Department of Health Sciences, University "Magna Græcia" of Catanzaro, Viale Europa (Località Germaneto), 88100, Catanzaro, Italy.
Endocrine. 2018 Apr;60(1):56-64. doi: 10.1007/s12020-017-1445-8. Epub 2017 Oct 19.
The forkhead transcription factor (FoxO1) is a master transcriptional regulator of fundamental cellular processes ranging from cell proliferation and differentiation to inflammation and metabolism. However, despite its relevance, the mechanism(s) underlying FoxO1 gene regulation are largely unknown. We have previously shown that the chromatin factor high-mobility group A1 (HMGA1) plays a key role in the transcriptional regulation of glucose-responsive genes, including some that are involved in FoxO1-mediated glucose metabolism. Here we investigated the impact of HMGA1 on FoxO1 gene expression.
FoxO1 protein and gene expression studies were performed by Western blot analysis combined with qRT-PCR of material from human cultured cells and EBV-transformed lymphoblasts, and from primary cultured hepatocytes from wild-type and Hmga1 mice. Reporter gene assays and chromatin immunoprecipitation for binding of HMGA1 to the endogenous FoxoO1 locus were performed in cells overexpressing HMGA1 and in cells pretreated with siRNA targeting HMGA1.
HMGA1 increased FoxO1 mRNA and protein expression in vitro, in cultured HepG2 and HEK-293 cells by binding FoxO1 gene promoter, thereby activating FoxO1 gene transcription. Forced expression of HMGA1 in primary cultured hepatocytes from Hmga1 mice and in EBV-transformed lymphoblasts from subjects with reduced expression of endogenous HMGA1 increased FoxO1 mRNA and protein levels.
These findings may contribute to the understanding of FoxO1 gene regulation and its role in metabolism.
叉头转录因子（FoxO1）是从细胞增殖和分化到炎症和代谢等基本细胞过程的主要转录调控因子。然而，尽管它具有相关性，但 FoxO1 基因调控的机制在很大程度上尚不清楚。我们之前已经表明，染色质因子高迁移率族蛋白 A1（HMGA1）在葡萄糖反应基因的转录调控中发挥关键作用，包括一些涉及 FoxO1 介导的葡萄糖代谢的基因。在这里，我们研究了 HMGA1 对 FoxO1 基因表达的影响。
通过 Western blot 分析结合来自人培养细胞和 EBV 转化的淋巴母细胞以及来自野生型和 Hmga1 小鼠的原代培养肝细胞的 qRT-PCR，进行 FoxO1 蛋白和基因表达研究。在过表达 HMGA1 的细胞中和用靶向 HMGA1 的 siRNA 预处理的细胞中进行了报告基因测定和 HMGA1 与内源性 FoxoO1 基因座结合的染色质免疫沉淀。
HMGA1 通过结合 FoxO1 基因启动子，在体外培养的 HepG2 和 HEK-293 细胞中增加 FoxO1 mRNA 和蛋白表达，从而激活 FoxO1 基因转录。在 Hmga1 小鼠的原代培养肝细胞和内源性 HMGA1 表达降低的 EBV 转化的淋巴母细胞中强制表达 HMGA1 增加了 FoxO1 mRNA 和蛋白水平。
这些发现可能有助于理解 FoxO1 基因调控及其在代谢中的作用。
