Downregulation of Hsp90 and the antimicrobial peptide Mtk suppresses poly(GR)-induced neurotoxicity in C9ORF72-ALS/FTD

Neuron. 2023 May 3;111(9):1381-1390.e6. doi: 10.1016/j.neuron.2023.02.029. Epub 2023 Mar 16.

Abstract

GGGGCC repeat expansion in the C9ORF72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat RNAs can be translated into dipeptide repeat proteins, including poly(GR), whose mechanisms of action remain largely unknown. In an RNA-seq analysis of poly(GR) toxicity in Drosophila, we found that several antimicrobial peptide genes, such as metchnikowin (Mtk), and heat shock protein (Hsp) genes are activated. Mtk knockdown in the fly eye or in all neurons suppresses poly(GR) neurotoxicity. These findings suggest a cell-autonomous role of Mtk in neurodegeneration. Hsp90 knockdown partially rescues both poly(GR) toxicity in flies and neurodegeneration in C9ORF72 motor neurons derived from induced pluripotent stem cells (iPSCs). Topoisomerase II (TopoII) regulates poly(GR)-induced upregulation of Hsp90 and Mtk. TopoII knockdown also suppresses poly(GR) toxicity in Drosophila and improves survival of C9ORF72 iPSC-derived motor neurons. These results suggest potential novel therapeutic targets for C9ORF72-ALS/FTD.

Keywords: ALS; C9ORF72; DPR; FTD; Hsp90; Mtk; TopoII; antimicrobial peptide; neurodegeneration; poly(GR).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amyotrophic Lateral Sclerosis* / genetics
  • Animals
  • C9orf72 Protein / genetics
  • C9orf72 Protein / metabolism
  • DNA Repeat Expansion
  • Dipeptides / genetics
  • Disease Models, Animal
  • Down-Regulation
  • Drosophila / metabolism
  • Frontotemporal Dementia* / genetics
  • Frontotemporal Dementia* / metabolism
  • Motor Neurons / metabolism

Substances

  • C9orf72 Protein
  • Dipeptides
  • Hsp83 protein, Drosophila
  • Mtk protein, Drosophila