Transglutaminase activity in aging articular chondrocytes and articular cartilage vesicles
Transglutaminase activity in aging articular chondrocytes and articular cartilage vesicles
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DOI：
10.1002/art.1780400526
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发表时间：
1997-05-01
影响因子：
--
通讯作者：
Henry, LA
中科院分区：
文献类型：
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作者：
Rosenthal, AK;Derfus, BA;Henry, LA
Objective.转氨酶（TGases）（E.C. 2.3.2.13）催化蛋白质的翻译后修饰，并与生长板软骨中的生物矿化有关。II型TGase参与活化潜伏性转化生长因子β（TGF β），TGF β是正常软骨矿化和病理性矿化的关键因素，导致老化关节软骨中焦磷酸钙二水合物（CPPD）晶体形成。为了探讨TGase水平与成熟关节软骨中CPPD晶体形成之间的可能关联，检测了来自老年和青年猪的关节软骨细胞以及猪关节软骨的关节软骨囊泡（ACV）部分中的TGase活性，此外，测定了TGase抑制剂对无机焦磷酸盐（PPi）产生的影响，PPi是CPPD晶体形成所必需的过程。用放射性测定法测量来自老猪（3-5岁）和幼猪（2-6周龄）膝关节的培养关节软骨细胞和ACV中的TGase活性。PPi水平测定软骨细胞条件培养基中存在的TGase抑制剂或对照化合物。老年软骨细胞胞浆部分中的TGase活性水平比同样培养的年轻软骨细胞高7倍。溶解的软骨细胞的膜部分中的平均+/-SD活性水平在陈旧的关节软骨细胞中为6.0+/-0.6单位/mg蛋白，在年轻的软骨细胞中检测不到。在ACV中，平均+/-SD TGase活性水平为1.23+/-0.1单位/mg蛋白。II型TGase蛋白存在于软骨细胞胞液和ACV中。TGF β使TGase活性增加至对照值的120%（P
Objective. Transglutaminases (TGases) (E.C. 2.3.2.13) catalyze a posttranslational modification of proteins and are associated with biomineralization in growth plate cartilage. Type II TGase participates in the activation of latent transforming growth factor beta (TGF beta), a crucial factor for both normal cartilage mineralization and the pathologic mineralization that results in calcium pyrophosphate dihydrate (CPPD) crystal formation in aging articular cartilage. To explore a possible association between TGase levels and CPPD crystal formation in mature articular cartilage, TGase activity in articular chondrocytes from old and young pigs and in the articular cartilage vesicle (ACV) fraction of porcine articular cartilage was examined, In addition, the effects of TGase inhibitors on the production of inorganic pyrophosphate (PPi), a process necessary for CPPD crystallogenesis, were determined.Methods. TGase activity was measured with a radiometric assay in cultured articular chondrocytes from the knee joints of old (3-5 years old) and young (2-6 weeks old) pigs and in the ACVs. PPi levels were measured in chondrocyte-conditioned media in the presence of TGase inhibitors or control compounds.Results. Levels of TGase activity in the cytosolic fraction of old chondrocytes were 7-fold higher than those in identically cultured young chondrocytes. The mean+/-SD activity level in the membrane fraction of lysed chondrocytes was 6.0+/-0.6 units/mg protein in old articular chondrocytes and was undetectable in young chondrocytes. In ACVs, the mean+/-SD TGase activity level was 1.23+/-0.1 units/mg protein. Type II TGase protein tvas present in chondrocyte cytosol and in ACVs. TGase activity was increased by TGF beta to 120% of control values (P