# NADH‐Reductive Stress Induced by Dihydrolipoamide Dehydrogenase Activation Contributes to Cuproptosis

## TL;DR

This study explains how copper causes a new type of cell death called cuproptosis by creating NADH-reductive stress in neural cells.

## Contribution

The study identifies NADH-reductive stress as a novel mechanism of cuproptosis triggered by copper-induced mitochondrial changes.

## Key findings

- Copper activates DLD under alkaline mitochondrial pH, leading to NADH accumulation.
- Copper-induced mPTP opening allows NADH to move to the cytosol, causing reductive stress and ATP depletion.
- Pharmacological targeting of NADH-reductive stress rescues copper-induced cell death in neuroblastoma cells.

## Abstract

Copper (Cu) is an essential trace element for cellular metabolism, while excessive Cu accumulation leads to neurotoxicity. Current therapeutic strategies for Cu overload remain inadequate in mitigating neurological symptoms. The recently discovered Cu‐dependent mitochondrial cell death pathway, cuproptosis, offers novel insights into Cu‐mediated neurotoxicity. In this study, the mechanistic link between mitochondrial respiration and cuproptosis is elucidated. The current study demonstrates that activated dihydrolipoamide dehydrogenase (DLD), induced by excess Cu under alkaline mitochondrial pH conditions, drives nicotinamide adenine dinucleotide (NADH) accumulation. Cu mediated mitochondrial permeability transition pore (mPTP) opening that facilitates NADH translocation to the cytosol, triggering NADH‐reductive stress. This promotes aberrant purine biosynthesis, leading to severe adenosine triphosphate depletion and energy stress. Pharmacological interventions targeting DLD activity, cytosolic NADH, mPTP opening, purine biosynthesis, or energy stress effectively rescued Cu‐induced cell death in SH‐SY5Y neuroblastoma cells. Collectively, these findings reveal characteristics of NADH‐reductive stress under excessive Cu exposure, establishing cuproptosis as a novel NADH‐reductive stress‐dependent cell death pathway. This mechanistic insight provides new therapeutic avenues for Cu‐associated neurological pathologies and new aspects to explore Cu cellular physiology.

This study demonstrates a cuproptosis mechanism involving nicotinamide adenine dinucleotide (NADH)‐reductive stress in neural cells. Copper activates dihydrolipoamide dehydrogenase under mitochondrial pH, accumulating NADH. Copper also induces mitochondrial permeability transition pore opening, facilitating NADH translocation to the cytosol and provoking reductive stress, aberrant purine biosynthesis, and adenosine triphosphate depletion, resulting in cell death. Targeting the NADH‐reductive stress pathway offers a novel therapeutic strategy for copper‐associated neurodegeneration.