New Approach Methodologies (NAMs) reveal triphenyl phosphate (TPP) disrupts lipid metabolism in estuarine fish via PPARγ activation: A concentration-dependent transcriptomic and molecular docking study

Abstract

There is an urgent need for a more efficient and ethical approach to chemical toxicity assessment. The emergence of New Approach Methodologies (NAMs) based on fish embryos transcriptomics provides a promising alternative. Triphenyl phosphate (TPP) — a pervasive contaminant in estuaries — disrupts lipid homeostasis in mammals via PPARγ activation, yet its ecotoxicological impacts on estuarine fish remain unknown. Leveraging NAMs, this study integrates concentration-dependent transcriptomics (CDT), molecular docking, and phenotypic toxicity assays to unravel effects of TPP on embryonic development and lipid metabolism in the benthic fish Mugilogobius chulae. We found that TPP induced significant lethality (LC₅₀ = 1.86 × 10⁶ ng/L) and teratogenicity (EC₅₀ = 5.27 × 10⁵ ng/L), suppressing spontaneous movement, heart rate, and hatching. At concentrations of 5270 ng/L and 52,700 ng/L, TPP elevated triglycerides, total cholesterol, and hepatotoxicity markers (alanine aminotransferase / aspartate aminotransferase). CDT analysis identified fatty acid metabolism pathways as the most sensitive targets, with TPP upregulating PPARγ while downregulating CD36 and ACSL5 — indicating blocked fatty acid oxidation and explaining lipid accumulation. Crucially, co-exposure with PPARγ antagonist GW9662 reversed metabolic disorders, validating the mechanistic role of PPARγ. Furthermore, molecular docking confirmed that TPP binds PPARγ with agonist-like affinity. This work establishes a NAM-based framework for deciphering the toxicity of contaminants of emerging concern in estuarine ecosystems, offering novel tools for ecological risk assessment.