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Molecular Pain BioMed Central - Semantic Scholar · PDF fileBioMed Central Page 1 of 12 (page number not for citation purposes) Molecular Pain ... Jingshan Lu 1, Tayo Katano , Emiko

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    Open AcceResearchInvolvement of S-nitrosylation of actin in inhibition of neurotransmitter release by nitric oxideJingshan Lu1, Tayo Katano1, Emiko Okuda-Ashitaka1, Yo Oishi2, Yoshihiro Urade2 and Seiji Ito*1

    Address: 1Department of Medical Chemistry, Kansai Medical University, Moriguchi, Japan and 2Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka, Japan

    Email: Jingshan Lu - [email protected]; Tayo Katano - [email protected]; Emiko Okuda-Ashitaka - [email protected]; Yo Oishi - [email protected]; Yoshihiro Urade - [email protected]; Seiji Ito* - [email protected]

    * Corresponding author

    AbstractBackground: The role of the diffusible messenger nitric oxide (NO) in the regulation of paintransmission is still a debate of matter, pro-nociceptive and/or anti-nociceptive. S-Nitrosylation, thereversible post-translational modification of selective cysteine residues in proteins, has emerged asan important mechanism by which NO acts as a signaling molecule. The occurrence of S-nitrosylation in the spinal cord and its targets that may modulate pain transmission remainunclarified. The "biotin-switch" method and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were employed for identifying S-nitrosylated proteins.

    Results: Here we show that actin was a major protein S-nitrosylated in the spinal cord by the NOdonor, S-nitroso-N-acetyl-DL-penicillamine (SNAP). Interestingly, actin was S-nitrosylated, more inthe S2 fraction than in the P2 fraction of the spinal homogenate. Treatment of PC12 cells withSNAP caused rapid S-nitrosylation of actin and inhibited dopamine release from the cells. Just likecytochalasin B, which depolymerizes actin, SNAP decreased the amount of filamentous actincytoskeleton just beneath the membrane. The inhibition of dopamine release was not attenuatedby inhibitors of soluble guanylyl cyclase and cGMP-dependent protein kinase.

    Conclusion: The present study demonstrates that actin is a major S-nitrosylated protein in thespinal cord and suggests that NO directly regulates neurotransmitter release by S-nitrosylation inaddition to the well-known phosphorylation by cGMP-dependent protein kinase.

    BackgroundNitric oxide (NO) is produced from L-arginine by 3 iso-forms of NO synthase (NOS), i.e., neuronal NOS (NOS-1), inducible NOS (NOS-2), and endothelial NOS (NOS-3); and it plays important roles in a wide variety of physi-ological and pathophysiological processes such as neuro-transmission, regulation of vascular tone, and mediation

    of immune responses [1,2]. The major intracellular recep-tor for NO is a soluble guanylyl cyclase that catalyzes thesynthesis of cGMP. This intracellular signaling moleculemodulates the activity of many targets in the cells includ-ing cGMP-dependent protein kinase (cGK), ion channels,and phosphodiesterases. In the central nervous system,NO is mainly produced by NOS-1 and has been impli-

    Published: 29 September 2009

    Molecular Pain 2009, 5:58 doi:10.1186/1744-8069-5-58

    Received: 16 June 2009Accepted: 29 September 2009

    This article is available from: http://www.molecularpain.com/content/5/1/58

    2009 Lu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

    Page 1 of 12(page number not for citation purposes)

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    cated in synaptic plasticity including long-term potentia-tion in the hippocampus and in pain transmission in thespinal cord [3-5]. Many behavioral studies including ourshave demonstrated that NO contributes to the develop-ment and maintenance of hyperalgesia and allodynia inmodels of acute and chronic pain, which are relieved bythe blockade of the NO/cGMP/cGK signaling pathway inthe spinal cord [6-9]. A rapid release of citrulline, a markerof NO synthesis, is observed in the spinal cord followinga subcutaneous injection of formalin and is associatedwith a biphasic flinching behavior of the injected paw[10]. On the other hand, spinally administered NOdonors cause a depression of ongoing impulse activity ofdorsal horn neurons [11]; and inhibition of spinal NOSleads to increased neuronal activity in the dorsal horn[12]. Furthermore, agents affecting NO and cGMP levelsshow no effect [13] or dual effects on nociception depend-ing on their concentrations [14,15]. Thus the involvementof NO in pain is not consistent and is still a matter ofdebate. Different from many conventional neurotrans-mitters that are stored in synaptic vesicles and released byexocytosis, the labile, free-radical mediator NO simplydiffuses from the nerve terminal into adjacent cells andacts as anterograde and retrograde messengers at nocicep-tive synapses in the spinal cord [3]. Therefore, the mecha-nisms through which NO mediates its nociception andpain transmission are not completely understood in thespinal cord [16].

    In addition to the NO/cGMP/cGK signaling pathway, S-nitrosylation by NO, i.e., the covalent attachment of a -NO group to a cysteine thiol, has emerged as an importantfeature of NO signaling [17,18]. Through this reversiblepost-translational modification, NO is able to regulate thefunction of many target enzymes, ion channels, and struc-tural proteins including cyclooxygenase-2 [19], solubleguanylyl cyclase [20], NMDA receptors [21-23], actin[17,24], and other pathogenic proteins [25,26]. Amongmethods for studying protein S-nitrosylation, the biotin-switch method has rapidly gained popularity because ofthe ease with which it can detect individual S-nitrosylatedproteins in biological samples [17,27]; and the use of thismethod has revealed that S-nitrosylation is involved inthe physiology and pathophysiology of the central nerv-ous system [18]. Although the NO/cGMP/cGK signalingpathway has been extensively examined in terms of theinvolvement of NO in nociception and pain transmission,S-nitrosylation has not been studied in the spinal cord sofar. Here, by using the biotin-switch method, we demon-strate that actin is a major S-nitrosylated protein in thespinal cord by the NO donor S-nitroso-N-acetyl-DL-peni-cillamine (SNAP) and that interestingly, actin was S-nitrosylated, more in the S2 fraction than in the P2 frac-tion of the spinal homogenate.

    MethodsMaterialsSNAP, nerve growth factor (NGF), 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) and KT5823 wereobtained from Wako Pure Chemical (Osaka, Japan). Trif-luoroacetic acid (TFA), S-methyl methanethiosulfonate(MMTS), -cyano-4-hydroxycinnamic acid (-CHCA),bovine serum albumin (BSA), imipramine hydrochloride,dopamine, 8-bromoadenosine 3', 5'-cyclic monophos-phate (8-Br-cAMP), 8-Br-cGMP, and glibenclamide werepurchased from Sigma-Aldrich (St. Louis, MO, USA). Pitu-itary adenylate cyclase-activating polypeptide (PACAP)and N-[6-(biotinamido)hexyl]-3'-(2'-pyridyldithio)pro-pionamide (biotin-HPDP) were supplied by Peptide Insti-tute (Osaka, Japan) and Pierce Chemical (Rockford, IL,USA), respectively. Other chemicals were of reagent grade.

    Preparation of S2 and P2 fractions from spinal cordsMale ddy mice (5 weeks old) were purchased from Shi-zuoka Laboratory Centre (Hamamatsu, Japan). The micewere housed under conditions of a 12-h light-12-h darkcycle, a constant temperature of 22 2C, and 60 10%humidity. They received food and water ad libitum. All ani-mal experiments were carried out in accordance with theNational Institutes of Health guide for the care and use oflaboratory animals and were approved by the AnimalExperimentation Committee of Kansai Medical Univer-sity.

    Under anesthesia with pentobarbital (50 mg/kg), mousespinal cords were quickly removed and homogenizedtwice for 30 s with a Polytron homogenizer containing 10volumes of HEN buffer consisting of 250 mM HEPES (pH7.7), 1 mM EDTA, and 0.1 mM neocuproine. Thehomogenate was centrifuged at 800 g for 10 min, andthe supernatant was recovered and then centrifuged at10,000 g for 20 min. After the resulting pellet had beendissolved in 10 volumes of HEN buffer, the resultingsupernatant and this dissolved pellet were employed as S2and P2 fractions, respectively.

    S-Nitrosylation of proteins in vitro and biotin-switch methodS-Nitrosylated proteins were detected by the biotin-switchmethod as described by Jaffrey et al. [17]. Briefly, S2 andP2 fractions of the spinal cord were incubated at roomtemperature without or with various concentrations ofSNAP for 1 h in the dark. Then, SNAP was removed fromthe reaction mixture by cold acetone precipitation; andthe pellets were subsequently dissolved in HENS buffercontaining 25 mM HEPES, pH 7.7, 0.1 mM EDTA, 0.01mM neocuproine, and 1% sodium dodecyl sulfate (SDS).The SNAP-treated fractions were blocked with fresh 4 mMMMTS for 20 min at 50C. After 2 steps of acetone precip-itation, the pellets were then resuspended in HENS buffer.

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    For labeling, the samples were subjected to the biotin-switch assay, in which the sample was mixed with 1 mMascorbic acid and 0.2-0.4 mM biotin-HPDP as final con-centrations and kept for 1 h in the dark. Biotinylated pro-teins were resolved by non-reducing SDS-polyacrylamidegel electrophoresis (PAGE), and transferred to a polyvi-nylidene difl

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