Little Chris B, Mittaz Laureane, Belluoccio Daniele, Rogerson Fraser M, Campbell Ian K, Meeker Clare T, Bateman John F, Pritchard Melanie A, Fosang Amanda J
Arthritis Research Group, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia.
Arthritis Rheum. 2005 May;52(5):1461-72. doi: 10.1002/art.21022.
To determine the role of the proteinase ADAMTS-1 in normal and accelerated catabolism of aggrecan in articular and growth plate cartilage of mice.
Expression of ADAMTS-1 was determined using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of RNA isolated from microdissected chondrocytes from different zones of mouse growth plate and articular cartilage. Real-time RT-PCR for ADAMTS-4, ADAMTS-5, and ADAMTS-9 was performed on femoral head cartilage of wild-type (WT) and ADAMTS-1-knockout (KO) mice. Histologic and immunohistologic evaluation of growth plate and articular cartilage was performed in WT and KO mice from birth to 12 weeks of age. The effect of ADAMTS-1 ablation on cartilage proteoglycan loss was studied in antigen-induced arthritis (AIA). Aggrecan catabolism in WT and KO mice was studied in an in vitro model of cartilage degradation, by quantitation of glycosaminoglycan loss and histologic, immunohistologic, and Western immunoblot analyses.
ADAMTS-1 messenger RNA (mRNA) was expressed in normal mouse articular and growth plate cartilage and was up-regulated in terminal hypertrophic differentiation of growth plate chondrocytes. There was no difference in mRNA levels in the cartilage of WT compared with KO mice for the other potential aggrecanases ADAMTS-4, ADAMTS-5, or ADAMTS-9. ADAMTS-1-KO mice were significantly smaller than their WT littermates; however, no morphologic differences between the genotypes were evident in growth plate or articular cartilage from birth to skeletal maturity (12-16 weeks). Similarly, no difference in cartilage aggrecan content or presence of aggrecan degradation products was detected between WT and KO mice. There was no difference between WT and KO mice in the degree of synovial inflammation or depletion of cartilage aggrecan in AIA. There was no difference between WT and KO cartilage in either basal or stimulated aggrecan loss in vitro; however, subtle changes in the aggrecanase-generated aggrecan catabolites were observed in interleukin-1-treated cartilage.
Although ADAMTS-1 is expressed in articular and growth plate cartilage and is able to cleave aggrecan at physiologically relevant sites, our results indicate that it does not play a significant nonredundant role in normal cartilage and bone development and growth. Similarly, ablation of ADAMTS-1 offered no protection from accelerated aggrecanolysis in an inflammatory model of arthritis or in an in vitro model of early cartilage degradation. ADAMTS-1 does not appear to be a viable target for treatment of cartilage destruction in arthritis.
确定蛋白酶ADAMTS-1在小鼠关节软骨和生长板软骨中聚集蛋白聚糖正常及加速分解代谢中的作用。
通过对从小鼠生长板和关节软骨不同区域显微切割的软骨细胞中分离的RNA进行逆转录-聚合酶链反应（RT-PCR）分析，来确定ADAMTS-1的表达。对野生型（WT）和ADAMTS-1基因敲除（KO）小鼠的股骨头软骨进行ADAMTS-4、ADAMTS-5和ADAMTS-9的实时RT-PCR检测。对出生至12周龄的WT和KO小鼠的生长板和关节软骨进行组织学和免疫组织学评估。在抗原诱导的关节炎（AIA）中研究ADAMTS-1基因缺失对软骨蛋白聚糖丢失的影响。通过定量糖胺聚糖丢失以及组织学、免疫组织学和Western免疫印迹分析，在软骨降解的体外模型中研究WT和KO小鼠的聚集蛋白聚糖分解代谢。
ADAMTS-1信使核糖核酸（mRNA）在正常小鼠关节软骨和生长板软骨中表达，并在生长板软骨细胞的终末肥大分化中上调。与KO小鼠相比，WT小鼠软骨中其他潜在的聚集蛋白聚糖酶ADAMTS-4、ADAMTS-5或ADAMTS-9的mRNA水平没有差异。ADAMTS-1基因敲除小鼠明显小于其WT同窝小鼠；然而，从出生到骨骼成熟（12 - 16周），在生长板或关节软骨中，不同基因型之间没有明显的形态学差异。同样，在WT和KO小鼠之间未检测到软骨聚集蛋白聚糖含量或聚集蛋白聚糖降解产物存在的差异。在AIA中，WT和KO小鼠在滑膜炎症程度或软骨聚集蛋白聚糖消耗方面没有差异。在体外，WT和KO软骨在基础或刺激后的聚集蛋白聚糖丢失方面没有差异；然而，在白细胞介素-1处理的软骨中观察到聚集蛋白聚糖酶产生的聚集蛋白聚糖分解代谢产物有细微变化。
尽管ADAMTS-1在关节软骨和生长板软骨中表达，并且能够在生理相关位点切割聚集蛋白聚糖，但我们的结果表明，它在正常软骨和骨骼发育及生长中不发挥重要的非冗余作用。同样，在关节炎的炎症模型或早期软骨降解的体外模型中，ADAMTS-1基因缺失并不能防止聚集蛋白聚糖的加速分解。ADAMTS-1似乎不是治疗关节炎中软骨破坏的可行靶点。
