Neurotoxins subvert the allosteric activation mechanism of SARM1 to induce neuronal loss

Cell Rep. 2021 Oct 19;37(3):109872. doi: 10.1016/j.celrep.2021.109872.

Abstract

SARM1 is an inducible TIR-domain NAD+ hydrolase that mediates pathological axon degeneration. SARM1 is activated by an increased ratio of NMN to NAD+, which competes for binding to an allosteric activating site. When NMN binds, the TIR domain is released from autoinhibition, activating its NAD+ hydrolase activity. The discovery of this allosteric activating site led us to hypothesize that other NAD+-related metabolites might activate SARM1. Here, we show the nicotinamide analog 3-acetylpyridine (3-AP), first identified as a neurotoxin in the 1940s, is converted to 3-APMN, which activates SARM1 and induces SARM1-dependent NAD+ depletion, axon degeneration, and neuronal death. In mice, systemic treatment with 3-AP causes rapid SARM1-dependent death, while local application to the peripheral nerve induces SARM1-dependent axon degeneration. We identify 2-aminopyridine as another SARM1-dependent neurotoxin. These findings identify SARM1 as a candidate mediator of environmental neurotoxicity and suggest that SARM1 agonists could be developed into selective agents for neurolytic therapy.

Keywords: NAMPT; NMNAT; Vacor; base exchange reaction; mass spectrometry; metabolism; myelin; neurolytic block; sciatic nerve; tibial nerve.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Activation, Metabolic
  • Allosteric Regulation
  • Animals
  • Armadillo Domain Proteins / genetics
  • Armadillo Domain Proteins / metabolism*
  • Axons / drug effects*
  • Axons / enzymology
  • Axons / pathology
  • Catalytic Domain
  • Cell Death
  • Cytokines / genetics
  • Cytokines / metabolism
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Enzyme Activation
  • Female
  • Ganglia, Spinal / drug effects*
  • Ganglia, Spinal / enzymology
  • Ganglia, Spinal / pathology
  • HEK293 Cells
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nerve Degeneration*
  • Neurotoxicity Syndromes / enzymology
  • Neurotoxicity Syndromes / etiology*
  • Neurotoxicity Syndromes / pathology
  • Neurotoxins / metabolism
  • Neurotoxins / toxicity*
  • Nicotinamide Phosphoribosyltransferase / genetics
  • Nicotinamide Phosphoribosyltransferase / metabolism
  • Nicotinamide-Nucleotide Adenylyltransferase / genetics
  • Nicotinamide-Nucleotide Adenylyltransferase / metabolism
  • Pyridines / metabolism
  • Pyridines / toxicity*
  • Sciatic Nerve / drug effects*
  • Sciatic Nerve / enzymology
  • Sciatic Nerve / pathology
  • Signal Transduction

Substances

  • Armadillo Domain Proteins
  • Cytokines
  • Cytoskeletal Proteins
  • Neurotoxins
  • Pyridines
  • SARM1 protein, mouse
  • 3-acetylpyridine
  • Nicotinamide Phosphoribosyltransferase
  • nicotinamide phosphoribosyltransferase, mouse
  • Nmnat protein, mouse
  • Nicotinamide-Nucleotide Adenylyltransferase