Isolation, Cloning, and Characterization of a Novel Phosphomannan-binding Lectin from Porcine Serum*
Isolation, Cloning, and Characterization of a Novel Phosphomannan-binding Lectin from Porcine Serum*
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DOI：
10.1074/jbc.m611820200
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发表时间：
2007-04
影响因子：
4.8
通讯作者：
B. Y. Ma;Natsuko Nakamura;V. Dlabac;H. Naito;S. Yamaguchi;Makiko Ishikawa;M. Nonaka;M. Ishiguro;N. Kawasaki;S. Oka;T. Kawasaki
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文献类型：
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作者：
B. Y. Ma;Natsuko Nakamura;V. Dlabac;H. Naito;S. Yamaguchi;Makiko Ishikawa;M. Nonaka;M. Ishiguro;N. Kawasaki;S. Oka;T. Kawasaki
甘露聚糖结合蛋白（MBP）是一种C型血清凝集素，它是先天免疫防御的重要组成部分，因为它通过凝集素途径激活补体系统。虽然猪已被提出是一个有吸引力的来源，异种移植的组织和器官，很少有人知道猪MBP。在我们以前的研究中，磷酸甘露聚糖，而不是甘露聚糖，被发现是一种有效的抑制剂的C1 q独立的杀菌活性的新生仔猪血清对一些粗糙的革兰氏阴性菌菌株。相比之下，磷酸甘露聚糖和甘露聚糖的抑制活性在针对大肠杆菌K-12和S-16的粗糙菌株的MBP依赖性杀菌活性的情况下非常相似。基于这些发现，我们推断，MBP样凝集素与轻微或完全不同的碳水化合物结合特异性可能存在于新生仔猪血清中，并负责C1 q-独立的杀菌活性。在此，我们报告了一种新的磷酸甘露聚糖结合凝集素（PMBL）的33 kDa的还原条件下，从新生和成年猪血清中分离和表征。猪PMBL通过与磷酸甘露聚糖（P-甘露聚糖）和甘露聚糖结合触发的凝集素途径功能性激活补体系统，与MBP不同，其被含甘露糖6-磷酸或半乳糖的寡糖有效抑制。本研究结果表明，猪PMBL在新生期至成年期的先天免疫防御过程中起着重要作用，建立新生仔猪先天免疫系统实验模型对阐明凝集素途径的生理功能和分子机制具有重要意义。
Mannan-binding protein (MBP) is a C-type serum lectin that is an important constituent of the innate immune defense because it activates the complement system via the lectin pathway. While the pig has been proposed to be an attractive source of xenotransplantable tissues and organs, little is known about porcine MBP. In our previous studies, phosphomannan, but not mannan, was found to be an effective inhibitor of the C1q-independent bactericidal activity of newborn piglet serum against some rough strains of Gram-negative bacteria. In contrast, the inhibitory activities of phosphomannan and mannan were very similar in the case of MBP-dependent bactericidal activity against rough strains of Escherichia coli K-12 and S-16. Based on these findings, we inferred that an MBP-like lectin with slightly or completely different carbohydrate binding specificity might exist in newborn piglet serum and be responsible for the C1q-independent bactericidal activity. Herein we report that a novel phosphomannan-binding lectin (PMBL) of 33 kDa under reducing conditions was isolated from both newborn and adult porcine serum and characterized. Porcine PMBL functionally activated the complement system via the lectin pathway triggered by binding with both phosphomannan (P-mannan) and mannan, which, unlike MBP, was effectively inhibited by mannose 6-phosphate- or galatose-containing oligosaccharides. Our observations suggest that porcine PMBL plays a critical role in the innate immune defense from the newborn stage to adult-hood, and the establishment of a newborn piglet experimental model for the innate immune system studies is a valuable step toward elucidation of the physiological function and molecular mechanism of lectin pathway.