Yamaguchi Masayoshi, Weitzmann M Neale
Division of Endocrinology and Metabolism and Lipids, Department of Medicine, Emory University School of Medicine, 1329 WMRB, Atlanta, GA 30322-0001, USA.
Int J Mol Med. 2009 Nov;24(5):671-5. doi: 10.3892/ijmm_00000278.
The xanthophyll beta-cryptoxanthin is a member of the carotenoid family of plant-derived pigments endowed with anti-osteoporotic properties in vivo. beta-cryptoxanthin was demonstrated to stimulate osteoblastic bone formation and simultaneously repress osteoclastic bone resorption in vitro. However, the mechanisms of action remain to be elucidated. The SMAD signal transduction pathway is established to play a critical role in osteoblast lineage commitment and differentiation. In this study we used transient transfection assays of a SMAD luciferase reporter to investigate whether beta-cryptoxanthin regulates SMAD activation in MC3T3 pre-osteoblastic cells. Beta-cryptoxanthin did not stimulate basal SMAD activity but amplified transforming growth factor (TGF)-beta1-induced SMAD activation. Interestingly, beta-cryptoxanthin did not affect bone morphogenetic protein-2 (BMP-2)-induced SMAD activation in osteoblastic cells, suggesting specificity of action on the TGF-beta1 pathway. This study suggests that the carotenoid beta-cryptoxanthin may promote osteoblast differentiation and activity by amplifying TGF-beta1-induced lineage commitment of osteoblast precursors.
叶黄素β-隐黄质是植物源性色素类胡萝卜素家族的成员，在体内具有抗骨质疏松特性。β-隐黄质在体外被证明可刺激成骨细胞的骨形成，同时抑制破骨细胞的骨吸收。然而，其作用机制仍有待阐明。SMAD信号转导通路在成骨细胞谱系的定向分化中起关键作用。在本研究中，我们使用SMAD荧光素酶报告基因的瞬时转染试验来研究β-隐黄质是否调节MC3T3前成骨细胞中的SMAD激活。β-隐黄质不会刺激基础SMAD活性，但会增强转化生长因子（TGF）-β1诱导的SMAD激活。有趣的是，β-隐黄质不影响成骨细胞中骨形态发生蛋白-2（BMP-2）诱导的SMAD激活，这表明其对TGF-β1通路具有作用特异性。本研究表明，类胡萝卜素β-隐黄质可能通过增强TGF-β1诱导的成骨细胞前体谱系定向分化来促进成骨细胞分化和活性。
