TRPA1 Channels as Multimodal Environmental Sensors: Structure-Function Insights From Aquatic Organisms

Transient receptor potential ankyrin 1 (TRPA1) is an evolutionarily conserved non-selective cation channel protein that converts diverse stimuli into intracellular Ca²⁺ signals. Aquatic organisms provide valuable comparative systems for examining how environmental complexity shapes TRPA1 structure and function. In water, TRPA1 channels may be exposed to combined pressures from thermal stratification, hydrodynamic disturbance, chemical diffusion, salinity fluctuation, and redox changes. Although research on aquatic TRPA1 has expanded in recent years, most studies have focused on individual species, isolated stimuli, or behavioral phenotypes. A structure-function-oriented synthesis linking channel architecture, stimulus-dependent gating, Ca²⁺ signaling, and physiological adaptation remains lacking. This review summarizes current knowledge of aquatic TRPA1 channels from a structure-function perspective. These channels generally retain a conserved architecture, including N-terminal ankyrin repeat domains, six transmembrane segments, and a central ion-conducting pore, while exhibiting lineage-specific variation in ankyrin repeat number, redox-sensitive cysteine residues, and transmembrane or regulatory amino acids. Such structural features may fine-tune conformational stability, ligand recognition, thermal responsiveness, redox sensitivity, and Ca²⁺ signal output across aquatic taxa. Functionally, TRPA1 has been implicated in sensing or regulating responses to temperature, light/radiation, salinity, reactive chemicals, and mechanical cues. Emerging evidence further points to cross-modal integration of temperature-chemical, light-chemical, and mechanical-redox signals. Through Ca²⁺-dependent signaling pathways, TRPA1-mediated activation can be linked to stress defense, feeding metabolism, reproduction, neurogenesis, immunity, aggregation behavior, and host-symbiont interactions. Overall, aquatic organisms provide comparative models for understanding how TRPA1 channels link local structural plasticity to multimodal environmental sensing and adaptive physiological regulation.