eIF4A3 regulates the TFEB-mediated transcriptional response via GSK3B to control autophagy

Cell Death Differ. 2021 Dec;28(12):3344-3356. doi: 10.1038/s41418-021-00822-y. Epub 2021 Jun 22.

Abstract

During autophagy, the coordinated actions of autophagosomes and lysosomes result in the controlled removal of damaged intracellular organelles and superfluous substrates. The evolutionary conservation of this process and its requirement for maintaining cellular homeostasis emphasizes the need to better dissect the pathways governing its molecular regulation. In our previously performed high-content screen, we assessed the effect of 1530 RNA-binding proteins on autophagy. Among the top regulators, we identified the eukaryotic translation initiation factor 4A-3 (eIF4A3). Here we show that depletion of eIF4A3 leads to a potent increase in autophagosome and lysosome biogenesis and an enhanced autophagic flux. This is mediated by the key autophagy transcription factor, TFEB, which becomes dephosphorylated and translocates from the cytoplasm to the nucleus where it elicits an integrated transcriptional response. We further identified an exon-skipping event in the transcript encoding for the direct TFEB kinase, GSK3B, which leads to a reduction in GSK3B expression and activity. Through analysis of TCGA data, we found a significant upregulation of eIF4A3 expression across several cancer types and confirmed the potential relevance of this newly identified signaling axis in human tumors. Hence, our data suggest a previously unrecognized role for eIF4A3 as a gatekeeper of autophagy through the control of TFEB activation, revealing a new mechanism for autophagy regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism*
  • DEAD-box RNA Helicases / metabolism*
  • Eukaryotic Initiation Factor-4A / metabolism*
  • Glycogen Synthase Kinase 3 beta / metabolism*
  • Humans
  • Transcription Factors / metabolism*
  • Transfection

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • TFEB protein, human
  • Transcription Factors
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Eukaryotic Initiation Factor-4A
  • EIF4A3 protein, human
  • DEAD-box RNA Helicases