Processing of carcinoembryonic antigen by Kupffer cells: Recognition of a penta-peptide sequence
Processing of carcinoembryonic antigen by Kupffer cells: Recognition of a penta-peptide sequence
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DOI：
10.1006/abbi.1996.0440
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发表时间：
1996-10-01
影响因子：
3.9
通讯作者：
Thomas, P
中科院分区：
文献类型：
--
作者：
Gangopadhyay, A;Thomas, P
癌胚抗原（CEA）通过位于N和A1免疫球蛋白样结构域之间的铰链区域的肽序列PELPK（残基108-112）与库普ffer细胞上80 kda的细胞表面受体结合。本研究旨在分析肽结合的特异性，确定80-kDa受体的生物分布，以及该受体对CEA的加工。我们合成了一些携带PELPK的牛血清白蛋白（BSA）衍生物及其相关序列。用n -羟基琥珀酰酰-4-叠氮苯甲酸酯将一系列肽（YPELPK、YPDLPK、YPDLPR和YPELGK）偶联到牛血清白蛋白上。将I-125肽偶联物、CEA和BSA静脉注射到大鼠CEA中，pelpk -白蛋白偶联物被快速清除。其他肽缀合物和BSA的清除速度要慢得多。每克组织中i -125标记的CEA和pelpk -白蛋白偶联物的活性在肝脏和脾脏中最高。较高浓度的pelpk -白蛋白偶联物的存在抑制了I-125-CEA的清除。在离体大鼠Kupffer细胞中，只有CEA和pelpk -白蛋白偶联物在体外结合并内化，较高浓度的pelpk -白蛋白偶联物抑制CEA的结合。同样，未标记CEA的存在也抑制了pel派克-白蛋白偶联物的结合。利用异功能交联剂，通过sds -聚丙烯酰胺凝胶电泳（SDS-PAGE）证实了pelpk -白蛋白与库普弗细胞表面80 kda蛋白的反应。这种半合成配体（pelpk -白蛋白）使我们能够检查80 kda受体的功能，而不受CEA的其他特性的干扰，包括其结合凝集素的能力和引起细胞的同型聚集。CEA与80 kda受体结合的结果可能与结直肠癌肝转移的发展有关。(C) 1996学术出版社，Inc.
Carcinoembryonic antigen (CEA) binds to an 80-kDa cell surface receptor on Kupffer cells via the peptide sequence PELPK (residues 108-112) located at the hinge region between the N and A1 immunoglobulinlike domains. This study is aimed at analyzing the specificity of the peptide binding, determining biodistribution of 80-kDa receptor, and processing of CEA by this receptor. We synthesized a number of bovine serum albumin (BSA) derivatives carrying PELPK and related sequences. A series of peptides (YPELPK, YPDLPK, YPDLPR, and YPELGK) were conjugated to bovine serum albumin using N-hydroxysuccinimidyl-4-azidobenzoate. When I-125 peptide conjugates, CEA, and BSA were injected intravenously into rats CEA and the PELPK-albumin conjugate were cleared rapidly. The other peptide conjugates and BSA cleared at a much slower rate. Activity of I-125-labeled CEA and PELPK-albumin conjugate per gram of tissue was highest for the liver and spleen. Clearance of I-125-CEA was inhibited by the presence of higher concentrations of the PELPK-albumin conjugate. With isolated rat Kupffer cells, only CEA and the PELPK-albumin conjugate were bound and internalized in vitro and CEA binding was inhibited by higher concentrations of the PELPK-albumin conjugate. Similarly, binding of the PELPK-albumin conjugate was inhibited by the presence of unlabeled CEA. Use of a heterobifunctional cross linking agent demonstrated reaction of the PELPK-albumin with an 80-kDa protein on the Kupffer cell surface by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). This semisynthetic ligand (PELPK-albumin) allows us to examine the function of the 80-kDa receptor without interference due to other properties of CEA including its ability to bind lectins and to cause homotypic aggregation of cells. The consequences of CEA binding to the 80-kDa receptor may have implications in the development of hepatic metastasis from colorectal cancer. (C) 1996 Academic Press, Inc.