Boland K, Manias K, Perlmutter D H
Department of Pediatrics, Cell Biology, and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Biol Chem. 1995 Nov 24;270(47):28022-8. doi: 10.1074/jbc.270.47.28022.
The serpin-enzyme complex (SEC) receptor was originally identified using a synthetic peptide (peptide 105Y) based on the sequence of a candidate receptor-binding domain of alpha 1-antitrypsin (1-AT) and was subsequently shown to be a receptor on the surface of hepatocytes, monocytes, and neutrophils for recognition of alpha 1-AT-elastase and several other serpin-enzyme complexes (Perlmutter, D. H., Glover, G. I., Rivetna, M., Schasteen, C. S., and Fallon, R.J. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 3753-3757). Studies of the minimal requirements for binding to SEC receptor (SEC-R) showed that a pentapeptide FVFLM within the carboxyl-terminal tail of alpha 1-AT was sufficient for binding to SEC-R and interacted with SEC-R in a sequence-specific manner (Joslin, G., Krause, J. E., Hershey, A. D., Adams, S. P., Fallon, R. J., and Perlmutter, D. H. (1991) J. Biol. Chem. 266, 21897-21902). Sequence motifs bearing homology with this pentapeptide domain were found in the amyloid-beta peptide, and amyloid-beta peptide 1-42 was shown to compete for binding to SEC-R on hepatoma cells (Joslin, G., Fallon, R. J., Bullock, J., Adams, S. P., and Perlmutter, D. H. (1991) J. Biol. Chem, 266, 11281-11288). In this study we examined the sequence specificity by which amyloid-beta peptide competes for binding to SEC-R and examined the possibility that SEC-R is expressed in cells of neuronal origin. The results show that amyloid-beta-(25-35) and amyloid-beta-(31-35) compete for binding to SEC-R as effectively as amyloid-beta-(1-39), amyloid-beta-(1-40), and amyloid-beta-(1-42). Amyloid-beta-(1-16) does not compete for binding to SEC-R. There is cross-competition for binding to the same site by 125I-peptide 105Y and amyloid-beta-(25-35) as well as by 125I-Y amyloid-beta-(25-35) and peptide 105Y. By deletions and substitutions within amyloid-beta-(25-35) and generation of chimeric amyloid-beta-alpha 1-AT peptides, amyloid-beta-(31-35) is shown to be critical for binding to the SEC receptor. However, the upstream region, amyloid-beta-(25-30), also contributes to recognition by SEC-R. The SEC-R is present on the surface of a neuronal cell line PC12 as well as that of murine cortical neurons in primary culture, and the specificity of neuronal SEC-R for amyloid-beta peptide is identical to that on hepatoma cells. Finally SEC-R mediates internalization and degradation of amyloid beta-peptide in PC12 cells.(ABSTRACT TRUNCATED AT 400 WORDS)
丝氨酸蛋白酶抑制剂 - 酶复合物（SEC）受体最初是通过基于α1 - 抗胰蛋白酶（1 - AT）候选受体结合域序列的合成肽（肽105Y）鉴定出来的，随后被证明是肝细胞、单核细胞和中性粒细胞表面用于识别α1 - AT - 弹性蛋白酶及其他几种丝氨酸蛋白酶抑制剂 - 酶复合物的受体（佩尔穆特，D. H.，格洛弗，G. I.，里维特纳，M.，沙斯特恩，C. S.，和法伦，R. J.（1990年）《美国国家科学院院刊》87，3753 - 3757）。对与SEC受体（SEC - R）结合的最低要求的研究表明，α1 - AT羧基末端尾巴内的五肽FVFLM足以与SEC - R结合，并以序列特异性方式与SEC - R相互作用（乔斯林，G.，克劳斯，J. E.，赫希，A. D.，亚当斯，S. P.，法伦，R. J.，和佩尔穆特，D. H.（1991年）《生物化学杂志》266，21897 - 21902）。在β - 淀粉样肽中发现了与该五肽结构域具有同源性的序列基序，并且β - 淀粉样肽1 - 42被证明可竞争与肝癌细胞上的SEC - R结合（乔斯林，G.，法伦，R. J.，布洛克，J.，亚当斯，S. P.，和佩尔穆特，D. H.（1991年）《生物化学杂志》266，11281 - 11288）。在本研究中，我们研究了β - 淀粉样肽竞争与SEC - R结合的序列特异性，并研究了SEC - R在神经源性细胞中表达的可能性。结果表明，β - 淀粉样肽（25 - 35）和β - 淀粉样肽（31 - 35）与β - 淀粉样肽（1 - 39）、β - 淀粉样肽（1 - 40）和β - 淀粉样肽（1 - 42）一样有效地竞争与SEC - R结合。β - 淀粉样肽（1 - 16）不竞争与SEC - R结合。125I - 肽105Y和β - 淀粉样肽（25 - 35）以及125I - Yβ - 淀粉样肽（25 - 35）和肽105Y对同一结合位点存在交叉竞争。通过对β - 淀粉样肽（25 - 35）进行缺失和替换以及生成嵌合β - 淀粉样肽 - α1 - AT肽，表明β - 淀粉样肽（31 - 35）对于与SEC受体结合至关重要。然而，上游区域β - 淀粉样肽（25 - 30）也有助于SEC - R的识别。SEC - R存在于神经母细胞瘤细胞系PC12以及原代培养的小鼠皮质神经元表面，并且神经元SEC - R对β - 淀粉样肽的特异性与肝癌细胞上的相同。最后，SEC - R介导PC12细胞中β - 淀粉样肽的内化和降解。（摘要截断于400字）
