Aenlle Kristina K, Curtis Kevin M, Roos Bernard A, Howard Guy A
Geriatric Research, Education, and Clinical Center and Research Service (K.K.A., K.M.C., B.A.R., G.A.H.), Veterans Affairs Medical Center, Miami, Florida 33125; Departments of Medicine (B.A.R., G.A.H.), Neurology (B.A.R.), and Biochemistry & Molecular Biology (K.M.C., G.A.H.), University of Miami Miller School of Medicine, Miami, Florida 33101.
Mol Endocrinol. 2014 May;28(5):722-30. doi: 10.1210/me.2013-1286. Epub 2014 Mar 27.
Hepatocyte growth factor (HGF) is a paracrine factor involved in organogenesis, tissue repair, and wound healing. We report here that HGF promotes osteogenic differentiation through the transcription of key osteogenic markers, including osteocalcin, osterix, and osteoprotegerin in human mesenchymal stem cells and is a necessary component for the establishment of osteoblast mineralization. Blocking endogenous HGF using PHA665752, a c-Met inhibitor (the HGF receptor), or an HGF-neutralizing antibody attenuates mineralization, and PHA665752 markedly reduced alkaline phosphatase activity. Moreover, we report that HGF promotion of osteogenic differentiation involves the rapid phosphorylation of p38 and differential regulation of its isoforms, p38α and p38β. Western blot analysis revealed a significantly increased level of p38α and p38β protein, and reverse transcription quantitative PCR revealed that HGF increased the transcriptional level of both p38α and p38β. Using small interfering RNA to reduce the transcription of p38α and p38β, we saw differential roles for p38α and p38β on the HGF-induced expression of key osteogenic markers. In summary, our data demonstrate the importance of p38 signaling in HGF regulation of osteogenic differentiation.
肝细胞生长因子（HGF）是一种参与器官发生、组织修复和伤口愈合的旁分泌因子。我们在此报告，HGF通过关键成骨标志物的转录促进人间充质干细胞的成骨分化，这些标志物包括骨钙素、osterix和骨保护素，并且是成骨细胞矿化形成的必要组成部分。使用c-Met抑制剂（HGF受体）PHA665752或HGF中和抗体阻断内源性HGF会减弱矿化，且PHA665752显著降低碱性磷酸酶活性。此外，我们报告HGF促进成骨分化涉及p38的快速磷酸化及其同工型p38α和p38β的差异调节。蛋白质印迹分析显示p38α和p38β蛋白水平显著升高，逆转录定量PCR显示HGF增加了p38α和p38β的转录水平。使用小干扰RNA降低p38α和p38β的转录，我们发现p38α和p38β在HGF诱导的关键成骨标志物表达中具有不同作用。总之，我们的数据证明了p38信号在HGF调节成骨分化中的重要性。
