京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第18923号 / 薬科博第37号 / 新制||薬||5(附属図書館) / 31874 / 京都大学大学院薬学研究科医薬創成情報科学専攻 / (主査)教授 岡村 均, 教授 中山 和久, 教授 竹島 浩 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

The circadian system provides animals with a means to adapt internal physiology to the constantly changing environmental stimuli that exists on a rotating planet. Light information is translated into molecular timing mechanisms within individual pacemaker cells of the mammalian hypothalamic suprachiasmatic nucleus (SCN) via transcriptionaltranslational feedback loops. Humoral and neural outputs from this master clock result in circadian rhythms of physiology and behavior. The hierarchy of the circadian system involves SCN synchronization of cellular clocks within peripheral tissues so that differential transcriptional profiles in individual organs reflect their specific function. The first step to investigating equine circadian regulation was to identify and isolate the core components of the molecular clock in the horse. Successful isolation and sequencing of equine Bmal1, Per2, Cry1 and Clock cDNAs revealed high sequence homology with their human counterparts. Real Time RT-PCR assays were subsequently designed to quantitatively assess clock gene expression in equine peripheral tissues. Synchronization of equine fibroblasts revealed temporal profiles of clock gene expression identical to those of the SCN and peripheral tissues of other species. However, while clock gene expression varies over time in equine adipose tissue, there was no observable oscillation of clock gene transcripts in equine blood. Spurred by recent reports of immune-circadian interactions, this novel finding prompted an investigation of clock gene expression in equine blood during a systemic inflammatory response. The results demonstrated that acute inflammation upregulates Per2 and Bmal1 in equine blood. Subsequent experiments identified neutrophils as the source of this upregulation and highlighted exciting new immunecircadian interplay during an innate immune response. Finally, the effect of a 6-h phase advance of the light/dark cycle, mimicking an easterly transmeridian journey, on circadian melatonin and core body temperature rhythms was investigated. In contrast to the gradual adaptation observed in other species, these markers of equine circadian phase adapt immediately to a time zone transition. Combined, the results of these experiments highlight important interspecies differences in circadian regulation with practical implications regarding the potential impact of jet lag on equine athletes. Furthermore, the results underline the relevance of chronobiological investigation in a large mammalian species such as the horse.

Hippocampus is one of the main components of the limbic system. It plays an important role in the process of memory formation and recent literature shows that, like in other peripheral organs and brain structures, there is a circadian clock present in the hippocampus. The aim of the thesis was to study the hippocampal circadian clock under various conditions. The first part of the thesis examines the influence of glucocorticoid hormones on the clock gene expression in the hippocampus. Glucocorticoids are mammalian steroid hormones secreted from the adrenal glands that affect many processes in the organism. The glucocorticoid secretion is under the control of the circadian system, causing their levels to exhibit a pronounced diurnal rhythm. The hippocampus provides feedback to the hypothalamo-pituitary-adrenal (HPA) axis and is thus involved in the regulation of glucocorticoid hormone secretion. Hippocampal neurons also express glucocorticoid hormone receptors (GR). This thesis explores the effect of the absence of glucocorticoid hormones on the clock gene expression in the hippocampus. The absence of glucocorticoids was due to adrenalectomy and its effect was further compared with the effect of endogenous glucocorticoid replacement by daily injections of the GR agonist dexamethasone, emulating...

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23364号 / 理博第4735号 / 新制||理||1679(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 森 哲, 教授 曽田 貞滋, 教授 中川 尚史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Made available in DSpace on 2015-07-22T20:49:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-28. Added 1 bitstream(s) on 2015-08-11T03:25:36Z : No. of bitstreams: 1 Publico-035.pdf: 841601 bytes, checksum: 09b2f23ec93052490c588d4826e2d818 (MD5) / Associação Fundo de Incentivo à Psicofarmacologia (AFIP) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os genes PER3 e CLOCK são importantes componentes do sistema molecular circadiano dos mamíferos. Vários estudos têm demonstrado existir uma associação entre polimorfismos nestes genes relógio e fenótipos circadianos nas diferentes populações. No entanto, as diferenças no padrão da freqüência alélica e a distribuição genotípica, são sistematicamente observadas nos estudos com diferentes grupos étnicos. Para investigar e comparar o padrão de distribuição em uma amostra de populações asiáticas e caucasianas que vivem no Brasil, utilizando a técnica de PCR, avaliou-se dois polimorfismos bem estudados nos genes relógio: o (VNTR) no gene PER3, um polimorfismo de número variável de repetições em tandem; e um polimorfismo com troca de um único nucleotídeo (SNP ) no gene CLOCK. O objetivo deste estudo foi, nos humanos, procurar pistas sobre os processos evolutivos relacionados aos ritmos circadianos, tendo sido selecionados 109 descendentes de asiáticos e 135 de caucasianos. As freqüências do alelo curto (4 repetições) no gene PER3 e do alelo T no gene CLOCK (respectivamente 0,86 e 0,84) entre os asiáticos foram significativamente maiores do que entre os caucasianos (respectivamente 0,69 e 0,71). Os resultados confirmaram diretamente a distribuição diferente destes polimorfismos entre os grupos étnicos caucasianos e asiáticos. Dadas as diferenças genéticas observadas entre os grupos, tornou-se evidente que, primeiro, as variações étnicas poderiam ter implicações para a interpretação dos resultados em estudos de associação do ritmo circadiano e, segundo, questiona quais foram as condições evolutivas que moldaram essas variações genéticas observadas nos genes relógio. / The Period 3 and Clock genes are important components of the mammalian molecular circadian system. Studies have shown association between polymorphisms in these clock genes and circadian phenotypes in different populations. Nevertheless, differences in the pattern of allele frequency and genotyping distribution are systematically observed in studies with different ethnic groups. To investigate and compare the pattern of distribution in a sample of Asian and Caucasian populations living in Brazil, we evaluated two well-studied polymorphisms in the clock genes: a variable number of tandem repeats (VNTR) in PER3 and a single nucleotide polymorphism (SNP) in CLOCK. The aim of this investigation was to search for clues about human evolutionary processes related to circadian rhythms. We selected 109 Asian and 135 Caucasian descendants. The frequencies of the shorter allele (4 repeats) in the PER3 gene and the T allele in the CLOCK gene among Asians (0.86 and 0.84, respectively) were significantly higher than among Caucasians (0.69 and 0.71, respectively). Our results directly confirmed the different distribution of these polymorphisms between the Asian and Caucasian ethnic groups. Given the genetic differences found between groups, two points became evident: first, ethnic variations may have implications for the interpretation of results in circadian rhythm association studies, and second, the question may be raised about which evolutionary conditions shaped these genetic clock variations. / FAPESP/CEPID: 98/14303-3 / TEDE / BV UNIFESP: Teses e dissertações

No description available.

博士(スポーツ健康科学) / Doctor of Philosophy in Health and Sports Science / 同志社大学 / Doshisha University

La première partie de mon travail de thèse a été de définir le rôle joué par le récepteur nucléaire Rev-erb alpha dans les mécanismes de synchronisation par la nourriture d’une horloge circadienne putative, non encore localisée, appelée « horloge alimentaire ». La seconde partie de mon travail a consisté à étudier la participation de Rev-erb alpha dans les régulations des métabolismes glucidique et lipidique. L’ensemble de nos données indique que le répresseur transcriptionnel Rev-erb alpha joue un rôle charnière dans les fonctions circadiennes ainsi que dans le métabolisme. En effet, d’un point de vue circadien, l’absence de Rev-erb alpha altère la synchronisation à l’heure des repas – démontré par une réduction des sorties comportementales et physiologiques de l’horloge alimentaire, ainsi que par l’absence d’ajustement du rythme de la protéine d’horloge PER2 dans l’oscillateur cérébelleux. Sur le plan métabolique, la délétion de ce gène modifie notamment le métabolisme des lipides – démontré par une accumulation excessive de tissu adipeux, une utilisation préférentielle des acides gras, ainsi qu’une perte de contrôle de l’expression de la Lipoprotéine lipase. / The work performed during this PhD thesis aimed at investigating the role of the transcriptional silencer Rev-erbα in both the circadian clockwork of the food-entrainable oscillator and metabolic regulations. Firstly, by evaluating food-anticipatory components in animals fed once a day at the same time, we showed that mice lacking Rev-erbα display a reduction in locomotor activity prior to food access compared to littermate controls. Accordingly, the rises in body temperature and corticosterone that anticipate mealtime are also diminished. Interestingly, daily p-ERK expression in hypothalamic regions and daily PER2 expression in the cerebellum of Rev-erbα KO mice are not phase-adjusted to feeding time. These results indicate that Rev-erbα participates in the integration of feeding signals and in food-seeking behaviors. Secondly, by investigating energy balance in fasted, normal chow or high-fat fed animals, we revealed that Rev-erbα KO mice exhibit greater reliance on lipid fuels as energy substrates, contributing to a mild hyperglycemic state. We also found that Lipoprotein lipase (Lpl) expression, is strongly up-regulated in peripheral tissues of Rev-erbα KO mice, predisposing mice to obesity. In this regard, we uncovered a new molecular pathway that ties clock-driven Lpl expression to energy homeostasis. These findings highlight the significance of daily Rev-erbα oscillations to prevent the appearance of the metabolic syndrome.In conclusion, we provide evidence that REV-ERBα may be a part of the food-entrainable oscillator clockwork that triggers food-anticipatory components, and represents a pivotal player to link the core clock machinery to metabolic pathways.