Guangdong Provincial Key Laboratory of Biomedical Imaging and Guangdong Provincial Engineering Research Center of Molecular Imaging, the Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong Province, 519000, People's Republic of China.
Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, 53002, People's Republic of China.
Cell Biol Toxicol. 2022 Oct;38(5):741-763. doi: 10.1007/s10565-021-09608-x. Epub 2021 May 5.
Adipogenesis is a multi-step process orchestrated by activation of numerous TFs, whose cooperation and regulatory network remain elusive. Activating transcription factor 4 (ATF4) is critical for adipogenesis, yet its regulatory network is unclarified. Here, we mapped genome-wide ATF4 binding landscape and its regulatory network by Chip-seq and RNA-seq and found ATF4 directly modulated transcription of genes enriching in fat cell differentiation. Motifs of TFs especially CTCF were found from ATF4 binding sites, suggesting a direct role of ATF4 in regulating adipogenesis associated with CTCF and other TFs. Deletion of CTCF attenuated adipogenesis while overexpression enhanced adipocyte differentiation, indicating CTCF is indispensable for adipogenesis. Intriguingly, combined analysis of Chip-seq data of these two TFs showed that ATF4 co-localized with CTCF in the promoters of key adipogenic genes including Cebpd and PPARg and co-regulated their transactivation. Moreover, ATF4 directly regulated CTCF expression and interacted with CTCF in differentiated 3T3-L1 cells. In vivo, downregulation of ATF4 suppressed the expression of CTCF, Cebpd, and PPARg, leading to reduced adipose tissue expansion in refeeding mice. Consistently, mRNA expression of ATF4 and CTCF was positively correlated with each other in human subcutaneous adipose tissue and inversely associated with BMI, indicating a possible involvement of these two TFs in adipose development. Taken together, our data propose for the first time that ATF4 and CTCF work cooperatively to control adipogenesis and adipose development via orchestrating transcription of adipogenic genes. Our findings reveal novel therapeutic targets in obesity treatment.
脂肪生成是一个由许多 TFs 激活调控的多步骤过程，其合作和调控网络仍不清楚。激活转录因子 4 (ATF4) 对脂肪生成至关重要，但它的调控网络尚不清楚。在这里，我们通过 Chip-seq 和 RNA-seq 绘制了全基因组 ATF4 结合图谱及其调控网络，发现 ATF4 直接调节富含脂肪细胞分化的基因的转录。从 ATF4 结合位点发现了 TFs 的基序，特别是 CTCF，表明 ATF4 在调节与 CTCF 和其他 TFs 相关的脂肪生成中具有直接作用。CTCF 的缺失减弱了脂肪生成，而过表达则增强了脂肪细胞分化，表明 CTCF 对脂肪生成是不可或缺的。有趣的是，对这两个 TF 的 Chip-seq 数据的综合分析表明，ATF4 与 CTCF 在包括 Cebpd 和 PPARg 在内的关键脂肪生成基因的启动子中共同定位，并共同调控它们的转录激活。此外，ATF4 直接调节 CTCF 的表达，并在分化的 3T3-L1 细胞中与 CTCF 相互作用。在体内，ATF4 的下调抑制了 CTCF、Cebpd 和 PPARg 的表达，导致再喂养小鼠的脂肪组织扩张减少。一致地，ATF4 和 CTCF 的 mRNA 表达在人类皮下脂肪组织中呈正相关，与 BMI 呈负相关，表明这两个 TF 可能参与脂肪发育。总之，我们的数据首次提出，ATF4 和 CTCF 通过协调脂肪生成基因的转录来协同控制脂肪生成和脂肪发育。我们的发现为肥胖症治疗提供了新的治疗靶点。
