scholarly journals The proposed channel-enzyme transient receptor potential melastatin 2 does not possess ADP ribose hydrolase activity

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Iordan Iordanov ◽  
Csaba Mihályi ◽  
Balázs Tóth ◽  
László Csanády
Keyword(s):  
Cell Death ◽  
Insulin Secretion ◽  
Transient Receptor Potential ◽  
Channel Gating ◽  
Receptor Potential ◽  
Cation Channel ◽  
Chimeric Proteins ◽  
Transient Receptor Potential Melastatin ◽  
Biochemical Studies ◽  
Transient Receptor

Transient Receptor Potential Melastatin 2 (TRPM2) is a Ca2+-permeable cation channel essential for immunocyte activation, insulin secretion, and postischemic cell death. TRPM2 is activated by ADP ribose (ADPR) binding to its C-terminal cytosolic NUDT9-homology (NUDT9H) domain, homologous to the soluble mitochondrial ADPR pyrophosphatase (ADPRase) NUDT9. Reported ADPR hydrolysis classified TRPM2 as a channel-enzyme, but insolubility of isolated NUDT9H hampered further investigations. Here we developed a soluble NUDT9H model using chimeric proteins built from complementary polypeptide fragments of NUDT9H and NUDT9. When expressed in E.coli, chimeras containing up to ~90% NUDT9H sequence remained soluble and were affinity-purified. In ADPRase assays the conserved Nudix-box sequence of NUDT9 proved essential for activity (kcat~4-9s-1), that of NUDT9H did not support catalysis. Replacing NUDT9H in full-length TRPM2 with soluble chimeras retained ADPR-dependent channel gating (K1/2~1-5 μM), confirming functionality of chimeric domains. Thus, TRPM2 is not a 'chanzyme'. Chimeras provide convenient soluble NUDT9H models for structural/biochemical studies.

scholarly journals Two Decades of Evolution of Our Understanding of the Transient Receptor Potential Melastatin 2 (TRPM2) Cation Channel

Life ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 397
Author(s):  
Andras Szollosi
Keyword(s):  
Structure Function ◽  
Cell Activation ◽  
Transient Receptor Potential ◽  
Immune Cell ◽  
Receptor Potential ◽  
Cation Channel ◽  
Biophysical Properties ◽  
Vast Number ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor

The transient receptor potential melastatin (TRPM) family belongs to the superfamily of TRP ion channels. It consists of eight family members that are involved in a plethora of cellular functions. TRPM2 is a homotetrameric Ca2+-permeable cation channel activated upon oxidative stress and is important, among others, for body heat control, immune cell activation and insulin secretion. Invertebrate TRPM2 proteins are channel enzymes; they hydrolyze the activating ligand, ADP-ribose, which is likely important for functional regulation. Since its cloning in 1998, the understanding of the biophysical properties of the channel has greatly advanced due to a vast number of structure–function studies. The physiological regulators of the channel have been identified and characterized in cell-free systems. In the wake of the recent structural biochemistry revolution, several TRPM2 cryo-EM structures have been published. These structures have helped to understand the general features of the channel, but at the same time have revealed unexplained mechanistic differences among channel orthologues. The present review aims at depicting the major research lines in TRPM2 structure-function. It discusses biophysical properties of the pore and the mode of action of direct channel effectors, and interprets these functional properties on the basis of recent three-dimensional structural models.

scholarly journals TRPM8 acute desensitization is mediated by calmodulin and requires PIP2: distinction from tachyphylaxis

2011 ◽  
Vol 106 (6) ◽  
pp. 3056-3066 ◽  
Author(s):  
Ignacio Sarria ◽  
Jennifer Ling ◽  
Michael X. Zhu ◽  
Jianguo G. Gu
Keyword(s):  
Transient Receptor Potential ◽  
Channel Gating ◽  
Somatosensory System ◽  
Receptor Potential ◽  
Dorsal Root Ganglion Neurons ◽  
Open Probability ◽  
Cold Environments ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor ◽  
Ganglion Neurons

The cold-sensing channel transient receptor potential melastatin 8 (TRPM8) features Ca2+-dependent downregulation, a cellular process underlying somatosensory accommodation in cold environments. The Ca2+-dependent functional downregulation of TRPM8 is manifested with two distinctive phases, acute desensitization and tachyphylaxis. Here we show in rat dorsal root ganglion neurons that TRPM8 acute desensitization critically depends on phosphatidylinositol 4,5-bisphosphate (PIP2) availability rather than PIP2 hydrolysis and is triggered by calmodulin activation. Tachyphylaxis, on the other hand, is mediated by phospholipase hydrolysis of PIP2 and protein kinase C/phosphatase 1,2A. We further demonstrate that PIP2 switches TRPM8 channel gating to a high-open probability state with short closed times. Ca2+-calmodulin reverses the effect of PIP2, switching channel gating to a low-open probability state with long closed times. Thus, through gating modulation, Ca2+-calmodulin provides a mechanism to rapidly regulate TRPM8 functions in the somatosensory system.

scholarly journals Farnesyl pyrophosphate is a new danger signal inducing acute cell death

PLoS Biology ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. e3001134
Author(s):  
Jing Chen ◽  
Xiaochen Zhang ◽  
Liping Li ◽  
Xianqiang Ma ◽  
Chunxiao Yang ◽  
...  
Keyword(s):  
Cell Death ◽  
Transient Receptor Potential ◽  
Calcium Influx ◽  
Receptor Potential ◽  
Farnesyl Pyrophosphate ◽  
Danger Signal ◽  
Vital Event ◽  
Mva Pathway ◽  
Transient Receptor Potential Melastatin ◽  
Transient Receptor

Cell death is a vital event in life. Infections and injuries cause lytic cell death, which gives rise to danger signals that can further induce cell death, inflammation, and tissue damage. The mevalonate (MVA) pathway is an essential, highly conserved and dynamic metabolic pathway. Here, we discover that farnesyl pyrophosphate (FPP), a metabolic intermediate of the MVA pathway, functions as a newly identified danger signal to trigger acute cell death leading to neuron loss in stroke. Harboring both a hydrophobic 15-carbon isoprenyl chain and a heavily charged pyrophosphate head, FPP leads to acute cell death independent of its downstream metabolic pathways. Mechanistically, extracellular calcium influx and the cation channel transient receptor potential melastatin 2 (TRPM2) exhibit essential roles in FPP-induced cell death. FPP activates TRPM2 opening for ion influx. Furthermore, in terms of a mouse model constructing by middle cerebral artery occlusion (MCAO), FPP accumulates in the brain, which indicates the function of the FPP and TRPM2 danger signal axis in ischemic injury. Overall, our data have revealed a novel function of the MVA pathway intermediate metabolite FPP as a danger signal via transient receptor potential cation channels.

scholarly journals Disease-associated mutations in TRPM3 render the channel overactive via two distinct mechanisms

2020 ◽  
Author(s):  
Siyuan Zhao ◽  
Yevgen Yudin ◽  
Tibor Rohacs
Keyword(s):  
Intellectual Disability ◽  
Therapeutic Intervention ◽  
Room Temperature ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Cation Channel ◽  
Transient Receptor Potential Melastatin ◽  
Heat Activation ◽  
Transient Receptor ◽  
Potential Therapeutic Intervention

ABSTRACTTransient Receptor Potential Melastatin 3 (TRPM3) is a Ca2+ permeable non-selective cation channel activated by heat and chemical agonists such as pregnenolone sulfate and CIM0216. TRPM3 mutations in humans were recently reported to be associated with intellectual disability and epilepsy; the functional effects of those mutations however were not reported. Here we show that both disease-associated mutations of TRPM3 render the channel overactive, but likely via different mechanisms. The Val to Met substitution in the S4-S5 loop induced a larger increase in basal activity and agonist sensitivity at room temperature than the Pro to Gln substitution in the extracellular segment of S6. In contrast, heat activation was increased more by the S6 mutant than by the S4-S5 segment mutant. Both mutants were inhibited by the TRPM3 antagonist primidone, suggesting a potential therapeutic intervention to treat this disease.

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