Endocytosis Mutants: Antigen Processing

内吞作用在许多过程中起着重要作用，包括营养摄取、生长因子作用、抗原呈递和维持质膜组成。体细胞遗传学已成功地用于分析复杂的内吞系统的比例。为了刺激T淋巴细胞，大多数蛋白抗原必须被切割成肽结构域，并与主要组织相容性复合体（MHC）的产物一起在抗原呈递细胞表面表达。为了提供与抗原呈递相关的特定酶的信息，我们将采用流动分选的方法分离组织蛋白酶B（一种内源性蛋白酶）缺陷的抗原呈递细胞系突变体。这些突变体向T细胞呈递抗原的能力将被确定。这些假定的突变体将有助于探索抗原呈递的机制，在体外重建内吞过程，以及分析水解酶被递送到内吞室的途径。细胞外环境物质的内化（内吞作用）是细胞的基本功能。在依赖于内吞作用的重要生理过程中，某些细胞类型（抗原呈递细胞）将免疫原性外来物质（抗原）加工和呈递给免疫系统的其他细胞。提出的研究将增强我们对外来抗原如何在抗原提呈细胞中加工的理解。这一知识不仅从免疫反应的角度来看是重要的，而且因为它将进一步深入了解细胞外物质通过内吞作用进入细胞的命运。

Endocytosis plays a fundamental role in a number of processes, including nutrient uptake, growth factor action, antigen presentation and maintenance of plasma membrane composition. Somatic cell genetics has been successfully used to analyze protions of the complex endocytic system. In order to stimulate T lymphocytes, most protein antigens must be cleaved into peptide domains and expressed on the surface of an antigen-presenting cell in association with the products of the major histocompatibility complex (MHC). To provide information about the specific enzymes involved in antigen presentation, mutants of an antigen-presenting cell line which are defective in cathepsin B, an endoprotease, will be isolated by flow sorting. The ability of these mutants to present antigen to T cells will be determined. The putative mutants will be useful in exploring the mechanism of antigen presentation, in reconstituting endocytic processing in vitro, and in analyzing the pathways by which hydrolytic enzymes are delivered to endocytic compartments. Internalization of materials from the extracellular environment (endocytosis) is a fundamental cellular function. Among the important physiological processes that depend upon endocytosis is the processing and presentation of immunogenic foreign substances (antigens) by certain cell types (antigen-presenting cells) to other cells of the immune system. The proposed research will enhance our understanding of how foreign antigens are processed in antigen presenting cells. This knowledge will be important not only from the point of view of the immune response, but also because it will provide further insight into the fate of extracellular materials taken into cells by endocytosis.