Graduate Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei 10617, Taiwan.
Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan.
Int J Mol Sci. 2020 Sep 30;21(19):7245. doi: 10.3390/ijms21197245.
The tripartite motif-containing protein 28 (TRIM28) is a transcription corepressor, interacting with histone deacetylase and methyltransferase complexes. TRIM28 is a crucial regulator in development and differentiation. We would like to investigate its function and regulation in adipogenesis. Knockdown of Trim28 by transducing lentivirus-carrying shRNAs impairs the differentiation of 3T3-L1 preadipocytes, demonstrated by morphological observation and gene expression analysis. To understand the molecular mechanism of Trim28-mediated adipogenesis, the RNA-seq was performed to find out the possible Trim28-regulated genes. Dlk1 (delta-like homolog 1) was increased in Trim28 knockdown 3T3-L1 cells both untreated and induced to differentiation. is an imprinted gene and known as an inhibitor of adipogenesis. Further knockdown of Dlk1 in Trim28 knockdown 3T3-L1 would rescue cell differentiation. The epigenetic analysis showed that DNA methylation of Dlk1 promoter and differentially methylated regions (DMRs) was not altered significantly in Trim28 knockdown cells. However, compared to control cells, the histone methylation on the promoter was increased at H3K4 and decreased at H3K27 in Trim28 knockdown cells. Finally, we found Trim28 might be recruited by transcription factor E2f1 to regulate expression. The results imply Trim28-Dlk1 axis is critical for adipogenesis.
三结构域蛋白 28（TRIM28）是一种转录共抑制因子，与组蛋白去乙酰化酶和甲基转移酶复合物相互作用。TRIM28 是发育和分化过程中的关键调节因子。我们希望研究其在脂肪生成中的功能和调节作用。通过转导携带 shRNA 的慢病毒来敲低 Trim28，会损害 3T3-L1 前脂肪细胞的分化，这可以通过形态观察和基因表达分析来证明。为了了解 Trim28 介导的脂肪生成的分子机制，进行了 RNA-seq 以找出可能受 Trim28 调节的基因。在未处理和诱导分化的情况下，Trim28 敲低的 3T3-L1 细胞中 Dlk1（delta-like 同源物 1）的表达增加。 是一个印迹基因，已知是脂肪生成的抑制剂。进一步敲低 Trim28 敲低的 3T3-L1 细胞中的 Dlk1 会挽救细胞分化。表观遗传分析表明，Trim28 敲低细胞中 Dlk1 启动子和差异甲基化区域（DMRs）的 DNA 甲基化没有明显改变。然而，与对照细胞相比，Trim28 敲低细胞中的 启动子上的组蛋白甲基化在 H3K4 上增加，在 H3K27 上减少。最后，我们发现转录因子 E2f1 可能募集 Trim28 来调节 表达。结果表明，Trim28-Dlk1 轴对于脂肪生成至关重要。
