Woo Min Seok, Khalil Atif Ali Khan, Gonzalez Frank J, Kim Jung-Hwan
Department of Pharmacology, School of Medicine, Institute of Medical Sciences, Gyeongsang National University, Jinju 52727, Republic of Korea.
Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Mol Cells. 2024 Dec;47(12):100148. doi: 10.1016/j.mocell.2024.100148. Epub 2024 Nov 12.
Growth arrest and DNA damage-inducible beta (GADD45b) plays a critical role in intracellular events such as cell growth and apoptosis. Although the functional study of GADD45b has been conducted, the mechanism for the transcriptional regulation of GADD45b is largely unknown. Due to the drastic induction of hepatic GADD45b mRNA by peroxisome proliferator-activated receptor alpha activation in wild-type mice, we investigated a key factor that affects the upregulation of GADD45b mRNA. Interestingly, we found that GADD45b-promoter luciferase activity was dramatically increased as the 5'-flanking regions were closer to the transcription start site in Hepa1c1c7 cells. Additionally, we found 2 E2F (E2F-myc activator/cell cycle regulator) binding motifs in the region (-150/-1) of the GADD45b promoter. Notably, E2F3 mRNA was significantly increased only in wild-type mice treated with WY-14643, a peroxisome proliferator-activated receptor alpha agonist, followed by the induction of GADD45b mRNA. Furthermore, gene functional studies and Chromatin Immunoprecipitation assays revealed that E2F3 could regulate the GADD45b gene via the E2F binding motif. Thus, we suggest that E2F3 may play a key role in regulating the GADD45b gene as a positive transcription factor.
生长停滞和DNA损伤诱导蛋白β（GADD45b）在细胞生长和凋亡等细胞内事件中起关键作用。尽管已经对GADD45b进行了功能研究，但其转录调控机制仍 largely unknown。由于在野生型小鼠中过氧化物酶体增殖物激活受体α激活可显著诱导肝脏GADD45b mRNA，我们研究了影响GADD45b mRNA上调的关键因素。有趣的是，我们发现，在Hepa1c1c7细胞中，随着5'-侧翼区域更靠近转录起始位点，GADD45b启动子荧光素酶活性显著增加。此外，我们在GADD45b启动子区域（-150/-1）发现了2个E2F（E2F- myc激活因子/细胞周期调节因子）结合基序。值得注意的是，仅在用过氧化物酶体增殖物激活受体α激动剂WY-14643处理的野生型小鼠中，E2F3显著增加，随后诱导GADD45b mRNA。此外，基因功能研究和染色质免疫沉淀试验表明，E2F3可通过E2F结合基序调节GADD45b基因。因此，我们认为E2F3作为一种正性转录因子可能在调控GADD45b基因中起关键作用。
