的异位表达破坏了小脑形态发生并导致小脑尺寸减小。在出生后的小脑中，HNF-3β转基因表达模式与胶质纤维酸性蛋白阳性的小脑星形胶质细胞和伯格曼胶质细胞共定位。由于长期表达，转基因小脑在星形胶质细胞扩散和伯格曼胶质细胞突起形成方面受损。这导致神经元细胞向皮质层状层迁移以及浦肯野树突状分支成熟受到破坏，从而导致叶片减少。利用cDNA阵列的差异杂交来鉴定小脑基因表达的改变，这与在转基因小脑形态发生、大小以及胶质细胞成熟中观察到的缺陷一致。这些包括胶质细胞形态分化所需的脑脂质结合蛋白表达减少，以及正常小脑形态发生和叶片形成所需的碱性螺旋-环-螺旋NeuroD/Beta2和同源结构域En-2转录因子表达减少。在出生后的转基因小脑中未检测到共济失调毛细血管扩张症（ATM）水平，而ATM是浦肯野树突状分支正常发育所必需的。此外，转基因小脑显示胰岛素样生长因子结合蛋白-1水平升高至比野生型小脑测量值高22倍，这种升高与转基因小脑尺寸减小一致。
