Peptidergic G Protein-Coupled Receptors (GPCRs) play a role in many of the most important biological functions, and the ability to modulate the activity of these critical proteins has tremendous potential to increase our understanding of biology and allow the development of new therapeutics. In some cases this knowledge will point towards the importance of interconnected proteins of the same or different classes, such as kinases, which interact in a complex and dynamic network in vivo. Understanding these systems will be crucial for addressing unmet therapeutic needs, and new chemical structures may be important at every step of the process.Our contribution to this pursuit includes the development of new ligands for the melanocortin receptors based on a bicyclic or tricyclic core structure. These were designed to be peptidomimetics, built from amino acids to leverage the accumulated knowledge of the group but with properties that complement those of peptides. Most of the molecules in this series bind to the melanocortin receptors, and many with significant selectivity. Some are selective for the MC5R, which may allow further study of this widely distributed but largely unexplored subtype. Others bind preferentially to the MC1R, a property which may be useful in the development of imaging agents targeting melanoma.Imaging using fluorescent probes can provide a tremendous amount of information in studies of receptor biology. With this in mind, we have developed new fluorescent ligands which bind to melanocortin receptors. These compounds use the previously discovered bicyclic template and incorporate the small organic fluorophores anthranilate and N-methylanthranilate.While these structures are in a sense bifunctional, as they exhibit both pharmacologic and fluorescent activity, other molecules may instead incorporate two different pharmacophores. We have synthesized designed multiple ligands (DMLs) of this type for the opioid and neurokinin receptors, as well as molecules which target both the opioid receptors and p38 MAP kinase. These structures merged known active ligands, such as fentanyl for the opioid activity, into one bifunctional molecule. In addition we have used our newly developed template to create a novel NK1R antagonist which may be part of the next generation of bifunctional ligands.

Monoamine oxidase (MAO) is a mitochondrial deaminating enzyme that exists as two isoforms, MAO-A and -B. The MAO-mediated reaction generates hydrogen peroxide (H2O2) as a normal by-product. Dysregulation of MAO has been implicated in a variety of neuropsychiatric and neurodegenerative disorders, as well as in the aging process. Endogenous regulators of MAO-A function include calcium (Ca2+) and the p38 mitogen-activated protein kinase (MAPK). Although the effect of p38(MAPK) is thought to rely on induction of mao-A gene expression, post-translational modification of the MAO-A protein is also possible. <p>Using standard biochemical approaches in combination with pharmacological interventions and recombinant DNA strategies, specific aspartic acid residues (within putative Ca2+-binding motifs) were demonstrated to contribute to MAO-A activity. Furthermore, MAO-A activity and its sensitivity to Ca2+ was negatively regulated by the p38(MAPK), which is usually activated during cell stress. The effect of p38(MAPK) on MAO-A function relies specifically on Serine209 in MAO-A, which resides in a p38(MAPK) consensus motif. The serine phosphorylation status of MAO-A determines its capacity for generating peroxy radicals and its toxicity in established cell lines (e.g. C6, N2a, HEK293A, HT-22) and in primary cortical neurons. p38(MAPK)-regulated MAO-A activity is also linked to neurotoxicity associated with the Alzheimer disease-related peptide, Ò-amyloid (AÒ). These data suggest a unique neuroprotective role for p38(MAPK) centered on a negative feedback regulation of the Ca2+-sensitive, H2O2-generating enzyme MAO-A.

Monoamine oxidase (MAO) is a mitochondrial deaminating enzyme that exists as two isoforms, MAO-A and -B. The MAO-mediated reaction generates hydrogen peroxide (H2O2) as a normal by-product. Dysregulation of MAO has been implicated in a variety of neuropsychiatric and neurodegenerative disorders, as well as in the aging process. Endogenous regulators of MAO-A function include calcium (Ca2+) and the p38 mitogen-activated protein kinase (MAPK). Although the effect of p38(MAPK) is thought to rely on induction of mao-A gene expression, post-translational modification of the MAO-A protein is also possible. <p>Using standard biochemical approaches in combination with pharmacological interventions and recombinant DNA strategies, specific aspartic acid residues (within putative Ca2+-binding motifs) were demonstrated to contribute to MAO-A activity. Furthermore, MAO-A activity and its sensitivity to Ca2+ was negatively regulated by the p38(MAPK), which is usually activated during cell stress. The effect of p38(MAPK) on MAO-A function relies specifically on Serine209 in MAO-A, which resides in a p38(MAPK) consensus motif. The serine phosphorylation status of MAO-A determines its capacity for generating peroxy radicals and its toxicity in established cell lines (e.g. C6, N2a, HEK293A, HT-22) and in primary cortical neurons. p38(MAPK)-regulated MAO-A activity is also linked to neurotoxicity associated with the Alzheimer disease-related peptide, Ò-amyloid (AÒ). These data suggest a unique neuroprotective role for p38(MAPK) centered on a negative feedback regulation of the Ca2+-sensitive, H2O2-generating enzyme MAO-A.

P68 RNA helicase is a RNA helicase and an ATPase belonging to the DEAD-box family. It is important for the growth of normal cells, and is implicated in diverse functions ranging from pre-mRNA splicing, transcriptional activation to cell proliferation, and early organ development. The protein is documented to be phosphorylated at several amino-acid residues. It was previously demonstrated in several cancer cell-lines that p68 gets phosphorylated at threonine residues during treatments with TNF-α and TRAIL. In this study, the role of threonine phosphorylation of p68 under the treatment of anti-cancer drug, oxaliplatin in the colon cancer cells is characterized. Oxaliplatin treatment activates p38 MAP-kinase, which subsequently phosphorylates p68 at T564 and/or T446. P68 phosphorylation, at least partially, influences the role of the drug on apoptosis induction. This study shows an important mechanism of action of the anti-cancer drug which could be used for improving cancer treatment. This study also shows that p68 is an important transcriptional regulator regulating transcription of the cytoskeletal gene TPPP/p25. Previous analyses revealed that p68 RNA helicase could regulate expression of genes responsible for controlling stability and dynamics of different cytoskeletons. P68 is found to regulate TPPP/p25 gene transcription by associating with the TPPP/p25 gene promoter. Expression of TPPP/p25 plays an important role in cellular differentiation while the involvement of p68 in the regulation of TPPP/p25 expression is an important event for neurite outgrowth. Loss of TPPP expression contributes to the development and progression of gliomas. Thus, our studies further enhance our understanding of the multiple cellular functions of p68 and its regulation of the cellular processes.

Les inhibiteurs des histones désacétylase (HDACi) constituent une classe prometteuse de médicaments anticancéreux. Ils peuvent déclencher la voie apoptotique et sont proposés pour le traitement des désordres hématologiques. Cependant, les HDACi qui ciblent les HDAC de classe II, tel que le vorinostat, sont également des agents réactivateurs potentiels de l’EBV, un virus qui infecte de manière latente plus de 90% de la population adulte dans le monde et est associée à de nombreux lymphomes de type B. L’étude de la commutation entre le cycle latent et le cycle lytique de l’EBV est essentielle pour appréhender l’impact des HDACi lors du!traitement des lymphomes B associés à l’EBV (risque du relargage de virions en grande quantité lors des traitements chimio thérapeutiques).Notre étude a porté sur l'effet de vorinostat (25 μM pendant 48h) sur des cellules tumorales B infectées par l’EBV : trois lignées de lymphomes de burkitt (BL2B95.8, BL41B95.8 et P3HR1), trois lignées lymphoblastoides (1602, PRI et RUD) et la lignée B95.8 de marmouset en cycle lytique de l’EBV (contrôle positif). Nous avons mis en évidence que le vorinostat peut induire la réactivation de l’EBV (P3HR1 et B95.8) ou à l’apoptose (BL41B95.8, BL2B95.8, 1602, PRI et RUD) avec une inhibition mutuelle de ces deux processus. Au niveau moléculaire, nous avons pu montrer que le vorinostat active constitutivement et simultanément le facteur de transcription initiateur de la réactivation MEF2D (par déphosphorylation) et la MAP kinase pro-apototique p38 (par phosphorylation) suite à la diminution de l’expression de la MAP kinase phosphatase (MPK1) dont p38 est un substrat. Le pré-traitement avec un inhibiteur de p38 (SB203580) a mis en évidence que cette MAP kinase est à la fois impliquée dans les processus de réactivation de l’EBV et d’’apoptose. Cependant, les lignées cellulaires pour lesquelles l'activation de p38 augmente fortement lors du traitement par le vorinostat, entrent directement en apoptose, sans qu’il puisse y avoir réactivation de l’EBV.Nos résultats suggèrent que le niveau d’activation de la MAP kinase p38 permet de réguler la balance réactivation/apoptose des cellules B infectées par l’EBV lorsqu’elles sont soumises à un agent inducteur de la réactivation, en particulier dans le cas de cellules de lymphomes B traitées par le vorinostat. Ils posent la question de l’utilisation des HDACi lors du traitement des lymphomes associés à l'EBV, avec le risque d’une réactivation virale selon le niveau d’activation intracellulaire de p38 et la nécessité d’utiliser simultanément un anti-viral tel que le ganciclovir. / Histone deacetylase inhibitors (HDAC) are a promising class of anticancer drugs. They can trigger the apoptotic pathway and are available for treatment of blood disorders. However, the HDACi that target HDAC class II, as vorinostat, also are potential reactivators agents of EBV, a virus that infects latently over 90% of the adult population worldwide and is associated with many type B lymphomas the study of switching between the latent cycle and the lytic cycle of EBV is essential to understand the impact of HDACi when treating B-cell lymphoma associated with EBV (salting risk virions in large quantities during the chemotherapeutic treatment).Our study focused on the effect of vorinostat (25 .mu.M for 48) on tumor B cells infected with EBV: three lines of Burkitt lymphoma (BL2B95.8, BL41B95.8 and P3HR1), three lymphoblastoid cell lines (1602 PRI and RUD) and B95.8 marmoset line in the lytic cycle of the EBV (positive control). We have demonstrated that vorinostat can induce EBV reactivation (P3HR1 and B95.8) or apoptosis (BL41B95.8, BL2B95.8, 1602, PRI and RUD) with a mutual inhibition of these two process. At the molecular level, we have shown that the active vorinostat constitutively and simultaneously initiating transcription factor reactivation MEF2D (by dephosphorylation) and MAP kinase p38 pro-apototique (phosphorylation) following the reduction in the expression of the MAP kinase phosphatase (MPK1) p38 which is a substrate. The pre-treatment with a p38 inhibitor (SB203580) showed that MAP kinase is both involved in the process of EBV reactivation and apoptosis. However, cell lines where p38 activation greatly increases during treatment with vorinostat, come directly into apoptosis, without there may EBV reactivation.Our results suggest that the level of activation of p38 MAP kinase helps regulate the balance reactivation / apoptosis of B cell EBV infected when exposed to an inducing agent for the reactivation, in particular in the case of cells B lymphoma treated with vorinostat. They raise the question of the use of HDACi in the treatment of lymphomas associated with EBV, with the risk of viral reactivation by level of intracellular activation of p38 and the need to simultaneously use an antiviral such as ganciclovir.

Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality in the United States. It is also well recognized that the incidence of CVD is substantially increased in postmenopausal women due to the loss of estrogen. Experimental and clinical data support vascular protective effects of estrogen by various mechanisms. However, administration of estrogen is also associated with an increased incidence of heart disease which limits its therapeutic potential. Given the demonstrated risks of conventional estrogen therapy, a search for novel, cost-effective, alternative vasoactive agents for prevention of CVD is of major importance in the effort to decrease the burden of CVD morbidity. Genistein, a major soy isoflavone, may be one of those alternative agents because of its selective affinity to estrogen receptor-beta and various beneficial effects on CVD. However, the mechanism of the cardioprotective effects of genistein is still unclear. The objectives of this study were (1) to investigate the effect of genistein on the expression of endothelial nitric oxide synthase (eNOS) both in vitro and in vivo; (2) to define the mechanism by which genistein regulates eNOS expression; and, (3) to examine whether genistein protects against tumor necrosis factor-alpha (TNF-α)-induced apoptosis in human aortic endothelial cells (HAECs). The results demonstrated that genistein, at physiologically achievable concentrations (1-10 μM) in individuals consuming soy products, enhanced the expression of eNOS protein and subsequently elevated nitric oxie (NO) synthesis in both HAECs and human umbilical vein endothelial cells, concomitant with the increased eNOS mRNA expression (2.6-fold of control) and eNOS promoter activity, suggesting that genistein activates eNOS transcription. Furthermore, dietary supplementation of genistein to spontaneously hypertensive rats restored aortic eNOS levels, improved aortic wall thickness, and alleviated hypertension, confirming the biological relevance of the in vitro findings. However, the effects of genistein on eNOS and NO were not mediated by activation of estrogen signaling, mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt kinase, protein kinase C or inhibition of typrosine kinases, but possibly through activating the cAMP/protein kinase A/cAMP responsive elemant binding protein pathway. These data suggest that genistein has direct genomic effects on the vascular wall that are unrelated to its known actions, leading to increase in eNOS expression and NO synthesis, thereby improving vascular homeostasis. We also found that genistein (5-10 μM) significantly inhibited TNF-α-induced apoptosis in HAECs as determined by caspase-3 activation, apoptotic cell detection and DNA laddering. The anti-apoptotic effect of genistein was associated with an enhanced expression of anti-apoptotic Bcl-2 protein and its promoter activity that was ablated by TNF-α. Moreover, this anti-apoptotic effect of genistein was not mediated by extracellular signal-regulated kinase 1/2, protein kinase A, or estrogen receptor. However, inhibition of p38 mitogen-activated protein kinase (p38) by SB203580 completely abolished the cytoprotective effect of genistein, suggesting that genistein acted through the p38-dependent pathway. Accordingly, stimulation of HAECs with genistein resulted in rapid and dose-dependent activation of p38. Unlike TNF-α which specifically activated p38α, genistein selectively induced phosphorylation of p38β, suggesting that p38β, but not p38α, is essential for the cytoprotective effect of genistein. These findings provide the evidence that genistein acts as a survival factor for vascular ECs to protect cells against apoptosis via activation of p38β. Taken together, the resuls of the present study suggest that genistein can act directly on vascular ECs, improves endothelium homeostasis by promoting eNOS expression and endothelial-derived NO synthesis through activating the cAMP/PKA/CREB cascade, and protects against TNF-α-induced apoptosis via activation of p38 β. These data potentially provide a basic mechanism underlying the physiological effects of genistein in the vasculature. / Ph. D.