Tetramethylthiuram disulfide induces stress granules and DNA damage through oxidative stress in human lung epithelial cells

TL;DR

Tetramethylthiuram disulfide harms lung cells by causing stress granules and DNA damage through oxidative stress, suggesting a health risk for workers exposed to it.

Contribution

This study reveals a mechanistic cascade linking TMTD exposure to oxidative stress, stress granule formation, DNA damage, and apoptosis in lung cells.

Findings

TMTD rapidly triggers stress granule formation and eIF2α phosphorylation in A549 cells.

Oxidative stress mediates TMTD-induced DNA damage and apoptosis, confirmed by antioxidant rescue experiments.

Repeated TMTD exposure leads to persistent cellular damage and increased apoptosis.

Abstract

Tetramethylthiuram disulfide (TMTD), widely used in rubber manufacturing and agriculture, presents occupational inhalation hazards, yet its effects on human lung epithelial cells remain poorly characterized. Here, we investigated TMTD-induced cellular stress responses in A549 lung epithelial cells, focusing on stress granule formation, oxidative stress, and DNA damage. TMTD induced concentration-dependent cytotoxicity, with brief exposure producing effects comparable to continuous exposure, indicating persistent cellular damage. Using live-cell imaging with A549 G3BP1-GFP knock-in cells, we demonstrated that TMTD rapidly triggered SG formation within minutes, accompanied by marked eIF2α phosphorylation. TMTD exposure caused dramatic intracellular ROS accumulation and robust γ-H2AX phosphorylation. Antioxidant rescue experiments using N-acetylcysteine confirmed that oxidative stress directly drives SG formation and DNA damage. Repeated TMTD exposure significantly increased apoptotic cell populations, demonstrating that cells cannot recover from recurrent exposure. Our findings reveal a mechanistic cascade whereby TMTD induces oxidative stress, triggers SG formation as an adaptive response, causes DNA damage, and ultimately leads to apoptosis when cellular stress overwhelms protective mechanisms. This study establishes stress granule formation as a sensitive early biomarker for TMTD exposure and highlights significant respiratory health risks for workers in rubber and agricultural industries, supporting the need for re-evaluation of occupational exposure limits and implementation of stringent protective measures.

Figures