Cellular and functional insights into FIH-mediated hydroxylation of TRPA1.

Transient receptor potential cation channel, subfamily A, member 1 (TRPA1), also known as transient receptor potential ankyrin 1, is an ion channel located on the plasma membrane of cells. It is best known as a sensor for pain, cold, and itch in humans and other mammals, as well as for detecting electrophilic sensory irritants, including allyl isothiocyanate. A previous study confirmed that TRPA1 undergoes hydroxylation at Asn336, catalyzed by the 2-oxoglutarate oxygenase factor-inhibiting hypoxia-inducible factor (FIH). However, the biological significance of this modification remains unclear. Here, we present cellular and functional studies on the consequences of FIH-mediated asparaginyl hydroxylation of TRPA1. Coimmunoprecipitation experiments indicate that TRPA1 interacts with FIH in cells, in a manner likely involving the FIH dimer interface, as demonstrated by studies with the L340R FIH variant, which is unable to dimerize. Functional studies suggest that FIH-mediated hydroxylation may be linked to allyl isothiocyanate-induced channel activation. This response is diminished or delayed in TRPA1-expressing human embryonic kidney 293T cells and absent in primary hippocampal cultures when FIH activity is lacking. These findings highlight a potential new avenue for the therapeutic manipulation of TRPA1.