The involvement of TRPA1-like in regulating cytoplasmic Ca2+, unfolded protein response and apoptosis of Yesso scallop Patinopecten yessoensis after low temperature treatment

Transient receptor potential ankyrin subtype 1 (TRPA1) is a nonselective cation channel involved in intracellular Ca²⁺ regulation and temperature sensing. In this study, we investigated the involvement of PyTRPA1-like in regulating UPR and apoptosis in haemocytes of the Yesso scallop Patinopecten yessoensis under low temperature stress (4 °C). The mRNA expression of PyTRPA1-like significantly increased at 1 h after treatment (p < 0.05), followed by elevated intracellular Ca²⁺ levels at 3 h (p < 0.05). Low temperature also significantly upregulated the mRNA expression of key UPR-related genes, including PyGRP78, PyIRE1, PyATF6β and PyPERK, while apoptosis-related genes PyCaspase-3 and PyBcl-2 showed time-dependent changes. Correspondingly, Caspase-3 activity and haemocyte apoptosis were significantly increased (p < 0.05). The combined treatment with the TRPA1 antagonist HC-030031 and low temperature significantly elevated intracellular Ca²⁺ levels, mRNA expression levels of PyBcl-2 and PyGRP78, Caspase-3 activity and apoptotic rate (p < 0.05), while significantly reducing PyIRE1 and PyPERK mRNA expression (p < 0.05). These findings suggest that PyTRPA1-like contributes to calcium influx and UPR activation under low temperature stress. Inhibition of PyTRPA1-like may induce compensatory calcium dysregulation and promote apoptosis partially independent of canonical UPR signaling