Study of the function of cystatin 10, a novel chondrocyte-specific gene.

本研究旨在阐明胱抑素10(Cst10)在软骨内成骨和骨软骨再生过程中的作用及其分子机制，并将其应用于医学治疗。Cst10是从小鼠耳廓软骨中鉴定出来的，属于半胱氨酸蛋白酶抑制剂超家族。Cst10在软骨中呈特异性表达，尤其在生长板肥大的软骨细胞中表达。我们在体外研究中发现，Cst10可诱导软骨细胞的后期分化和凋亡。为了进一步研究Cst10在体内的生理作用，我们建立了Cst10基因缺失的小鼠(Cst10KO)，并对其骨和软骨进行了分析。Cst10KO发育和生长正常，主要器官无异常。放射学和组织学分析显示生长板钙化受损，与…相邻的原发海绵体积显著减少。虽然Cst10KO的骨生长和骨转换与野生型(WT)和杂合子窝产仔相似，但由于缺乏Cst10而增加了生长板。在生长板来源的原代软骨细胞的培养中，Cst10KO细胞比WT细胞的后期分化受到抑制，这表明Cst10在软骨细胞中的表达是软骨基质的终末分化和钙化。在Cst10KO中，与软骨内骨化相关的其他病理条件下的钙化也显著受损，如骨关节炎膝关节模型的骨折愈合和骨赘形成。此外，尽管52周龄的WT显示出髌骨和跟骨的肌腱附着处的钙化，但在Cst10KO中没有发现这些异位钙化。体外和体内实验结果表明，Cst10是软骨细胞钙化的诱导剂，在骨关节炎和异位钙化的发病机制中起重要作用，但不影响生理性骨的生长和转换。较少

This study was conducted to elucidate the role and the molecular mechanism of cystatin 10 (Cst10), in the process of endochondral ossification and osteochondral regeneration, and to apply the novel gene, Cst10, to the medical treatment.Cst10 was identified from the mouse auricular cartilage and belongs to the cystatin superfamily, the family of cysteine protease inhibitors. Expression of Cst10 was specific to cartilage, especially to hypertrophic chondrocytes of the growth plate. We found from in vitro studies that Cst10 induced later differentiation and apoptosis of chondrocytes. In order to further investigate the physiological role of Cst10 in vivo, we created mice lacking the Cst10 gene (Cst10KO) and analyzed their bone and cartilage. Cst10KO developed and grew normally without abnormalities of major organs. Radiological and histological analysis revealed an impairment of calcification of the growth plate and a significant decrease in the volume of primary spongiosa adjacent to the … More growth plate by Cst10 deficiency, although bone growth and bone turnover of the Cst10KO remained similar to those of wild type (WT) and heterozygote littermates. In the culture of primary chondrocytes derived from the growth plate, later differentiation of Cst10KO cells was suppressed compared to that of WT cells, which showed the roles of Cst10 expressing in chondrocytes are terminal differentiation and calcification of cartilaginous matrix. In the Cst10KO, calcification was also significantly impaired in other pathological conditions related to endochondral ossification, such as fracture healing and osteophyte formation in osteoarthritis knee model. Furthermore, although WT exhibited calcification of the tendon insertion of patella and calcaneus at 52 weeks of age, these ectopic calcifications were not seen in the Cst10KO. Cst10 was expressed exclusively in type X collagen expressing, matured cells in these calcification regions of WT.These in vitro and in vivo results revealed that Cst10 is an inducer of chondrocyte calcification and contributes to the pathogenesis of osteoarthritis and ectopic calcification without affecting the physiological bone growth or turnover. Less