Zhou Tingting, Guo Shuyu, Zhang Yuxin, Weng Yajuan, Wang Lin, Ma Junqing
Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, 136 Hanzhong Road, Nanjing, Jiangsu, 210029, China.
J Mol Histol. 2017 Jun;48(3):187-197. doi: 10.1007/s10735-017-9719-2. Epub 2017 Apr 9.
Osteoblasts play a major role in bone remodeling and are regulated by transcription factors. GATA4, a zinc finger transcription factor from the GATA family, has an unclear role in osteoblast differentiation. In this study, the role of GATA4 in osteoblast differentiation was studied both in vitro and in vivo by GATA4 knockdown. GATA4 expression increased during osteoblast differentiation. GATA4 knockdown in osteoblast precursor cells reduced alkaline phosphatase activity and decreased the formation of calcified nodule in an osteogenic-induced cell culture system. In vivo, micro-CT showed that local injection of lentivirus-delivered GATA4 shRNA caused reduced new bone formation during tooth movement. Histological analyses such as total collagen and Goldner's trichrome staining confirmed these results. In vivo immunohistochemical analysis showed reduced expression of osterix (OSX), osteopontin (OPN), and osteocalcin (OCN) in the shGATA4 group (P < 0.05). Consistently, both western blotting and quantitative reverse-transcription PCR proved that expression of osteogenesis-related genes, including OSX, OPN, and OCN, was significantly repressed in the shGATA4 group in vitro (P < 0.01). For further analysis of the pathways involved in this process, we examined the MAPK signaling pathway, and found knockdown of GATA4, downregulated p38 signaling pathways (P < 0.01). Collectively, these results imply GATA4 is a regulator of osteoblastic differentiation via the p38 signaling pathways.
成骨细胞在骨重塑中起主要作用，并受转录因子调控。GATA4是GATA家族的一种锌指转录因子，在成骨细胞分化中的作用尚不清楚。在本研究中，通过敲低GATA4，在体外和体内研究了GATA4在成骨细胞分化中的作用。在成骨细胞分化过程中，GATA4表达增加。在成骨诱导细胞培养系统中，敲低成骨细胞前体细胞中的GATA4可降低碱性磷酸酶活性，并减少钙化结节的形成。在体内，显微CT显示局部注射慢病毒传递的GATA4 shRNA会导致牙齿移动过程中新生骨形成减少。总胶原蛋白和Goldner三色染色等组织学分析证实了这些结果。体内免疫组化分析显示，shGATA4组中osterix（OSX）、骨桥蛋白（OPN）和骨钙素（OCN）的表达降低（P < 0.05）。同样，蛋白质印迹法和定量逆转录PCR均证明，体外shGATA4组中包括OSX、OPN和OCN在内的成骨相关基因的表达均受到显著抑制（P < 0.01）。为了进一步分析参与该过程的信号通路，我们检测了MAPK信号通路，发现敲低GATA4会下调p38信号通路（P < 0.01）。总体而言，这些结果表明GATA4是通过p38信号通路调控成骨细胞分化的因子。
