University of Melbourne Department of Paediatrics, Royal Children's Hospital, Parkville, Victoria 3052, Australia.
Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia.
Int J Mol Sci. 2019 Jan 29;20(3):573. doi: 10.3390/ijms20030573.
A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4 and ADAMTS-5 are the principal aggrecanases in mice and humans; however, mice lacking the catalytic domain of both enzymes (TS-4/5∆cat) have no skeletal phenotype, suggesting there is an alternative aggrecanase for modulating normal growth and development in these mice. We previously identified aggrecanase activity that (a) cleaved at E↓G rather than E↓A bonds in the aggrecan core protein, and (b) was upregulated by retinoic acid but not IL-1α. The present study aimed to identify the alternative aggrecanase. Femoral head cartilage explants from TS-4/5∆cat mice were stimulated with IL-1α or retinoic acid and total RNA was analysed by microarray. In addition to ADAMTS-5 and matrix metalloproteinase (MMP)-13, which are not candidates for the novel aggrecanase, the microarray analyses identified MMP-11, calpain-5 and ADAMTS-9 as candidate aggrecanases upregulated by retinoic acid. When calpain-5 and MMP-11 failed to meet subsequent criteria, ADAMTS-9 emerged as the most likely candidate for the novel aggrecanase. Immunohistochemistry revealed ADAMTS-9 expression throughout the mouse growth plate and strong expression, particularly in the proliferative zone of the TS-4/5-∆cat mice. In conclusion, ADAMTS-9 has a novel specificity for aggrecan, cleaving primarily at E↓G rather than E↓A bonds in mouse cartilage. ADAMTS-9 might have more important roles in normal skeletal development compared with ADAMTS-4 and ADAMTS-5, which have key roles in joint pathology.
解整合素金属蛋白酶与凝血酶样金属蛋白酶 4 和 5（ADAMTS-4 和 ADAMTS-5）是小鼠和人类中主要的聚集蛋白水解酶；然而，缺乏两种酶的催化结构域的小鼠（TS-4/5∆cat）没有骨骼表型，这表明在这些小鼠中存在一种替代的聚集蛋白水解酶来调节正常的生长和发育。我们之前鉴定了一种聚集蛋白水解酶活性，它（a）在聚集蛋白核心蛋白中裂解 E↓G 而不是 E↓A 键，（b）被维甲酸上调但不受白细胞介素 1α（IL-1α）的影响。本研究旨在鉴定替代的聚集蛋白水解酶。用白细胞介素 1α（IL-1α）或维甲酸刺激 TS-4/5∆cat 小鼠的股骨头软骨外植体，并用微阵列分析总 RNA。除了 ADAMTS-5 和基质金属蛋白酶（MMP）-13 不是新型聚集蛋白水解酶的候选物外，微阵列分析还鉴定出 MMP-11、钙蛋白酶-5 和 ADAMTS-9 作为维甲酸上调的候选聚集蛋白水解酶。当钙蛋白酶-5 和 MMP-11 未能满足后续标准时，ADAMTS-9 成为新型聚集蛋白水解酶的最可能候选物。免疫组织化学显示 ADAMTS-9 在整个小鼠生长板中表达，并在 TS-4/5-∆cat 小鼠的增殖区强烈表达。总之，ADAMTS-9 对聚集蛋白具有新的特异性，主要在小鼠软骨中裂解 E↓G 而不是 E↓A 键。与在关节病理学中具有关键作用的 ADAMTS-4 和 ADAMTS-5 相比，ADAMTS-9 在正常骨骼发育中可能具有更重要的作用。
