Hyaluronidase-4 is produced by mast cells and can cleave serglycin chondroitin sulfate chains into lower molecular weight forms
Hyaluronidase-4 is produced by mast cells and can cleave serglycin chondroitin sulfate chains into lower molecular weight forms
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DOI：
10.1074/jbc.ra119.008647
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发表时间：
2019-07-26
影响因子：
4.8
通讯作者：
Whitelock, John M.
中科院分区：
文献类型：
--
作者：
Farrugia, Brooke L.;Mizumoto, Shuji;Whitelock, John M.
肥大细胞代表一种异质细胞群，众所周知，肥大细胞在激活时会产生肝素并释放组胺。丝氨酸是肥大细胞α颗粒内的一种蛋白多糖，主要由糖胺多聚糖、肝素或硫酸软骨素(CS)修饰，在颗粒稳态中具有已知的作用。肝素酶是一种肝素降解酶，存在于α颗粒中，有助于颗粒的动态平衡，但此前尚未有类似的CS降解酶的报道。在这项研究中，我们使用了几种方法，包括表位特异性抗体、免疫组织化学和EM分析，证明了人HMC-1肥大细胞产生CS降解酶透明质酸酶-1(HYAL1)和HYAL4。我们观察到，在体外用HYAL1和HYAL4处理两个模型的CS蛋白多糖和丝氨酸后，CS链被切割成具有非还原末端寡糖结构的低分子形式，类似于细菌裂解酶软骨素酶ABC消化后产生的CS短桩新表位。我们发现，这些结构既与CS连接区相关，也与CS链非还原末端更远的结构相关。此外，我们注意到HYAL4将CS链裂解成长度从四糖到十二糖的较低分子量形式。这些结果提供了肥大细胞产生HYAL4的第一个证据，并且这种酶可能通过裂解附着在丝氨酸上的CS糖胺多糖链在维持这些细胞的α颗粒稳态中发挥特定的作用。
Mast cells represent a heterogeneous cell population that is well-known for the production of heparin and the release of histamine upon activation. Serglycin is a proteoglycan that within mast cell alpha-granules is predominantly decorated with the glycosaminoglycans heparin or chondroitin sulfate (CS) and has a known role in granule homeostasis. Heparanase is a heparin-degrading enzyme, is present within the alpha-granules, and contributes to granule homeostasis, but an equivalent CS-degrading enzyme has not been reported previously. In this study, using several approaches, including epitope-specific antibodies, immunohistochemistry, and EM analyses, we demonstrate that human HMC-1 mast cells produce the CS-degrading enzymes hyaluronidase-1 (HYAL1) and HYAL4. We observed that treating the two model CS proteoglycans aggrecan and serglycin with HYAL1 and HYAL4 in vitro cleaves the CS chains into lower molecular weight forms with nonreducing end oligosaccharide structures similar to CS stub neoepitopes generated after digestion with the bacterial lyase chondroitinase ABC. We found that these structures are associated with both the CS linkage region and with structures more distal toward the nonreducing end of the CS chain. Furthermore, we noted that HYAL4 cleaves CS chains into lower molecular weight forms that range in length from tetra- to dodecasaccharides. These results provide first evidence that mast cells produce HYAL4 and that this enzyme may play a specific role in maintaining alpha-granule homeostasis in these cells by cleaving CS glycosaminoglycan chains attached to serglycin.