Papers by Jean-C,aude Galleyrand
Biochemistry Usa, 1989
Synthesis, conformation, and biological properties of the Ala'O analogue of des-Trp',Nle12minigas... more Synthesis, conformation, and biological properties of the Ala'O analogue of des-Trp',Nle12minigastrin are reported. Replacement of the Gly residue in the original sequence with Ala remarkably changes the conformational preference of the hormone in trifluoroethanol. C D and N M R results indicate that the conformational change is mainly located in the C-terminal portion of the molecule, with probable extension of the N-terminal a-helix throughout the entire sequence. The structural modification causes a 10-fold decrease in the biological potency of the hormone, which is about as active as the C-terminal tetrapeptide amide. These findings support our previous hypothesis that the optimal bioactive conformation of the native hormone is U-shaped, with mutual interactions among the two end segments. previous investigations on the synthetic analogues of human gastrin, des-Trp1,NleI2-minigastrin 2 3-7 8 9 10 11 13 1 3 14 H-Leu-[Glula-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH~ and Nle15-little gastrin 1 2 3 4
The American journal of physiology
... by anion exchange chromatography on Dowex AG-1X8 (formate form) and was quantified using the ... more ... by anion exchange chromatography on Dowex AG-1X8 (formate form) and was quantified using the method of Berridge and Irvine (2). Separation ... A recent report from Lotti and Chang (16) showed that L365,260 and L364,718 could inhibit gastrin-induced acid secretion in vivo ...
Brazilian Journal of Medical and Biological Research
The synthesis of analogs of the C-terminal tridecapeptide of gastrin is described. These pseudope... more The synthesis of analogs of the C-terminal tridecapeptide of gastrin is described. These pseudopeptide analogs were obtained either by replacing the C-terminal phenylalanine amide with 2-phenylethylalcohol or with 2-phenylethylamine, or by replacing the peptide bond between Trp and Leu, or between Leu and Asp with an aminomethylene (CH2NH). The ability of these compounds to stimulate gastric acid secretion in anesthetized rats and to inhibit binding of labeled CCK-8 to isolated cells from rabbit fundic mucosa was tested. [desPhe13, Leu11]-HG-12-I-beta-phenylethylester 33, [desPhe13, Leu11]-HG-12-II-beta-phenylethylester 38, [desPhe13, Leu11]-HG-12-I-beta-phenylethylamide 32, and [desPhe13, Leu11]-HG-12-II-beta-phenylethylamide 37 acted as gastrin receptor antagonists, while [Trp10-psi(CH2NH)-Leu11]-HG-13-I 31 and [Trp10-psi(CH2NH)-Leu11]-HG-13-II 36 acted as agonists. Unexpectedly, [Leu11-psi(CH2NH)-Asp12]-HG-13-I 30 and [Leu11-psi (CH2NH)-Asp12]-HG-13-II 35 were almost devoid of affinity for the gastrin receptor.
British Journal of Pharmacology, 2009
The growth hormone secretagogue receptor 1a (GHSR-1a) is a G-protein coupled receptor, involved i... more The growth hormone secretagogue receptor 1a (GHSR-1a) is a G-protein coupled receptor, involved in the biological actions of ghrelin by triggering inositol phosphates and calcium intracellular second messengers. It has also been reported that ghrelin could activate the 44-and 42-kDa extracellular signal-regulated protein kinases (ERK1/2) in different cell lines, but it is not clear whether this regulation is GHSR-1a dependent or not. 2 To provide direct evidence for the coupling of GHSR-1a to ERK1/2 activation, this pathway has been studied in a heterologous expression system. 3 Thus, in Chinese hamster ovary (CHO) cells we showed that ghrelin induced, via the human GHSR-1a, a transient and dose-dependent activation of ERK1/2 leading to activation of the transcriptional factor Elk1. 4 We then investigated the precise mechanisms involved in GHSR-1a-mediated ERK1/2 activation using various specific inhibitors and dominant-negative mutants and found that internalization of GHSR-1a was not necessary. Our results also indicate that phospholipase C (PLC) was involved in GHSR-1a-mediated ERK1/2 activation, however, pathways like tyrosine kinases, including Src, and phosphoinositide 3-kinases were not found to be involved. GHSR-1a-mediated ERK1/2 activation was abolished both by a general protein kinase C (PKC) inhibitor, Go¨6983, and by PKC depletion using overnight pretreatment with phorbol ester. Moreover, the calcium chelator, BAPTA-AM, and the inhibitor of conventional PKCs, Go¨6976, had no effect on the GHSR-1a-mediated ERK1/2 activation, suggesting the involvement of novel PKC isoforms (e, d), but not conventional or atypical PKCs. Further analyses suggest that PKCe is required for the activation of ERK1/2. 5 Taken together, these data suggest that ghrelin, through GHSR-1a, activates the Elk1 transcriptional factor and ERK1/2 by a PLC-and PKCe-dependent pathway.
Biochemistry, 1989
Synthesis, conformation, and biological properties of the Ala'O analogue of des-Trp',Nle12minigas... more Synthesis, conformation, and biological properties of the Ala'O analogue of des-Trp',Nle12minigastrin are reported. Replacement of the Gly residue in the original sequence with Ala remarkably changes the conformational preference of the hormone in trifluoroethanol. C D and N M R results indicate that the conformational change is mainly located in the C-terminal portion of the molecule, with probable extension of the N-terminal a-helix throughout the entire sequence. The structural modification causes a 10-fold decrease in the biological potency of the hormone, which is about as active as the C-terminal tetrapeptide amide. These findings support our previous hypothesis that the optimal bioactive conformation of the native hormone is U-shaped, with mutual interactions among the two end segments. previous investigations on the synthetic analogues of human gastrin, des-Trp1,NleI2-minigastrin 2 3-7 8 9 10 11 13 1 3 14 H-Leu-[Glula-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH~ and Nle15-little gastrin 1 2 3 4
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1989
The differentiation between gastrin (HG) and cholecystokinin {CCK) receptors in gastric mucosa wa... more The differentiation between gastrin (HG) and cholecystokinin {CCK) receptors in gastric mucosa was examined on isolated parietal (F3) and non-parietal (FI) ceils from rabbit fundic mucosa separated by elutriation. Direct binding assays on enriched ceil populations were performed using Izs|-iabeied HG-|7, g2sl-labeied CCK-8 and IzS|dabe|ed CCK-39 as probes. (1) On FI ceils, the dissociation constants (/(a) for the two labeled CCKs were nearly the same (62 pM for CCK-8 and 74 plM for CCK-39) but the binding capacity for CCK-8 ~as 2-times higher than for CCK-39. HG-17 also bound to this cell population, but its K d value was about 2-times higher (110 pM) than that of CCK. The presence of two distinct classes of sites on F1 cells can be suggested from competition studies: one more specific for CCK, which bound CCK-8 and CCK-39 with the same affinity, and another class more specific for gastrin, which bound CCK-$ and HG~I7 with the same affinity and CCK-39 with a low affinity. (2) On F3 ceils, CCK-8 and HG-17 bound with similar affinities (K d values 81 pNl for CCK-8 and 87 pM for HG-17), but CCK-39 did not specifically bind to this cell population. The presence of a binding site more specific for HG than for CCK on F3 cells was confirmed by competition studies in which CCK-33 competed for binding with iabe|ed HG-17 and labeled CCK-B with a 50-times lower affinity than the other peptides.
British Journal of Pharmacology, 2016
BACKGROUND AND PURPOSE Using an in-house bioinformatics programme, we identified and synthesized ... more BACKGROUND AND PURPOSE Using an in-house bioinformatics programme, we identified and synthesized a novel nonapeptide, H-Pro-Pro-Thr-Thr-Thr-Lys-Phe-Ala-Ala-OH. Here, we have studied its biological activity, in vitro and in vivo, and have identified its target in the brain. EXPERIMENTAL APPROACH The affinity of the peptide was characterized using purified whole brain and striatal membranes from guinea pigs and rats. Its effect on behaviour in rats following intra-striatal injection of the peptide was investigated. A photoaffinity UV cross-linking approach combined with subsequent affinity purification of the ligand covalently bound to its receptor allowed identification of its target. KEY RESULTS The peptide bound with high affinity to a single class of binding sites, specifically localized in the striatum and substantia nigra of brains from guinea pigs and rats. When injected within the striatum of rats, the peptide stimulated in vitro and in vivo dopamine release and induced dopamine-like motor effects. We purified the target of the peptide, a~151 kDa protein that was identified by MS/MS as angiotensin converting enzyme (ACE I). Therefore, we decided to name the peptide acein. CONCLUSION AND IMPLICATIONS The synthetic nonapeptide acein interacted with high affinity with brain membrane-bound ACE. This interaction occurs at a different site from the active site involved in the well-known peptidase activity, without modifying the peptidase activity. Acein, in vitro and in vivo, significantly increased stimulated release of dopamine from the brain. These results suggest a more important role for brain ACE than initially suspected.
... Cooperation Between GHS-Rla and GHS-Rlb : Action on MAPKinase Pathway. Valérie Scheuermann 1 ... more ... Cooperation Between GHS-Rla and GHS-Rlb : Action on MAPKinase Pathway. Valérie Scheuermann 1 , Joanne Ryan 1 , Aline Moulin 1 , Luc Demange 1 , Didier Gagne 1 , Jean-Claude Galleyrand 1 , Jean-Alain Fehrentz 1 , Daniel Perissoud 2 , Jean Martinez 1. (14/06/2007). ...
Comptes rendus des séances de la Société de biologie et de ses filiales
The diterpene, forskolin, direct activator of the catalytic subunit of the adenylate cyclase from... more The diterpene, forskolin, direct activator of the catalytic subunit of the adenylate cyclase from various tissues, also stimulates gastric acid secretion: in vitro, with an isolated parietal cell preparation, forskolin dose-dependently stimulated acid secretion (EC50: 1 microM) (measured by accumulation in the acidic spaces of the weak base [14C]-aminopyrine) and the maximal acid secretory value at 0.1 mM was 4 times higher than that obtained with histamine. Forskolin dramatically increased the production of intracellular cyclic-AMP at a level 4 times higher than that obtained with histamine at the same concentration. In vivo, gastric acid secretion of the rat is dose-dependently increased. The doses required to get a significant response (100 nmol/kg) were 1,000 times higher than those required for gastrin and 100 times lower than those for histamine, but the same maximal value was obtained. Cimetidine did not significantly modified this response. These results demonstrate that, both in vitro and in vivo, forskolin is a potent stimulant for gastric acid secretion.
Molecular pharmacology, 1997
The aim of this study was to analyze the role of cholecystokinin (CCK(B)) receptor in human lymph... more The aim of this study was to analyze the role of cholecystokinin (CCK(B)) receptor in human lymphoblastic Jurkat T cells. We investigated the trophic effect resulting from activation of such a receptor by using the reporter gene strategy. For this purpose, we transiently transfected Jurkat T cells with the reporter plasmid p[(TRE)3-tk-Luc] and found that CCK-8 was able to dose-dependently induce luciferase expression related to activator protein-1 (AP-1) activation with a maximal response identical to that obtained with compounds known to activate AP-1 complex (quantitatively, the same level of induction was obtained with 1 nM 12-O-tetradecanoylphorbol-13-acetate, 100 microM diacylglycerol, or 4 nM epidermal growth factor). The involvement of the CCK(B) receptor in such a stimulation was demonstrated by the inhibiting effect of the selective CCK(B) receptor antagonist PD-135,158. This effect was confirmed in COS-7 cells transfected with the cDNA of CCK(B) receptor cloned from Jurkat...
Molecular pharmacology, 2000
It has previously been reported that the cholecystokinin analog JMV-180 behaves differently on th... more It has previously been reported that the cholecystokinin analog JMV-180 behaves differently on the rat and the mouse cholecystokinin-A receptor (CCK-AR). In mice this analog acts as an agonist on low- and high-affinity sites of the CCK-AR, whereas in rats this compound acts as an agonist on high-affinity sites and as an antagonist on low-affinity sites. In an attempt to understand why the same compound behaves differently on these two CCK-A receptors, we cloned the cDNA encoding the mouse CCK-AR. We then investigated a cellular model able to mimic the effect that was observed in rats and mice. HeLa cells were transiently cotransfected with plasmids leading to expression of the rat or mouse CCK-AR in the presence of pFos-Luc as reporter plasmid; such a plasmid placed the regulatory part of the human c-Fos gene upstream from the firefly luciferase structural gene (Luc). We then observed that the two CCK-A receptors behaved differently, not only in the presence of compound JMV-180 but ...
International journal of peptide and protein research, 1994
In the course of our study concerning gastrin and cholecystokinin (CCK) receptors, we have synthe... more In the course of our study concerning gastrin and cholecystokinin (CCK) receptors, we have synthesized and characterized a new labeled gastrin ligand, 125I-BH-[Leu15]-gastrin-(5-17) [(3-[125I]iodo-4-hydroxyphenyl)-propionyl-[Leu15]-gastrin-(5-17)]. Binding of 125I-BH-[Leu15]-gastrin-(5-17) to isolated canine fundic mucosal cells was specific, saturable and of high affinity. 125I-BH-[Leu15]-gastrin- (5-17) and 125I-BH-CCK-8[(3-[125I]iodo-4-hydroxyphenyl)-propionyl-CCK-8] interact with isolated canine fundic mucosal cells with small differences in maximal binding capacities and affinities, 3800 +/- 900 binding sites/cell (Kd = 0.52 +/- 0.23 nM) and 6200 +/- 1100 binding sites/cell (Kd = 0.31 +/- 0.18 nM), respectively. The relative order of potencies for gastrin and CCK analogs in displacing 125I-BH-[Leu15]-gastrin-(5-17) binding correlated well with those obtained using 125I-BH-CCK-8. Selective CCK/gastrin antagonists L-364,718 (MK-329) and L-365,260 also inhibited 125I-BH-[Leu15]-ga...
Peptides for the New Millennium
Peptides, 1992
Binding to gastrin receptors and gastric acid secretion experiments were performed with gastrin d... more Binding to gastrin receptors and gastric acid secretion experiments were performed with gastrin derivatives modified at the C-terminal tetrapeptide amide from HG-13 sequence. 1. When the ultimate phenylalanine amide was replaced by a phenethylester or a phenetylamide moiety, the resulting compound bound to gastrin receptors (Kd approximately 10 nM) and exhibited antagonist activity on gastrin-induced acid secretion in the anesthetized rat. 2. Changing the peptide bond between Trp and Leu residues to a -omega(CH2-NH)- bond resulted in a compound which also bound to gastrin receptors (Kd approximately 10 nM) but presented agonist activity on acid secretion in the rat. In contrast, when the peptide bond between Leu and Asp residues was replaced by a -omega(CH2-NH)- bond, the resulting compound was devoid of any affinity for gastrin receptor (Kd greater than 10(-6) M) and of any biological activity. 3. The HG-13 derivatives were synthesized in sulfated and unsulfated forms: O-sulfation of the HG-13 tyrosine residue did not change its intrinsic in vivo activity but enhanced its affinity for gastrin receptors (Kd approximately 0.3 nM). On the contrary, O-sulfation of the various chemically modified HG-13 had no significant effect in either in vitro or in vivo experiments. 4. Finally, no significant difference between binding on parietal (F3) and nonparietal (F1) cells was observed, in agreement with the presence of a gastrin-type receptor in these two cell populations.
Neuropeptides, 1996
We have investigated the potential role of gastrin in the regulation of cell growth in human astr... more We have investigated the potential role of gastrin in the regulation of cell growth in human astrocytic tumors. To this end we have used synthetic analogs of gastrin and cholecystokinin (CCK) which behave as gastrin and/or CCK antagonists, e.g. compounds JMV-97, JMV-209 and JMV-179. Their effects on astrocytic tumor cell proliferation was investigated by the use of the colorimetric MTT assay. The in vitro biological models used in the present study included the SW1088, U87 and U373 astrocytic tumor cell lines. The results demonstrated marked influence of gastrin and CCK antagonists in the regulation of astrocytic tumor growth. This suggests that gastrin and/or CCK antagonists might be tested in experimental glioblastoma.
Journal of Pharmacology and Experimental Therapeutics, 2002
It is well known that the amidated C-terminal part of gastrin is crucial for its interaction with... more It is well known that the amidated C-terminal part of gastrin is crucial for its interaction with the classical seven transmembrane domain receptors CCK-1 or CCK-2. Nevertheless, over the past 10 years, several groups have characterized new binding sites using peptides related to gastrin (particularly glycineextended forms of gastrin) on various tumoral and nontumoral cell lines. In the present study, we focused on the human astrocytic tumoral cell line U373. Although it has been described that gastrin was able to inhibit the motility of these cells, we were unable to detect any classical CCK/gastrin receptor.
Journal of Peptide Science, 2010
Human ACE is a central component of the renin-angiotensin system and a major therapeutic target f... more Human ACE is a central component of the renin-angiotensin system and a major therapeutic target for cardiovascular diseases. The somatic form of the enzyme (sACE) comprises two homologous metallopeptidase domains (N and C), each bearing a zinc active site with similar but distinct substrate and inhibitor specificities. In this study, we present the biological activity of silacaptopril, a silylated analogue of captopril, and its binding affinity towards ACE. Based on the recently determined crystal structures of both the ACE domains, a series of docking calculations were carried out in order to study the structural characteristics and the binding properties of silacaptopril and its analogues with ACE.
Journal of Molecular Biology, 2010
Three homology models of the human ghrelin receptor (GHS-R1a) have been generated from the availa... more Three homology models of the human ghrelin receptor (GHS-R1a) have been generated from the available X-ray structures of rhodopsin (RHO model), opsin (OPS model) and beta-2 adrenergic receptor (B2 model). The latter was used as a starting point for combined molecular dynamics simulation (MDS) and full atom normal modes analysis (NMA). A lowfrequency normal mode (mode 16) perfectly reproduced the intracellular motions observed between B2 and RHO models; in the opposite direction along the same mode, the generated structures are closer to the OPS model, suggesting a direct link with GHS-R1a activation. This was in agreement with motions of the seven transmembranous segments, increase of the solvent accessibility of the 140-ERY-142 sequence, and flip of the Trp276 (CWLP) residue, some features related to GPCRs activation. According to our model, His280 was proposed to stabilize Trp276 in the active state; this was verified by site-directed mutagenesis and biochemical characterization of the resulting H280A and H280S mutants, which were fully functional but sharing an important decrease of their basal activities. Docking performed with short ghrelin derivatives Gly-Ser-Ser [octa]-Phe-NH 2 and Gly-Ser-Ser [octa]-Phe-Leu-NH 2 allowed the identification of a robust position of these peptides in the active site of the receptor. This model was refined by MDS and validated by docking experiments performed on a set of 55 ghrelin receptor ligands based on the 1,2,4-triazole scaffold. Finally, NMA performed on the obtained peptide-receptor complex suggested stabilization of the Trp276 residue and of the whole receptor in the active state, preventing the motion observed along mode 16 computed for the unbound receptor. Our results show that NMA offers a powerful approach to study the conformational diversity and the activation mechanism of GPCRs.
Uploads
Papers by Jean-C,aude Galleyrand