Galectin-8 and galectin-9 are novel substrates for thrombin
Galectin-8 and galectin-9 are novel substrates for thrombin
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DOI：
10.1093/glycob/cwl028
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发表时间：
2006-11-01
期刊：
影响因子：
4.3
通讯作者：
Nakamura, Takanori
中科院分区：
文献类型：
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作者：
Nishi, Nozomu;Itoh, Aiko;Nakamura, Takanori
半乳糖凝集素-8和半乳糖凝集素-9各自由通过接头肽连接的两个碳水化合物识别结构域（CRD）组成，属于半乳糖凝集素家族的串联重复类型亚类。选择性剪接分别导致半乳糖凝集素-8和9的至少两种和三种不同的剪接变体（同种型）的形成，具有串联重复类型结构。同种型共享相同的CRD，仅在接头区不同。在寻找同种型之间的生物活性差异时，我们发现它们具有最长接头肽的同种型，即半乳糖凝集素-8L和半乳糖凝集素-9L（G8 L和G9 L），对凝血酶切割高度敏感，而主要同种型，半乳糖凝集素-8M和半乳糖凝集素-9M（G8 M和G9 M），以及迄今为止检测的人半乳糖凝集素家族的其他成员对凝血酶具有抗性。蛋白水解片段的氨基酸序列分析和定点诱变显示凝血酶切割位点（分别为G8 L和G9 L的-IAPRT-和-PRPRG-）位于接头肽内。虽然完整的G8 L刺激中性粒细胞粘附底物比G8 M更有效，活性G8 L，但不是G8 M的凝血酶消化降低。类似地，凝血酶处理几乎完全消除了G9 L的嗜酸性粒细胞化学引诱物（ECA）活性。这些观察结果表明，G8 L和G9 L在凝血和炎症方面发挥独特的作用。
Galectin-8 and galectin-9, which each consist of two carbohydrate recognition domains (CRDs) joined by a linker peptide, belong to the tandem-repeat-type subclass of the galectin family. Alternative splicing leads to the formation of at least two and three distinct splice variants (isoforms) of galectin-8 and galectin-9, respectively, with tandem-repeat-type structures. The isoforms share identical CRDs and differ only in the linker region. In a search for differences in biological activity among the isoforms, we found that their isoforms with the longest linker peptide, that is, galectin-8L and galectin-9L (G8L and G9L), are highly susceptible to thrombin cleavage, whereas the predominant isoforms, galectin-8M and galectin-9M (G8M and G9M), and other members of human galectin family so far examined were resistant to thrombin. Amino acid sequence analysis of proteolytic fragments and site-directed mutagenesis showed that the thrombin cleavage sites (-IAPRT- and -PRPRG- for G8L and G9L, respectively) resided within the linker peptides. Although intact G8L stimulated neutrophil adhesion to substrate more efficiently than G8M, the activity of G8L but not that of G8M decreased on thrombin digestion. Similarly, thrombin treatment almost completely abolished eosinophil chemoattractant (ECA) activity of G9L. These observations suggest that G8L and G9L play unique roles in relation to coagulation and inflammation.