Calcineurin A/TAX-6 signaling inhibits noxious heat-evoked nuclear accumulation of CMK-1 in the FLP thermo-nociceptive neurons of Caenorhabditis elegans

Calcium signaling is central to neural plasticity. In <i>C. elegans</i> , the CaM kinase I/ CMK-1 and the phosphatase Calcineurin A/ TAX-6 antagonistically regulate thermo-nociceptive behavior via partially overlapping neuronal circuits. Following prolonged exposure to noxious temperature (90 min, 28°C) CMK-1 localization shifts from cytoplasmic to nuclear in FLP neurons, which reduces behavioral responsiveness. We examined whether Calcineurin A/ TAX-6 influences this process. Using CMK-1 ::mNeonGreen, we found that Calcineurin A/ TAX-6 activation blocks, while its loss slightly enhances, CMK-1 nuclear translocation at 28°C. These results reveal that Calcineurin A/ TAX-6 signaling negatively regulates CMK-1 nuclear accumulation, providing a potential mechanism for opposing modulation of thermo-nociceptive plasticity.