Transnitrosylation Directs TRPA1 Selectivity in N-Nitrosamine Activators

Abstract

S-Nitrosylation, the addition of a nitrosyl group to cysteine thiols, regulates various protein functions to mediate nitric oxide (NO) bioactivity. Recent studies have demonstrated that selectivity in protein S-nitrosylation signaling pathways is conferred through transnitrosylation, a transfer of the NO group, between proteins via interaction. We previously demonstrated that sensitivity to activation by synthetic NO-releasing agents via S-nitrosylation is a common feature of members of the transient receptor potential (TRP) family of Ca 21 -permeable cation channels. However, strategies to confer subtype selectivity to nitrosylating agents targeted to TRP channels are yet to be developed. Here, we show selective activation of TRPA1 channels by novel NO donors derived from the ABBH (7-azabenzobicyclo[2.2.1]heptane) N-nitrosamines, which exhibit transnitrosylation reactivity to thiols without releasing NO. The NNO-ABBH1 (N-nitroso-2-exo,3-exo-ditrifluoromethyl-7-azabenzobicyclo[2.2.1]heptane) elicits S-nitrosylation of TRPA1 proteins, and dose-dependently induces robust Ca 21 influx via both recombinant and native TRPA1 channels, but not via other NO-activated TRP channels. TRPA1 activation by NNO-ABBH1 is suppressed by specific cysteine mutations but not by NO scavenging, suggesting that cysteine transnitrosylation underlies the activation of TRPA1 by NNO-ABBH1. This is supported by the correlation of N-NO bond reactivity and TRPA1-activating potency in a congeneric series of ABBH N-nitrosamines. Interestingly, nonelectrophilic derivatives of ABBH also activate TRPA1 selectively, but less potently, compared with NNO-ABBH1. Thus, ABBH N-nitrosamines confer subtype selectivity on S-nitrosylation in TRP channels through synergetic effects of two chemical processes: cysteine transnitrosylation and molecular recognition of the nonelectrophilic moiety.

Interactive Effects of Dietary Fat/Carbohydrate Ratio and Body Mass Index on Iron Deficiency Anemia among Taiwanese Women

“…A possible relationship between obesity and hypoferremia has recently been described in children [1,2,3] and women [4,5,6,7,8,9,10]. However, whether being overweight or obese is associated with increased risk of anemia or iron deficiency anemia (IDA) is still being debated [7,8,9,10,11,12,13,14].…”

“…However, whether being overweight or obese is associated with increased risk of anemia or iron deficiency anemia (IDA) is still being debated [7,8,9,10,11,12,13,14]. Cheng and colleagues conducted a systematic review of 25 studies investigating iron status in obese populations and reported obese people tended to have higher hemoglobin (Hb) and ferritin concentrations, but lower transferrin saturation compared to non-obese controls [15].…”

Deciphering Subtype-Selective Modulations in TRPA1 Biosensor Channels

“…Receptor-activated (TRPC5, TRPC1 and TRPC4) and thermosensor (TRPV1, TRPV3, TRPV4 and TRPA1) TRP channels are activated by exogenous NO-releasing donors through S -nitrosylation [ 29 , 32 ], but with very limited TRP subtype selectivity. Recently, this problem was partly solved with our finding that the 7-azabenzobicyclo[2.2.1]heptane (ABBH) N -nitrosamine selectively S -nitrosylates TRPA1 through transnitrosylation without releasing NO [ 76 ].…”

“…In contrast, the ABBH N -nitrosamines constitute a new class of NO donors that, at physiological pH and temperature, transnitrosylate thiols to generate S -nitrosothiols without releasing NO [ 150 - 152 ]. Surprisingly, our intracellular Ca 2+ imaging measurements have demonstrated that N -nitroso-2-exo,3-exo-ditrifluoromethyl-7-azabenzobicyclo [2.2.1] heptane (NNO-ABBH1) induces robust Ca 2+ influx via recombinant human TRPA1 channels, but not via other SNAP-activated TRP channels, suggesting that NNO-ABBH1 selectively S -nitrosylates TRPA1 [ 76 ] (Fig. 4 ).…”

“…Strikingly, the chemical structure seems to be important even for the activation of TRPA1 by specific electrophiles. A novel NO donor derived from the 7-azabenzobicyclo [2.2.1] heptane N -nitrosamines confer selectivity to modulatory action of NO on TRPA1 over the other NO-sensitive TRP channels [ 76 ]. This subtype selectivity may be conferred through synergistic effects of two chemical processes: cysteine transnitrosylation and molecular recognition of a non-electrophilic moiety of the novel N -nitrosamine.…”