Department of Applied Biological Chemistry, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, 183-8509, Japan.
Department of Agricultural Chemistry, Graduate School of Agricultural Science, Tohoku University, Sendai, 980-8572, Japan.
Commun Biol. 2023 Oct 4;6(1):1009. doi: 10.1038/s42003-023-05386-w.
Regulated Ire1-dependent decay (RIDD) is a feedback mechanism in which the endoribonuclease Ire1 cleaves endoplasmic reticulum (ER)-localized mRNAs encoding secretory and membrane proteins in eukaryotic cells under ER stress. RIDD is artificially induced by chemicals that generate ER stress; however, its importance under physiological conditions remains unclear. Here, we demonstrate the occurrence of RIDD in filamentous fungus using Aspergillus oryzae as a model, which secretes copious amounts of amylases. α-Amylase mRNA was rapidly degraded by IreA, an Ire1 ortholog, depending on its ER-associated translation when mycelia were treated with dithiothreitol, an ER-stress inducer. The mRNA encoding maltose permease MalP, a prerequisite for the induction of amylolytic genes, was also identified as an RIDD target. Importantly, RIDD of malP mRNA is triggered by inducing amylase production without any artificial ER stress inducer. Our data provide the evidence that RIDD occurs in eukaryotic microorganisms under physiological ER stress.
调控的 Ire1 依赖的降解（RIDD）是一种反馈机制，其中内切核糖核酸酶 Ire1 在真核细胞的内质网（ER）应激下切割内质网定位的编码分泌和膜蛋白的 mRNA。RIDD 是通过产生 ER 应激的化学物质人为诱导的；然而，其在生理条件下的重要性仍不清楚。在这里，我们使用米曲霉作为模型证明了丝状真菌中存在 RIDD，米曲霉大量分泌淀粉酶。当用二硫苏糖醇（一种 ER 应激诱导剂）处理菌丝体时，依赖于其 ER 相关翻译，Ire1 同源物 IreA 迅速降解α-淀粉酶 mRNA。麦芽糖通透酶 MalP 的 mRNA 编码，它是诱导淀粉酶基因表达的前提条件，也被鉴定为 RIDD 的靶标。重要的是，在没有任何人工 ER 应激诱导剂的情况下，通过诱导淀粉酶产生触发了 malP mRNA 的 RIDD。我们的数据提供了证据表明，在生理 ER 应激下，RIDD 发生在真核微生物中。
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