The vitamin K-dependent carboxylation system in human osteosarcoma U2-OS cells. Antidotal effect of vitamin K1 and a novel mechanism for the action of warfarin.
The vitamin K-dependent carboxylation system in human osteosarcoma U2-OS cells. Antidotal effect of vitamin K1 and a novel mechanism for the action of warfarin.
复制标题
人骨肉瘤 U2-OS 细胞中维生素 K 依赖性羧化系统。
DOI：
10.1042/bj2690459
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
KeyJr,LL
中科院分区：
文献类型：
--
作者：
Wallin,R;Rossi,F;Loeser,R;KeyJr,LL
成骨细胞样人骨肉瘤细胞系（U2-OS）已被证明具有维生素K依赖性羧化系统，该系统与人HepG 2细胞和大鼠肝和肺中的系统相似。在从这些细胞制备的“体外”系统中，维生素K1显示出克服华法林对由维生素K依赖性羧化酶进行的γ-羧化的抑制。这些数据表明，成骨细胞，参与骨骼中维生素K依赖性蛋白质合成的细胞，可以使用维生素K1作为华法林中毒的解毒剂，如果足够的维生素K1可以在组织中积累。在骨肉瘤和HepG 2细胞中分别鉴定出5种维生素K依赖蛋白的前体。在来自骨肉瘤细胞的微粒体（微粒体组分）中，这些前体揭示了85、78、56、35和31 kDa的表观分子量。当骨肉瘤细胞在华法林存在下培养时，78 kDa前体的维生素K依赖性14 C标记增强。选择性14 C标记的前体也证明了微粒体从HepG 2细胞和大鼠肺华法林治疗后。在HepG 2细胞中，该前体被鉴定为（凝血）因子X的前体。来自不同细胞和组织的微粒体中维生素K依赖性蛋白质前体的这种独特的14 C标记模式反映了华法林作用的新机制。
An osteoblast-like human osteosarcoma cell line (U2-OS) has been shown to possess a vitamin K-dependent carboxylation system which is similar to the system in human HepG2 cells and in liver and lung from the rat. In an ‘in vitro’ system prepared from these cells, vitamin K1 was shown to overcome warfarin inhibition of gamma-carboxylation carried out by the vitamin K-dependent carboxylase. The data suggest that osteoblasts, the cells involved in synthesis of vitamin K-dependent proteins in bone, can use vitamin K1 as an antidote to warfarin poisoning if enough vitamin K1 can accumulate in the tissue. Five precursors of vitamin K-dependent proteins were identified in osteosarcoma and HepG2 cells respectively. In microsomes (microsomal fractions) from the osteosarcoma cells these precursors revealed apparent molecular masses of 85, 78, 56, 35 and 31 kDa. When osteosarcoma cells were cultured in the presence of warfarin, vitamin K-dependent 14C-labelling of the 78 kDa precursor was enhanced. Selective 14C-labelling of one precursor was also demonstrated in microsomes from HepG2 cells and from rat lung after warfarin treatment. In HepG2 cells this precursor was identified as the precursor of (clotting) Factor X. This unique 14C-labelling pattern of precursors of vitamin K-dependent proteins in microsomes from different cells and tissues reflects a new mechanism underlying the action of warfarin.