Impact of a UV filter 4-Methylbenzylidene Camphor (4-MBC) on Liver Metabolism in Clown Anemonefish: Disruption of Insulin Sensitivity, Lipid Metabolism and Endoplasmic Reticulum Function

UV filters, such as 4-Methylbenzylidene camphor (4-MBC), are emerging environmental contaminants that threaten marine life and ecosystem integrity. This study investigated metabolic disruptions in the liver of clown anemonefish ( Amphiprion ocellaris ) after exposure to 4-MBC (0, 10, 50   µg/L) for 7 or 14 days. Exposure led to 4-MBC accumulation and significant liver metabolic disturbances and endocrine disruption in the fish. Random forest analysis identified vitellogenin and testosterone levels as key factors distinguishing treatment groups. Molecular docking showed high binding affinity of 4-MBC to 17β-hydroxysteroid dehydrogenase and vitellogenin in the liver. Additionally, 4-MBC exposure reduced thyroid hormone levels and disrupted glucose and lipid metabolism, with more severe effects at 7 days compared to 14 days. Transcriptome analysis revealed that 4-MBC interfered with hepatic insulin sensitivity by disrupting pathways involving Insulin Receptor (INSR), Phosphoinositide 3-Kinase (PI3K), Insulin Receptor Substrate (IRS), and others. It also impacted genes related to lipid accumulation, gluconeogenesis, and lipid utilization. Furthermore, 4-MBC disrupted the endoplasmic reticulum (ER)’s protein degradation system, causing ER stress and activating lipogenic pathways, which enhanced lipid accumulation. The reduction in thyroid hormones and metabolic dysfunctions may impair the reproductive health and population stability of clown anemonefish. These findings underscore the potential ecotoxicity of 4-MBC and its adverse effects on coral reef fish populations, raising concerns about its environmental impact.