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Vyse S, Desmond H, Huang PH. Advances in mass spectrometry based strategies to study receptor tyrosine kinases. IUCrJ 2017; 4:119-130. [PMID: 28250950 PMCID: PMC5330522 DOI: 10.1107/s2052252516020546] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/27/2016] [Indexed: 06/06/2023]
Abstract
Receptor tyrosine kinases (RTKs) are key transmembrane environmental sensors that are capable of transmitting extracellular information into phenotypic responses, including cell proliferation, survival and metabolism. Advances in mass spectrometry (MS)-based phosphoproteomics have been instrumental in providing the foundations of much of our current understanding of RTK signalling networks and activation dynamics. Furthermore, new insights relating to the deregulation of RTKs in disease, for instance receptor co-activation and kinome reprogramming, have largely been identified using phosphoproteomic-based strategies. This review outlines the current approaches employed in phosphoproteomic workflows, including phosphopeptide enrichment and MS data-acquisition methods. Here, recent advances in the application of MS-based phosphoproteomics to bridge critical gaps in our knowledge of RTK signalling are focused on. The current limitations of the technology are discussed and emerging areas such as computational modelling, high-throughput phospho-proteomic workflows and next-generation single-cell approaches to further our understanding in new areas of RTK biology are highlighted.
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Affiliation(s)
- Simon Vyse
- Division of Cancer Biology, The Institute of Cancer Research, London SW3 6JB, England
| | - Howard Desmond
- Division of Cancer Biology, The Institute of Cancer Research, London SW3 6JB, England
| | - Paul H. Huang
- Division of Cancer Biology, The Institute of Cancer Research, London SW3 6JB, England
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Bazenet C, Desmond H, Frank E, Doherty P, Eilers A, Gatchalian C, Glicksman M, Graczyk P, Gusovsky F, Ham J, Kaplan D, Klymkoswsky M, Kotkow K, Krolewski R, Lang P, O'Neil AL, McCarthy MJ, Meiri K, Miller F, Neumage MM, Ozek C, Philpott K, Piccinotti S, Price F, Raff M, Ratcliffe M, Relton J, Rhodes K, Schwob J, Smales C, Smith T, Spadoni C, Taylor J, Vekrellis K, Whitfield J. Lee Rubin: Our mentor and role model. Science 2017; 355:806. [DOI: 10.1126/science.aam8703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Bernier F, Sato Y, Matijevic M, Desmond H, McGrath S, Burns L, Kaplow JM, Albala B. P4–411: Clinical study of E2609, a novel BACE1 inhibitor, demonstrates target engagement and inhibition of BACE1 activity in CSF. Alzheimers Dement 2013. [DOI: 10.1016/j.jalz.2013.08.244] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | | | - Lynne Burns
- Eisai Inc. Andover Massachusetts United States
| | | | - Bruce Albala
- Eisai Inc. Woodcliff Lake New Jersey United States
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Deas E, Plun-Favreau H, Gandhi S, Desmond H, Kjaer S, Loh SHY, Renton AEM, Harvey RJ, Whitworth AJ, Martins LM, Abramov AY, Wood NW. PINK1 cleavage at position A103 by the mitochondrial protease PARL. Hum Mol Genet 2010; 20:867-79. [PMID: 21138942 PMCID: PMC3033179 DOI: 10.1093/hmg/ddq526] [Citation(s) in RCA: 336] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mutations in PTEN-induced kinase 1 (PINK1) cause early onset autosomal recessive Parkinson's disease (PD). PINK1 is a 63 kDa protein kinase, which exerts a neuroprotective function and is known to localize to mitochondria. Upon entry into the organelle, PINK1 is cleaved to produce a ∼53 kDa protein (ΔN-PINK1). In this paper, we show that PINK1 is cleaved between amino acids Ala-103 and Phe-104 to generate ΔN-PINK1. We demonstrate that a reduced ability to cleave PINK1, and the consequent accumulation of full-length protein, results in mitochondrial abnormalities reminiscent of those observed in PINK1 knockout cells, including disruption of the mitochondrial network and a reduction in mitochondrial mass. Notably, we assessed three N-terminal PD-associated PINK1 mutations located close to the cleavage site and, while these do not prevent PINK1 cleavage, they alter the ratio of full-length to ΔN-PINK1 protein in cells, resulting in an altered mitochondrial phenotype. Finally, we show that PINK1 interacts with the mitochondrial protease presenilin-associated rhomboid-like protein (PARL) and that loss of PARL results in aberrant PINK1 cleavage in mammalian cells. These combined results suggest that PINK1 cleavage is important for basal mitochondrial health and that PARL cleaves PINK1 to produce the ΔN-PINK1 fragment.
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Affiliation(s)
- Emma Deas
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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Morgan L, Shah B, Rivers LE, Barden L, Groom AJ, Chung R, Higazi D, Desmond H, Smith T, Staddon JM. Inflammation and dephosphorylation of the tight junction protein occludin in an experimental model of multiple sclerosis. Neuroscience 2007; 147:664-73. [PMID: 17560040 DOI: 10.1016/j.neuroscience.2007.04.051] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 03/30/2007] [Accepted: 04/04/2007] [Indexed: 01/09/2023]
Abstract
Multiple sclerosis (MS) is a disease of the CNS in which inflammation, demyelination and neurodegeneration contribute to its initiation and progression. A frequently employed model of MS is experimental autoimmune encephalomyelitis (EAE). Here, to gain new insights into the disease process, an analysis of proteins in extracts of lumbar spinal cord from naïve and EAE rats was undertaken. The data mainly confirm that inflammation and blood-brain barrier (BBB) breakdown are the major hallmarks of disease in this model. Given their importance in the BBB, junctional proteins were further investigated. Occludin, a protein localizing to tight junctions in brain endothelial cells, showed strikingly increased migration in EAE when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This increased migration was mimicked by in vitro phosphatase treatment, implying its dephosphorylation in EAE. Occludin dephosphorylation coincided with the onset of inflammation, slightly preceding visible signs of disease, and was just prior to apparent changes in BBB permeability. These findings suggest occludin is a target for signaling processes in EAE, perhaps regulating the response of the BBB to the inflammatory environment as seen in MS.
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MESH Headings
- Animals
- Disease Models, Animal
- Electrophoresis, Gel, Two-Dimensional/methods
- Encephalitis/etiology
- Encephalitis/metabolism
- Encephalitis/pathology
- Encephalomyelitis, Autoimmune, Experimental/complications
- Encephalomyelitis, Autoimmune, Experimental/metabolism
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Endothelial Cells/cytology
- Female
- Immunoprecipitation/methods
- Mass Spectrometry/methods
- Membrane Proteins/metabolism
- Occludin
- Phosphoric Monoester Hydrolases/pharmacology
- Phosphorylation/drug effects
- Rats
- Rats, Inbred Lew
- Spinal Cord/pathology
- Tight Junctions/metabolism
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Affiliation(s)
- L Morgan
- Eisai London Research Laboratories Ltd., University College London, London, UK
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Graczyk PP, Khan A, Bhatia GS, Palmer V, Medland D, Numata H, Oinuma H, Catchick J, Dunne A, Ellis M, Smales C, Whitfield J, Neame SJ, Shah B, Wilton D, Morgan L, Patel T, Chung R, Desmond H, Staddon JM, Sato N, Inoue A. The neuroprotective action of JNK3 inhibitors based on the 6,7-dihydro-5H-pyrrolo[1,2-a]imidazole scaffold. Bioorg Med Chem Lett 2005; 15:4666-70. [PMID: 16153829 DOI: 10.1016/j.bmcl.2005.07.076] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 07/26/2005] [Accepted: 07/29/2005] [Indexed: 11/27/2022]
Abstract
Imidazole-based structures of p38 inhibitors served as a starting point for the design of JNK3 inhibitors. Construction of a 6,7-dihydro-5H-pyrrolo[1,2-a]imidazole scaffold led to the synthesis of the (S)-enantiomers, which exhibited p38/JNK3 IC50 ratio of up to 10 and were up to 20 times more potent inhibitors of JNK3 than the relevant (R)-enantiomers. The JNK3 inhibitory potency correlated well with inhibition of c-Jun phosphorylation and neuroprotective properties of the compounds in low K+-induced cell death of rat cerebellar granule neurones.
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Affiliation(s)
- Piotr P Graczyk
- Eisai London Research Laboratories, University College London, Bernard Katz Building, Gower Street, London WC1E 6BT, UK.
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Smales C, Ellis M, Baumber R, Hussain N, Desmond H, Staddon JM. Occludin phosphorylation: identification of an occludin kinase in brain and cell extracts as CK2. FEBS Lett 2003; 545:161-6. [PMID: 12804768 DOI: 10.1016/s0014-5793(03)00525-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In epithelial and endothelial cells, tight junctions limit paracellular flux of ions, proteins and other macromolecules. However, mechanisms regulating tight junction function are not clear. Occludin, a tight junction protein, undergoes phosphorylation changes in several situations but little is known about occludin kinases. A recombinant C-terminal fragment of occludin is a substrate for a kinase in crude extracts of brain. This activity was purified about 10000-fold and identified as CK2 (casein kinase 2) by peptide mass fingerprinting, immunoblotting and mutation of CK2 sites within the occludin sequence. CK2 is therefore a candidate kinase for regulation of occludin phosphorylation in vivo.
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Affiliation(s)
- Caroline Smales
- Eisai London Research Laboratories Ltd., Bernard Katz Building, University College London, Gower Street, London, WC1E 6BT, UK
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Eilers A, Whitfield J, Shah B, Spadoni C, Desmond H, Ham J. Direct inhibition of c-Jun N-terminal kinase in sympathetic neurones prevents c-jun promoter activation and NGF withdrawal-induced death. J Neurochem 2001; 76:1439-54. [PMID: 11238729 DOI: 10.1046/j.1471-4159.2001.00150.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
c-Jun N-terminal kinases (JNKs) regulate gene expression by phosphorylating transcription factors, such as c-Jun. Studies with JNK: knockout mice suggest that JNK activity may be required for excitotoxin-induced apoptosis in the adult hippocampus and for apoptosis in the developing embryonic neural tube. Here we investigate the role of JNKs in classical neurotrophin-regulated developmental neuronal death by using nerve growth factor (NGF)-dependent sympathetic neurones. In this system, NGF withdrawal leads to an increase in JNK activity, an increase in c-Jun protein levels and c-Jun N-terminal phosphorylation before the cell death commitment point, and c-Jun activity is required for cell death. To inhibit JNK activity in sympathetic neurones we have used two different JNK inhibitors that act by distinct mechanisms: the compound SB 203580 and the JNK binding domain (JBD) of JNK interacting protein 1 (JIP-1). We demonstrate that JNK activity is required for c-Jun phosphorylation, c-jun promoter activation and NGF withdrawal-induced apoptosis. We also show that ATF-2, a c-Jun dimerization partner that can regulate c-jun gene expression, is activated following NGF deprivation. Finally, by co-expressing the JBD and a regulatable c-Jun dominant negative mutant we demonstrate that JNK and AP-1 function in the same pro-apoptotic signalling pathway after NGF withdrawal.
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Affiliation(s)
- A Eilers
- Eisai London Research Laboratories, University College London, London, UK
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Abstract
Using a new, sensitive assay of bacterial growth inhibition, inducible antibacterial activity has been identified in the haemolymph of the mosquito, Aedes aegypti following inoculation with bacteria or with microfilariae of the filarial nematode Brugia pahangi, but not after inoculation with sterile culture medium. A lower level of antibacterial activity has also been observed in untreated individual mosquitoes. Following bacterial inoculation, a basic, inducible antibacterial peptide has been detected using native PAGE at pH 4, which corresponds with a 4.5 kDa peptide detected by tricine SDS-PAGE followed by silver staining. A peptide has been purified from immune haemolymph by ultrafiltration, followed by reversed-phase HPLC, yielding a single major peak with antibacterial activity. Partial amino acid sequence analysis of this fraction has revealed substantial homology with insect defensins. The data are consistent with the peptide being another member of this family, and we propose the name Aedes aegypti defensin.
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Affiliation(s)
- R Chalk
- Centre for Applied Entomology and Parasitology, Biological Sciences, Keele University, Staffordshire, U.K
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Abstract
The main haemorrhagic fraction of Bothrops jararaca venom, showing in vitro fibrinogenolytic activity and an inhibitory effect on platelets aggregation induced by collagan, was studied in rats. Development of coagulopathy and/or haemorrhage was studied 2 hr after s.c. injection of batroxobin, B. jararaca whole venom and its haemorrhagic fraction. Incoagulable blood, together with low fibrinogen levels, were found only in rats injected with batroxobin and whole venom; thrombocytopenia alone was detected in rats given s.c. injections of haemorrhagin. Intravenous injection of low doses of haemorrhagin (less than 15 micrograms) resulted in significant thrombocytopenia, without any alterations in the blood coagulation mechanism. Severe damage to the vascular endothelium and skeletal muscle following s.c. injection of haemorrhagin together with signs of systemic haemorrhage in the kidneys, lungs and liver occurred. Levels of factor VIII and von Willebrand factor antigen were within the normal range in all animals. Serum levels of both whole venom and haemorrhagin were significantly correlated. This study confirms that B. jararaca haemorrhagin plays a vital role in systemic bleeding.
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Affiliation(s)
- A S Kamiguti
- Department of Haematology, Royal Liverpool Hospital, U.K
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Abstract
Venoms of nine different snake species of the genus Bothrops were fractionated using fast protein liquid chromatography (FPLC). Basic proteins with phospholipase A2 and/or myotoxic activities were isolated from venoms of B. jararacussu, B. moojeni, B. neuwiedi and B. pradoi. B. jararaca venom possessed very low concentrations of these proteins, which were undetectable in venoms of B. atrox, B. alternatus, B. cotiara and B. erythromelas. Basic proteins from B. moojeni and B. pradoi venoms were isolated in pure form. All active fractions possessed a common band of 15,000 mol. wt which caused a rise in serum creatine phosphokinase levels and histopathological changes in muscle cells following i.m. injection into mice. Levels of phospholipase A2 activity were variable. The implications of the possession of varying levels of myotoxins and phospholipase A2 in these venoms are discussed.
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Desmond H, Varro A, Young J, Gregory H, Nemeth J, Dockray GJ. The constitution and properties of phosphorylated and unphosphorylated C-terminal fragments of progastrin from dog and ferret antrum. Regul Pept 1989; 25:223-33. [PMID: 2756156 DOI: 10.1016/0167-0115(89)90264-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Antibodies to the extreme C-terminal tryptic (nona-) peptide fragment of porcine progastrin have been used in radioimmunoassay to identify progastrin fragments in dog, ferret and pig antral mucosa extracts and to monitor their purification. In addition to previously characterised phosphorylated and unphosphorylated C-terminal tryptic peptides of porcine progastrin a minor form corresponding to the C-terminal octapeptide (i.e. des-Ser C-terminal nonapeptide) was isolated and characterised. The latter form together with phosphorylated and unphosphorylated forms of the nonapeptides were also isolated and chemically characterised from dog antrum, and the unphosphorylated nonapeptide was characterised from ferret antrum. The primary amino acid sequences of the dog, ferret and pig nonapeptides were identical. In ferret the unphosphorylated nonapeptide predominated, and in dog the phosphorylated form predominated; in pig both forms of the nonapeptide were well represented. Intact progastrin was identified in gel filtration eluates of extracts of all 3 species, but occurred only in relatively low concentrations. The nonapeptides did not stimulate acid secretion in the conscious gastric fistula rat and they did not modify the acid response to G17. Phosphorylation of progastrin-derived peptides is evidently well conserved across a range of species even though there appear to be differences in the relative proportions of phosphorylated and unphosphorylated forms.
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Affiliation(s)
- H Desmond
- Department of Physiology, University of Liverpool, U.K
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Varro A, Desmond H, Pauwels S, Gregory H, Young J, Dockray GJ. The human gastrin precursor. Characterization of phosphorylated forms and fragments. Biochem J 1988; 256:951-7. [PMID: 3223964 PMCID: PMC1135508 DOI: 10.1042/bj2560951] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
There is a potential phosphorylation site in the C-terminal region of the precursor for the acid-stimulating hormone gastrin, which is immediately adjacent to an important cleavage point. In the present study we have sought to identify, separate, quantify and characterize phosphorylated and unphosphorylated forms of human progastrin and its fragments. Identification was made by two radioimmunoassays: (a) a novel assay employing an antibody raised to intact human progastrin; and (b) an assay using antibody reacting with the C-terminal tryptic fragment of human progastrin, as well as progastrin itself. Two forms of human progastrin isolated from a gastrinoma were separated by ion-exchange h.p.l.c., and had similar elution positions on reverse-phase h.p.l.c. and on gel filtration. The more acidic peptide contained close to equimolar amounts of phosphate. On trypsinization, peptides were released that co-eluted on ion-exchange h.p.l.c. with, and had the immunochemical properties of, naturally occurring C-terminal fragments of progastrin. One of the latter was isolated and shown by Edman degradation after derivatization with ethanethiol to have the sequence Ser (P)-Ala-Glu-Asp-Glu-Asn. Similar peptides occur in antral mucosa resected from ulcer patients. The unphosphorylated forms of progastrin predominated, whereas the phosphorylated forms of the C-terminal fragments were predominant. This distribution could be explained by preferential cleavage of phosphorylated progastrin. We conclude that in human progastrin, Ser-96 can occur in the phosphorylated form; this residue immediately follows a pair of basic residues (Arg-Arg) that are cleaved during synthesis of the biologically active product.
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Affiliation(s)
- A Varro
- Physiological Laboratory, University of Liverpool, U.K
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Dockray GJ, Varro A, Desmond H, Young J, Gregory H, Gregory RA. Post-translational processing of the porcine gastrin precursor by phosphorylation of the COOH-terminal fragment. J Biol Chem 1987; 262:8643-7. [PMID: 3597391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The gene sequence encoding porcine preprogastrin is known; in order to clarify pathways of post-translational processing of the predicted precursor peptide we have characterized material reacting with antibodies to a synthetic peptide corresponding to the expected extreme COOH-terminal portion of the precursor. Radioimmunoassay was used to identify and monitor the purification of peptides in porcine antral mucosa. Two peptides (I and II) were isolated to homogeneity by steps involving gel filtration, ion exchange, and reversed-phase high performance liquid chromatography. The two co-eluted on gel filtration but were separated on anion-exchange chromatography. The more acidic peptide (II) was less hydrophobic on high performance liquid chromatography. Automated gas-phase microsequencing revealed the less acidic peptide (I) to have the sequence of porcine preprogastrin 96-104 (SAEEGDQRP); it would be produced by tryptic-like cleavage of Arg95-Ser96. The second peptide did not yield a phenylthiohydantoin-derivative on the first cycle but thereafter it sequenced as the first peptide (i.e. -AEEGDQRP). Incubation in alkali liberated almost equimolar amounts of phosphate from peptide II but not from I. In addition, alkaline phosphatase liberated phosphate and converted the acidic peptide to the less acidic one. The results suggest that serine in the first position is phosphorylated in peptide II but not I. The tripeptide -Ser(P)-Ala-Glu- also occurs in adrenocorticotropic hormone; this tripeptide is a substrate for physiological casein kinase. Potential phosphorylation sites occur at comparable positions in the precursors of a number of regulatory peptides.
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Dockray GJ, Varro A, Desmond H, Young J, Gregory H, Gregory RA. Post-translational processing of the porcine gastrin precursor by phosphorylation of the COOH-terminal fragment. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47462-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Desmond H, Pauwels S, Varro A, Gregory H, Young J, Dockray GJ. Isolation and characterization of the intact gastrin precursor from a gastrinoma. FEBS Lett 1987; 210:185-8. [PMID: 3792562 DOI: 10.1016/0014-5793(87)81334-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Antibodies to the extreme C-terminal region of human progastrin have been used to monitor the isolation of high-Mr immunoreactive material in a gastrinoma extract. Microsequence analysis of the product revealed amino acid residues in the first 18 positions corresponding to those predicted from the cDNA sequence for preprogastrin starting at position 22; the sequence and immunochemical data together allow the identification of this material as intact progastrin. Implications for gastrin biosynthesis are discussed.
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Pauwels S, Desmond H, Dimaline R, Dockray GJ. Identification of progastrin in gastrinomas, antrum, and duodenum by a novel radioimmunoassay. J Clin Invest 1986; 77:376-81. [PMID: 3753710 PMCID: PMC423357 DOI: 10.1172/jci112315] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Recent studies on the gene sequence encoding the human pyloric antral hormone, gastrin, indicate a precursor of 101 residues. We have now raised antibodies to a synthetic analogue corresponding to (Tyr)-human progastrin COOH-terminal pentapeptide. The antibodies could be used in radioimmunoassay to measure this peptide, but they did not react with corresponding fragments of procholecystokinin, porcine progastrin, or other human progastrin-derived peptides, notably heptadecapeptide gastrin (G17), and 34-residue gastrin (G34). Radioimmunoassay of human antral and duodenal extracts revealed a major peak of activity that corresponded to the native COOH-terminal fragment of progastrin, and occurred in approximately equimolar amounts with COOH-terminal G17 immunoreactivity. In addition, there was a minor peak of apparently higher molecular weight material. In some gastrinomas the latter material was the predominant immunoreactive form, and it occurred in higher molar concentrations than any other form of gastrin. Digestion of this material with trypsin liberated peptides that reacted with antibodies specific for the NH2-terminus of G34, and G17. On this basis the high molecular weight component was identified as a form of gastrin that extended from the COOH-terminus of the precursor to a point at least beyond the NH2-terminus of G34, and probably included the entire progastrin sequence. The results suggest differences in posttranslational processing pathways of progastrin in antrum, duodenum, and gastrinomas. They also indicate that the present experimental approach allows the identification of progastrin-like substances, which should open the way to studying the mechanisms of gastrin biosynthesis.
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Williams RG, Jonsson AC, Desmond H, Pauwels S, Dockray GJ. Antibodies to the N-terminus of human Gastrin-34 react with material in rat and ferret brain. Neurochem Int 1986; 8:535-40. [PMID: 20493085 DOI: 10.1016/0197-0186(86)90188-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/1985] [Accepted: 10/28/1985] [Indexed: 11/18/2022]
Abstract
Antibodies specific for the N-terminus of human big gastrin, or NT G34, reveal in immunohistochemistry extensive systems of nerve cell bodies and fibres in the rat and ferret brain. However, when the same antibodies were used in radioimmunoassay of rat and ferret brain tissue extracts they failed to reveal immunoreactive material. At least one of the antibodies used for radioimmunoassay could be shown to react with NT G34 in rat pyloric antral extracts. Antibodies specific for other peptides derived from progastrin failed to reveal the systems demonstrated with the N-terminal G34 antibodies. It is concluded that expression of the gastrin gene is unlikely to account for the present observations. Instead we suggest that a novel peptide with low affinity for NT G34 specific antibodies is found in rat and ferret central neurones.
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Affiliation(s)
- R G Williams
- MRC Secretory Control Group, Department of Physiology, University of Liverpool, Brownlow Hill, Liverpool L69 3BX, U.K
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Dockray GJ, Desmond H, Gayton RJ, Jonsson AC, Raybould H, Sharkey KA, Varro A, Williams RG. Cholecystokinin and gastrin forms in the nervous system. Ann N Y Acad Sci 1985; 448:32-43. [PMID: 3861124 DOI: 10.1111/j.1749-6632.1985.tb29904.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cholecystokinin octapeptide is the predominant representative of the gastrin-CCK family in the central nervous system. Other forms occur in low concentrations, or restricted locations, as do the gastrins. The pathways of biosynthetic processing can now be studied in detail, following the elucidation of the cDNA sequence for the two peptides. In the vagus both CCK and gastrin can be found. Brain stem neurons receiving an input from gastric mechanoreceptors respond to CCK-8, but most do not respond to gastrin given intravenously or intra-arterially. This system, which may well be involved in mediating the peripheral satiety effect of CCK, is therefore able to distinguish between the two peptides.
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Desmond H, Dockray GJ, Spurdens M. Identification by specific radioimmunoassay of two novel peptides derived from the C-terminus of porcine preprogastrin. Regul Pept 1985; 11:133-42. [PMID: 4035006 DOI: 10.1016/0167-0115(85)90073-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A radioimmunoassay has been developed using antibodies to a synthetic analogue of the C-terminal hexapeptide sequence of the porcine gastrin precursor. Boiling water extracts of porcine antral mucosa contained immunoreactive material that diluted in parallel with standard peptide. Concentrations of immunoreactivity were 5.5 +/- 0.8 nmol X g-1 (mean +/- S.E.M.) in antral mucosa and were closely similar to those of C-terminal heptadecapeptide gastrin immunoreactivity (5.0 +/- 0.6 nmol X g-1). Approximately 30-fold lower concentrations were found in porcine duodenum. A similar distribution was found in ferret, but human, rat and chicken antrum did not contain significant quantities of immunoreactivity. Gel filtration of porcine antral extracts on Sephadex G-50 revealed a single peak of immunoreactivity eluting in a similar position to G17, but on anion-exchange chromatography two peaks of immunoreactive material were separated. These also differed in their retention time on reverse phase HPLC. Both peptides are probably derived by tryptic cleavage at the C-terminus of porcine preprogastrin. No evidence was found to suggest that there are significant quantities of unprocessed preprogastrin in hog antral mucosa. The precise chemical difference between the two immunoreactive peptides identified here remains to be established; together, however, they provide specific markers for progastrin synthesis.
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