L’Urotensine II (UII) est un peptide cyclique de 11 acides aminés initialement isolé à partir de l’urophyse de gobie. Cette hormone est impliquée dans l'homéostasie cardiovasculaire et exerce la majorité de ses effets par l'intermédiaire du récepteur de l'urotensine (UT). Le récepteur UT est couplé préférentiellement à la protéine G hétérotrimérique G?q et les propriétés fonctionnelles de ce récepteur ont principalement été étudiées pour sa capacité à induire la production d'inositol phosphate ainsi que la mobilisation de Ca[indice supérieur 2+] intracellulaire. Il a été rapporté que UT peut également coupler à d'autres protéines G hétérotrimériques G?i/o et qu’il peut activer plusieurs voies indépendantes de la protéine G, tels que la voie des MAP Kinase et de la beta-arrestine. Notre hypothèse stipule que différents ligands d’UT peuvent induire ou stabiliser différentes conformations du récepteur, chacune conduisant à une signalisation spécifique, ce concept est connu sous le nom de sélectivité fonctionnelle ou signalisation biaisée. Nous avons sélectionné 6 analogues de UII qui diffèrent dans leur structure chimique et nous avons évalué leur capacité à activer plusieurs voies de signalisation: G?q G?i, G?13, ERK, NF?B et le recrutement de la ?-arrestine. Par ailleurs, la technologie de transfert d’énergie bioluminescente par résonnance (BRET) fut utilisée pour évaluer l’activation spécifique des protéines G?q, G?i, G?13 ainsi que le recrutement de la ?-arrestine-2. Nous avons montré que la substitution de la lysine en huitième position de UII affecte la propriété du peptide à activer certaines voies de signalisation. De plus, l’analogue Nle8-UII agit comme agoniste complet sur la voie G?q mais active faiblement le recrutement de la ?-arrestine-2 ainsi que la voie NF?B. Cette étude a permis d’identifier des ligands sélectifs pour certaines voies de signalisation d’UT et pourrait permettre la conception de ligands sélectifs pour UT dans diverses pathologies associées à ce récepteur. [symboles non conformes]

Amino acids (AA) are required for protein accretion and the need for a specific AA depends on the physiological status, breed, and the health of the pig. Inasmuch as the AA requirements for growing pigs are given in an ideal AA ratio for protein accretion, the utilization of all AA is beyond growth and at least 30% of the total dietary AA will be used by the splanchnic tissue. A ban in the use of antimicrobial growth promoters (AGP) in piglets’ diets is likely to increase incidences of disease occurrence and exert additional AA requirements. Immune challenge models were used to determine standardized ileal digestible (SID) Lys and sulfur amino acids (SAA):Lys requirements for piglets under an antibiotic-free feeding regime. The first objective was to establish the dietary Lys requirement for piglets raised under both clean and unclean sanitary conditions. The Lys requirement could not be determined in the first experiment. However, from the second and third experiments the dietary SID Lys content for optimal growth of 7 to 16 kg weaned piglets was estimated to be 1.32%. The objective of fourth experiment was to determine the optimum SID SAA:Lys ratio in piglets when reared under clean or unclean conditions. Based on performance parameters, the optimum SAA:Lys ratios were 58 and 61 for piglets raised under clean and unclean conditions, respectively. However, VH estimates were 60 and 66 SAA:Lys under clean and unclean sanitary conditions, respectively. The objective for the fifth experiment was to determine SID SAA:Lys ratio of piglets under an enterotoxigenic Escherichia coli challenge using genes for expression of key products in the Met metabolic pathway. Gene expressions of methionine adenosyltransferase 1 and 2-α, 5-methyltetrahydrofolate-homocysteine methyltransferase, and cystathionine γ-lyase was done for liver and ileal tissue. The gene expressions indicates that the dietary SAA:Lys ratio of 60 was enough to support piglet’s immune response and performance during an immune challenge. Therefore, under an antibiotic-free feeding regime, the Lys requirement recommended by NRC (2012) is sufficient, however, the SAA:Lys should be raised to 60 in diets of both healthy and immune challenged piglets.

The splanchnic bed is a group of organs (liver, intestines, stomach, pancreas and spleen) which are active in the metabolism of amino acids. However, the impact of this group of organs on the dietary requirements of humans has yet to be determined. The focus of this research will be the requirements of two indispensable amino acids, threonine and lysine, and the impact of the splanchnic bed on amino acid kinetics. Threonine is an indispensable amino acid which is critical in the production of mucins in the gut and contributes significantly to collagen, elastin and tooth enamel formation in mammals. The first study was designed to determine the threonine requirement for the parenterally-fed, stable, post-surgical neonate. The mean threonine parenteral requirement, as experimentally derived in human neonates, was 32.8 mg•kg-1•d-1 which was less than the recommended enteral intake of 76 mg•kg-1•d-1 suggesting a splanchnic uptake in humans of 57%. Lysine is an indispensable amino acid used primarily, in the mammalian body, for protein synthesis but it also acts as a precursor for carnitine synthesis. The second study was devised to determine the lysine requirement for the parenterally-fed, stable, post-surgical neonate. The mean lysine parenteral neonatal requirement as experimentally determined in human neonates, was 104.9 mg•kg-1•d-1 which was less than the recommended enteral intake of 119 mg•kg-1•d-1 suggesting a splanchnic uptake in humans of 12%. The third study was intended to increase our knowledge of the metabolism of threonine and lysine by the splanchnic bed. Adult humans were fed isotopic threonine and lysine both enterally and parenterally. We determined that retention of threonine and lysine by the splanchnic bed was 16.7% and 17.1% respectively, which were not significantly different. The conclusion was that, in healthy human adult males, there was no difference in the extraction of threonine and lysine by the splanchnic bed which was different from our findings in parenterally fed piglets and human neonates.

The splanchnic bed is a group of organs (liver, intestines, stomach, pancreas and spleen) which are active in the metabolism of amino acids. However, the impact of this group of organs on the dietary requirements of humans has yet to be determined. The focus of this research will be the requirements of two indispensable amino acids, threonine and lysine, and the impact of the splanchnic bed on amino acid kinetics. Threonine is an indispensable amino acid which is critical in the production of mucins in the gut and contributes significantly to collagen, elastin and tooth enamel formation in mammals. The first study was designed to determine the threonine requirement for the parenterally-fed, stable, post-surgical neonate. The mean threonine parenteral requirement, as experimentally derived in human neonates, was 32.8 mg•kg-1•d-1 which was less than the recommended enteral intake of 76 mg•kg-1•d-1 suggesting a splanchnic uptake in humans of 57%. Lysine is an indispensable amino acid used primarily, in the mammalian body, for protein synthesis but it also acts as a precursor for carnitine synthesis. The second study was devised to determine the lysine requirement for the parenterally-fed, stable, post-surgical neonate. The mean lysine parenteral neonatal requirement as experimentally determined in human neonates, was 104.9 mg•kg-1•d-1 which was less than the recommended enteral intake of 119 mg•kg-1•d-1 suggesting a splanchnic uptake in humans of 12%. The third study was intended to increase our knowledge of the metabolism of threonine and lysine by the splanchnic bed. Adult humans were fed isotopic threonine and lysine both enterally and parenterally. We determined that retention of threonine and lysine by the splanchnic bed was 16.7% and 17.1% respectively, which were not significantly different. The conclusion was that, in healthy human adult males, there was no difference in the extraction of threonine and lysine by the splanchnic bed which was different from our findings in parenterally fed piglets and human neonates.

Lysine acetylation is a post-translational modification (PTM) studied extensively in the context of histone proteins as a regulator of chromatin dynamics. Recent proteomic studies have revealed that as much as 10% of prokaryotic and mammalian proteins undergo lysine acetylation, and as such, the study of its biological consequences is rapidly expanding to include virtually all cellular processes. Unravelling the complex regulatory network governed by lysine acetylation will require an in depth knowledge of the lysine acetyltransferase enzymes that mediate catalysis, and moreover the development of methods that can identify enzyme-substrate relationships in vivo. This is complex task and will be aided significantly through the use of model organisms and systems biology approaches. The work presented in this thesis explores the function of the highly conserved NuA4 lysine acetyltransferase enzyme complex in the model organism Saccharomyces cerevisiae using systems biology approaches. By exploiting genetic screening tools available to the budding yeast model, I have systematically assessed the cellular roles of NuA4, thereby identifying novel cellular processes impacted by the function of the complex, such as vesicle-mediated transport and the stress response, and moreover identified specific pathways and proteins that are impacted by NuA4 KAT activity, including cytokinesis through the regulation of septin protein dynamics. Moreover, I have developed a mass spectrometry-based technique to identify NuA4-dependent acetylation sites amongst proteins that physically interact with NuA4 in vivo. Together this work demonstrates the diversity of processes impacted by NuA4 function in vivo and moreover highlights the utility of global screening techniques to characterize KAT function.

Thesis (Ph.D.)--Ohio University, March, 2007. / Title from PDF t.p. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 157-172).

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 44-48).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.