Division of Biology, Kansas State University, Manhattan, Kansas, United States of America.
Department of Software and Information Systems Engineering, Ben-Gurion University of the Negev, Beer-sheva, Israel.
PLoS Genet. 2019 Oct 4;15(10):e1008067. doi: 10.1371/journal.pgen.1008067. eCollection 2019 Oct.
microRNAs (miRNAs) are potent regulators of gene expression that function in diverse developmental and physiological processes. Argonaute proteins loaded with miRNAs form the miRNA Induced Silencing Complexes (miRISCs) that repress gene expression at the post-transcriptional level. miRISCs target genes through partial sequence complementarity between the miRNA and the target mRNA's 3' UTR. In addition to being targeted by miRNAs, these mRNAs are also extensively regulated by RNA-binding proteins (RBPs) through RNA processing, transport, stability, and translation regulation. While the degree to which RBPs and miRISCs interact to regulate gene expression is likely extensive, we have only begun to unravel the mechanisms of this functional cooperation. An RNAi-based screen of putative ALG-1 Argonaute interactors has identified a role for a conserved RNA binding protein, HRPK-1, in modulating miRNA activity during C. elegans development. Here, we report the physical and genetic interaction between HRPK-1 and ALG-1/miRNAs. Specifically, we report the genetic and molecular characterizations of hrpk-1 and its role in C. elegans development and miRNA-mediated target repression. We show that loss of hrpk-1 causes numerous developmental defects and enhances the mutant phenotypes associated with reduction of miRNA activity, including those of lsy-6, mir-35-family, and let-7-family miRNAs. In addition to hrpk-1 genetic interaction with these miRNA families, hrpk-1 is required for efficient regulation of lsy-6 target cog-1. We report that hrpk-1 plays a role in processing of some but not all miRNAs and is not required for ALG-1/AIN-1 miRISC assembly. We suggest that HRPK-1 may functionally interact with miRNAs by both affecting miRNA processing and by enhancing miRNA/miRISC gene regulatory activity and present models for its activity.
微小 RNA（miRNAs）是基因表达的有效调控因子，在多种发育和生理过程中发挥作用。装载有 miRNAs 的 Argonaute 蛋白形成 miRNA 诱导的沉默复合物（miRISCs），在转录后水平抑制基因表达。miRISCs 通过 miRNA 和靶 mRNA 的 3'UTR 之间的部分序列互补性靶向基因。除了被 miRNAs 靶向外，这些 mRNA 还通过 RNA 加工、运输、稳定性和翻译调节被 RNA 结合蛋白（RBPs）广泛调节。虽然 RBP 和 miRISC 相互作用调节基因表达的程度可能很广泛，但我们才刚刚开始揭示这种功能合作的机制。基于 RNAi 的推定 ALG-1 Argonaute 相互作用体的筛选已确定保守的 RNA 结合蛋白 HRPK-1 在调节秀丽隐杆线虫发育过程中的 miRNA 活性方面的作用。在这里，我们报告了 HRPK-1 和 ALG-1/miRNAs 之间的物理和遗传相互作用。具体来说，我们报告了 hprk-1 的遗传和分子特征及其在秀丽隐杆线虫发育和 miRNA 介导的靶标抑制中的作用。我们发现 hprk-1 的缺失会导致许多发育缺陷，并增强与 miRNA 活性降低相关的突变表型，包括 lsy-6、mir-35 家族和 let-7 家族 miRNAs。除了 hprk-1 与这些 miRNA 家族的遗传相互作用外，hprk-1 还需要有效地调节 lsy-6 靶标 cog-1。我们报告 hprk-1 对一些而不是所有 miRNA 的加工都有作用，并且不需要 ALG-1/AIN-1 miRISC 组装。我们认为 HRPK-1 可能通过影响 miRNA 加工和增强 miRNA/miRIS 基因调节活性来与 miRNAs 发挥功能相互作用，并提出了其活性的模型。
