生物谷报道: Scripps 研究院的研究人员发现名为TRPA1的蛋白质能传送痛觉讯号，也就是说它是许多毒性或刺激性化合物的感应器。科学家Ardem Patapoutian表示：这些毒性化合物能直接或间接的与TRPA1蛋白的cysteine胺基酸结合，TRPA1的活化作用与化合物的入侵有直接的关系。此研究发表于1月21日的Nature期刊。
Cysteines是组成蛋白质的二十个胺基酸之一，能够进行氧化及还原作用，也许TRPA1的cysteine天生就很容易被修饰，任何能与cysteine反应的试剂都能活化TRPA1。虽然目前对cysteine修饰与离子通道活化间的机制仍不清楚，但是一般来说，化合物活化离子通道是以锁与钥机制(lock-and-key mechanism)来进行，两者通常都具有蛋白质结构的相似性，然而，毒性化合物活化TRAP1的机制却完全不以此机制进行，一旦毒性化合物与TRPA1结合就不分开。
研究人员也发现另一个称为KEAP1(Kelch-like ECH-associated protein 1)的蛋白质，也会受到cysteine修饰试剂的活化，是自由基造成氧化伤害的感测蛋白。目前，各大药厂也都将TRAP1视为慢性疼痛的目标蛋白，希望更了解TRPA1与疼痛的机制以开发治疗慢性疼痛的药物。
FIGURE 2. TRPA1 agonist binds to reactive cysteines, three of which are required for normal channel function.
a, Schematic of the method used to identify sites covalently bound by IA during on-cell treatment. b, Cartoon representation of TRPA1 showing each cysteine residue as a circle. c, MTSEA-biotin activates TRPA1 when applied in the intracellular recording solution in whole-cell configuration. Left panel, whole-cell currents at 120mV; right panel, instantaneous TRPA1 current–voltage relationships at points indicated in left panel. d, e, Voltage-gated whole-cell currents mediated by TRPA1 are significantly attenuated in three cysteine mutants: C415S, C422S and C622S. d, Voltage-evoked currents (left) and tail current analysis (right) of a representative wild-type (WT) TRPA1-expressing cell. e, Steady-state current density evoked by voltage steps is shown for the indicated constructs (mean s.e.m., n = 17–23). All values for the cysteine mutants are significantly different from wild type (P < 0.005) and all values with the exception of C415S at +100 mV are significantly different from vector controls (P < 0.05). f, g, Whole-cell currents elicited by application of 30 M MO and 100 M icilin and normalized to leak-subtracted currents evoked by a step to +180 mV. Plotted is the ratio standard error for the number of individual determinations (cells) shown. *P < 0.05; **P < 0.01; ***P < 0.005 (Student's t-test).
原文出处:
Noxious compounds activate TRPA1 ion channels through covalent modification of cysteines
Lindsey J. Macpherson, Adrienne E. Dubin, Michael J. Evans, Felix Marr, Peter G. Schultz, Benjamin F. Cravatt, Ardem Patapoutian
SUMMARY: The nervous system senses peripheral damage through nociceptive neurons that transmit a pain signal. TRPA1 is a member of the Transient Receptor Potential (TRP)
CONTEXT: We noted that many TRPA1-activating compounds are electrophiles able to react with cysteines. For example, the nucleophilic mercapto group of cysteines can attack the ,-unsaturated bond of cinnamaldehyde (CA) via a Michael addition...
Nature (21 Jan 2007) Letters to Editor
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相关基因:
TRPA1
Official Symbol: TRPA1 and Name: transient receptor potential cation channel, subfamily A, member 1 [Homo sapiens]
Other Aliases: ANKTM1
Other Designations: ankyrin-like protein 1; ankyrin-like with transmembrane domains 1
Chromosome: 8; Location: 8q13
MIM: 604775
GeneID: 8989
KEAP1
Official Symbol: KEAP1 and Name: kelch-like ECH-associated protein 1 [Homo sapiens]
Other Aliases: INrf2, KIAA0132, KLHL19, MGC10630, MGC1114, MGC20887, MGC4407, MGC9454
Other Designations: cytosolic inhibitor of Nrf2
Chromosome: 19; Location: 19p13.2
MIM: 606016
GeneID: 9817
作者简介:
Ardem Patapoutian
Department of Cell Biology
10550 N. Torrey Pines Rd, ICND210F
La Jolla, CA 92037
office tel: 858-784-9856
Lab Website: http://www.scripps.edu/cb/patapoutian/
Research Description
The sense of touch consists of the perception of discrete types of thermal, mechanical, and chemical stimuli. Electrophysiologists have long realized that recognition of touch is executed by neurons of restricted specificity, such that warm stimuli can activate a different class of neurons than cold stimuli do, for instance. However, little is known about the molecular basis of touch perception. Our lab is characterizing the genes involved in the first step of touch sensation: those that encode the molecular sensors of touch stimuli.
With the completion of the human genome project, we have powerful new methods to identify these elusive sensory molecules. We recently identified the first gene involved in our ability to sense cold temperatures. This gene, trpm8, encodes for a protein present at the plasma membrane of cold-sensing neurons that belongs to the Transient Receptor Potential (TRP) channel family. Interestingly, TRPM8 is also activated by menthol, a commonly-used cooling compound. More recently, we have identified a novel sensory channel that responds to warm and hot temperatures, TRPV3. TRPV3 is closely related to TRPM8 and represents the fourth TRP family member to sense temperature. We are continuing to identify additional sensory receptors, and we are also working towards understanding the mechanism of activation of these channels. How do these proteins actually sense temperature at the molecular level? As mentioned above, sensory neurons are highly specialized and are activated by distinct thermal and mechanical stimuli. How these neurons become specialized during development is not yet understood. In the adult, the sensory neuron subtypes are distinguished by many anatomical features but by few molecular markers. Perhaps the most extensive molecular understanding of developing somatic sensory neurons comes from studies of neurotrophins and their trk receptors. Our lab is building on these studies to extend our knowledge of the molecular processes that control
the specification of these neuronal subtypes that arise from a shared precursor. We are using transgenic and genomic technologies to address these questions.
Our long-term goal is to synthesize an integrated picture of sensory neuron development and function. The two approaches discussed above will yield insights into the basic biology of the peripheral nervous system and may also have an impact on novel treatments for pain.
Recent Publications
Macpherson LJ, Geierstanger BH, Viswanath V, Bandell M, Eid SR, Hwang S, Patapoutian A. The Pungency of Garlic: Activation of TRPA1 and TRPV1 in Response to Allicin. Curr Biol. 2005 May 24;15(10):929-34.
Moqrich A, Hwang SW, Earley TJ, Petrus MJ, Murray AN, Spencer KS, Andahazy M, Story GM, Patapoutian A. Impaired thermosensation in mice lacking TRPV3, a heat and camphor sensor in the skin. Science. 2005 Mar 4;307(5714):1468-72.
Rosenzweig M, Brennan KM, Tayler TD, Phelps PO, Patapoutian A, Garrity PA. The Drosophila ortholog of vertebrate TRPA1 regulates thermotaxis. Genes Dev. 2005 Feb 15;19(4):419-24. Epub 2005 Jan 28.
Moqrich A, et al. Expressing TrkC from the TrkA locus causes a subset of dorsal root ganglia neurons to switch fate. Nat Neurosci. 2004 Aug;7(8):812-8. Epub 2004 Jul 11.
Bandell M, Story GM, Hwang SW, Viswanath V, Eid SR, Petrus MJ, Earley TJ, Patapoutian A. Noxious cold ion channel TRPA1 is activated by pungent compounds and bradykinin. Neuron. 2004 Mar 25;41(6):849-57.
Patapoutian A, Peier AM, Story GM, Viswanath V. ThermoTRP channels and beyond: mechanisms of temperature sensation. Nat Rev Neurosci. 2003 Jul;4(7):529-39.
Viswanath V, Story GM, Peier AM, Petrus MJ, Lee VM, Hwang SW, Patapoutian A, Jegla T. Opposite thermosensor in fruitfly and mouse. Nature. 2003 Jun 19;423(6942):822-3.
Story GM, Peier AM, Reeve AJ, Eid SR, Mosbacher J, Hricik TR, Earley TJ, Hergarden AC, Andersson DA, Hwang SW, McIntyre P, Jegla T, Bevan S, Patapoutian A. ANKTM1, a TRP-like Channel Expressed in Nociceptive Neurons, Is Activated by Cold Temperatures. Cell. 2003 Mar 21;112(6):819-29.
Peier AM, Reeve AJ, Andersson DA, Moqrich A, Earley TJ, Hergarden AC, Story GM, Colley S, Hogenesch JB, McIntyre P, Bevan S, Patapoutian A. A heat-sensitive TRP channel expressed in keratinocytes. Science. 2002 Jun 14;296(5575):2046-9.
Su AI, Cooke MP, Ching KA, Hakak Y, Walker JR, Wiltshire T, Orth AP, Vega RG, Sapinoso LM, Moqrich A, Patapoutian A, Hampton GM, Schultz PG, Hogenesch JB. Large-scale analysis of the human and mouse transcriptomes. Proc Natl Acad Sci U S A. 2002 Apr 2;99(7):4465-70.
Peier AM, Moqrich A, Hergarden AC, Reeve AJ, Andersson DA, Story GM, Earley TJ, Dragoni I, McIntyre P, Bevan S, Patapoutian A. A trp channel that senses cold stimuli and menthol. Cell. 2002 Mar 8;108:705-15.
