A tRNA processing enzyme is a key regulator of the mitochondrial unfolded protein response

Elife. 2022 Apr 22;11:e71634. doi: 10.7554/eLife.71634.

Abstract

The mitochondrial unfolded protein response (UPRmt) has emerged as a predominant mechanism that preserves mitochondrial function. Consequently, multiple pathways likely exist to modulate UPRmt. We discovered that the tRNA processing enzyme, homolog of ELAC2 (HOE-1), is key to UPRmt regulation in Caenorhabditis elegans. We find that nuclear HOE-1 is necessary and sufficient to robustly activate UPRmt. We show that HOE-1 acts via transcription factors ATFS-1 and DVE-1 that are crucial for UPRmt. Mechanistically, we show that HOE-1 likely mediates its effects via tRNAs, as blocking tRNA export prevents HOE-1-induced UPRmt. Interestingly, we find that HOE-1 does not act via the integrated stress response, which can be activated by uncharged tRNAs, pointing toward its reliance on a new mechanism. Finally, we show that the subcellular localization of HOE-1 is responsive to mitochondrial stress and is subject to negative regulation via ATFS-1. Together, we have discovered a novel RNA-based cellular pathway that modulates UPRmt.

Keywords: C. elegans; ELAC2/HOE-1; cell biology; mitochondria; mitochondrial unfolded protein response; tRNAs.

MeSH terms

  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins* / genetics
  • Caenorhabditis elegans Proteins* / metabolism
  • Mitochondria / metabolism
  • Transcription Factors / metabolism
  • Unfolded Protein Response

Substances

  • Caenorhabditis elegans Proteins
  • Transcription Factors