Fu Rui, Wellman Kimberly, Baldwin Amber, Rege Juilee, Walters Kathryn, Hirsekorn Antje, Riemondy Kent, Rainey William E, Mukherjee Neelanjan
University of Colorado Denver School of Medicine.
University of Michigan School of Medicine.
RNA. 2021 Jun 1;27(8):933-45. doi: 10.1261/rna.078727.121.
Angiotensin II (AngII) stimulates adrenocortical cells to produce aldosterone, a master regulator of blood pressure. Despite extensive characterization of the transcriptional and enzymatic control of adrenocortical steroidogenesis, there are still major gaps in the precise regulation of AII-induced gene expression kinetics. Specifically, we do not know the regulatory contribution of RNA-binding proteins (RBPs) and RNA decay, which can control the timing of stimulus-induced gene expression. To investigate this question, we performed a high-resolution RNA-seq time course of the AngII stimulation response and 4-thiouridine pulse labeling in a steroidogenic human cell line (H295R). We identified twelve temporally distinct gene expression responses that contained mRNA encoding proteins known to be important for various steps of aldosterone production, such as cAMP signaling components and steroidogenic enzymes. AngII response kinetics for many of these mRNAs revealed a coordinated increase in both synthesis and decay. These findings were validated in primary human adrenocortical cells stimulated ex vivo with AngII. Using a candidate screen, we identified a subset of RNA-binding protein and RNA decay factors that activate or repress AngII-stimulated aldosterone production. Among the repressors of aldosterone were BTG2, which promotes deadenylation and global RNA decay. BTG2 was induced in response to AngII stimulation and promoted the repression of mRNAs encoding pro-steroidogenic factors indicating the existence of an incoherent feedforward loop controlling aldosterone homeostasis. These data support a model in which coordinated increases in transcription and decay facilitate the major transcriptomic changes required to implement a pro-steroidogenic expression program that actively resolved to prevent aldosterone overproduction.
血管紧张素II（AngII）刺激肾上腺皮质细胞产生醛固酮，醛固酮是血压的主要调节因子。尽管对肾上腺皮质类固醇生成的转录和酶促控制已有广泛的表征，但在AngII诱导的基因表达动力学的精确调控方面仍存在重大差距。具体而言，我们尚不清楚RNA结合蛋白（RBP）和RNA降解的调控作用，它们可以控制刺激诱导的基因表达时间。为了研究这个问题，我们在一种类固醇生成的人类细胞系（H295R）中进行了AngII刺激反应的高分辨率RNA测序时间进程和4-硫尿苷脉冲标记。我们确定了十二个在时间上不同的基因表达反应，其中包含编码已知对醛固酮产生的各个步骤很重要的蛋白质的mRNA，如cAMP信号成分和类固醇生成酶。许多这些mRNA的AngII反应动力学显示合成和降解均协调增加。这些发现在用AngII离体刺激的原代人肾上腺皮质细胞中得到了验证。通过候选筛选，我们确定了一组激活或抑制AngII刺激的醛固酮产生的RNA结合蛋白和RNA降解因子。醛固酮的抑制因子包括BTG2，它促进去腺苷酸化和整体RNA降解。BTG2在AngII刺激下被诱导，并促进对编码促类固醇生成因子的mRNA的抑制，表明存在一个控制醛固酮稳态的非相干前馈环。这些数据支持了一个模型，即转录和降解的协调增加促进了实施促类固醇生成表达程序所需的主要转录组变化，该程序积极发挥作用以防止醛固酮过度产生。
