An environmental pollutant, 9,10‐phenanthrenequinone, activates human TRPA1 via critical cysteines 621 and 665

Abstract

Transient receptor potential ankyrin 1 (TRPA1) is activated by noxious cold, mechanical stimulation, and irritant chemicals. In our recent study, 9, 10‐phenanthrenequinone (9,10‐PQ) is the most potent irritant for activation of NRF2 among 1395 cigarette smoke components and it may be, therefore, important to find its additional targets. Here, we show that 9,10‐PQ functions as an activator of TRPA1 in human embryonic kidney (HEK) cells expressing human wild‐type TRPA1 (HEK‐wTRPA1) and human alveolar A549 (A549) cells. Application of 9,10‐PQ at 0.1–10 μmol/L induced a concentration‐dependent Ca2+ response as well as inward currents at −50 mV in HEK‐wTRPA1 cells. The current response was blocked by TRPA1 antagonists, HC‐030031 (HC) and A‐967079. To test whether 9,10‐PQ affects the cysteine residues of TRPA1, we expressed mutant TRPA1 channels in HEK cells (HEK‐muTRPA1) in which six different cysteine residues were replaced with serine. Among them, a mutation of cysteine 621 (C621S) abolished the 9,10‐PQ‐induced Ca2+ and current responses. The channel activity induced by 9,10‐PQ was also abolished in excised inside‐out patches isolated from HEK‐muTRPA1 cells with the C621S substitution. Although a mutation of cysteine 665 (C665S) reduced the 9,10‐PQ‐induced response, channel sensitization by pretreatment with Cu2+ plus 1,10‐phenanthroline and by internal dialysis of 3 μmol/L Ca2+ restored the response. However, a double mutant with C621S and C665S substitutions had little response to 9,10‐PQ, even when sensitized by Ca2+ dialysis. In A549 cells, 9,10‐PQ induced an HC‐sensitive Ca2+ response. Our findings demonstrate that 9,10‐PQ activation of human TRA1 is dependent on cysteine residues 621 and 665.

HIF-1α Dependent Upregulation of ZIP8, ZIP14, and TRPA1 Modify Intracellular Zn2+ Accumulation in Inflammatory Synoviocytes

“…TRPA1 is widely expressed in neuronal and non-neuronal cells, and it acts as a biological sensor that is activated by environmental irritants and oxidative-and thiol-reactive compounds [13][14][15][16][17]. Because transgenic mice lacking TRPA1 exhibit suppressed sensitivity to mechanical stimulation, cold stimuli, and TNF-α-induced mechanical hyperalgesia [18][19][20][21][22], TRPA1 has been identified as a nociceptor mediating acute and inflammatory pain [21][22][23][24][25].…”

Electrophile-Induced Conformational Switch of the Human TRPA1 Ion Channel Detected by Mass Spectrometry

“…The human TRPA1 (hTRPA1) contains 28 cysteine, 76 lysine and 43 histidine residues, all of which are potential targets for an electrophilic attack. Studies have suggested that several conserved N-terminal cysteines in hTRPA1 (Cys421, Cys621, Cys641, and Cys665; hTRPA1 numbering will be used throughout this paper) are critical for the activation by thiol-reactive electrophiles and oxidants [ 5 , 6 , 10 , 11 , 12 ]. In addition, a lysine (Lys710) has also been shown to contribute to activation of hTRPA1 by reaction with thiocyanates and ketoaldehydes [ 5 , 13 ].…”

Effect of dibenz(b,f)-1,4-oxazepine aerosol on the breathing pattern and respiratory variables by continuous recording and analysis in unanaesthetised mice

“…Other than TRPA1, cigarette smoke activates, TRPV1 and nicotinic acetylcholine receptors (nAChR). The sensory effect of cigarette smoke is more due to nAChR and TRPV1, and the activation may cause cough [ 31 , 35 ]. In an experiment using mouse model inhaling through a tracheal cannula, by passing the trigeminal nerves, pulmonary irritation caused less decrease in respiratory rate.…”