Academic literature on the topic 'Profile expression'

Mestrado em Biologia Molecular e Celular<br>O ferro é essencial para processos metabólicos fundamentais. Dada a sua natureza reactiva, a homeostasia do ferro é um processo altamente regulado em mamíferos. Um desequilíbrio no metabolismo do ferro tem sido associado a patologias como anemia, hemocromatose e doença de Alzheimer. Ferritina, hepcidina e transferrina são algumas das principais proteínas envolvidas na manutenção dos níveis de ferro no organismo. A Lipocalina 2 (LCN2) é uma proteína de 25 kDa pertencente à família das lipocalinas que tem sido descrita como participante em vários eventos biológicos, tais como diferenciação do rim, protecção de falha renal, apoptose, sobrevivência celular e resposta de fase aguda no fígado, baço, sangue e alguns tecidos epiteliais. Muito relevante é o facto de a LCN2 ser capaz de se ligar a sideróforos bacterianos carregados com ferro. Durante infecções bacterianas, a LCN2 compete com as bactérias pelo ferro disponível, limitando assim a proliferação bacteriana. Este efeito bacteriostático enaltece o papel de LCN2 na resposta imune inata. Dada a capacidade de LCN2 para se ligar a sideróforos carregados com ferro e o facto de existirem células que conseguem capturar este complexo, a LCN2 tem sido proposta como proteína central num putativo mecanismo de entrega de ferro alternativo ao da transferrina. De maneira a compreender melhor o papel de LCN2 no metabolismo do ferro bem como na resposta imune inata, caracterizamos por análise immunohistoquimica o padrão de expressão da proteína em ratinho, do desenvolvimento fetal até um ano de idade, em condições controlo/fisiológicas (injecção com salino) e após estímulo inflamatório agudo (injecção com LPS). A expressão de LCN2 durante o desenvolvimento embrionário foi predominante no fígado e rim. O sinal da proteína persistiu em ambos os órgãos na primeira semana de vida de animais controlo, sugerindo uma ligação da proteína a processos de diferenciação e/ou desenvolvimento. No período pós natal, nos animais injectados com salino a imunoreactividade de LCN2 foi detectada no baço, timo e rim. A injecção com LPS induziu expressão de LCN2 no baço, rim, fígado e barreiras do cérebro. Os dados aqui apresentados indicam que a presença e o perfil de distribuição de LCN2 em alguns tecidos de ratinho são dependentes da idade e estado fisiológico.<br>Iron is essential for key metabolic mechanisms. Given its reactive nature, iron homeostasis is a highly regulated process in mammals. Iron imbalance as been associated to pathologies such as anemia, hemochromatosis and Alzheimer's disease.Ferritin, hepcidin and transferrin are some of the key proteins involved in the maintenance of organism iron levels. Lipocalin 2 (LCN2) is a 25 kDa protein from the lipocalin family that has been reported to participate in a broad range of biological events, such as kidney differentiation, protection from renal failure, apoptosis, cell survival and acute phase response in the liver, spleen, blood cells and some epithelial tissues. Importantly, LCN2 is capable of binding to bacterial siderophores loaded with iron. During bacterial infection scenarios, LCN2 competes with bacteria for iron resources, thus limiting bacterial proliferation. This bacteriostatic effect highlights the role of LCN2 in the innate immune system response. Given the ability of LCN2 to bind iron loaded siderophores and the finding that cells can uptake this complex, LCN2 has been proposed as a central participant in a putative transferrin-alternative pathway for iron delivery. In order to further understand the role of LCN2 in iron metabolism as well in the innate immune system response, we characterized through immunohistochemical analysis the protein expression pattern in mice, from fetal development to one year of age, both in control/physiological conditions (saline injection) and after an acute inflammatory stimulus (LPS injection). LCN2 expression during embryonic development was predominant in the liver and kidney. The protein signal persisted in both organs in the first week of life of control animals, thus suggesting that the protein may be linked to differentiation and/or development processes. In control post-natal animals LCN2 immunoreactivity was detected in the spleen, thymus and kidney. LPS injection induced increased LCN2 expression in the spleen, kidney, liver and barriers of the brain. The present data indicates that LCN2 presence and distribution pattern in some mice tissues is dependent of age and physiological state.

Since the beginning of this work in 1998, it is estimated that 1780 men died of prostate cancer in Quebec. Molecular analysis of prostate cancer will eventually lead to the discovery of key genes involved in its onset and progression. The present project was to compare gene expression profiles in human non-tumorigenic versus tumorigenic prostate cell lines generated in our laboratory. A putative tumor suppressor gene present on 12q13 would be responsible for the non-tumorigenic phenotype of one cell line as discovered earlier by our team.<br>In order to compare gene expression patterns, expression arrays from Clontech, bearing 588 genes known to be involved in human cancers, were hybridized with cDNA derived from two related cell lines available in our laboratory. This one experiment provided interesting hints on differentially expressed genes that could be involved in human prostate cancer. Interesting clones were confirmed by Northern blots. When commercial antibody was available, analysis was extended at the protein level. A combination of these analyses revealed no striking difference in the level of expression for the genes previously identified by the arrays hybridization.<br>Simultaneously, differential display PCR techniques, allowing the discovery of unknown differentially expressed molecules and thus complementing the previous approach, were applied to compare related cell lines and unique hybrids. Cloning and sequencing of differential fragments brought us to what could be a new cDNA expressed in many human cell lines.<br>Prostate cancer is not well characterized enough to allow accurate diagnosis or appropriate therapy strategies. Differentially expressed molecules analyzed in this project as well as the putative new cDNA might fulfil part of this lack in the understanding of this disease.

The goal of the thesis is the development of an exemplary application profile for one institution guiding the use of Rights Expression Languages (REL) to include the rights information of digital documents in the metadata. Cultural heritage institutions face many challenges with regard to the growing number of digital documents. One challenge is the effective and efficient management, administration and presentation or publication of the documents according to their inherent rights. A basic issue is the inclusion of the rights information in the metadata file of the digital documents to enable automated administration of the documents. The application profile is supposed to show the REL’s potential for solving the challenge. Whether RELs can be applied practically in the cultural heritage sector is not in the scope of the thesis and must be examined in a large scale study. As applied research, the thesis does not follow a strict quantitative or qualitative research method but gathers, examines and evaluates data to develop an application profile. Due to the focus on technical issues, it aims at developers and not at end users. To reach the thesis’ goal, RELs are located in the area of digital rights. Four RELs are examined basi-cally by literature analysis. In addition, various representative licenses from one library are chosen which are “translated” into the most appro-priate REL. The findings flow into a prototype application profile which is evaluated in one iteration step by experts according to heuristic evaluation to identify technical and conceptual flaws. Based on the identified flaws, the prototype is revised. Finally, the exemplary application profile for the METS metadata schema is presented and recommendations for further elaborated appli-cation profiles are given.

Mestrado em Biologia Molecular e Celular<br>miRNAs are short (~22 nt) non-coding RNA molecules that control gene expression at post-transcription level by degrading or inhibiting particular target genes. miRNAs are abundant in vertebrate genomes where they play an important role on the control of cell proliferation and differentiation, apoptosis, neurogenesis and synaptic plasticity. Although legally commercialize, alcohol is toxic for living organisms and its consumption can induce dependence. The regular alcohol intake increases the risk of hepatic disease and certain cancers, having a deleterious effect on the immune, endocrine and nervous system. The brain is not only an important target for alcohol metabolites, but also a rich source of miRNAs. Using miRNA microarrays approach, we aimed to understand how chronic (0.25% EtOH) and acute (0.25%; 0.5%, 1 e 1.5% EtOH) ethanol exposure affects miRNA expression. The results demonstrate that chronic ethanol intake deregulated the expression of 32 miRNAs. From those, miR-9, miR-23a, miR-30e, miR-133a, miR-181 were over-expressed and miR-16a, miR-145 and miR-181b were inhibited. The putative target genes for those miRNAs are implicated in cell cycle, differentiation, apoptosis and cell adhesion. The acute ethanol exposure also deregulated miRNA expression profile and each ethanol concentration shows a distinct miRNA expression profile. For example, the pro-apoptotic miRNA miR- 23a is up-regulated in chronic ethanol exposure but is down-regulated in the higher ethanol concentrations (1 e 1.5% EtOH) of acute test. These results suggest that alcohol consumption, even consumed in a short-period or concentration, affects the expression of miRNAs. Possibly, these alterations have implications on cellular cycle and apoptosis and therefore they could contribute to a higher risk of developing tumours.<br>Os miRNAs são pequenas moléculas (~22 nt) de RNA não-codificante que regulam a expressão genética ao nível pós-transcripcional através da degradação ou inibição dos genes alvo. Os miRNAs são abundantes nos genomas eucariótas, onde desempenham funções importantes no controlo da proliferação e diferenciação celular, apoptose, neurogénese e plasticidade sináptica. Apesar de ser uma substância legal, o álcool é tóxico para os seres vivos e o seu consumo regular pode induzir dependência. O consumo excessivo de álcool aumenta o risco de doença hepática e de determinados cancros e tem efeitos deletérios ao nível do sistema imunitário, endócrino e nervoso. O cérebro, para além de ser um importante alvo dos metabolitos do álcool, é um dos órgãos com maior expressão de miRNAs. Através da análise de microarrays de miRNAs pretendeu-se entender de que modo a exposição crónica ao etanol (0.25% EtOH) e a exposição aguda a um pulso de etanol (0.25%; 0.5%, 1 e 1.5% EtOH) afectam a expressão dos miRNAs. A expressão de 32 miRNAs foi significativamente alterada pela exposição crónica ao etanol, destacando-se o aumento da expressão do miR-9, miR-23a, miR-30e, miR- 133a, miR-181 e a diminuição na expressão do miR-16a, miR-145 e miR-181b. Genes envolvidos no ciclo celular, diferenciação, apoptose e adesão celular parecem ser os alvos preferenciais destes miRNAs. A exposição aguda também alterou a expressão de vários miRNAs, que variam consoante a concentração de etanol utilizada. Por exemplo, a expressão do miRNA próapoptótico miR-23a aumentou durante a exposição crónica ao etanol e diminuiu com o aumento da concentração do tóxico (1 e 1.5% EtOH) durante o teste agudo. Estes resultados sugerem que o consumo de álcool, mesmo num curto espaço de tempo ou concentração, afecta a expressão dos miRNAs. Possivelmente essas alterações têm implicações no ciclo celular e apotose, podendo contribuir deste modo para um risco acrescido de desenvolver tumores.

<p>Worldwide obesity is an increasing problem. Apart from the fact that obesity greatly  impairs the health, quality and length of life for the affected individuals, it is also has the  potential to become a major socioeconomic problem in a near future. However preventive  actions require an understanding of the cause. Before the psychological influence on  eating can be evaluated a profound understanding of the biological regulatory system and  how this interacts with the food consumed is required. On the assumption that food  consumption is regulated by interplay between food and genes, the food itself may  influence the genes that regulate consumption, hence change the expression levels of the  genes regulating food intake.     To evaluate the interplay between food and gene expression, the project contained several  parts, reflecting different aspects of the area of research. The feeding studies had in  common that they were initial trials in a larger project. The results of these will be  evaluated and used in combination with further studies.     The mice typed for food preference illustrate the complexity of the feeding regulatory  system by pointing out the differences between individuals even in a relatively small  group of animals. Mice in general like food high in fat and here the animals that showed a  preference for sugar also showed a significant increase in their intake of chow. Since  chow consists mainly of carbohydrates the results might indicate a preference not for  sucrose in particular but for carbohydrates in general. The effect this may have on other  studies is still unclear as further studies are needed to determine whether the difference  may be the result of an innate genetic difference.      Leucine has been previously shown to reduce the total caloric intake. When given in  combination with palatable food the addition of Leucine primarily reduced the intake of  chow. From a dietary perspective this would translate to a preference to sweets and fast  food at the expense of food with more nutritious content.     The RT-PCR analysis’s gives clues to how the energy regulatory circuitry responds to the  intake of selected macronutrients. When it comes to gene expression there is a significant  effect of macronutrients on the gene expression levels. The common theme for many of  the genes tested seems to be down regulation of satiety signals, as if to support over  feeding on palatable diets and in many cases sucrose in particular.     The intake of macronutrients such as sugar or fat has been showed to have an effect on  the feeding regulatory circuitry, demonstrated by the change in gene expression levels.   The response to said macronutrients is site specific which is clearly shown both by RTPCR analysis of samples from different parts of the brain, such as the brainstem or  hypothalamus, and by immunohistochemistry of selected areas. The  immunohistochemistry also confirms that the novel Oxytocin receptor-antagonist, who is  injected IP, actually passes over the blood-brain barrier and has an actual affect on the  regions of interest. The areas affected by the antagonist can be visualized and identified  through the staining of active sites.</p>