Omata Yuji, Okawa Maseri, Haraguchi Mai, Tsuruta Akito, Matsunaga Naoya, Koyanagi Satoru, Ohdo Shigehiro
Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Department of Glocal Healthcare Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
J Biol Chem. 2022 Aug;298(8):102184. doi: 10.1016/j.jbc.2022.102184. Epub 2022 Jun 23.
Multidrug resistance-associated protein 4 (MRP4), a member of the C subfamily of ATP-binding cassette transporters, is highly expressed in the kidneys of mammals and is responsible for renal elimination of numerous drugs. Adenosine deaminase acting on RNA 1 (ADAR1) has been reported to regulate gene expression by catalyzing adenosine-to-inosine RNA editing reactions; however, potential roles of ADAR1 in the regulation of MRP4 expression have not been investigated. In this study, we found that downregulation of ADAR1 increased the expression of MRP4 in human renal cells at the posttranscriptional level. Luciferase reporter assays and microarray analysis revealed that downregulation of ADAR1 reduced the levels of microRNA miR-381-3p, which led to the corresponding upregulation of MPR4 expression. Circular RNAs (circRNAs) are a type of closed-loop endogenous noncoding RNAs that play an essential role in gene expression by acting as miRNA sponges. We demonstrate that ADAR1 repressed the biogenesis of circRNA circHIPK3 through its adenosine-to-inosine RNA editing activity, which altered the secondary structure of the precursor of circHIPK3. Furthermore, in silico analysis suggested that circHIPK3 acts as a sponge of miR-381-3p. Indeed, we found overexpression of circHIPK3 induced the expression of MRP4 through its interference with miR-381-3p. Taken together, our study provides novel insights into regulation of the expression of xenobiotic transporters through circRNA expression by the RNA editing enzyme ADAR1.
多药耐药相关蛋白4（MRP4）是ATP结合盒转运体C亚家族的成员，在哺乳动物肾脏中高度表达，负责多种药物的肾脏清除。据报道，作用于RNA 1的腺苷脱氨酶（ADAR1）通过催化腺苷到肌苷的RNA编辑反应来调节基因表达；然而，ADAR1在MRP4表达调控中的潜在作用尚未得到研究。在本研究中，我们发现ADAR1的下调在转录后水平上增加了人肾细胞中MRP4的表达。荧光素酶报告基因检测和微阵列分析表明，ADAR1的下调降低了微小RNA miR-381-3p的水平，从而导致MPR4表达相应上调。环状RNA（circRNA）是一种闭环内源性非编码RNA，通过充当miRNA海绵在基因表达中发挥重要作用。我们证明，ADAR1通过其腺苷到肌苷的RNA编辑活性抑制circRNA circHIPK3的生物合成，这改变了circHIPK3前体的二级结构。此外，计算机分析表明circHIPK3充当miR-381-3p的海绵。事实上，我们发现circHIPK3的过表达通过干扰miR-381-3p诱导了MRP4的表达。综上所述，我们的研究为RNA编辑酶ADAR1通过circRNA表达调控外源性转运体的表达提供了新的见解。
