Placental Endogenous Retrovirus Expression

描述（由申请人提供）：大约1%的人类基因组似乎是源自逆转录病毒。这些“内源性”逆转录病毒因子在人类发育中的作用尚不清楚。少数器官在生理条件下表达内源性逆转录病毒；人类胎盘就是其中之一。正常人胎盘绒毛细胞滋养细胞表达内源性逆转录病毒基因组（ERV-3） env区域的分化相关转录。ERV-3的表达与正常滋养细胞分化的强烈关联表明，ERV-3在胎盘发育中具有生理作用。为了支持这一假设，有以下观察结果。1) ERV-3 env mRNA和env蛋白在合胞滋养细胞和自发分化的单核绒毛细胞滋养细胞中表达升高。2) ERV-3 env mRNA的分化相关增加与b-hCG mRNA和蛋白的增加以及细胞间融合同时发生。3)转染BeWo绒毛膜癌细胞作为滋养层分化的模型，以ERV-3 env的意义链转染，得到稳定的转染物，滋养层分化的大多数方面发生：生长减少，形态分化，b-hCG mRNA和hCG蛋白的产生增加。4)在诱导细胞分化时，转染反义链可减少b-hCG mRNA的产生。这些初步数据支持了一个假设，即ERV-3 env的表达是正常滋养细胞分化途径中的一个重要步骤，可能通过调节hCG的表达。该R03申请的具体目的是为成功的R01申请积累足够的初步数据，以检验这一假设，个人具体目标是：目标1)是开发试剂，例如单克隆抗体和转染诱导质粒系统的细胞系，用于研究ERV3 env在绒毛滋养细胞分化中的作用；目的2)确定新分离的绒毛细胞滋养细胞分化是否需要ERV-3 env表达；目的3)确定类固醇是否可诱导ERV-3 env表达。选择这些特定的目标是为了解决以前不成功的R01应用程序中提出的问题。

DESCRIPTION (provided by applicant): Approximately 1% of the human genome appears to be of retroviral origin. The purpose of these "endogenous" retroviral elements in human development remains unknown. A small number of organs express endogenous retroviruses under physiologic conditions; the human placenta is one of these. The normal human placental villous cytotrophoblast expresses differentiation-related transcription of the env region of a single copy endogenous retroviral genome (ERV-3). The strong association of ERV-3 expression with normal trophoblast differentiation suggests a physiologic role for ERV-3 in placental development. In support of this hypothesis, are the following observations. 1) ERV-3 env mRNA and Env protein are increased in syncytiotrophoblast and in spontaneously differentiating mononuclear villous cytotrophoblast. 2) Differentiation-related increase in ERV-3 env mRNA is concurrent with increased b-hCG mRNA and protein and intercellular fusion. 3) Transfection of BeWo choriocarcinoma cells, a model for trophoblast differentiation, with the sense strand of ERV-3 env resulted in a stable transfectant in which most aspects of trophoblast differentiation occurred: decreased growth, morphologic differentiation, and increased b-hCG mRNA and hCG protein production. 4) Transfection with the antisense strand decreased b-hCG mRNA production when the cells were induced to differentiate. These preliminary data support a hypothesis that ERV-3 env expression is an important step in the pathway of normal trophoblast differentiation, potentially through regulation of hCG expression. The specific aim of this R03 application is to accumulate adequate preliminary data for a successful R01 application to test this hypothesis, The individual specific Aims are: Aim 1) is to develop reagents, e.g.,monoclonal antibody and cell lines transfected with inducible plasmid systems, for studying the role of ERV3 env in villous trophoblast differentiation; Aim 2) is to determine whether ERV-3 env expression is necessary for differentiation of freshly isolated villous cytotrophoblasts; and Aim 3) is to determine whether ERV-3 env expression is inducible by steroids. These specific aims were chosen to address issues raised in previously unsuccessful R01 applications.