Fate of two mast cell tryptases in V3 mastocytosis and normal BALB/c mice undergoing passive systemic anaphylaxis: prolonged retention of exocytosed mMCP-6 in connective tissues, and rapid accumulation of enzymatically active mMCP-7 in the blood.
Fate of two mast cell tryptases in V3 mastocytosis and normal BALB/c mice undergoing passive systemic anaphylaxis: prolonged retention of exocytosed mMCP-6 in connective tissues, and rapid accumulation of enzymatically active mMCP-7 in the blood.
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DOI：
10.1084/jem.184.3.1061
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发表时间：
1996-09-01
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小鼠肥大细胞蛋白酶颗粒蛋白酶mMCP-6和mMCP-7是由位于17号染色体上的高度同源基因编码的。由于这些蛋白酶在肥大细胞被激活时被释放，我们通过检查它们在被动全身性过敏反应小鼠中的命运来寻找其独特功能的基础。免疫球蛋白e致敏小鼠10 min-1 h后，正常BALB/c小鼠大部分舌肥大细胞和心脏肥大细胞以及V3肥大细胞增多症小鼠大部分脾肥大细胞和肝肥大细胞附近的细胞外基质中出现大量蛋白酶/蛋白多糖大分子复合物。这些复合物可以被抗mMCP-6 Ig密集染色，而不能被抗mmcp -7 Ig密集染色。Ag攻毒后不久，在V3肥大细胞增多症小鼠血浆中检测到大量适当折叠的酶活性mMCP-7。这种血浆定位的胰蛋白酶在多聚体状态下约为150 kD，在单体状态下约为32 kD，具有与成熟的mMCP-7相同的NH2末端，并且不与任何蛋白酶抑制剂共价结合。比较蛋白质模型和静电计算结果表明，mMCP-6在远离活性位点的表面含有一个明显的富含赖氨酸/精氨酸的结构域。mMCP-7中该结构域的缺失为其选择性地与胞外化的大分子复合物分离提供了解释。胞吐的mMCP-6保留在活化的组织肥大细胞周围的细胞外基质中，表明它有局部作用。相比之下，mMCP-7从颗粒核心的快速耗散，以及它无法被循环蛋白酶抑制剂灭活，表明这种胰蛋白酶可以切割位于更远位点的蛋白质。
The mouse mast cell protease granule tryptases designated mMCP-6 and mMCP-7 are encoded by highly homologous genes that reside on chromosome 17. Because these proteases are released when mast cells are activated, we sought a basis for distinctive functions by examining their fates in mice undergoing passive systemic anaphylaxis. 10 min-1 h after antigen (Ag) was administered to immunoglobulin (Ig)E-sensitized mice, numerous protease/proteoglycan macromolecular complexes appeared in the extracellular matrix adjacent to most tongue and heart mast cells of normal BALB/c mice and most spleen and liver mast cells of V3 mastocytosis mice. These complexes could be intensively stained by anti- mMCP-6 Ig but not by anti-mMCP-7 Ig. Shortly after Ag challenge of V3 mastocytosis mice, large amounts of properly folded, enzymatically active mMCP-7 were detected in the plasma. This plasma-localized tryptase was approximately 150 kD in its multimeric state and approximately 32 kD in its monomeric state, possessed an NH2 terminus identical to that of mature mMCP-7, and was not covalently bound to any protease inhibitor. Comparative protein modeling and electrostatic calculations disclosed that mMCP-6 contains a prominent Lys/Arg-rich domain on its surface, distant from the active site. The absence of this domain in mMCP-7 provides an explanation for its selective dissociation from the exocytosed macromolecular complex. The retention of exocytosed mMCP-6 in the extracellular matrix around activated tissue mast cells suggests a local action. In contrast, the rapid dissipation of mMCP-7 from granule cores and its inability to be inactivated by circulating protease inhibitors suggests that this tryptase cleaves proteins located at more distal sites.