INTESTINAL & PLACENTAL FC-RECEPTORS FOR IMMUNOGLOBULIN

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基本信息

批准号：
2402980
负责人：
NEIL E SIMISTER
金额：
$ 6.92万
依托单位：
BRANDEIS UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1996
资助国家：
美国
起止时间：
1996-06-01 至 2001-05-30
项目状态：
已结题

项目摘要

Acquisition of maternal antibodies is critical to the immunologic defense of the newborn. In suckling rats and mice, a receptor for the Fc region of immunoglobulin G (IgG) transports IgG from milk across the intestinal epithelium into the blood (FcRn, n for neonate). FcRn is very similar in structure to class I major histocompatibility complex proteins. Late in gestation, the same receptor appears to transport IgG across the fetal yolk sac in these species. Prenatal transport accounts for only a small fraction of the maternal IgG that rodents receive, but in humans IgG transport occurs mostly, and perhaps only, before birth. A homolog of FcRn is expressed in human placenta and is likely to mediate materno-fetal IgG transport. A major goal of the proposal is to determine whether human FcRn is indeed responsible for placental IgG transport. Specific aims toward this goal include the localization of FcRn in human placenta by immunocytochemistry and in situ hybridization. The presence of the receptor in one or both of the cellular barriers between maternal and fetal blood, the syncytiotrophoblast and fetal vessel endothelia, would be consistent with a transport role. The specificity of human FcRn for different human IgG subclasses, measured by a competitive binding assay, will be compared with the relative efficiency of placental transport of these subclasses. A relatively low affinity for IgG2, which is transported poorly, would suggest that FcRn has a role in IgG transport from mother to fetus. The molecular mechanism of transcytosis of IgG by FcRn is not known. The second major goal of this proposal is to determine how this process occurs. Specific aims related to this goal include the characterization of the trafficking of rat FcRn functionally expressed in the polarized Madin-Darby canine kidney (MDCK) cell line. Sorting signals in the cytoplasmic region of rat FcRn will be located by site-directed mutagenesis, and expression of mutant receptors in MDCK cells. Proteins that interact with sorting signals will be sought using a yeast two-hybrid method. The funding of this RCDA would allow a 50% increase in the time available to the P.I. for research. This additional time would be particularly valuable now, because the emphasis of the project is shifting from the molecular biology methods in which the laboratory personnel have been trained to cell biology techniques that the P.I. must teach. In order to complete the proposed research it will also be necessary for the P.I. to learn new experimental methods. The reduction in non-research responsibilities would facilitate the timely completion of the project. Lastly, the proposed work almost completes the studies that follow directly from the discovery by the P.I. of MHC class I-related FcRs, and additional time will be essential to consider and plan future research directions.

获得母体抗体对于免疫防御至关重要新生儿。在吮吸大鼠和小鼠中，FC区域的受体免疫球蛋白G（IgG）从牛奶中运输IgG 上皮进入血液（FCRN，n用于新生儿）。 FCRN非常相似 I类主要组织相容性复合蛋白的结构。迟到妊娠，同一受体似乎在胎儿跨过IgG 这些物种中的蛋黄囊。产前运输只有一个小账户啮齿动物收到的母体IgG的一部分，但在人类IgG中运输主要发生，甚至可能是出生前。一个同源 FCRN在人胎盘中表达，很可能介导materno-fetal IgG运输。该提案的主要目标是确定人类FCRN是否确实是负责胎盘IgG运输。针对这个目标的具体目标包括通过免疫细胞化学在人胎盘中的定位和原位杂交。受体在一个或两个中的存在母体和胎儿血液之间的细胞屏障，合胞素成素细胞和胎儿血管内皮与运输角色。人类FCRN对不同人类IgG的特异性通过竞争结合测定法测量的子类将与这些亚类的胎盘运输的相对效率。一个对IgG2的相对较低的亲和力（运输较差）将表明FCRN在从母亲到胎儿的IgG运输中起作用。 FCRN尚不清楚通过FCRN对IgG的转胞细胞增多的分子机制。这该提案的第二个主要目标是确定该过程如何发生。与此目标有关的具体目的包括特征在极化中功能表达的大鼠FCRN的运输 Madin-Darby犬肾（MDCK）细胞系。在大鼠FCRN的细胞质区域将通过位置定向 MDCK细胞中突变受体的诱变和表达。蛋白质与排序信号相互作用将使用酵母两杂交寻求方法。此RCDA的资金将使可用时间增加50％到P.I.进行研究。这个额外的时间尤其是现在有价值，因为该项目的重点是从实验室人员的分子生物学方法经过P.I.的细胞生物学技术训练必须教。为了完成拟议的研究，P.I.到学习新的实验方法。非研究的减少责任将有助于及时完成该项目。最后，拟议的工作几乎完成了随后的研究直接来自P.I.的发现MHC I类相关的FCR和额外的时间对于考虑和计划未来的研究至关重要方向。