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Jackson EK. Discovery and Roles of 2',3'-cAMP in Biological Systems. Handb Exp Pharmacol 2017; 238:229-252. [PMID: 26721674 DOI: 10.1007/164_2015_40] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In 2009, investigators using ultra-performance liquid chromatography-tandem mass spectrometry to measure, by selected reaction monitoring, 3',5'-cAMP in the renal venous perfusate from isolated, perfused kidneys detected a large signal at the same m/z transition (330 → 136) as 3',5'-cAMP but at a different retention time. Follow-up experiments demonstrated that this signal was due to a positional isomer of 3',5'-cAMP, namely, 2',3'-cAMP. Soon thereafter, investigative teams reported the detection of 2',3'-cAMP and other 2',3'-cNMPs (2',3'-cGMP, 2',3'-cCMP, and 2',3'-cUMP) in biological systems ranging from bacteria to plants to animals to humans. Injury appears to be the major stimulus for the release of these unique noncanonical cNMPs, which likely are formed by the breakdown of RNA. In mammalian cells in culture, in intact rat and mouse kidneys, and in mouse brains in vivo, 2',3'-cAMP is metabolized to 2'-AMP and 3'-AMP; and these AMPs are subsequently converted to adenosine. In rat and mouse kidneys and mouse brains, injury releases 2',3'-cAMP, 2'-AMP, and 3'-AMP into the extracellular compartment; and in humans, traumatic brain injury is associated with large increases in 2',3'-cAMP, 2'-AMP, 3'-AMP, and adenosine in the cerebrospinal fluid. These findings motivate the extracellular 2',3'-cAMP-adenosine pathway hypothesis: intracellular production of 2',3'-cAMP → export of 2',3'-cAMP → extracellular metabolism of 2',3'-cAMP to 2'-AMP and 3'-AMP → extracellular metabolism of 2'-AMP and 3'-AMP to adenosine. Since 2',3'-cAMP has been shown to activate mitochondrial permeability transition pores (mPTPs) leading to apoptosis and necrosis and since adenosine is generally tissue protective, the extracellular 2',3'-cAMP-adenosine pathway may be a protective mechanism [i.e., removes 2',3'-cAMP (an intracellular toxin) and forms adenosine (a tissue protectant)]. This appears to be the case in the brain where deficiency in CNPase (the enzyme that metabolizes 2',3'-cAMP to 2-AMP) leads to increased susceptibility to brain injury and neurological diseases. Surprisingly, CNPase deficiency in the kidney actually protects against acute kidney injury, perhaps by preventing the formation of 2'-AMP (which turns out to be a renal vasoconstrictor) and by augmenting the mitophagy of damaged mitochondria. With regard to 2',3'-cNMPs and their downstream metabolites, there is no doubt much more to be discovered.
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Affiliation(s)
- Edwin K Jackson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, 100 Technology Drive, Room 514, Pittsburgh, PA, 15219, USA.
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Ilinskaya ON, Ulyanova VV, Yarullina DR, Gataullin IG. Secretome of Intestinal Bacilli: A Natural Guard against Pathologies. Front Microbiol 2017; 8:1666. [PMID: 28919884 PMCID: PMC5586196 DOI: 10.3389/fmicb.2017.01666] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 08/17/2017] [Indexed: 12/12/2022] Open
Abstract
Current studies of human gut microbiome usually do not consider the special functional role of transient microbiota, although some of its members remain in the host for a long time and produce broad spectrum of biologically active substances. Getting into the gastrointestinal tract (GIT) with food, water and probiotic preparations, two representatives of Bacilli class, genera Bacillus and Lactobacillus, colonize epithelium blurring the boundaries between resident and transient microbiota. Despite their minor proportion in the microbiome composition, these bacteria can significantly affect both the intestinal microbiota and the entire body thanks to a wide range of secreted compounds. Recently, insufficiency and limitations of pure genome-based analysis of gut microbiota became known. Thus, the need for intense functional studies is evident. This review aims to characterize the Bacillus and Lactobacillus in GIT, as well as the functional roles of the components released by these members of microbial intestinal community. Complex of their secreted compounds is referred by us as the "bacillary secretome." The composition of the bacillary secretome, its biological effects in GIT and role in counteraction to infectious diseases and oncological pathologies in human organism is the subject of the review.
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Affiliation(s)
| | - Vera V. Ulyanova
- Department of Microbiology, Kazan Federal UniversityKazan, Russia
| | | | - Ilgiz G. Gataullin
- Department of Surgery and Oncology, Regional Clinical Cancer CenterKazan, Russia
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Sokurenko Y, Ulyanova V, Zelenikhin P, Kolpakov A, Blokhin D, Müller D, Klochkov V, Ilinskaya O. The Role of Metals in the Reaction Catalyzed by Metal-Ion-Independent Bacillary RNase. Bioinorg Chem Appl 2016; 2016:4121960. [PMID: 28096759 PMCID: PMC5209602 DOI: 10.1155/2016/4121960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/27/2016] [Accepted: 11/02/2016] [Indexed: 11/18/2022] Open
Abstract
Extracellular enzymes of intestinal microbiota are the key agents that affect functional activity of the body as they directly interact with epithelial and immune cells. Several species of the Bacillus genus, like Bacillus pumilus, a common producer of extracellular RNase binase, can populate the intestinal microbiome as a colonizing organism. Without involving metal ions as cofactors, binase depolymerizes RNA by cleaving the 3',5'-phosphodiester bond and generates 2',3'-cyclic guanosine phosphates in the first stage of a catalytic reaction. Maintained in the reaction mixture for more than one hour, such messengers can affect the human intestinal microflora and the human body. In the present study, we found that the rate of 2',3'-cGMP was growing in the presence of transition metals that stabilized the RNA structure. At the same time, transition metal ions only marginally reduced the amount of 2',3'-cGMP, blocking binase recognition sites of guanine at N7 of nucleophilic purine bases.
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Affiliation(s)
- Yulia Sokurenko
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008, Russia
| | - Vera Ulyanova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008, Russia
| | - Pavel Zelenikhin
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008, Russia
| | - Alexey Kolpakov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008, Russia
| | - Dmitriy Blokhin
- Institute of Physics, Kazan Federal University, Kremlevskaya Str. 16a, Kazan 420008, Russia
| | - Dieter Müller
- Institute for Anatomy and Cell Biology, Justus Liebig University Giessen, Aulweg 123, 35385 Giessen, Germany
| | - Vladimir Klochkov
- Institute of Physics, Kazan Federal University, Kremlevskaya Str. 16a, Kazan 420008, Russia
| | - Olga Ilinskaya
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlevskaya Str. 18, Kazan 420008, Russia
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Van Damme T, Blancquaert D, Couturon P, Van Der Straeten D, Sandra P, Lynen F. Wounding stress causes rapid increase in concentration of the naturally occurring 2',3'-isomers of cyclic guanosine- and cyclic adenosine monophosphate (cGMP and cAMP) in plant tissues. PHYTOCHEMISTRY 2014; 103:59-66. [PMID: 24735826 DOI: 10.1016/j.phytochem.2014.03.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 02/16/2014] [Accepted: 03/10/2014] [Indexed: 05/21/2023]
Abstract
3',5'-Cyclic guanosine monophosphate (cGMP) and 3',5'-cyclic adenosine monophosphate (cAMP) are well reported second messenger molecules involved in cellular signal transduction, in physiological functions such as neurotransmission in animals and in the modulation of cell growth and differentiation. In plants, 3',5'-cyclic nucleotides have been implicated in the regulation of ion homeostasis, hormone and stress responses. The behavior of the 2',3'-cyclic nucleotide variants is also known in animal tissue but no quantitative information is available about 2',3'-cAMP and 2',3'-cGMP in plant material. A recently developed HILIC-SPE/LC-MS/MS method for the analysis of cyclic nucleotides in blood and animal tissue was therefore adapted to measure 2',3'-cAMP and 2',3'-cGMP concentrations in plant material. Cyclic nucleotide concentrations were measured in Arabidopsis thaliana (Col-0) leaves before and after the application of wounding stress. A significant (∼5-fold) up-regulation of 2',3'-cAMP and 2',3'-cGMP was measured in Arabidopsis leaves compared to the control samples. The results indicate a thus far unreported strong correlation between plant stress and both 2',3'-cAMP and 2',3'-cGMP levels in plant material, and may open new avenues towards understanding the role of cyclic nucleotides in plants.
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Affiliation(s)
- Thomas Van Damme
- Department of Organic Chemistry, Pfizer Analytical Research Center, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
| | - Dieter Blancquaert
- Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Pauline Couturon
- Department of Organic Chemistry, Separation Science Group, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - Pat Sandra
- Department of Organic Chemistry, Pfizer Analytical Research Center, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium; Department of Organic Chemistry, Separation Science Group, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium
| | - Frédéric Lynen
- Department of Organic Chemistry, Pfizer Analytical Research Center, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium; Department of Organic Chemistry, Separation Science Group, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent, Belgium.
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Ørvoll E, Lysaa RA, Ravna AW, Sager G. Misoprostol and the Sildenafil analog (PHAR-0099048) Modulate Cellular Efflux of cAMP and cGMP Differently. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/pp.2013.41015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Determination of cyclic guanosine- and cyclic adenosine monophosphate (cGMP and cAMP) in human plasma and animal tissues by solid phase extraction on silica and liquid chromatography-triple quadrupole mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 909:14-21. [PMID: 23153638 DOI: 10.1016/j.jchromb.2012.10.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 09/25/2012] [Accepted: 10/02/2012] [Indexed: 01/13/2023]
Abstract
3',5'-Cyclic guanosine monophosphate (cGMP) and 3',5'-cyclic adenosine monophosphate (cAMP) are essential second messenger molecules. They are involved in signal transduction within cells, in physiological functions such as neurotransmission and in the modulation of cell growth and differentiation of organisms, respectively. A quantitative solid phase extraction method (SPE) based on hydrophilic interaction on silica was developed and applied to both plasma and tissue samples. The stable isotope-labeled internal standards ²D₁, ¹⁵N₃-3',5'-cGMP and ¹³C₁₀, ¹⁵N₅-3',5'-cAMP were added prior to the sample preparation to ensure high precision and accuracy. The samples were analyzed by reversed-phase liquid chromatography (RP-LC). Negative electrospray (ESI)-MS/MS was used to selectively monitor several transitions of each metabolite. The method for the analysis of 3',5'-cAMP and 3',5'-cGMP in plasma was validated in the range of 0.15-20 ng/mL (R²=0.9996 and 0.9994 for 3',5'-cAMP and 3',5'-cGMP, respectively). Basal plasma concentrations for fifteen healthy human patients determined with this method varied between 4.66-9.20 ng/mL for 3',5'-cAMP and between 0.30-1.20 ng/mL for 3',5'-cGMP, with precisions better than 9.1%. 3',5'-cGMP and 3',5'-cAMP together with their 2',3'-isomers were also determined in a semi quantitative way in animal tissues. The structures of the isomers were confirmed by analysis with LC-high resolution time-of-flight MS and subsequently by comparison of retention times with standards.
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Werner K, Schwede F, Genieser HG, Geiger J, Butt E. Quantification of cAMP and cGMP analogs in intact cells: pitfalls in enzyme immunoassays for cyclic nucleotides. Naunyn Schmiedebergs Arch Pharmacol 2011; 384:169-76. [PMID: 21713381 PMCID: PMC3145891 DOI: 10.1007/s00210-011-0662-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 06/08/2011] [Indexed: 11/28/2022]
Abstract
Immunoassays are routinely used as research tools to measure intracellular cAMP and cGMP concentrations. Ideally, this application requires antibodies with high sensitivity and specificity. The present work evaluates the cross-reactivity of commercially available cyclic nucleotide analogs with two non-radioactive and one radioactive cAMP and cGMP immunoassay. Most of the tested cyclic nucleotide analogs showed low degree competition with the antibodies; however, with Rp-cAMPS, 8-Br-cGMP and 8-pCPT-cGMP, a strong cross-reactivity with the corresponding cAMP and cGMP, respectively, immunoassays was observed. The determined EIA-binding constants enabled the measurement of the intracellular cyclic nucleotide concentrations and revealed a time- and lipophilicity-dependent cell membrane permeability of the compounds in the range of 10–30% of the extracellular applied concentration, thus allowing a more accurate prediction of the intracellular analog levels in a given experiment.
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Affiliation(s)
- Katharina Werner
- Institute for Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Grombuehlstrasse 12, Wuerzburg, Germany
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Ravna AW, Sylte I, Sager G. A molecular model of a putative substrate releasing conformation of multidrug resistance protein 5 (MRP5). Eur J Med Chem 2008; 43:2557-67. [PMID: 18313803 DOI: 10.1016/j.ejmech.2008.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 10/08/2007] [Accepted: 01/07/2008] [Indexed: 01/31/2023]
Abstract
The ATP-binding cassette (ABC) transporter multidrug resistance protein 5 (MRP5) contributes to the cellular export of organic anions, including guanosine 3'-5' cyclic monophosphate (cGMP). The structural knowledge of this protein is limited, and in lack of an MRP5 X-ray structure, a model of MRP5 was constructed based on the homology with the bacterial ABC transporter Sav1866 from Staphylococcus aureus, which has been crystallised in an outward-facing, substrate releasing conformation. Two putative binding sites were identified, and docking of cGMP indicated that TMHs 1-3, 6, 11 and 12 were in contact with the ligands in binding site 1, while TMHs 1, 3, 5-8 were in contact with the ligands in binding site 2. The proposed MRP5 model may be used for further experimental studies of the molecular structure and function of this member of the ABC-transporter superfamily.
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Affiliation(s)
- Aina Westrheim Ravna
- Department of Pharmacology, Institute of Medical Biology, Faculty of Medicine, University of Tromsø, MH-Building, Breivika, N-9037 Tromsø, Norway
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de Wolf CJF, Yamaguchi H, van der Heijden I, Wielinga PR, Hundscheid SL, Ono N, Scheffer GL, de Haas M, Schuetz JD, Wijnholds J, Borst P. cGMP transport by vesicles from human and mouse erythrocytes. FEBS J 2006; 274:439-50. [PMID: 17229149 DOI: 10.1111/j.1742-4658.2006.05591.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
cGMP secretion from cells can be mediated by ATP-binding cassette (ABC) transporters ABCC4, ABCC5, and ABCC11. Indirect evidence suggests that ABCC4 and ABCC5 contribute to cGMP transport by erythrocytes. We have re-investigated the issue using erythrocytes from wild-type and transporter knockout mice. Murine wild-type erythrocyte vesicles transported cGMP with an apparent Km that was 100-fold higher than their human counterparts, the apparent Vmax being similar. Whereas cGMP transport into human vesicles was efficiently inhibited by the ABCC4-specific substrate prostaglandin E1, cGMP transport into mouse vesicles was inhibited equally by Abcg2 and Abcc4 inhibitors/substrates. Similarly, cGMP transport into vesicles from Abcc4-/- and Abcg2-/- mice was 42% and 51% of that into wild-type mouse vesicles, respectively, whereas cGMP transport into vesicles from Abcc4(-/-)/Abcg2(-/-) mice was near background. The knockout mice were used to show that Abcg2-mediated cGMP transport occurred with lower affinity but higher Vmax than Abcc4-mediated transport. Involvement of Abcg2 in cGMP transport by Abcc4-/- erythrocyte vesicles was supported by higher transport at pH 5.5 than at pH 7.4, a characteristic of Abcg2-mediated transport. The relative contribution of ABCC4/Abcc4 and ABCG2/Abcg2 in cGMP transport was confirmed with a new inhibitor of ABCC4 transport, the protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride.
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Affiliation(s)
- Cornelia J F de Wolf
- Department of Molecular Biology, the Netherlands Cancer Institute, Amsterdam, the Netherlands
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Abstract
The biokinetics of guanosine 3',5'-cyclic monophosphate (cGMP) is characterized by three distinct processes: synthesis by guanylate cyclases (GCs), conversion of cGMP to GMP by cyclic nucleotide phosphodiesterases (PDEs) and the excretion of unchanged cGMP by transport proteins in the cell membrane. Efflux is observed in virtually all cell types including cells which originate from brain. Studies of intact cells, in which metabolic inhibitors and probenecid reduced extrusion of cGMP and wherein cGMP was extruded against concentration gradients, indicated the existence of ATP requiring organic anion transport system(s). Functional studies of inside-out vesicles have revealed cGMP transport systems wherein translocation is coupled to hydrolysis of ATP. The extrusion of cGMP is inhibited by a number of unrelated compounds and this indicates that cGMP is substrate for multispecific transporters. Recent transfection studies suggest that members of the MRP (multidrug resistance protein) family; MRP4, MRP5 and MRP8 translocate cGMP across the cell membrane. Many of the MRPs have been detected in brain. In addition tertiary active transport by the organic anion transporter family has also been identified. At least one member (OAT1) shows relative high affinity for cGMP and is also expressed in brain. The biological significance of cGMP transporters has to be clarified. Their role in cGMP biokinetics, being responsible for one of the cellular elimination pathways, is well established. However, there is growing evidence that extracellular cGMP has effects on cell physiology and pathophysiology by an auto- or paracrine mechanism.
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Affiliation(s)
- Georg Sager
- Department of Pharmacology, Faculty of Medicine, Institute of Medical Biology, University of Tromsø, NB 9037, Tromsø, Norway.
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Boadu E, Sager G. Reconstitution of ATP-dependent cGMP transport into proteoliposomes by membrane proteins from human erythrocytes. Scandinavian Journal of Clinical and Laboratory Investigation 2004; 64:41-8. [PMID: 15025427 DOI: 10.1080/00365510410003895] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The cellular efflux of cGMP from human erythrocytes has previously been characterized in functional studies. The purpose of the present study was to find membrane proteins with the ability to restore ATP-dependent uptake of cGMP into proteoliposomes. Human erythrocyte membranes were solubilized with CHAPS (3-([3-cholamidopropyl]dimethylammonio)-1-propanesulfonate) and gel filtration gave three protein fractions with the ability to restore active transport. Only two of these fractions were retained on a lentil lectin column. By using these two purification steps, active transport was 11 times higher in the first fraction compared to the original material and SDS-PAGE showed the presence of proteins with sizes of 145 kDa and 165 kDa. The second fraction gave 20 times higher active transport after purification and comprised proteins with sizes of 145 kDa and 180 kDa. At present three members of the MRP (multi-resistance associated protein) family have been detected in human erythrocytes: MRPI, MRP4 and MRP5. The last two proteins have been shown to transport cyclic nucleotides. The present findings are compatible with MRP4 as the 145 kDa protein, MRP5 as the 165 kDa protein and MRP1 as the 180 kDa protein. However, the 145 kDa protein could also be SMRP (short multi-resistance protein), the gene splice variant of MRP5. Immunoprecipitation of MRP5 from CHAPS-solubilized extract reduced active transport and specific binding by about 45% and 40%, respectively. This shows that MRP5 is an important cGMP-transporting protein in human erythrocytes.
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Affiliation(s)
- E Boadu
- Department of Pharmacology, Institute of Medical Biology, Medical Faculty, University of Tromsø, Norway
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12
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Xu HL, Gavrilyuk V, Wolde HM, Baughman VL, Pelligrino DA. Regulation of rat pial arteriolar smooth muscle relaxation in vivo through multidrug resistance protein 5-mediated cGMP efflux. Am J Physiol Heart Circ Physiol 2004; 286:H2020-7. [PMID: 14715514 DOI: 10.1152/ajpheart.01105.2003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Multidrug resistance protein 5 (MRP5) has been linked to cGMP cellular export in peripheral vascular smooth muscle cells (VSMCs) and is widely expressed in brain vascular tissue. In the present study, we examined whether knockdown of MRP5 in pial arterioles [via antisense oligodeoxynucleotide (ODN) applications] affected nitric oxide (NO)/cGMP-induced dilations. The antisense or (as a control) missense ODN was applied to the cortical surface approximately 24 h before study via closed cranial windows. The efficacy of the antisense vs. missense ODN in eliciting selective reductions in MRP5 expression was confirmed by analysis of MRP5 mRNA in pial tissue. Unexpectedly, in initial studies, a significantly lower maximal pial arteriolar diameter increase in the presence of the NO donor S-nitrosoacetylpenicillamine (SNAP) was seen in the antisense vs. missense ODN-treated rats (35 vs. 48% diameter increase, respectively). It was suspected that this related to a reduced vascular smooth muscle cell sensitivity to cGMP due to prolonged exposure to increased intracellular cGMP levels elevated by overnight restriction of cGMP efflux. That postulate was supported by a finding of a diminished vasodilating response to the cGMP-dependent protein kinase-activating cGMP analog 8-p-chlorophenylthio-cGMP in antisense vs. missense ODN-treated rats. To prevent desensitization, additional rats were studied in the presence of chronic NOS inhibition via Nomega-nitro-L-arginine. In the NO synthase (NOS)-inhibited rats, the maximal SNAP response was much higher in the antisense (62% increase) vs. the missense ODN (40% increase) group. A similar result was obtained when monitoring responses to the soluble guanylyl cyclase-activating drugs YC-1 and BAY 41-2272. Moreover, in the presence of NOS inhibition, the normal SNAP-induced rise in periarachnoid cerebrospinal fluid cGMP levels, which reflects cGMP efflux, was absent in the antisense ODN-treated rats, a finding consistent with loss of MRP5 function. In conclusion, if one minimizes the confounding effects of basal cGMP production, a clearer picture emerges, one that indicates an important role for MRP5-mediated cGMP efflux in the regulation of NO-induced cerebral arteriolar relaxation.
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Affiliation(s)
- Hao-Liang Xu
- Neuroanesthesia Research Laboratory, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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Klokouzas A, Wu CP, van Veen HW, Barrand MA, Hladky SB. cGMP and glutathione-conjugate transport in human erythrocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3696-708. [PMID: 12950253 DOI: 10.1046/j.1432-1033.2003.03753.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The nature of cGMP transport in human erythrocytes, its relationship to glutathione conjugate transport, and possible mediation by multidrug resistance-associated proteins (MRPs) have been investigated. MRP1, MRP4 and MRP5 are detected in immunoblotting studies with erythrocytes. MRP1 and MRP5 are also detected in multidrug resistant COR-L23/R and MOR/R cells but at greatly reduced levels in the parent, drug sensitive COR-L23/P cells. MRP4 is detected in MOR/R but not COR-L23/R cells. Uptake of cGMP into inside-out membrane vesicles prepared by a spontaneous, one-step vesiculation process is shown to be by a low affinity system that accounts for more than 80% of the transport at all concentrations above 3 micro m. This transport is reduced by MRP inhibitors and substrates including MK-571, methotrexate, estradiol 17-beta-d-glucuronide, and S(2,4-dinitrophenyl)glutathione (DNP-SG) and also by glibenclamide and frusemide but not by the monoclonal Ig QCRL-3 that inhibits high-affinity transport of DNP-SG by MRP1. It is concluded that the cGMP exporter is distinct from MRP1 and has properties similar to those reported for MRP4. Furthermore the evidence suggests that the protein responsible for cGMP transport is the same as that mediating low-affinity DNP-SG transport in human erythrocytes.
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Sundkvist E, Jaeger R, Sager G. Pharmacological characterization of the ATP-dependent low K(m) guanosine 3',5'-cyclic monophosphate (cGMP) transporter in human erythrocytes. Biochem Pharmacol 2002; 63:945-9. [PMID: 11911846 DOI: 10.1016/s0006-2952(01)00940-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The efflux pump for cGMP has been shown to be an ATP-energized multiorganic anion transporter. The present study was performed to extend the knowledge of the pharmacological characteristics of this efflux pump. Inside-out vesicles prepared from fresh blood were incubated with [3H]-cGMP (1 microM) with or without various concentrations of competitors for 120min at 37 degrees. The tested compounds could be divided in four groups: one with high affinity (K(i) < 5 microM), a second with moderate affinity (K(i): 5-50 microM), a third with low affinity (K(i): 0.1-5mM) and the fourth with extremely low or no affinity at all. With the mean K(i)-values given in parenthesis, the high affinity group consisted of mifepristone (0.2 microM), zaprinast (0.35 microM), dipyridamole (0.35 microM), estradiol 3-beta-glucuronide (0.42 microM), genistein (0.43 microM), estradiol 17-beta-glucuronide (0.47 microM), onapristone (1.3 microM), progesterone (1.7 microM) and sildenafil (3.6 microM). The inhibitors with medium affinity were estradiol (8 microM), sulfinpyrazone (13 microM), daunorubicin (23 microM), megestrol acetate (26 microM), doxorubicin (28 microM), 6-thioguanine (28 microM) and 6-thioguanosine-5'-monophosphate (32 microM). The low affinity group comprised 6-TIMP (220 microM), 6-methylmercaptopurine (MMP) (220 microM), vincristine (270 microM), medroxyprogesterone (680 microM), para-aminohippurate (PAH) (1.9mM) and taurocholate (2.2mM). No or minimal effect was seen in the presence of 6-mercaptopurine (6-MP), methotrexate, 9-(2-phosphonylmethoxyethyl)adenine and mitoxantrone. The cGMP transporter had a unique pharmacological profile, different from that of MRP1, but with some characteristics in common with MRP4 and MRP5.
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Affiliation(s)
- Elisabeth Sundkvist
- Department of Pharmacology, Medical Faculty, Institute of Medical Biology, University of Tromsø, N-9037, Tromsø, Norway
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