Caenorhabditis elegans inositol hexaphosphate pathways couple to RNA interference and pathogen defense

• 成果类型: Article
• 署名作者: Xu, Wenjing; Sun, Yifan; Breen, Peter; Ruvkun, Gary; Mao, Kai
• 署名单位: Northwest A&F University - China; Harvard University; Harvard University Medical Affiliates; Massachusetts General Hospital; Harvard University; Harvard Medical School
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-9951
• DOI: 10.1073/pnas.2416982121
• 发表日期: 2024-12-03
• 关键词: unfolded protein response; c. elegans; vulval induction; synmuv genes; adar1; expression; hexakisphosphate; regulator

摘要

RNA interference (RNAi) is an evolutionarily conserved pathway that defends against viral infections in diverse organisms. Caenorhabditis elegans mutations that enhance RNAi have revealed pathways that may regulate antiviral defense. A genetic screen for C. elegans mutations that fail to up- regulate a defense response reporter transgene detected mutations that enhance RNAi to silence this reporter gene in the inositol polyphosphate multikinase impk-1, the synMuv B gene lin-15B, and the pathogen defense response gene pals- 22 . Using other assays for enhanced RNAi, we found that the impk-1 alleles and an ippk-1 gene inactivation of a later step in inositol hexaphosphate (IP6) synthesis, and the lin-15B and pals- 22 alleles enhance RNAi. IP6 has been known for decades to bind and stabilize human adenosine deaminase that acts on RNA (ADAR) as well as the paralog tRNA editing ADAT. We show that the C. elegans IP6 pathway is also required for mRNA and tRNA editing. Thus, a deficiency in two axes of RNA editing enhances the already potent C. elegans RNAi antiviral defense, suggesting adenosine to inosine RNA editing may normally moderate this siRNA antiviral defense pathway. The C. elegans IP6- deficient mutants are synthetic lethal with a set of enhanced RNAi mutants that act in the polyploid hypodermis to regulate collagen secretion and signaling from that tissue, implicating IP6 signaling especially in this tissue. This enhanced antiviral RNAi response uses the C. elegans RIG- I- like receptor DRH-1 to activate the unfolded protein response (UPR). The production of primary siRNAs, rather than secondary siRNAs, contributes to this activation of the UPR through XBP-1 signaling. The gon-14 and pal- 17 mutants that also emerged from this screen act in the mitochondrial defense pathway rather than by enhancing RNAi.