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Andresen H, Pérez‐Ternero C, Robinson J, Dickey DM, Hobbs AJ, Potter LR, Levy FO, Cataliotti A, Moltzau LR. Novel enhancers of guanylyl cyclase-A activity acting via allosteric modulation. Br J Pharmacol 2023; 180:3254-3270. [PMID: 37522273 PMCID: PMC10952227 DOI: 10.1111/bph.16203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 06/30/2023] [Accepted: 07/11/2023] [Indexed: 08/01/2023] Open
Abstract
BACKGROUND AND PURPOSE Guanylyl cyclase-A (GC-A), activated by endogenous atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), plays an important role in the regulation of cardiovascular and renal homeostasis and is an attractive drug target. Even though small molecule modulators allow oral administration and longer half-life, drug targeting of GC-A has so far been limited to peptides. Thus, in this study we aimed to develop small molecular activators of GC-A. EXPERIMENTAL APPROACH Hits were identified through high-throughput screening and optimized by in silico design. Cyclic GMP was measured in QBIHEK293A cells expressing GC-A, GC-B or chimerae of the two receptors using AlphaScreen technology. Binding assays were performed in membrane preparations or whole cells using 125 I-ANP. Vasorelaxation was measured in aortic rings isolated from Wistar rats. KEY RESULTS We have identified small molecular allosteric enhancers of GC-A, which enhanced ANP or BNP effects in cellular systems and ANP-induced vasorelaxation in rat aortic rings. The mechanism of action appears novel and not mediated through previously described allosteric binding sites. In addition, the selectivity and activity depend on a single amino acid residue that differs between the two similar receptors GC-A and GC-B. CONCLUSION AND IMPLICATIONS We describe a novel allosteric binding site on GC-A, which can be targeted by small molecules to enhance ANP and BNP effects. These compounds will be valuable tools in further development and proof-of-concept of GC-A enhancement for the potential use in cardiovascular therapy.
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Affiliation(s)
- Henriette Andresen
- Department of Pharmacology, Institute of Clinical MedicineUniversity of Oslo and Oslo University HospitalOsloNorway
- Institute for Experimental Medical ResearchUniversity of Oslo and Oslo University HospitalOsloNorway
| | - Cristina Pérez‐Ternero
- William Harvey Research Institute, Barts & The London School of Medicine and DentistryQueen Mary University of LondonLondonUK
| | - Jerid Robinson
- Department of Biochemistry, Molecular Biology, and BiophysicsUniversity of Minnesota Medical SchoolMinneapolisMinnesotaUSA
| | - Deborah M. Dickey
- Department of Biochemistry, Molecular Biology, and BiophysicsUniversity of Minnesota Medical SchoolMinneapolisMinnesotaUSA
| | - Adrian J. Hobbs
- William Harvey Research Institute, Barts & The London School of Medicine and DentistryQueen Mary University of LondonLondonUK
| | - Lincoln R. Potter
- Department of Biochemistry, Molecular Biology, and BiophysicsUniversity of Minnesota Medical SchoolMinneapolisMinnesotaUSA
| | - Finn Olav Levy
- Department of Pharmacology, Institute of Clinical MedicineUniversity of Oslo and Oslo University HospitalOsloNorway
| | - Alessandro Cataliotti
- Institute for Experimental Medical ResearchUniversity of Oslo and Oslo University HospitalOsloNorway
| | - Lise Román Moltzau
- Department of Pharmacology, Institute of Clinical MedicineUniversity of Oslo and Oslo University HospitalOsloNorway
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Otto NM, Potter LR. Vicinal glutamates are better phosphomimetics: Phosphorylation is required for allosteric activation of guanylyl cyclase-A. Front Mol Neurosci 2022; 15:1012784. [DOI: 10.3389/fnmol.2022.1012784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/22/2022] [Indexed: 11/06/2022] Open
Abstract
Multisite phosphorylation of guanylyl cyclase (GC)-A, also known as NPR-A or NPR1, is required for receptor activation by natriuretic peptides (NPs) because alanine substitutions for the first four GC-A phosphorylation sites produce an enzyme that cannot be stimulated by NPs. In contrast, single Glu substitutions for the first six chemically identified GC-A phosphorylation sites to mimic the negative charge of phosphate produced an enzyme that is activated by NPs but had an elevated Michaelis constant (Km), resulting in low activity. Here, we show that vicinal (double adjacent) Glu substitutions for the same sites to mimic the two negative charges of phosphate produced a near wild type (WT) enzyme with a low Km. Unlike the enzyme with single glutamate substitutions, the vicinally substituted enzyme did not require the functionally identified Ser-473-Glu substitution to achieve WT-like activity. Importantly, the negative charge associated with either phosphorylation or glutamate substitutions was required for allosteric activation of GC-A by ATP. We conclude that vicinal Glu substitutions are better phosphomimetics than single Glu substitutions and that phosphorylation is required for allosteric activation of GC-A in the absence and presence of NP. Finally, we suggest that the putative functionally identified phosphorylation sites, Ser-473 in GC-A and Ser-489 in GC-B, are not phosphorylation sites at all.
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3
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Bose A, Visweswariah SS. The pseudokinase domain in receptor guanylyl cyclases. Methods Enzymol 2022; 667:535-574. [PMID: 35525553 DOI: 10.1016/bs.mie.2022.03.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cyclic GMP is produced by enzymes called guanylyl cyclases, of which the membrane-associated forms contain an intracellular pseudokinase domain that allosterically regulates the C-terminal guanylyl cyclase domain. Ligand binding to the extracellular domain of these single transmembrane-spanning domain receptors elicits an increase in cGMP levels in the cell. The pseudokinase domain (or kinase-homology domain) in these receptors appears to be critical for ligand-mediated activation. While the pseudokinase domain does not possess kinase activity, biochemical evidence indicates that the domain can bind ATP and thereby allosterically regulate the catalytic activity of these receptors. The pseudokinase domain also appears to be the site of interaction of regulatory proteins, as seen in the retinal guanylyl cyclases that are involved in visual signal transduction. In the absence of structural information on the pseudokinase-guanylyl cyclase domain organization of any member of this family of receptors, biochemical evidence has provided clues to the physical interaction of the pseudokinase and guanylyl cyclase domain. An α-helical linker region between the pseudokinase domain and the guanylyl cyclase domain regulates the basal activity of these receptors in the absence of a stimulatory ligand and is important for stabilizing the structure of the pseudokinase domain that can bind ATP. Here, we present an overview of salient features of ATP-mediated regulation of receptor guanylyl cyclases and describe biochemical approaches that allow a clearer understanding of the intricate interplay between the pseudokinase domain and catalytic domain in these proteins.
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Affiliation(s)
- Avipsa Bose
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Sandhya S Visweswariah
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.
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Edmund AB, Walseth TF, Levinson NM, Potter LR. The pseudokinase domains of guanylyl cyclase-A and -B allosterically increase the affinity of their catalytic domains for substrate. Sci Signal 2019; 12:12/566/eaau5378. [PMID: 30696704 DOI: 10.1126/scisignal.aau5378] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Natriuretic peptides regulate multiple physiologic systems by activating transmembrane receptors containing intracellular guanylyl cyclase domains, such as GC-A and GC-B, also known as Npr1 and Npr2, respectively. Both enzymes contain an intracellular, phosphorylated pseudokinase domain (PKD) critical for activation of the C-terminal cGMP-synthesizing guanylyl cyclase domain. Because ATP allosterically activates GC-A and GC-B, we investigated how ATP binding to the PKD influenced guanylyl cyclase activity. Molecular modeling indicated that all the residues of the ATP-binding site of the prototypical kinase PKA, except the catalytic aspartate, are conserved in the PKDs of GC-A and GC-B. Kinase-inactivating alanine substitutions for the invariant lysine in subdomain II or the aspartate in the DYG-loop of GC-A and GC-B failed to decrease enzyme phosphate content, consistent with the PKDs lacking kinase activity. In contrast, both mutations reduced enzyme activation by blocking the ability of ATP to decrease the Michaelis constant without affecting peptide-dependent activation. The analogous lysine-to-alanine substitution in a glutamate-substituted phosphomimetic mutant form of GC-B also reduced enzyme activity, consistent with ATP stimulating guanylyl cyclase activity through an allosteric, phosphorylation-independent mechanism. Mutations designed to rigidify the conserved regulatory or catalytic spines within the PKDs increased guanylyl cyclase activity, increased sensitivity to natriuretic peptide, or reduced the Michaelis constant in the absence of ATP, consistent with ATP binding stabilizing the PKD in a conformation analogous to that of catalytically active kinases. We conclude that allosteric mechanisms evolutionarily conserved in the PKDs promote the catalytic activation of transmembrane guanylyl cyclases.
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Affiliation(s)
- Aaron B Edmund
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA
| | - Timothy F Walseth
- Department of Pharmacology, University of Minnesota, 6-120 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA
| | - Nicholas M Levinson
- Department of Pharmacology, University of Minnesota, 6-120 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA
| | - Lincoln R Potter
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA. .,Department of Pharmacology, University of Minnesota, 6-120 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA
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5
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The regulatory role of the kinase-homology domain in receptor guanylyl cyclases: nothing 'pseudo' about it! Biochem Soc Trans 2018; 46:1729-1742. [PMID: 30420416 DOI: 10.1042/bst20180472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/08/2018] [Accepted: 10/11/2018] [Indexed: 01/05/2023]
Abstract
The availability of genome sequence information and a large number of protein structures has allowed the cataloging of genes into various families, based on their function and predicted biochemical activity. Intriguingly, a number of proteins harbor changes in the amino acid sequence at residues, that from structural elucidation, are critical for catalytic activity. Such proteins have been categorized as 'pseudoenzymes'. Here, we review the role of the pseudokinase (or kinase-homology) domain in receptor guanylyl cyclases. These are multidomain single-pass, transmembrane proteins harboring an extracellular ligand-binding domain, and an intracellular domain composed of a kinase-homology domain that regulates the activity of the associated guanylyl cyclase domain. Mutations that lie in the kinase-homology domain of these receptors are associated with human disease, and either abolish or enhance cGMP production by these receptors to alter downstream signaling events. This raises the interesting possibility that one could identify molecules that bind to the pseudokinase domain and regulate the activities of these receptors, in order to alleviate symptoms in patients harboring these mutations.
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Regulation of the Natriuretic Peptide Receptor 2 (Npr2) by Phosphorylation of Juxtamembrane Serine and Threonine Residues Is Essential for Bifurcation of Sensory Axons. J Neurosci 2018; 38:9768-9780. [PMID: 30249793 DOI: 10.1523/jneurosci.0495-18.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 08/28/2018] [Accepted: 09/18/2018] [Indexed: 12/31/2022] Open
Abstract
cGMP signaling elicited by activation of the transmembrane receptor guanylyl cyclase Npr2 (also known as guanylyl cyclase B) by the ligand CNP controls sensory axon bifurcation of DRG and cranial sensory ganglion (CSG) neurons entering the spinal cord or hindbrain, respectively. Previous studies have shown that Npr2 is phosphorylated on serine and threonine residues in its kinase homology domain (KHD). However, it is unknown whether phosphorylation of Npr2 is essential for axon bifurcation. Here, we generated a knock-in mouse line in which the seven regulatory serine and threonine residues in the KHD of Npr2 were substituted by alanine (Npr2-7A), resulting in a nonphosphorylatable enzyme. Real-time imaging of cGMP in DRG neurons with a genetically encoded fluorescent cGMP sensor or biochemical analysis of guanylyl cyclase activity in brain or lung tissue revealed the absence of CNP-induced cGMP generation in the Npr27A/7A mutant. Consequently, bifurcation of axons, but not collateral formation, from DRG or CSG in this mouse mutant was perturbed at embryonic and mature stages. In contrast, axon branching was normal in a mouse mutant in which constitutive phosphorylation of Npr2 is mimicked by a replacement of all of the seven serine and threonine sites by glutamic acid (Npr2-7E). Furthermore, we demonstrate that the Npr27A/7A mutation causes dwarfism as described for global Npr2 mutants. In conclusion, our in vivo studies provide strong evidence that phosphorylation of the seven serine and threonine residues in the KHD of Npr2 is an important regulatory element of Npr2-mediated cGMP signaling which affects physiological processes, such as axon bifurcation and bone growth.SIGNIFICANCE STATEMENT The branching of axons is a morphological hallmark of virtually all neurons. It allows an individual neuron to innervate different targets and to communicate with neurons located in different regions of the nervous system. The natriuretic peptide receptor 2 (Npr2), a transmembrane guanylyl cyclase, is essential for the initiation of bifurcation of sensory axons when entering the spinal cord or the hindbrain. By using two genetically engineered mouse lines, we show that phosphorylation of specific serine and threonine residues in juxtamembrane regions of Npr2 are required for its enzymatic activity and for axon bifurcation. These investigations might help to understand the regulation of Npr2 and its integration in intracellular signaling systems.
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Dickey DM, Otto NM, Potter LR. Skeletal overgrowth-causing mutations mimic an allosterically activated conformation of guanylyl cyclase-B that is inhibited by 2,4,6,-trinitrophenyl ATP. J Biol Chem 2017; 292:10220-10229. [PMID: 28450398 DOI: 10.1074/jbc.m117.780536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 04/24/2017] [Indexed: 11/06/2022] Open
Abstract
Activating mutations in the receptor for C-type natriuretic peptide (CNP), guanylyl cyclase B (GC-B, also known as Npr2 or NPR-B), increase cellular cGMP and cause skeletal overgrowth, but how these mutations affect GTP catalysis is poorly understood. The A488P and R655C mutations were compared with the known mutation V883M. Neither mutation affected GC-B concentrations. The A488P mutation decreased the EC50 5-fold, increased Vmax 2.6-fold, and decreased the Km 13-fold, whereas the R655C mutation decreased the EC50 5-fold, increased the Vmax 2.1-fold, and decreased the Km 4.7-fold. Neither mutation affected maximum activity at saturating CNP concentrations. Activation by R655C did not require disulfide bond formation. Surprisingly, the A488P mutant only activated the receptor when it was phosphorylated. In contrast, the R655C mutation converted GC-B-7A from CNP-unresponsive to CNP-responsive. Interestingly, neither mutant was activated by ATP, and the Km and Hill coefficient of each mutant assayed in the absence of ATP were similar to those of wild-type GC-B assayed in the presence of ATP. Finally, 1 mm 2,4,6,-trinitrophenyl ATP inhibited all three mutants by as much as 80% but failed to inhibit WT-GC-B. We conclude that 1) the A488P and R655C missense mutations result in a GC-B conformation that mimics the allosterically activated conformation, 2) GC-B phosphorylation is required for CNP-dependent activation by the A488P mutation, 3) the R655C mutation abrogates the need for phosphorylation in receptor activation, and 4) an ATP analog selectively inhibits the GC-B mutants, indicating that a pharmacologic approach could reduce GC-B dependent human skeletal overgrowth.
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Affiliation(s)
- Deborah M Dickey
- From the Department of Biochemistry, Molecular Biology, and Biophysics and
| | - Neil M Otto
- From the Department of Biochemistry, Molecular Biology, and Biophysics and
| | - Lincoln R Potter
- From the Department of Biochemistry, Molecular Biology, and Biophysics and .,the Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
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8
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Otto NM, McDowell WG, Dickey DM, Potter LR. A Glutamate-Substituted Mutant Mimics the Phosphorylated and Active Form of Guanylyl Cyclase-A. Mol Pharmacol 2017; 92:67-74. [PMID: 28416574 DOI: 10.1124/mol.116.107995] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/04/2017] [Indexed: 12/30/2022] Open
Abstract
Multisite phosphorylation is required for activation of guanylyl cyclase (GC)-A, also known as NPR-A or NPR1, by cardiac natriuretic peptides (NPs). Seven chemically identified sites (Ser-487, Ser-497, Thr-500, Ser-502, Ser-506, Ser-510, and Thr-513) and one functionally identified putative site (Ser-473) were reported. Single alanine substitutions for Ser-497, Thr-500, Ser-502, Ser-506, and Ser-510 reduced maximal velocity (Vmax), whereas glutamate substitutions had no effect or increased Vmax Ala but not Glu substitution for Ser-497 increased the Michaelis constant (Km) approximately 400%. A GC-A mutant containing Glu substitutions for all seven chemically identified sites (GC-A-7E) had a Km approximately 10-fold higher than phosphorylated wild-type (WT) GC-A, but one additional substitution for Ser-473 to make GC-A-8E resulted in the same Vmax, Km, and EC50 as the phosphorylated WT enzyme. Adding more glutamates to make GC-A-9E or GC-A-10E had little effect on activity, and sequential deletion of individual glutamates in GC-A-8E progressively increased the Km Double Ala substitutions for Ser-497 and either Thr-500, Ser-510 or Thr-513 in WT-GC-A increased the Km 23- to 70-fold but the same mutations in GC-A-8E only increased the Km 8-fold, consistent with one site affecting the phosphorylation of other sites. Phosphate measurements confirmed that single-site Ala substitutions reduced receptor phosphate levels more than expected for the loss of a single site. We conclude that a concentrated region of negative charge, not steric properties, resulting from multiple interdependent phosphorylation sites is required for a GC-A conformation capable of transmitting the hormone binding signal to the catalytic domain.
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Affiliation(s)
- Neil M Otto
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota
| | - William G McDowell
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Deborah M Dickey
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Lincoln R Potter
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota
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Phosphorylation of the dimeric cytoplasmic domain of the phytosulfokine receptor, PSKR1. Biochem J 2016; 473:3081-98. [PMID: 27487840 DOI: 10.1042/bcj20160593] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/03/2016] [Indexed: 11/17/2022]
Abstract
Phytosulfokines (PSKs) are plant peptide hormones that co-regulate plant growth, differentiation and defense responses. PSKs signal through a plasma membrane localized leucine-rich repeat receptor-like kinase (phytosulfokine receptor 1, PSKR1) that also contains a functional cytosolic guanylate cyclase with its cyclase catalytic center embedded within the kinase domain. To functionally characterize this novel type of overlapping dual catalytic function, we investigated the phosphorylation of PSKR1 in vitro Tandem mass spectrometry of the cytoplasmic domain of PSKR1 (PSKR1cd) revealed at least 11 phosphorylation sites (8 serines, 2 threonines and 1 tyrosine) within the PSKR1cd. Phosphomimetic mutations of three serine residues (Ser686, Ser696 and Ser698) in tandem at the juxta-membrane position resulted in enhanced kinase activity in the on-mutant that was suppressed in the off-mutant, but both mutations reduced guanylate cyclase activity. Both the on and off phosphomimetic mutations of the phosphotyrosine (Tyr888) residue in the activation loop suppressed kinase activity, while neither mutation affected guanylate cyclase activity. Size exclusion and analytical ultracentrifugation analysis of the PSKR1cd suggest that it is reversibly dimeric in solution, which was further confirmed by biflourescence complementation. Taken together, these data suggest that in this novel type of receptor domain architecture, specific phosphorylation and dimerization are possibly essential mechanisms for ligand-mediated catalysis and signaling.
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Dickey DM, Edmund AB, Otto NM, Chaffee TS, Robinson JW, Potter LR. Catalytically Active Guanylyl Cyclase B Requires Endoplasmic Reticulum-mediated Glycosylation, and Mutations That Inhibit This Process Cause Dwarfism. J Biol Chem 2016; 291:11385-93. [PMID: 26980729 DOI: 10.1074/jbc.m115.704015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Indexed: 01/18/2023] Open
Abstract
C-type natriuretic peptide activation of guanylyl cyclase B (GC-B), also known as natriuretic peptide receptor B or NPR2, stimulates long bone growth, and missense mutations in GC-B cause dwarfism. Four such mutants (L658F, Y708C, R776W, and G959A) bound (125)I-C-type natriuretic peptide on the surface of cells but failed to synthesize cGMP in membrane GC assays. Immunofluorescence microscopy also indicated that the mutant receptors were on the cell surface. All mutant proteins were dephosphorylated and incompletely glycosylated, but dephosphorylation did not explain the inactivation because the mutations inactivated a "constitutively phosphorylated" enzyme. Tunicamycin inhibition of glycosylation in the endoplasmic reticulum or mutation of the Asn-24 glycosylation site decreased GC activity, but neither inhibition of glycosylation in the Golgi by N-acetylglucosaminyltransferase I gene inactivation nor PNGase F deglycosylation of fully processed GC-B reduced GC activity. We conclude that endoplasmic reticulum-mediated glycosylation is required for the formation of an active catalytic, but not ligand-binding domain, and that mutations that inhibit this process cause dwarfism.
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Affiliation(s)
- Deborah M Dickey
- From the Departments of Biochemistry, Molecular Biology, and Biophysics and
| | - Aaron B Edmund
- From the Departments of Biochemistry, Molecular Biology, and Biophysics and
| | - Neil M Otto
- From the Departments of Biochemistry, Molecular Biology, and Biophysics and
| | - Thomas S Chaffee
- From the Departments of Biochemistry, Molecular Biology, and Biophysics and
| | - Jerid W Robinson
- From the Departments of Biochemistry, Molecular Biology, and Biophysics and
| | - Lincoln R Potter
- From the Departments of Biochemistry, Molecular Biology, and Biophysics and Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
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Hammarén HM, Virtanen AT, Silvennoinen O. Nucleotide-binding mechanisms in pseudokinases. Biosci Rep 2015; 36:e00282. [PMID: 26589967 PMCID: PMC4718504 DOI: 10.1042/bsr20150226] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/11/2015] [Accepted: 11/20/2015] [Indexed: 01/01/2023] Open
Abstract
Pseudokinases are classified by the lack of one or several of the highly conserved motifs involved in nucleotide (nt) binding or catalytic activity of protein kinases (PKs). Pseudokinases represent ∼10% of the human kinome and they are found in all evolutionary classes of kinases. It has become evident that pseudokinases, which were initially considered somewhat peculiar dead kinases, are important components in several signalling cascades. Furthermore, several pseudokinases have been linked to human diseases, particularly cancer, which is raising interest for therapeutic approaches towards these proteins. The ATP-binding pocket is a well-established drug target and elucidation of the mechanism and properties of nt binding in pseudokinases is of significant interest and importance. Recent studies have demonstrated that members of the pseudokinase family are very diverse in structure as well as in their ability and mechanism to bind nts or perform phosphoryl transfer reactions. This diversity also precludes prediction of pseudokinase function, or the importance of nt binding for said function, based on primary sequence alone. Currently available data indicate that ∼40% of pseudokinases are able to bind nts, whereas only few are able to catalyse occasional phosphoryl transfer. Pseudokinases employ diverse mechanisms to bind nts, which usually occurs at low, but physiological, affinity. ATP binding serves often a structural role but in most cases the functional roles are not precisely known. In the present review, we discuss the various mechanisms that pseudokinases employ for nt binding and how this often low-affinity binding can be accurately analysed.
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Affiliation(s)
- Henrik M Hammarén
- School of Medicine, University of Tampere, Biokatu 8, FI-33014 Tampere, Finland
| | - Anniina T Virtanen
- School of Medicine, University of Tampere, Biokatu 8, FI-33014 Tampere, Finland
| | - Olli Silvennoinen
- School of Medicine, University of Tampere, Biokatu 8, FI-33014 Tampere, Finland Clinical Hematology, Department of Internal Medicine, Tampere University Hospital, Medisiinarinkatu 3, FI-33520 Tampere, Finland
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Abstract
Over 30 receptor-like kinases contain a guanylate cyclase (GC) catalytic centre embedded within the C-terminal region of their kinase domain in the model plant Arabidopsis. A number of the kinase GCs contain both functional kinase and GC activity in vitro and the natural ligands of these receptors stimulate increases in cGMP within isolated protoplasts. The GC activity could be described as a minor or moonlighting activity. We have also identified mammalian proteins that contain the novel GC centre embedded within kinase domains. One example is the interleukin 1 receptor-associated kinase 3 (IRAK3). We compare the GC functionality of the mammalian protein IRAK3 with the cytoplasmic domain of the plant prototype molecule, the phytosulfokine receptor 1 (PSKR1). We have developed homology models of these molecules and have undertaken in vitro experiments to compare their functionality and structural features. Recombinant IRAK3 produces cGMP at levels comparable to those produced by PSKR1, suggesting that IRAK3 contains GC activity. Our findings raise the possibility that kinase-GCs may switch between downstream kinase-mediated or cGMP-mediated signalling cascades to elicit desired outputs to particular stimuli. The challenge now lies in understanding the interaction between the GC and kinase domains and how these molecules utilize their dual functionality within cells.
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14
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Sürmeli NB, Müskens FM, Marletta MA. The Influence of Nitric Oxide on Soluble Guanylate Cyclase Regulation by Nucleotides: ROLE OF THE PSEUDOSYMMETRIC SITE. J Biol Chem 2015; 290:15570-15580. [PMID: 25907555 DOI: 10.1074/jbc.m115.641431] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Indexed: 01/09/2023] Open
Abstract
Activation of soluble guanylate cyclase (sGC) by the signaling molecule nitric oxide (NO) leads to formation of the second messenger cGMP, which mediates numerous physiological processes. NO activates sGC by binding to the ferrous heme cofactor; the relative amount of NO with respect to sGC heme affects the enzyme activity. ATP can also influence the activity by binding to an allosteric site, most likely the pseudosymmetric site located in the catalytic domain. Here, the role of the pseudosymmetric site on nucleotide regulation was investigated by point mutations at this site. ATP inhibition kinetics of wild type and a pseudosymmetric site (α1-C594A/β1-D477A) variant of sGC was determined at various levels of NO. Results obtained show that in the presence of less than 1 eq of NO, there appears to be less than complete activation and little change in the nucleotide binding parameters. The most dramatic effects are observed for the addition of excess NO, which results in an increase in the affinity of GTP at the catalytic site and full activation of sGC. The pseudosymmetric site mutation only affected nucleotide affinities in the presence of excess NO; there was a decrease in the affinity for ATP in both the allosteric and catalytic sites. These observations led to a new kinetic model for sGC activity in the presence of excess NO. This model revealed that the active and allosteric sites show cooperativity. This new comprehensive model gives a more accurate description of sGC regulation by NO and nucleotides in vivo.
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Affiliation(s)
- Nur Başak Sürmeli
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037
| | - Frederike M Müskens
- Department of Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, 3584 CG Utrecht, The Netherlands
| | - Michael A Marletta
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037.
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Schwarz R, Reif A, Scholz CJ, Weissflog L, Schmidt B, Lesch KP, Jacob C, Reichert S, Heupel J, Volkert J, Kopf J, Hilscher M, Weber H, Kittel-Schneider S. A preliminary study on methylphenidate-regulated gene expression in lymphoblastoid cells of ADHD patients. World J Biol Psychiatry 2015; 16:180-9. [PMID: 25162476 DOI: 10.3109/15622975.2014.948064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Methylphenidate (MPH) is a commonly used stimulant medication for treating attention-deficit/hyperactivity disorder (ADHD). Besides inhibiting monoamine reuptake there is evidence that MPH also influences gene expression directly. METHODS We investigated the impact of MPH treatment on gene expression levels of lymphoblastoid cells derived from adult ADHD patients and healthy controls by hypothesis-free, genome-wide microarray analysis. Significant findings were subsequently confirmed by quantitative Real-Time PCR (qRT PCR) analysis. RESULTS The microarray analysis from pooled samples after correction for multiple testing revealed 138 genes to be marginally significantly regulated due to MPH treatment, and one gene due to diagnosis. By qRT PCR we could confirm that GUCY1B3 expression was differential due to diagnosis. We verified chronic MPH treatment effects on the expression of ATXN1, HEY1, MAP3K8 and GLUT3 in controls as well as acute treatment effects on the expression of NAV2 and ATXN1 specifically in ADHD patients. CONCLUSIONS Our preliminary results demonstrate MPH treatment differences in ADHD patients and healthy controls in a peripheral primary cell model. Our results need to be replicated in larger samples and also using patient-derived neuronal cell models to validate the contribution of those genes to the pathophysiology of ADHD and mode of action of MPH.
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Affiliation(s)
- Ricarda Schwarz
- Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Würzburg , Würzburg , Germany
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16
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Pan S, Chen HH, Correia C, Dai H, Witt TA, Kleppe LS, Burnett JC, Simari RD. Cell surface protein disulfide isomerase regulates natriuretic peptide generation of cyclic guanosine monophosphate. PLoS One 2014; 9:e112986. [PMID: 25419565 PMCID: PMC4242536 DOI: 10.1371/journal.pone.0112986] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 10/21/2014] [Indexed: 12/21/2022] Open
Abstract
Rationale The family of natriuretic peptides (NPs), including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP), exert important and diverse actions for cardiovascular and renal homeostasis. The autocrine and paracrine functions of the NPs are primarily mediated through the cellular membrane bound guanylyl cyclase-linked receptors GC-A (NPR-A) and GC-B (NPR-B). As the ligands and receptors each contain disulfide bonds, a regulatory role for the cell surface protein disulfide isomerase (PDI) was investigated. Objective We utilized complementary in vitro and in vivo models to determine the potential role of PDI in regulating the ability of the NPs to generate its second messenger, cyclic guanosine monophosphate. Methods and Results Inhibition of PDI attenuated the ability of ANP, BNP and CNP to generate cGMP in human mesangial cells (HMCs), human umbilical vein endothelial cells (HUVECs), and human aortic smooth muscle cells (HASMCs), each of which were shown to express PDI. In LLC-PK1 cells, where PDI expression was undetectable by immunoblotting, PDI inhibition had a minimal effect on cGMP generation. Addition of PDI to cultured LLC-PK1 cells increased intracellular cGMP generation mediated by ANP. Inhibition of PDI in vivo attenuated NP-mediated generation of cGMP by ANP. Surface Plasmon Resonance demonstrated modest and differential binding of the natriuretic peptides with immobilized PDI in a cell free system. However, PDI was shown to co-localize on the surface of cells with GC-A and GC-B by co-immunoprecpitation and immunohistochemistry. Conclusion These data demonstrate for the first time that cell surface PDI expression and function regulate the capacity of natriuretic peptides to generate cGMP through interaction with their receptors.
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Affiliation(s)
- Shuchong Pan
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America
| | - Horng H. Chen
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America
| | - Cristina Correia
- Division of Oncology Research, Mayo Clinic, Rochester, MN, United States of America
| | - Haiming Dai
- Division of Oncology Research, Mayo Clinic, Rochester, MN, United States of America
| | - Tyra A. Witt
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America
| | - Laurel S. Kleppe
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America
| | - John C. Burnett
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America
| | - Robert D. Simari
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America
- * E-mail:
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17
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Egbert JR, Shuhaibar LC, Edmund AB, Van Helden DA, Robinson JW, Uliasz TF, Baena V, Geerts A, Wunder F, Potter LR, Jaffe LA. Dephosphorylation and inactivation of NPR2 guanylyl cyclase in granulosa cells contributes to the LH-induced decrease in cGMP that causes resumption of meiosis in rat oocytes. Development 2014; 141:3594-604. [PMID: 25183874 DOI: 10.1242/dev.112219] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In mammals, the meiotic cell cycle of oocytes starts during embryogenesis and then pauses. Much later, in preparation for fertilization, oocytes within preovulatory follicles resume meiosis in response to luteinizing hormone (LH). Before LH stimulation, the arrest is maintained by diffusion of cyclic (c)GMP into the oocyte from the surrounding granulosa cells, where it is produced by the guanylyl cyclase natriuretic peptide receptor 2 (NPR2). LH rapidly reduces the production of cGMP, but how this occurs is unknown. Here, using rat follicles, we show that within 10 min, LH signaling causes dephosphorylation and inactivation of NPR2 through a process that requires the activity of phosphoprotein phosphatase (PPP)-family members. The rapid dephosphorylation of NPR2 is accompanied by a rapid phosphorylation of the cGMP phosphodiesterase PDE5, an enzyme whose activity is increased upon phosphorylation. Later, levels of the NPR2 agonist C-type natriuretic peptide decrease in the follicle, and these sequential events contribute to the decrease in cGMP that causes meiosis to resume in the oocyte.
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Affiliation(s)
- Jeremy R Egbert
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Leia C Shuhaibar
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Aaron B Edmund
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Dusty A Van Helden
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jerid W Robinson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tracy F Uliasz
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Valentina Baena
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Andreas Geerts
- Bayer Pharma AG, Pharma Research Center, Wuppertal D-42096, Germany
| | - Frank Wunder
- Bayer Pharma AG, Pharma Research Center, Wuppertal D-42096, Germany
| | - Lincoln R Potter
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laurinda A Jaffe
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
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Structures of soluble guanylate cyclase: implications for regulatory mechanisms and drug development. Biochem Soc Trans 2014; 42:108-13. [PMID: 24450636 PMCID: PMC3901396 DOI: 10.1042/bst20130228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Activation of cGMP synthesis leads to vasodilation, and is an important mechanism in clinical treatment of angina, heart failure, and severe peripheral and pulmonary hypertension. The nitric oxide-responsive sGC (soluble guanylate cyclase) has been the target of recent drug discovery efforts. The present review surveys recent data on the structure and regulation of sGC, and the prospects of new avenues for therapeutic intervention.
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Hoffmann LS, Chen HH. cGMP: transition from bench to bedside: a report of the 6th International Conference on cGMP Generators, Effectors and Therapeutic Implications. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:707-18. [PMID: 24927824 DOI: 10.1007/s00210-014-0999-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 05/30/2014] [Indexed: 02/06/2023]
Abstract
Essential physiological homeostatic processes such as vascular tone, fluid balance, cardiorenal function, and sensory processes are regulated by the second messenger cyclic guanosine 3', 5'-monophosphate (cGMP). Dysregulation of cGMP-dependent pathways plays an important role in cardiovascular diseases such as hypertension, pulmonary hypertension, heart failure, or erectile dysfunction. Thus, the cGMP pathway consisting of the cGMP-generating guanylyl cyclases, protein kinases, and phosphodiesterases (PDE) has evolved to an important drug target and is the focus of a wide variety of research fields ranging from unraveling mechanisms on the molecular level to understanding the regulation of physiological and pathophysiological processes by cGMP. Based on the results from basic and preclinical research, therapeutic drugs have been developed which modulate the cGMP pathway and are investigated in clinical trials. Riociguat, a nitric oxide (NO)-independent soluble guanylyl cyclase stimulator; recombinant B-type natriuretic peptide (BNP); or recombinant atrial natriuretic peptide (ANP) and PDE5 inhibitors are cGMP-modulating drugs that are already available for the treatment of pulmonary hypertension, acute heart failure, and erectile dysfunction, respectively. The latest results from basic to clinical research on cGMP were presented on the 6th International Conference on cGMP in Erfurt, Germany, and are summarized in this article.
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Affiliation(s)
- Linda S Hoffmann
- Institute of Pharmacology and Toxicology, Biomedical Center, University of Bonn, Bonn, Germany,
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20
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Dove S, Danker KY, Stasch JP, Kaever V, Seifert R. Structure/activity relationships of (M)ANT- and TNP-nucleotides for inhibition of rat soluble guanylyl cyclase α1β1. Mol Pharmacol 2014; 85:598-607. [PMID: 24470063 DOI: 10.1124/mol.113.091017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Soluble guanylyl cyclase (sGC) plays an important role in cardiovascular function and catalyzes formation of cGMP. sGC is activated by nitric oxide and allosteric stimulators and activators. However, despite its therapeutic relevance, the regulatory mechanisms of sGC are still incompletely understood. A major reason for this situation is that no crystal structures of active sGC have been resolved so far. An important step toward this goal is the identification of high-affinity ligands that stabilize an sGC conformation resembling the active, "fully closed" state. Therefore, we examined inhibition of rat sGCα1β1 by 38 purine- and pyrimidine-nucleotides with 2,4,6,-trinitrophenyl and (N-methyl)anthraniloyl substitutions at the ribosyl moiety and compared the data with that for the structurally related membranous adenylyl cyclases (mACs) 1, 2, 5 and the purified mAC catalytic subunits VC1:IIC2. TNP-GTP [2',3'-O-(2,4,6-trinitrophenyl)-GTP] was the most potent sGCα1β1 inhibitor (Ki, 10.7 nM), followed by 2'-MANT-3'-dATP [2'-O-(N-methylanthraniloyl)-3'-deoxy-ATP] (Ki, 16.7 nM). Docking studies on an sGCαcat/sGCβcat model derived from the inactive heterodimeric crystal structure of the catalytic domains point to similar interactions of (M)ANT- and TNP-nucleotides with sGCα1β1 and mAC VC1:IIC2. Reasonable binding modes of 2'-MANT-3'-dATP and bis-(M)ANT-nucleotides at sGC α1β1 require a 3'-endo ribosyl conformation (versus 3'-exo in 3'-MANT-2'-dATP). Overall, inhibitory potencies of nucleotides at sGCα1β1 versus mACs 1, 2, 5 correlated poorly. Collectively, we identified highly potent sGCα1β1 inhibitors that may be useful for future crystallographic and fluorescence spectroscopy studies. Moreover, it may become possible to develop mAC inhibitors with selectivity relative to sGC.
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Affiliation(s)
- Stefan Dove
- Department of Medicinal Chemistry II, University of Regensburg, Regensburg, Germany (S.D.); Institute of Pharmacology,(K.Y.D., V.K., R.S.) and Research Core Unit Metabolomics (V.K.), Hannover Medical School, Hannover, Germany; and Institute of Cardiovascular Research, Bayer HealthCare, Wuppertal, Germany (J.-P.S.)
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Robinson JW, Dickey DM, Miura K, Michigami T, Ozono K, Potter LR. A human skeletal overgrowth mutation increases maximal velocity and blocks desensitization of guanylyl cyclase-B. Bone 2013; 56:375-82. [PMID: 23827346 PMCID: PMC4413012 DOI: 10.1016/j.bone.2013.06.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 06/12/2013] [Accepted: 06/24/2013] [Indexed: 01/12/2023]
Abstract
C-type natriuretic peptide (CNP) increases long bone growth by stimulating guanylyl cyclase (GC)-B/NPR-B/NPR2. Recently, a Val to Met missense mutation at position 883 in the catalytic domain of GC-B was identified in humans with increased blood cGMP levels that cause abnormally long bones. Here, we determined how this mutation activates GC-B. In the absence of CNP, cGMP levels in cells expressing V883M-GC-B were increased more than 20 fold compared to cells expressing wild-type (WT)-GC-B, and the addition of CNP only further increased cGMP levels 2-fold. In the absence of CNP, maximal enzymatic activity (Vmax) of V883M-GC-B was increased 15-fold compared to WT-GC-B but the affinity of the enzymes for substrate as revealed by the Michaelis constant (Km) was unaffected. Surprisingly, CNP decreased the Km of V883M-GC-B 10-fold in a concentration-dependent manner without increasing Vmax. Unlike the WT enzyme the Km reduction of V883M-GC-B did not require ATP. Unexpectedly, V883M-GC-B, but not WT-GC-B, failed to inactivate with time. Phosphorylation elevated but was not required for the activity increase associated with the mutation because the Val to Met substitution also activated a GC-B mutant lacking all known phosphorylation sites. We conclude that the V883M mutation increases maximal velocity in the absence of CNP, eliminates the requirement for ATP in the CNP-dependent Km reduction, and disrupts the normal inactivation process.
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Affiliation(s)
- Jerid W. Robinson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - Deborah M. Dickey
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Kohji Miura
- Department of Pediatrics, Osaka Graduate School of Medicine, Osaka, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka Graduate School of Medicine, Osaka, Japan
| | - Lincoln R. Potter
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
- Corresponding author at: University of Minnesota — Twin Cities, 6-155 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA. Fax: +1 612 624 7282. (L.R. Potter)
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22
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Potter LR. A twenty year journey to understand how ATP activates guanylyl cyclase A and B. BMC Pharmacol Toxicol 2013. [PMCID: PMC3765477 DOI: 10.1186/2050-6511-14-s1-o13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Nucleotidyl cyclase activity of particulate guanylyl cyclase A: comparison with particulate guanylyl cyclases E and F, soluble guanylyl cyclase and bacterial adenylyl cyclases CyaA and edema factor. PLoS One 2013; 8:e70223. [PMID: 23922959 PMCID: PMC3726482 DOI: 10.1371/journal.pone.0070223] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 06/17/2013] [Indexed: 11/19/2022] Open
Abstract
Guanylyl cyclases (GCs) regulate many physiological processes by catalyzing the synthesis of the second messenger cGMP. The GC family consists of seven particulate GCs (pGCs) and a nitric oxide-activated soluble GC (sGC). Rat sGC α1β1 possesses much broader substrate specificity than previously assumed. Moreover, the exotoxins CyaA from Bordetella pertussis and edema factor (EF) from Bacillus anthracis possess nucleotidyl cyclase (NC) activity. pGC-A is a natriuretic peptide-activated homodimer with two catalytic sites that act cooperatively. Here, we studied the NC activity of rat pGC-A in membranes of stably transfected HEK293 cells using a highly sensitive and specific HPLC-MS/MS technique. GTP and ITP were effective, and ATP and XTP were only poor, pGC-A substrates. In contrast to sGC, pGC-A did not use CTP and UTP as substrates. pGC-E and pGC-F expressed in bovine rod outer segment membranes used only GTP as substrate. In intact HEK293 cells, pGC-A generated only cGMP. In contrast to pGCs, EF and CyaA showed very broad substrate-specificity. In conclusion, NCs exhibit different substrate-specificities, arguing against substrate-leakiness of enzymes and pointing to distinct physiological functions of cyclic purine and pyrimidine nucleotides.
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Seifert R, Beste KY. Allosteric Regulation of Nucleotidyl Cyclases: An Emerging Pharmacological Target. Sci Signal 2012; 5:pe37. [DOI: 10.1126/scisignal.2003466] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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