Department of Biotechnology, College of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur, 603 203, Tamil Nadu, India.
Department of Biotechnology, College of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur, 603 203, Tamil Nadu, India.
Biochimie. 2022 Oct;201:1-6. doi: 10.1016/j.biochi.2022.06.013. Epub 2022 Jun 30.
In skeletal tissues, transforming growth factor-beta 1 (TGF-β1) serves a number of activities. For example, in osteoblastic cells, TGF-β1 stimulates the expression of matrix metalloproteinase-13 (MMP-13, a bone remodeling gene), which requires the bone transcription factor Runx2. Although TGF-β1 is known to stimulate Runx2 acetylation, the sites involved in MMP-13 gene activation remain unknown. Mass spectrometry analysis revealed that Runx2 was acetylated at one site (K134) and three sites (K24, K134, and K169) following control and TGF-β1-treatment, respectively, in osteoblastic cells. In addition, we mutated the lysine residues in the Runx2 construct into arginine and transfected the construct into mouse mesenchymal stem cells (C3H10T1/2). Wild-type Runx2 expression and acetylation were significantly increased by TGF-β1-treatment, whereas this effect was decreased in the presence of the Runx2 double mutant construct (K24 + K169) in C3H10T1/2 cells. TGF-β1 enhanced MMP-13 promoter activity in cells transfected with the wild-type Runx2 construct, but this effect was considerably reduced in cells transfected with the Runx2 double mutant construct (K24 + K169), according to a luciferase reporter test. Hence, the stability of Runx2 may be mediated by TGF-β1-induced acetylation at K24 and K169 and is required for MMP-13 expression in osteoblastic cells. These findings add to our knowledge of TGF-β1, Runx2, and MMP-13's physiological roles in bone metabolism.
在骨骼组织中，转化生长因子-β1（TGF-β1）具有多种作用。例如，在成骨细胞中，TGF-β1 刺激基质金属蛋白酶-13（MMP-13，一种骨重塑基因）的表达，这需要骨转录因子 Runx2。尽管已知 TGF-β1 刺激 Runx2 乙酰化，但参与 MMP-13 基因激活的位点仍不清楚。质谱分析显示，在成骨细胞中，Runx2 在一个位点（K134）和三个位点（K24、K134 和 K169）处被乙酰化，分别在对照和 TGF-β1 处理后。此外，我们将 Runx2 构建体中的赖氨酸残基突变为精氨酸，并将构建体转染到小鼠间充质干细胞（C3H10T1/2）中。野生型 Runx2 表达和乙酰化在 TGF-β1 处理后显著增加，而在 C3H10T1/2 细胞中存在 Runx2 双突变体构建体（K24+K169）时，这种效应降低。根据荧光素酶报告试验，TGF-β1 增强了转染野生型 Runx2 构建体的细胞中 MMP-13 启动子活性，但在转染 Runx2 双突变体构建体（K24+K169）的细胞中，这种效应显著降低。因此，Runx2 的稳定性可能由 TGF-β1 诱导的 K24 和 K169 乙酰化介导，并且是成骨细胞中 MMP-13 表达所必需的。这些发现增加了我们对 TGF-β1、Runx2 和 MMP-13 在骨代谢中生理作用的认识。
