Ecrg4 expression and its product augurin in the choroid plexus: impact on fetal brain development, cerebrospinal fluid homeostasis and neuroprogenitor cell response to CNS injury.
Ecrg4 expression and its product augurin in the choroid plexus: impact on fetal brain development, cerebrospinal fluid homeostasis and neuroprogenitor cell response to CNS injury.
复制标题
DOI：
10.1186/2045-8118-8-6
复制
发表时间：
2011-01-18
影响因子：
7.3
通讯作者：
Baird A
中科院分区：
文献类型：
--
作者：
Gonzalez AM;Podvin S;Lin SY;Miller MC;Botfield H;Leadbeater WE;Roberton A;Dang X;Knowling SE;Cardenas-Galindo E;Donahue JE;Stopa EG;Johanson CE;Coimbra R;Eliceiri BP;Baird A
脑脊液(CSF)的含量和组成在很大程度上由脉络丛(CP)决定，具体地说，是由一个专门的上皮细胞(CPE)层决定的，CPE层负责响应、合成和将多肽激素传入和传出脑脊液。这些CPE与室管膜细胞一起，在整个中枢神经系统(CNS)传递动态平衡信号，并调节脑脊液的流体动力学。一个新的候选信号是Auurin，它是一个新发现的14 kDa蛋白质，由食道癌相关基因-4(Ecrg4)编码，它是一个假定的肿瘤抑制基因，在正常组织中的存在和功能仍然是未知的。本研究的目的是探讨Ecrg4及其产物Auurin是否参与中枢神经系统的发育及其对中枢神经系统损伤的反应。用原位杂交和定量RT-PCR方法研究Ecrg4基因在中枢神经系统及周围组织中的表达。免疫印迹、免疫组织化学和酶联免疫吸附试验检测Ecrg4编码的蛋白Augurin。通过脑室注射含有Ecrg4基因的腺病毒载体，在大鼠中枢神经系统损伤的皮层刺激性损伤模型中研究了Auurin过度表达的生物学后果。通过对Ecrg4基因敲除导致的斑马鱼胚胎发育过程中中枢神经系统表型的研究，评估了Auurin表达降低的生物学后果。基因表达和免疫组织化学分析表明，CP是中枢神经系统中Ecrg4的主要来源，Ecrg4mRNA主要定位于脉络丛上皮(CPE)、脊髓的脑室和中央管细胞。然而，在大脑受到刺伤后，奥古林染色和Ecrg4基因的表达都急剧下降。如果在体内通过过表达Ecrg4来避免Auurin的丢失，室管膜下区细胞的BrdU掺入减少。相反，在发育中的斑马鱼胚胎中，Ecrg4基因敲除导致GFAP阳性细胞的增殖增加，并诱导出剂量依赖的脑积水样表型，这种表型可以通过联合注射反义吗啉和Ecrg4 mRNA来挽救。Ecrg4基因在CP中的异常高表达提示其产物Auurin在CP-CSF-CNS功能中发挥作用。这些结果都与一个模型一致，该模型认为损伤导致的奥古林障碍的减少抑制了室管膜-室管膜下交界处的靶细胞。我们推测CP和室管膜上皮改变祖细胞对中枢神经系统损伤的反应的能力可能部分是通过Ecrg4介导的。如果是这样的话，DNA甲基化对其启动子的经典控制可能涉及到神经前体在中枢神经系统的命运和功能的表观遗传机制。
The content and composition of cerebrospinal fluid (CSF) is determined in large part by the choroid plexus (CP) and specifically, a specialized epithelial cell (CPe) layer that responds to, synthesizes, and transports peptide hormones into and out of CSF. Together with ventricular ependymal cells, these CPe relay homeostatic signals throughout the central nervous system (CNS) and regulate CSF hydrodynamics. One new candidate signal is augurin, a newly recognized 14 kDa protein that is encoded by esophageal cancer related gene-4 (Ecrg4), a putative tumor suppressor gene whose presence and function in normal tissues remains unexplored and enigmatic. The aim of this study was to explore whether Ecrg4 and its product augurin, can be implicated in CNS development and the response to CNS injury. Ecrg4 gene expression in CNS and peripheral tissues was studied by in situ hybridization and quantitative RT-PCR. Augurin, the protein encoded by Ecrg4, was detected by immunoblotting, immunohistochemistry and ELISA. The biological consequence of augurin over-expression was studied in a cortical stab model of rat CNS injury by intra-cerebro-ventricular injection of an adenovirus vector containing the Ecrg4 cDNA. The biological consequences of reduced augurin expression were evaluated by characterizing the CNS phenotype caused by Ecrg4 gene knockdown in developing zebrafish embryos. Gene expression and immunohistochemical analyses revealed that, the CP is a major source of Ecrg4 in the CNS and that Ecrg4 mRNA is predominantly localized to choroid plexus epithelial (CPe), ventricular and central canal cells of the spinal cord. After a stab injury into the brain however, both augurin staining and Ecrg4 gene expression decreased precipitously. If the loss of augurin was circumvented by over-expressing Ecrg4 in vivo, BrdU incorporation by cells in the subependymal zone decreased. Inversely, gene knockdown of Ecrg4 in developing zebrafish embryos caused increased proliferation of GFAP-positive cells and induced a dose-dependent hydrocephalus-like phenotype that could be rescued by co-injection of antisense morpholinos with Ecrg4 mRNA. An unusually elevated expression of the Ecrg4 gene in the CP implies that its product, augurin, plays a role in CP-CSF-CNS function. The results are all consistent with a model whereby an injury-induced decrease in augurin dysinhibits target cells at the ependymal-subependymal interface. We speculate that the ability of CP and ependymal epithelium to alter the progenitor cell response to CNS injury may be mediated, in part by Ecrg4. If so, the canonic control of its promoter by DNA methylation may implicate epigenetic mechanisms in neuroprogenitor fate and function in the CNS.