Han Younho, Jin Yifeng, Lee Sung Ho, Khadka Daulat Bikram, Cho Won-Jea, Lee Kwang Youl
College of Pharmacy & Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea.
College of Pharmacy & Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea.
Pharmacol Res. 2017 May;119:463-475. doi: 10.1016/j.phrs.2017.03.002. Epub 2017 Mar 7.
The Q8 compound is a unique derivative of berberine. The present study investigated the functional role of Q8 to evaluate its potential for use in bone regeneration, especially in osteoblast differentiation. The safe concentration of Q8 increased BMP4-induced alkaline phosphatase (ALP) activity, and induced RNA expression of ALP, bone sialoprotein (BSP), and osteocalcin (OC). The activities of ALP-, BSP- and OC-luciferase reporters were also increased by Q8. During osteoblast differentiation, Q8 stabilized the Runx2 and Osterix protein abundance by blocking the ubiquitin-proteasome pathway, which in turn promoted Runx2 and Osterix induced transcriptional activity and subsequently increased the osteoblast differentiation. Meanwhile, depletion of Runx2 and Osterix markedly abolished the bone anabolic effect of Q8 on osteoblast differentiation. To evaluate the signal transduction pathway involved in the Q8-mediated regulation of Runx2 and Osterix, we examined the reporter assay using various kinase inhibitors. Treatment with a protein kinase A (PKA) inhibitor, H89 inhibited the Q8-mediated regulation of Runx2 and Osterix. Based on these findings, this study demonstrates that Q8 promotes the osteoblast differentiation by stabilization of Runx2/Osterix through the increased activation of PKA signaling. The enhancement of osteoblast function by Q8 may contribute to the prevention for osteoporosis.
Q8化合物是黄连素的一种独特衍生物。本研究调查了Q8的功能作用，以评估其在骨再生，特别是在成骨细胞分化方面的应用潜力。Q8的安全浓度可提高骨形态发生蛋白4（BMP4）诱导的碱性磷酸酶（ALP）活性，并诱导ALP、骨唾液酸蛋白（BSP）和骨钙素（OC）的RNA表达。Q8还可提高ALP、BSP和OC荧光素酶报告基因的活性。在成骨细胞分化过程中，Q8通过阻断泛素-蛋白酶体途径稳定Runx2和Osterix蛋白丰度，进而促进Runx2和Osterix诱导的转录活性，随后增加成骨细胞分化。同时，Runx2和Osterix的缺失显著消除了Q8对成骨细胞分化的骨合成代谢作用。为了评估参与Q8介导的Runx2和Osterix调节的信号转导途径，我们使用各种激酶抑制剂进行了报告基因检测。用蛋白激酶A（PKA）抑制剂H89处理可抑制Q8介导的Runx2和Osterix调节。基于这些发现，本研究表明Q8通过增加PKA信号的激活来稳定Runx2/Osterix，从而促进成骨细胞分化。Q8对成骨细胞功能的增强可能有助于预防骨质疏松症。
