A novel dual-pathway AhR mechanism underpins cardiac senescence induced by 6PPDQ

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPDQ), an emerging tire-wear-derived environmental pollutant, has been associated with cardiac senescence, though its pathogenic mechanism remains unclear. Using in vitro (differentiated H9c2 cardiomyocytes, mechanistically optimized dose, 500 μg/L) and in vivo (zebrafish, environmentally relevant concentrations, 2 μg/L) models, we demonstrate that 6PPDQ induces cardiac senescence through indoleamine 2,3-dioxygenase 1 (IDO1)/kynurenine-mediated activation of the aryl hydrocarbon receptor (AhR). This process engages two parallel and functionally independent AhR signaling branches. In the canonical genomic pathway, AhR transcriptionally upregulates Cyp1a1, leading to reactive oxygen species overproduction, DNA damage, and ultimately cellular senescence evidenced by an increased proportion of SA-β-galactosidase positive cells, elevated p21 and p16 expression, compromised Lamin B1 integrity, and diminished cardiac function. Concurrently, non-genomic AhR pathway is initiated via Src kinase, which propagates signals through PI3K/AKT. This signaling cascade functionally correlates with transcription factor EB (TFEB) cytoplasmic retention, impairing its nuclear translocation and the subsequent transcription of key autophagy-lysosomal genes such as Lamp1 and Lamp2. Consequently, 6PPDQ disrupts lysosomal biogenesis and autophagic flux, marked by lysosomal depletion, p62 accumulation and defective autophagosome clearance, thereby accelerating cardiac senescence. Importantly, pharmacological inhibition of AhR attenuates DNA damages, facilitates TFEB nuclear translocation, recovers the autophagic flux, thereby mitigating the senescent phenotype induced by 6PPDQ. Reciprocal cross-pathway inhibition further confirmed that these branches do not functionally interact. Collectively, our findings delineate a kynurenine-driven, dual-pathway mechanism: genomic (Cyp1a1/ROS/DNA damage) and non-genomic (autophagy-lysosomal disruption) AhR signaling underlying 6PPDQ induced cardiac aging. These results establish AhR as pivotal node in pollutant related cardiovascular aging, offering novel mechanistic insights and potential therapeutic targets.