Adverse outcome pathway-oriented exploration of neurodevelopmental toxicity of tris(1,3-dichloropropyl) phosphate linked to membrane thyroid hormone receptor activation

Evidence indicates that organophosphate esters (OPEs), as thyroid disruptors, preferentially bind to thyroid hormone membrane receptor integrin α v β 3 rather than nuclear receptors, leading to neurodevelopmental impairments. However, the causal relationship and mechanisms linking integrin α v β 3 to adverse outcomes (AOs) are still not fully understood. Herein, we conducted an adverse outcome pathway (AOP)-oriented exploration of the neurodevelopmental toxicity and mechanisms of tri(1,3-dichloropropyl) phosphate (TDCPP), a representative OPE. TDCPP at environmentally relevant concentrations caused locomotor impairment and motor neuron development damage to zebrafish larvae. Transcriptional analysis suggested that these AOs might be mediated by TDCPP binding to integrin α v β 3 and transduced via the mitogen-activated protein kinase (MAPK) and calcium signaling pathways. Competitive binding assay confirmed TDCPP's binding to integrin α v β 3 ; moreover, TDCPP-induced outcomes were attenuated by integrin α v β 3 inhibition or by integrin α v β 3 silencing. These effects were also suppressed by inhibitors of MAPK or intracellular calcium signaling. These results revealed that the interaction of TDCPP with integrin α v β 3 rewired MAPK and calcium signaling pathways, resulting in locomotor impairment. Furthermore, we constructed a quantitative response–response relationship linking integrin α v β 3 binding to locomotor impairment. These findings advance our understanding of OPE-induced neurodevelopmental toxicity, thereby establishing a foundation for developing a novel AOP. • TDCPP exposure resulted in locomotor impairment as an AO. • Competitive binding assay confirmed the binding of TDCPP to integrin α v β 3 (MIE). • TDCPP-induced AO may involve MAPK and calcium signaling pathways. • A quantitative response–response relationship linking MIE to AO was established.