Lau K-H William, Baylink David J
Musculoskeletal Disease Center, Jerry L. Pettis Memorial VA Medical Center, Loma Linda, California 92357, USA.
J Bone Miner Res. 2003 Oct;18(10):1897-900. doi: 10.1359/jbmr.2003.18.10.1897.
Although type 5 TRACP is recognized as a histochemical and biochemical marker of osteoclasts, there is evidence that bone forming cells, osteoblasts, and osteocytes also express a type 5 TRACP. Accordingly, an osteoblastic type 5 TRACP has been purified from human osteoblasts and from bovine cortical bone matrices. Comparison of biochemical properties of osteoblastic type 5 TRACP with those of osteoclastic type 5 TRACP suggests that osteoblastic type 5 TRACP is a different isoenzyme from osteoclastic type 5 TRACP. Two properties of osteoblastic type 5 TRACP may be relevant to its physiological functions: (1) it acts as a protein-tyrosine phosphatase (protein tyrosine phosphorylation) under physiologically relevant conditions, and (2) it is sensitive to inhibition by clinically relevant concentrations of fluoride. Because fluoride is a stimulator of osteoblastic proliferation and differentiation and a potent osteogenic agent and because protein tyrosine phosphorylation plays an important regulatory role in cell proliferation and differentiation, these unique properties and other evidence summarized in this review led to the proposal that the osteogenic action of fluoride is mediated, at least in part, by the fluoride-mediated inhibition of osteoblastic type 5 TRACP/protein tyrosine phosphorylation, which leads to a stimulation of osteoblast proliferation and differentiation, and subsequently, an increase in bone formation.
尽管5型抗酒石酸酸性磷酸酶（TRACP）被认为是破骨细胞的组织化学和生化标志物，但有证据表明，骨形成细胞、成骨细胞和骨细胞也表达5型TRACP。因此，已从人成骨细胞和牛皮质骨基质中纯化出成骨细胞型5型TRACP。成骨细胞型5型TRACP与破骨细胞型5型TRACP的生化特性比较表明，成骨细胞型5型TRACP是一种与破骨细胞型5型TRACP不同的同工酶。成骨细胞型5型TRACP的两个特性可能与其生理功能相关：（1）在生理相关条件下，它作为一种蛋白酪氨酸磷酸酶（蛋白质酪氨酸磷酸化）发挥作用；（2）它对临床相关浓度的氟化物抑制敏感。由于氟化物是成骨细胞增殖和分化的刺激剂以及一种有效的成骨剂，并且由于蛋白质酪氨酸磷酸化在细胞增殖和分化中起重要调节作用，本综述总结的这些独特特性和其他证据导致提出这样的观点，即氟化物的成骨作用至少部分是由氟化物介导的对成骨细胞型5型TRACP/蛋白质酪氨酸磷酸化的抑制所介导的，这导致成骨细胞增殖和分化的刺激，随后骨形成增加。
