References of "Pirotte, Bernard"
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See detailFrom Metabolomics Study of Age-Related Macular Degeneration (AMD) to the Development of New Pyruvate Dehydrogenase Kinase Inhibitors (PDK)
Arslan, Deniz ULg; Schoumacher, Matthieu ULg; Pirotte, Bernard ULg et al

Poster (2016, May)

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly population of industrialized countries. This blindness results from the deterioration of the macula, a small part of ... [more ▼]

Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly population of industrialized countries. This blindness results from the deterioration of the macula, a small part of the retina specialized for the high-acuity vision. Exudative AMD, called “wet”, is characterized by the formation of new blood vessels growing under the retina according to a process named choroidal neovascularization (CNV). Currently, the aetiology and pathogenesis of AMD remain unclear. Nevertheless, a recent metabolomics study performed on the serum of “wet” AMD patients and on a CNV murine model, that mimics the effect of “wet” AMD, have demonstrated that lactate level is clearly involved in the severity of the pathology as well as the relationship between lactate, CNV and AMD. According to this result, we suggest a new therapeutic approach of AMD based on the normalization of blood lactate level. The modulation of the lactate plasma concentration by treatment of the animals with synthetic compounds and more specifically Pyruvate Dehydrogenase Kinase (PDK) inhibitors significantly decrease the CNV. PDK and its four isoforms (PDK1-4) regulate the activity of the pyruvate dehydrogenase complex (PDH), a mitochondrial enzyme that plays a major role in the metabolic pathway of glucose, by reversible phosphorylation. Starting from these results, development of new PDK inhibitors could open the way to innovative treatment opportunities in AMD disease. Different analogues of (R)-3,3,3-trifluoro-2-hydroxy-2-methylpropanamide (fig.1) have been already synthetized and pharmacological evaluation is currently in progress. According to the results obtained, various pharmacomodulations will be investigated [less ▲]

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See detailFrom Metabolomics to Identification of a new therapeutic approach for Age-Related Macular Degeneration (AMD)
Schoumacher, Matthieu ULg; De Tullio, Pascal ULg; LAMBERT, Vincent ULg et al

Poster (2016, May)

Age-related macular degeneration (AMD) is the leading cause of vision loss in the western world among people aged 50 or older. 90% of all vision loss due to AMD result from the exudative form, which is ... [more ▼]

Age-related macular degeneration (AMD) is the leading cause of vision loss in the western world among people aged 50 or older. 90% of all vision loss due to AMD result from the exudative form, which is characterized by choroidal neovascularization (CNV). Age-related changes that induce pathologic CNV are incompletely understood and critical issues remain to be addressed. Metabolomics is defined as the comprehensive study of endogenous metabolites changes in various biological systems. This newly emerging “omic” science provides a unique opportunity to correlate variation of the metabolome with pathological occurrence or progression and/or to identify metabolites that are implicated in the disease. We apply a 1H NMR metabolomics approach on sera collected from AMD patient and healthy volunteers and form a mice model of laser-induced CNV which mimics the effect of exudative AMD. After post-processing treatments, the different spectra were analyzed by statistical discriminant methodologies (PCA, ICA, PLS-DA, O-PLS-DA). These approaches allow the differentiation between control and AMD patients and between laser-induced mice and the control mice group. Moreover, the same discriminating spectral zones have been identified in human and mice model, leading to the emergence of different putative biomarkers. Among these markers, lactate emerges as a key metabolite in both settings. Mechanistically, lactate produced locally and by inflammatory cells, plays a critical role in the onset of the inflammatory and angiogenic phases. In mice model of laser-induced CNV, normalization of circulating lactate by dichloroacetate a pyruvate dehydrogenase kinase (PDK) inhibitor, decreases CNV development. Our data support the innovative concept of lactate as a parainflammation- and angio-metabolite associated to AMD and CNV progression. Moreover, control of blood lactate level via inhibition of PDK provides new options for the treatment of exudative AMD. This study demonstrates the ability of metabolomics for drug target discovery and opens new perspectives for AMD treatment and patient follow-up. [less ▲]

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See detailEffect of Ribes nigrum leaf extracts on endothelium-dependent vasorelaxation
Tabart, Jessica; Shini-Kerth, Valérie; PINCEMAIL, Joël ULg et al

Poster (2016, April 22)

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See detailTargeted and random mutagenesis of orphan GPCRs of the SREB family
Laschet, Céline ULg; Dupuis, Nadine ULg; Derj, Anouar ULg et al

Poster (2016, January 25)

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See detailInsight into SUCNR1 (GPR91) structure and function
Gilissen, Julie ULg; Jouret, François ULg; Pirotte, Bernard ULg et al

in Pharmacology & Therapeutics (2016)

SUCNR1 (or GPR91) belongs to the family of G protein-coupled receptors (GPCR), which represents the largest group of membrane proteins in human genome. The majority of marketed drugs targets GPCRs ... [more ▼]

SUCNR1 (or GPR91) belongs to the family of G protein-coupled receptors (GPCR), which represents the largest group of membrane proteins in human genome. The majority of marketed drugs targets GPCRs, directly or indirectly. SUCNR1 has been classified as an orphan receptor until a landmark study paired it with succinate, a citric acid cycle intermediate. According to the current paradigm, succinate triggers SUCNR1 signaling pathways to indicate local stress that may affect cellular metabolism. SUCNR1 implication has been well documented in renin-induced hypertension, ischemia/reperfusion injury, inflammation and immune response, platelet aggregation and retinal angiogenesis. In addition, the SUCNR1-induced increase of blood pressure may contribute to diabetic nephropathy or cardiac hypertrophy. The understanding of SUCNR1 activation, signaling pathways and functions remains largely elusive, which calls for deeper investigations. SUCNR1 shows a high potential as an innovative drug target and is probably an important regulator of basic physiology. In order to achieve the full characterization of this receptor,more specific pharmacological tools such as small-molecules modulators will represent an important asset. In this review, we describe the structural features of SUCNR1, its current ligands and putative binding pocket. We give an exhaustive overview of the known and hypothetical signaling partners of the receptor in different in vitro and in vivo systems. The link between SUCNR1 intracellular pathways and its pathophysiological roles are also extensively discussed. [less ▲]

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See detailFROM METABOLOMICS STUDY OF AGE RELATED MACULAR DEGENERATION (AMD) TO THE DEVELOPMENT OF NEW PDK INHIBITORS
Arslan, Deniz ULg; Schoumacher, Matthieu ULg; Pirotte, Bernard ULg et al

in Arslan, Deniz (Ed.) Gazi Pharma Symposium Abstract Book (2015, November 12)

Metabolomics is one of the most recent technologies in the Omics sciences defined as “the comprehensive characterization of small molecules (called metabolites) in different biological samples.” This ... [more ▼]

Metabolomics is one of the most recent technologies in the Omics sciences defined as “the comprehensive characterization of small molecules (called metabolites) in different biological samples.” This methodology can be applied in many areas, such as biomarker discovery, clinical studies, drug efficacy and toxicity evaluation, diagnostic tools, quality control or drug discovery. Its capability to extract biochemical information associated with a cellular or biological system makes this technique a powerful tool for Medicinal Chemistry. In this work, we present a 1H NMR metabolomics study applied to therapeutic target discovery. Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly population of industrialized countries. This blindness results from the deterioration of the macula, a small part of the retina specialized for the high-acuity vision. Exudative AMD, called “wet”, is characterized by the formation of new blood vessels growing under the retina according to a process named choroidal neovascularization (CNV). Currently, the aetiology and pathogenesis of AMD remain unclear. Nevertheless, a recent metabolomics study performed on the serum of “wet” AMD patients and on a CNV murine model, that mimics the effect of “wet” AMD, have demonstrated that lactate level is clearly involved in the severity of the pathology as well as the relationship between lactate, CNV and AMD. According to this result, we suggest a new therapeutic approach of AMD based on the normalization of blood lactate level. The modulation of the lactate plasma concentration by treatment of the animals with synthetic compounds and more specifically Pyruvate Dehydrogenase Kinase (PDK) inhibitors significantly decrease the CNV. Starting from these results, development of new PDK inhibitors could open the way to innovative treatment opportunities in AMD disease. [less ▲]

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See detailDesign and synthesis of PET-probes targeting AMPA-subtype receptors
Deverdenne, François ULg; Claes, Giselle ULg; Goffin, Eric ULg et al

Poster (2015, June 05)

The AMPA subtype of glutamatergic receptors is the main actor in the excitatory neurotransmission in the mammalian central nervous system. These receptors are involved in the expression and the ... [more ▼]

The AMPA subtype of glutamatergic receptors is the main actor in the excitatory neurotransmission in the mammalian central nervous system. These receptors are involved in the expression and the maintenance of the long-term potentiation, a phenomenon closely linked to cognitive and memorization processes. Based on experimental data collected in recent years, the use of AMPA potentiators seems to be an interesting approach in the treatment of cognitive deficits (e.g. Alzheimer disease), schizophrenia or depression. Such AMPA signal potentiation could be mediated by positive allosteric modulators (PAMs) of the AMPA receptors, a class of compounds able to produce a fine signal tuning in the presence of the endogenous ligand in the synapse, providing less toxicity than direct agonists. With this approach, the laboratory of Medicinal Chemistry of Liège university developed many series of AMPA potentiators , among which 1,2,4-benzothiadiazine 1,1-dioxides (BTDs). In order to better understand the in vivo mapping of AMPA receptors and its evolution in neurological diseases, the present work aims at developing the design and the synthesis of BTDs positive allosteric modulators radiolabeled with a fluorine-18 atom. Based on previously synthesized series in this field, we investigate the synthesis of a new class of high-affinity AMPA potentiators characterized by the presence of a fluorine atom at selected positions on the structure of the AMPA potentiators. Thanks to in vitro pharmacological evaluations, we will further determine the best candidates for their fluorine-18 radiolabeling. [less ▲]

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See detailDesign, synthesis and pharmacological evaluation of dimeric ligands for the benzothiadiazine dioxide allosteric binding site of the AMPA receptors
Drapier, Thomas ULg; Francotte, Pierre ULg; Pirotte, Bernard ULg et al

Conference (2015, June 04)

L-glutamic acid is the major excitatory neurotransmitter in the brain. It exerts its effects through metabotropic and ionotropic receptors. Among the latter, three subtypes have been identified: NMDA ... [more ▼]

L-glutamic acid is the major excitatory neurotransmitter in the brain. It exerts its effects through metabotropic and ionotropic receptors. Among the latter, three subtypes have been identified: NMDA, AMPA and KA receptors. It is now well established that a deficit in glutamatergic signaling may be responsible for neurological disorders such as schizophrenia, depression, mild cognitive impairment and ADHD. Enhancement of the signal through positive allosteric modulators of AMPA receptors might be a therapeutic issue for these diseases. These compounds are expected to exert a fine tuning of the signal. Since they require the presence of the endogenous ligand to be active, they are expected to induce less toxicity than agonists. In this context, based on the structure of known allosteric modulators of AMPA receptors such as cyclothiazide (1) and IDRA 21 (2), the Laboratory of Medicinal Chemistry (University of Liège) has developed a series of 1,2,4-benzothiadiazine 1,1-dioxides with high potency as AMPA receptor potentiators, among which compounds (3) and (4). Crystallographic data obtained by the Department of Medicinal Chemistry (University of Copenhagen) highlighted that (3) and (4) bind to two contiguous sites at the dimer interface of the ligand binding domain of the AMPA receptor1,2. From these data, we may expect that the synthesis of dimeric molecules could lead to further improvement in affinity and activity. Our work consists in the development of a family of dimeric benzothiadiazine dioxides and their evaluation in a pharmacological assay. Several structural parameters such as the position of the bridge on the aromatic ring between the two heterocycles as well as its nature and length will be studied in order to determine their impact on the activity and thus the affinity. [less ▲]

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See detailDesign and synthesis of PET-probes targeting AMPA subtype receptors
Deverdenne, François ULg; Claes, Giselle ULg; Goffin, Eric ULg et al

Poster (2015, May 13)

The AMPA subtype of glutamatergic receptors is the main actor in the fast excitatory neurotransmission in the mammalian central nervous system. These receptors are involved in the expression and the ... [more ▼]

The AMPA subtype of glutamatergic receptors is the main actor in the fast excitatory neurotransmission in the mammalian central nervous system. These receptors are involved in the expression and the maintenance of the long-term potentiation, a phenomenon closely linked to cognitive and memorization processes. Based on experimental data, it also appears that glutamatergic systems are involved in several pathological diseases. For instance, a lack of glutamatergic neurotransmission is observed in cognitive disorders or schizophrenia and an excessive activity is observed in Parkinson or Huntington diseases. The in vivo study of glutamate receptors mapping and its evolution appears to be an essential step for a better understanding of its implications. However, according to the literature, design of such a probe remains difficult due to the lack of specificity of the probes. Taking into account the potential in vitro and in vivo activity and specificity of benzothiadizine dioxides (BTDs) acting as AMPA positive allosteric modulators, we are investing the development of new compounds of this class radiolabeled with a fluorine-18 atom. Hence, we are currently developing new series of BTDs characterized by the presence of a fluorine atom and a 7-phenoxy-substituent that are expected to be more active and more specific. Finally, pharmacological tests to evaluate the best candidates for the radiochemical synthesis and in vivo evaluations are currently in progress. [less ▲]

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See detailßarrestin coupling of the orphan GPCR GPR27
Dupuis, Nadine ULg; Gilissen, Julie ULg; Derj, Anouar ULg et al

Poster (2015, January 27)

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See detailIdentification, Design and Evaluation of Pharmacological tools for the orphan GPCR GPR22
Geubelle, Pierre ULg; Gilissen, Julie ULg; Dupuis, Nadine ULg et al

Poster (2015, January 27)

GPCRs are the largest family of membrane receptors and are characterized by 7 transmembrane domains. GPR22 is a GPCR that has no known endogenous ligand and is thus considered "orphan". Its presence ... [more ▼]

GPCRs are the largest family of membrane receptors and are characterized by 7 transmembrane domains. GPR22 is a GPCR that has no known endogenous ligand and is thus considered "orphan". Its presence situated at the heart and brain levels makes it a potential target for new therapeutic pathways. This study consist in the identification of a synthetic ligand of GPR22 receptor to use it as a pharmacological tool in the study of the signaling channels of GPR22 in order to understand its role and to validate it as a new therapeutic target. The initial hypothesis was that GPR22 is coupled to the Gαi protein. [less ▲]

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See detailForskolin-free cAMP assay for Gi-coupled receptors
Gilissen, Julie ULg; Geubelle, Pierre ULg; Dupuis, Nadine ULg et al

in Biochemical Pharmacology (2015)

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See detailSemisynthesis and in Vitro Photodynamic Activity Evaluations of Halogenated and Glycosylated Derivatives of Pheophorbide a
Cieckiewicz, Ewa ULg; Mathieu, Véronique; Angenot, Luc ULg et al

in European Journal of Organic Chemistry (2015), 2015(27), 6061--6074

The present work focuses on the semisynthesis of halogenated and glycosylated derivatives of pheophorbide a (Pha). Because of the low reaction yields enocuntered en route to halogenated derivatives, we ... [more ▼]

The present work focuses on the semisynthesis of halogenated and glycosylated derivatives of pheophorbide a (Pha). Because of the low reaction yields enocuntered en route to halogenated derivatives, we then focused only on the semisynthesis of glycosylated derivatives of Pha with the aim at enhancing the Pha specificity for cancer cells by introducing β-galactose moieties expected to bind gal-1. We applied LC-SPE-NMR/MS, to facilitate the direct identification of glycosylated derivatives. The transposition of these analytical methods to a preparative scale facilitated the isolation of glycosylated compounds in quantities sufficient to evaluate in vitro photodynamic efficacies. The in vitro growth inhibitory activity of semisynthesized compounds was then evaluated using the MTT colorimetric assay in the presence and absence of light. However, this pharmacological evaluation method seems to be unable to efficiently yield information about carbohydrate effects in relation to possible compound specificities for gal-1 overexpressed by B16F10 cancer cells. [less ▲]

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See detailToward the First Class of Suicide Inhibitors of Kallikreins Involved in Skin Diseases
Tan, Xiao; Soualmia, Feryel; Furio, Laetitia et al

in Journal of Medicinal Chemistry (2015), 58

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See detailThermodynamic Characterization of New Positive Allosteric Modulators Binding to the Glutamate Receptor A2 Ligand-Binding Domain: Combining Experimental and Computational Methods Unravels Differences in Driving Forces
Nørholm, Ann-Beth; Francotte, Pierre ULg; Goffin, Eric ULg et al

in Journal of Chemical Information & Modeling (2014), 54(12), 3404-3416

Positive allosteric modulation of the ionotropic glutamate receptor GluA2 presents a potential treatment of cognitive disorders, for example, Alzheimer’s disease. In the present study, we describe the ... [more ▼]

Positive allosteric modulation of the ionotropic glutamate receptor GluA2 presents a potential treatment of cognitive disorders, for example, Alzheimer’s disease. In the present study, we describe the synthesis, pharmacology, and thermodynamic studies of a series of monofluoro-substituted 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides. Measurements of ligand binding by isothermal titration calorimetry (ITC) showed similar binding affinities for the modulator series at the GluA2 LBD but differences in the thermodynamic driving forces. Binding of 5c (7-F) and 6 (no-F) is enthalpy driven, and 5a (5-F) and 5b (6-F) are entropy driven. For 5d (8-F), both quantities were equal in size. Thermodynamic integration (TI) and one-step perturbation (OSP) were used to calculate the relative binding affinity of the modulators. The OSP calculations had a higher predictive power than those from TI, and combined with the shorter total simulation time, we found the OSP method to be more effective for this setup. Furthermore, from the molecular dynamics simulations, we extracted the enthalpies and entropies, and along with the ITC data, this suggested that the differences in binding free energies are largely explained by the direct ligand-surrounding enthalpies. Furthermore, we used the OSP setup to predict binding affinities for a series of polysubstituted fluorine compounds and monosubstituted methyl compounds and used these predictions to characterize the modulator binding pocket for this scaffold of positive allosteric modulators.10.1021/ci500559b [less ▲]

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See detailIdentification, Design and Evaluation of Pharmacological tools for the orphan GPCR GPR22
Geubelle, Pierre ULg; Gilissen, Julie ULg; Dupuis, Nadine ULg et al

Poster (2014, November 21)

GPCRs are the largest family of membrane receptors and are characterized by seven transmembrane domains. This family of receptors is currently the most successfully targeted protein for therapeutic ... [more ▼]

GPCRs are the largest family of membrane receptors and are characterized by seven transmembrane domains. This family of receptors is currently the most successfully targeted protein for therapeutic purposes. GPR22 is a GPCR that was discovered in 1997. It has no known endogenous ligand and is thus considered "orphan". Its presence situated at the heart and brain levels makes it a potential target for new therapeutic pathways. The only information about its signaling channel could be its coupling with G proteins. This study consist in the identification of a synthetic ligand of GPR22 receptor to use it as a pharmacological tool in the study of the signaling channels of GPR22 in order to understand its role and to validate it as a new therapeutic target. The initial hypothesis was that GPR22 is coupled to the Gαi protein. [less ▲]

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