Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2018-06-19T19:39:34Z No. of bitstreams: 2 Tese - Roberto Araujo Bezerra - 2017.pdf: 6402541 bytes, checksum: ed090dd91775b5a16e6798f3fdfa191e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-06-27T10:33:26Z (GMT) No. of bitstreams: 2 Tese - Roberto Araujo Bezerra - 2017.pdf: 6402541 bytes, checksum: ed090dd91775b5a16e6798f3fdfa191e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-27T10:33:26Z (GMT). No. of bitstreams: 2 Tese - Roberto Araujo Bezerra - 2017.pdf: 6402541 bytes, checksum: ed090dd91775b5a16e6798f3fdfa191e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-06-08 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The world's fishery production is constantly growing, with expansion of aquaculture parks, fish farms and fish-pay, however, these activities can trigger damages to aquatic systems. The process of eutrophication is characterized by the excess of nutrients available in the water, which when associated with high temperatures and luminosity, provide cyanobacteria blooms, some of which are toxic. Microcystins pose risks to human and other animal health due to the consumption of contaminated fish and can cause serious problems for the aquatic community. The present study had as main objective to evaluate the mutagenic damages that toxic blooms of Microcystis aeruginosa and Microcystis panniformis in different densities of cells can cause when exposed to the Piaractus brachypomus (pirapitinga), native species of the Amazon basin and commercialized in fish farms and fish-pays of the Goiânia metropolitan region, and to evaluate the profile of fish consumption by the community of the Federal University of Goiás. The results showed that even at low densities, the effect of microcystins generated different genomic damages in fish. Juveniles presented erythrocytic nuclear alterations exposed to M. aeruginosa - reniformes: 33%; binucleate: 28.6%; micronucleus: 28.1% and exposed to M. panniformis reniformes: 6.43%; binucleate: 75.5%; micronucleus: 2.4%. There was a higher concentration of microcystins produced by M. panniformis cells. As for the profile of the academic community, more than 80% consume fish, since tilapia is the most preferred species among respondents (22.4%). Of these, only 49.6% go to fish-pay and the main reason for going is leisure with family or friends (46.7%), however, only 21.7% take into account the hygiene of the place, but are unaware of the quality of the waters of these places, as well as that of fish. It was concluded in this study that the group most threatened by the action of cyanotoxins are the fish consumers themselves due to the low concentration found in the muscular tissues and that when investigated, some do not reach the peak of detection, passing unnoticed by the human population. / A produção pesqueira mundial está em constante crescimento, com expansão de parques aquícolas, pisciculturas e pesque-pague, no entanto, essas atividades podem desencadear danos aos sistemas aquáticos. O processo de eutrofização é caracterizado pelo excesso de nutrientes disponibilizados na água, que quando associados a elevadas temperaturas e luminosidade, proporcionam florações de cianobactérias, sendo algumas tóxicas. As microcistinas oferecem riscos à saúde humana e de outros animais devido ao consumo de peixe contaminado, podendo causar sérios problemas à comunidade aquática. O presente estudo teve como objetivo principal avaliar os danos mutagênicos que florações tóxicas de Microcystis aeruginosa e Microcystis panniformis em diferentes densidades de células podem ocasionar quando expostas à Piaractus brachypomus (pirapitinga), espécie nativa da bacia Amazônica e comercializada em pisciculturas e pesque-pague da região metropolitana de Goiânia/GO, e avaliar o perfil do consumo de peixes pela comunidade da Universidade Federal de Goiás. Os resultados demonstraram que mesmo em baixas densidades, o efeito das microcistinas geraram diferentes danos genômicos nos peixes. Os juvenis apresentaram alterações nucleares eritrocíticas expostos à M. aeruginosa - reniformes: 33%; binucleadas: 28,6%; micronúcleo: 28,1% e expostos à M. panniformis – reniformes: 6,43%; binucleadas: 75,5%; micronúcleo: 2,4%. Verificou-se maior concentração de microcistinas produzidas por células de M. panniformis. Quanto ao perfil da comunidade acadêmica, mais de 80% consomem peixes, posto que a tilápia é a espécie de maior preferência pelos entrevistados (22,4%). Destes, apenas 49,6% frequentam pesque-pague e o principal motivo pela ida é o lazer em família ou com amigos (46,7%), todavia, apenas 21,7% levam em consideração a higiene do local, mas desconhecem a qualidade das águas desses locais, bem como a dos peixes. Concluiu-se neste estudo, que o grupo mais ameaçado pela ação das cianotoxinas são os próprios consumidores de peixe, devido à baixa concentração encontrada nos tecidos musculares e que quando investigadas, algumas não atingem o pico de detecção, passando despercebido pala população humana.

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The genotoxicological effects of five intra-peritoneal administered oestrogens (17β- oestradiol, daidzein, diethylstilboestrol, genistein, and equol), were examined. Male hooded- Lister rats were used to examine to what extent DNA damage occurred. The alkaline Comet assay was the chosen method used to assess double-strand DNA breakage by examining the Olive tail moment and %age tail DNA. Tissues from the testis, bone marrow, liver and blood were analysed after an 8-day duration of exposure. Statistically significant increases in DNA damage were observed in the testis with daidzein and in the blood with diethylstilboestrol. In addition, a further study was carried out to examine the effects of bulk and nanotised forms of non-steroidal anti-inflammatory drugs (NSAIDs), aspirin and ibuprofen, in the Comet and micronucleus assays, on whole blood taken from prostate cancer patients or volunteers. These were used because it is known that the sensitivity of DNA to genotoxins can be heightened in patients with cancer. Patients’ and volunteers’ blood was cultured with either the bulk or nano-forms for 44 hours at 37°C, 5% CO2. Data were obtained for the Comet assay as above and the number of binucleated cells scored for the micronucelus assay. The results show the nanotised forms of the NSAIDs decreased the levels of strand breakage and lowered the numbers of micronuclei generated compared with their bulk forms. There was no clear difference between the sensitivity of the healthy controls and the prostate cancer patients, with only one individual showing evidence of heightened sensitivity.

Cancer is one of the leading causes of death across the globe which needs appropriate and cost-effective treatment. Several recent studies have suggested that dietary intake of various flavonoids such as myricetin have a protective effect against different types of cancers and cardiovascular diseases. The present study was conducted to investigate the genoprotective and genotoxic effects of myricetin nano and bulk forms on the lymphocytes from pre-cancerous and multiple myeloma cancer patients compared to those from healthy individuals. Also, to investigate the protective potential of myricetin bulk and nano against the oxidative stress produced in vitro by 2- amino-1-methyl-6 phenylimidazo [4, 5-b] pyridine and reactive oxygen species- induced DNA damage using the Comet assay, micronucleus assay, cellular reactive oxygen species and glutathione detection assay, Western blotting, real-time polymerase chain reaction and immunofluorescence. Lymphocytes from the patient groups showed significantly higher levels of basal DNA damage compared to the lymphocytes from healthy individuals which was observed throughout the in vitro treatment. Myricetin in both forms has not induced any significant DNA damage in all of the investigative groups at selective lower concentrations; in fact, the results demonstrate a reduction in DNA damage upon treating with myricetin nano in lymphocytes from pre-cancerous patients demonstrated by significant reduction in micronuclei formation in mononucleated cells. DNA repair capacity of myricetin bulk and nano was determined by co-treating the drugs with hydrogen peroxide. Myricetin significantly reduced the oxidative stress related damage caused by hydrogen peroxide, where myricetin nano seemed to be more effective employing the Comet assay. In the presence of myricetin bulk and nano, the damaging effects of 2- amino-1-methyl-6 phenylimidazo [4,5-b] pyridine were considerably decreased, where myricetin nano was more effective. This could be because nanoparticles have a larger surface area which could improve their reactivity and also the reduction in size of the particles could improve the anti-cancer properties of this compound. Myricetin has shown genoprotective and anti-oxidant effects by demonstrating the potential to reduce DNA damage caused by over-production of reactive oxygen species and oxidative stress. It has also shown anti-cancer potential in the lymphocytes from multiple myeloma patients by regulating the apoptosis related proteins, dependent on oxidative stress. Therefore, this study suggests that myricetin supplementation in our regular diet with enhanced bioavailability could have potential health beneficial effects and possibly protect against various diseases including cancer.

Lung cancer is one of the main causes of death worldwide, with most patients suffering from an advanced unresectable or metastatic non-small cell lung cancer. The mortality trends are mostly related to patterns of tobacco use, specifically from cigarettes. Tobacco is the basic etiological agent found as a consequence of the inhalation of tobacco smoke. Published data show the use of interferons (IFNs) in the treatment of lung tumours due to their potential in displaying antiproliferative, anti-angiogenic, immunoregulatory, and proapoptotic effects. Type1 IFNs have been employed as treatments for many types of cancer, both for haematological cancers and solid tumours. The IFN-γ (naked) functions as an anticancer agent against various forms of cancer. Hence, this study aimed to investigate the genoprotective and genotoxic effects of IFN-γ liposome (nano) on 42 blood samples from lung cancer patients, compared to the same sample size from healthy individuals. The effectiveness of IFN- γ liposome against oxidative stress was also evaluated in this study. A concentration of 100U/ml of IFN-γ liposome was used to treat the lymphocytes in: Comet and micronucleus assays, Comet repair, Western blotting and real-time polymerase chain reaction (qPCR) were based on a preliminary test for the optimal dose. The lymphocytes from lung cancer patients presented with higher DNA damage levels than those of healthy individuals. IFN-γ liposome was not found to induce any DNA damage in the lymphocytes. Also, it caused a significant reduction in DNA damage in the lymphocytes from lung cancer patients in; Comet, Comet repair and micronucleus assays. Furthermore, the 100U/ml of IFN-γ liposome significantly reduced the oxidative stress caused by H2O2 and appeared to be effective in both groups using the Comet and micronucleus assays. Results from; Comet, Comet repair and micronucleus assays were consistent. The data obtained indicated that IFN-γ in both forms (naked INF-γ and INF-γ nano-liposome) may potentially be effective for the treatment of lung cancer and showed the ability of IFN-γ liposome to reduce the DNA damage more than the naked form. The IFN-γ in both forms has also shown anti-cancer potential in the lymphocytes from lung cancer patients by regulating the expression of p53, p21, Bcl-2 at mRNA and protein levels by up-regulating the p53 and p21 to mediate cell cycle arrest and DNA repair in lung cancer patients. The findings of this study are consistent with the view that the naked IFN-γ and liposome could have a significant role in cancer treatment, including lung cancer. / Mutah University in Jordan

Certaines protéines régulatrices dites nucléo-cytoplasmique naviguent entre le noyau et le cytoplasme. En réponse à une perturbation de l'environnement de la cellule, ces protéines relocalisent massivement dans le noyau pour y activer des mécanismes permettant la survie cellulaire. Chez la levure S. pombe, 285 protéines présentent la particularité d'être nucléo-cytoplasmiques. Une étude exhaustive de certaines de ces protéines a été ici entreprise. L'objectif était d'identifier celles présentes chez S. cerevisiae qui sont vitales dans la réponse aux stress endommageant l'ADN. Parmi les protéines candidates, celles i) étant les plus conservées chez l'ensemble des organismes eucaryotes, ii) de fonction inconnue ou peu décrite et iii) dont la répartition nucléo-cytoplasmique change après stress ont été sélectionnées à l'aide d'un crible génétique mis au point chez S. cerevisiae. Douze protéines ont été identifiées comme relocalisant au noyau sous l'effet du stress radiatif ou métaux lourds. Parmi elles, la protéine Pat1 (YCR077C) décrite à ce jour comme un activateur de la dégradation cytoplasmique des ARNs messagers a été choisie et une étude plus approfondie de son activité entreprise. Par une approche TAP-tag couplée à une stratégie de protéomique de type shotgun, le réseau de partenaires protéiques de Pat1 a été établi en absence de stress et en condition de stress UV. La région potentiellement impliquée dans la localisation cellulaire de la protéine Pat1 est sujette à de multiples phosphorylations dont le degré augmente après stress UV. Enfin, les résultats sur les partenaires spécifiques de Pat1 identifiés par protéomique en condition de stress ont été corroborés par une analyse de sa relocalisation chez les différents mutants correspondants. L'ensemble de nos résultats mettent en exergue une nouvelle fonctionnalité pour la protéine Pat1 spécifiquement menée au noyau des cellules qu'il reste désormais à préciser. / Some regulatory proteins called nucleo-cytoplasmic proteins, shuttle between the nucleus and the cytoplasm. Upon environmental stress, these proteins relocate massively to the nucleus where they activate pro-survival mechanisms. In the yeast S. pombe, 285 proteins are nucleo-cytoplasmic. An exhaustive study of some of these proteins was carried out herein. The goal was to identify the ones that are present in S. cerevisiae and vital in the DNA damage response. Among the candidate proteins, the ones i) that are the most conserved in the eukaryotic cells, ii) with unknown function or poorly characterized, and iii) whose nucleo-cytoplasmic repartition changes upon stress were selected by the use of a genetic screen monitored in S. cerevisiae. Twelve proteins were found to accumulate in the nucleus upon irradiating or heavy metal stresses. Pat1 (YCR077C) currently described as a cytosolic mRNA decay activator was chosen and a more complete investigation about its activity was undertaken. By the mean of a TAP-tag approach combined with a shotgun proteomic analysis, the Pat1 interaction network was established without any stress and after UV stress illumination. Pat1 exhibits a domain potentially involved in its relocation that is subjected to multiple phosphorylations whose state enhances after UV stress. Finally, the data about the specific partners of Pat1 identified by proteomic analysis in stress condition were confirmed by the study of Pat1 relocation in the corresponding deleted strains. Altogether, our data suggest a novel function for the Pat1 protein that needs to be further investigated.

Muitos genes têm sido indicados como responsivos ao estresse genotóxico, mas devido à necessidade de validação, a busca por marcadores gênicos continua. Vários genes são relacionados ao sistema ubiquitina-proteassomo (UPS), o qual é responsável pela remoção seletiva de proteínas, sendo que falhas no UPS têm sido relacionadas a doenças neurodegenerativas e ao câncer. Assim, o presente trabalho teve como objetivo a busca e confirmação de marcadores gênicos de resposta ao estresse genotóxico, por meio do estudo da expressão transcricional e protéica dos genes ERN1, EIF2AK3, GADD153 e TRAF2, visando à confirmação das respostas em linhagens de fibroblastos (GM07492A e AS405) e de glioblastoma (U87MG), sob tratamentos com peróxido de hidrogênio (H2O2) e Bleomicina (Blm). Foram utilizados o Ensaio Cometa, a análise de expressão gênica transcricional por qPCR em tempo real e de expressão gênica ao nível protéico (imunofluorescência). Os resultados mostraram que os tratamentos empregados foram capazes de induzir danos no DNA, sendo que a sensibilidade ao tratamento e a capacidade de recuperação das linhagens foi variável dependendo do agente testado. A análise de expressão gênica mostrou que GM07492A apresentou indução dos genes ERN1 e GADD153 após tratamento com H2O2 (resposta precoce, zero e 2 h) e Blm (durante todo pós-tratamento). A linhagem AS405 exibiu indução de ERN1 e GADD153 para H2O2, enquanto que para Blm foram induzidos os genes EIF2AK3 e GADD153. Para U87MG, a indução de EIF2AK3 pelo H2O2 ocorreu de modo tardio, enquanto GADD153 mostrou-se induzido após ambos os tratamentos. A proteína ERN1 apresentou expressão discreta e pontual, inclusive nos pontos onde não houve indução transcricional, indicando uma expressão basal. Essa proteína se expressou em GM07492A no tratamento com Blm em zero hora, diferentemente de AS405. Para U87MG tratada com H2O2 observou-se discreta expressão de ERN1, sendo mais evidente para Blm. Quanto à proteína GADD153, esta foi expressa em fibroblastos nos vários tempos analisados. No entanto, U87MG mostrou expressão nuclear apenas nas células tratadas, sendo mais evidente para H2O2 comparativamente à Blm. Assim, as alterações observadas nos perfis de expressão gênica são compatíveis com a indução de danos no DNA, indicando o envolvimento de genes do UPS nas respostas celulares ao estresse genotóxico. Em conjunto, os resultados estimulam uma avaliação mais detalhada desses genes como marcadores de resposta ao estresse e evidencia a sua importância no cenário da via UPS. / Many genes have been reported as responsive to genotoxic stress, but due to the need of validation, the search for genetic markers still continues. Several genes are related to the ubiquitin-proteasome system (UPS), which is responsible for the selective removal of proteins, and UPS failures have been associated to neurodegenerative diseases and cancer. Thus, this study aimed the search and confirmation of genetic markers that were responsive to genotoxic stress. For this, we evaluated the transcriptional or protein expression of the genes ERN1, EIF2AK3, GADD153 and TRAF2, seeking confirmation of responses in fibroblast cell lines (GM07492A and AS405) and glioblastoma (U87MG) under treatment with hydrogen peroxide (H2O2) and bleomycin (BLM). We used the Comet Assay, the transcriptional analysis of gene expression by quantitative real-time PCR and protein expression byimmunofluorescence. The results showed that the treatments employed were able to induce DNA damage, and that cell sensitivity to treatments and recovery capability of cell lines varied according to the tested agent. The gene expression analysis showed that GM07492A presented induction of ERN1 and GADD153 genes after treatment with H2O2 (early response, zero and 2 h) and Blm (throughout the post-treatment). The cell line AS405 showed induction of GADD153 and ERN1 after H2O2, whereas with Blm the genes induced were EIF2AK3 and GADD153. For U87MG, the induction of EIF2AK3 by H2O2 occurred at a later stage, while GADD153 was promptly induced after both treatments. The protein ERN1 showed discreet and punctual expression, even at time point without transcriptional induction, indicating a basal expression. This protein was expressed in GM07492A by treatment with Blm at zero hour, differently of AS405. For U87MG treated with H2O2, ERN1 showed a slight expression, being more evident for Blm. Regarding GADD153, protein expression was observed in fibroblasts at all time point. However, U87MG showed nuclear expression only in cells treated with H2O2, being more evident that in BLM-treated cells. Thus, the observed changes in gene expression profiles are consistent with the induction of DNA damage, which indicates the participation of UPS genes in cellular responses to genotoxic stress. Together, the results encourage further evaluation of these genes as markers of stress response, demonstrating its importance in the UPS acting scope.

Μηχανισμοί οι οποίοι εξασφαλίζουν τη σωστή διαδοχή των φάσεων του κυτταρικού κύκλου συμβάλλουν στη διασφάλιση της γονιδιωματικής σταθερότητας των κυττάρων. Η αδειοδότηση της αντιγραφής του DNA, η συγκρότηση επί των αφετηριών της αντιγραφής του DNA του προ-ανιγραφικού συμπλόκου, καθορίζει τη σωστή χρονικά και τοπικά έναρξη της αντιγραφής. Βασικό συστατικό αυτού του συμπλόκου είναι ο παράγοντας Cdt1. Η Geminin προσδένεται στο Cdt1, αναστέλοντας τη δράση του από την S μέχρι και την Μ φάση, παρεμποδίζοντας, έτσι, την αδειοδότηση της αντιγραφής. Παρά το οτι φυσική αλληλεπίδραση των δύο πρωτεϊνών έχει δειχθεί τόσο in vitro όσο και in vivo, προηγούμενες μελέτες δείχνουν οτι έκφραση των Cdt1 και Geminin εντοπίζεται σε διαφορετικές φάσεις του κυτταρικού κύκλου. Τα φυσιολογικά κύτταρα, ανάλογα με τα μηνύματα που δέχονται, είτε παραμένουν σε μιτωτικό κύκλο, είτε εξέρχονται από αυτόν προς φάση ηρεμίας (ή G0), διαφοροποίηση ή γήρανση. Αυστηρός συντονισμός των παραπάνω διαδικασιών είναι απαραίτητος προκειμένου να διασφαλιστεί η ομοιόσταση των πολύπλοκων δομών των ιστών των μεταζώων. Προηγούμενες μελέτες προτείνουν το σύστημα της αδειοδότησης της αντιγραφής του DNA ως έναν βασικό ρυθμιστή της εξόδου από τον κυτταρικό κύκλο και της επανεισόδου στη G1. Οι παράγοντες Cdt1 και Geminin ρυθμίζονται αρνητικά κατά την έξοδο των κυττάρων σε G0, ενώ έκφρασή τους χαρακτηρίζει διαιρούμενα κύτταρα. Σε αντίθεση με τις άλλες καταστάσεις εκτός κυτταρικού κύκλου, λίγα είναι γνωστά αναφορικά με τη ρύθμιση των Cdt1 και Geminin κατά την κυτταρική γήρανση. Στο πρώτο μέρος της διατριβής εστιαστήκαμε στη μελέτη του προτύπου έκφρασης των Cdt1 και Geminin κατά τη διάρκεια του κυτταρικού κύκλου πρωτογενών ανθρώπινων ινοβλαστών, και στη σύγκρισή του με εκείνο των καρκινικών κυττάρων. Διαπιστώσαμε οτι τόσο η ενδοκυτταρική εντόπιση όσο και η ικανότητα των Cdt1 και Geminin να εκφράζονται σε συγκεκριμένες φάσεις του κυτταρικού κύκλου, δεν διαφοροποιούνται στους πρωτογενείς φυσιολογικούς ινοβλάστες σε σχέση με κύτταρα που προέρχονται από καρκινικό ιστό. Επιπλέον, δείξαμε οτι ο παράγοντας Cdt1 εκφράζεται αποκλειστικά σε BrdU-αρνητικά κύτταρα, σε αντίθεση με την Geminin, η οποία δείχνει να συσσωρεύεται σταδιακά μετά την έναρξη της S φάσης, ενώ δεν εντοπίστηκε συνέκφραση των δύο πρωτεϊνών στο χρονικό παράθυρο της G1/S μετάβασης. Στο δεύτερο μέρος της εργασίας εστιαστήκαμε στη μελέτη της έκφρασης του παράγοντα αδειοδότησης Cdt1 και του αρνητικού ρυθμιστή αυτού, Geminin, κατά την είσοδο των κυττάρων σε κυτταρική γήρανση και εξετάσαμε την πιθανή λειτουργική εμπλοκή τους στην εξέλιξη του φαινομένου. Δείξαμε οτι, ενώ οι παράγοντες Cdt1 και Geminin διατηρούν τη σωστή ενδοκυτταρική εντόπιση και το σωστό πρότυπο έκφρασης κατά τη διάρκεια του κυτταρικού κύκλου, υφίστανται αρνητική ρύθμιση σε κύτταρα που εισέρχονται σε κυτταρική γήρανση, τόσο αναπαραγωγική όσο και πρόωρη, επαγόμενη από οξειδωτικό στρες. Το γεγονός οτι η μείωση της έκφρασης της Geminin προηγήθηκε της εμφάνισης του γηρασμένου φαινοτύπου, μας ώθησε στην περαιτέρω διερεύνιση του λειτουργικού ρόλου της Geminin στην επαγωγή της κυτταρικής γήρανσης. Για το σκοπό αυτό, απορρυθμίσαμε τα επίπεδα έκφρασης της Geminin σε πρωτογενή φυσιολογικά κύτταρα ανθρώπου και ποντικού, αξιοποιώντας την τεχνολογία του RNAi και ρετροϊικά συστήματα υπερέκφρασης γονιδίων αντίστοιχα. Δείξαμε οτι η μείωση της έκφρασης της Geminin σε ανθρώπινους ινοβλάστες (χρησιμοποιώντας siRNAs αλλά και pSUPER πλασμιδιακούς φορείς αποσιώπησης γονιδίων που κατασκευάστηκαν ειδικά για την Geminin) επάγει αύξηση της κυτταρικής γήρανσης της καλλιέργειας. Επιπλέον, κύτταρα που στερούνταν της έκφρασης της Geminin ήταν πιο επιρρεπή σε γήρανση επαγόμενη από οξειδωτικό στρες, σε σχέση με τα κύτταρα-μάρτυρες. Ετεροζυγώτες για το γονίδιο της Geminin εμβρυικοί ινοβλάστες ποντικού εμφάνιζαν μεγαλύτερα ποσοστά κυτταρικής γήρανσης σε σχέση με τους αντίστοιχους ινοβλάστες αγρίου τύπου. Αντίθετα, αύξηση των επιπέδων της Geminin σε αγρίου τύπου εμβρυικούς ινοβλάστες ποντικού προκάλεσε μείωση της εμφανιζόμενης γήρανσης. Τέλος, η μείωση των επιπέδων έκφρασης του παράγοντα αδειοδότησης Cdt1 σε ανθρώπινα κύτταρα ήταν, επίσης, σε θέση να επάγει ισχυρό φαινότυπο κυτταρικής γήρανσης. Συνοψίζοντας, τα αποτελέσματα μας αναδεικνύουν την κρισιμότητα του ισοζυγίου Cdt1:Geminin στα κύτταρα, και προτείνουμε οτι η διατάραξη της ισορροπίας αυτής είναι ικανή να επάγει κυτταρική γήρανση, μέσω διαδικασιών όπως η υπεραδειοδότηση ή η υποαδειοδότηση της αντιγραφής του DNA. / Genome integrity relies on the strict alternation of S and M phases of the cell cycle, so that one and only round of DNA replication takes place per cell cycle. This is achieved through replication licensing, which involves the formation of a multi-protein complex, the pre-replicative complex, onto origins of replication. Cdt1 is a crucial component of this complex and Geminin, a small protein shown to tightly bind Cdt1, inhibits its licensing function from S to M phase, when licensing is illegitimate. Although previous experimental evidence shows that Cdt1 and Geminin are expressed in different phases of the cell cycle, physical interaction between these two proteins has been demonstrated in vitro as well as in vivo. The fate of a normal cell is not perpetual division. Cells may exit the mitotic cell cycle to enter quiescence, to terminally differentiate or to senesce. These “out-of-cycle-states” must be strictly regulated in order to establish and maintain the hierarchical organization of complex tissues in metazoa. Replication licensing has been proposed to coordinate cell-cycle exit and re-entry in vitro and in metazoan tissues. Cdt1 and Geminin down-regulation during exit to quiescence supports the idea that their expression correlates with cell proliferation. In contrast to other out-of-cycle states, little is known about the regulation of Cdt1 and Geminin expression during cellular senescence. Senescence refers to the irreversible resting state of cells grown for succeeding passages in culture, as a response to DNA damage caused by telomeres erosion. Other stimuli, such as oxidative or oncogenic stress, may force mitotically competent cells to respond similarly, a phenomenon termed as Stress Induced Premature Senescence (SIPS). The first part of this work focused on the study of the expression patterns of Cdt1 and Geminin during the unperturbed cell cycle of primary human fibroblasts and compared to that of tumor-derived cell lines. The cell cycle specific expression and the intracellular localization of both proteins, as assessed at a single-cell level using indirect immunofluorescence and a new monoclonal antibody against Geminin, appear similar in primary fibroblasts compared to the cancer cells examined. Cdt1 is strictly expressed in BrdU-negative cells, whereas Geminin starts accumulating after S phase onset. The two proteins are, therefore, not co-expressed at the ”time-window” of G1/S transition of the cell cycle. We showed that Cdt1 levels, but not those of Geminin, are mainly regulated in a proteasome-dependent way during normal cell cycle of human primary and cancer cells. The second part of this work focused on the investigation of Cdt1 and Geminin during cellular senescence and their possible role in the establishment of the senescence phenotype. To this end, primary human fibroblasts were maintained in culture for succeeding passages in order to induce them to undergo replicative senescence. Alternatively, an H202-induced senescence protocol was applied to force cells to undergo premature senescence (Stress-Induced Premature Senescence/SIPS). We show that, although Cdt1 and Geminin retain their nuclear localization and are correctly expressed during specific phases of the cell cycle during both replicative and Η202-induced premature senescence, their expression levels are down-regulated. In SIPS-experiments, Geminin down-regulation is an early event during the establishment of the senescent-phenotype, as assessed by senescence-associated β-Galactosidase and BrdU incorporation assays. This prompted us to further examine Geminin’s functional significance in the establishment of cellular senescence. To achieve this, we interfered with Geminin expression levels in human and mouse cells. Using RNA interference techniques, we were able to show that Geminin depletion from human cells is able to induce a senescent-phenotype in a fraction of the treated culture. Similarly, Geminin-depleted human cells were more susceptible to Η202-induced premature senescence, compared to control cells. Heterozygotes for Geminin mouse embryonic fibroblasts were more prone to senescence compared to their control counterparts. In contrast, when Geminin was over-expressed in control mouse embryonic fibroblasts cultures, senescent phenotype was reduced. Finally, a strong senescent-phenotype was induced when the licensing regulator, Cdt1, was silenced within human cells. Taken together, we conclude that Cdt1:Geminin balance within cells is crucial, and when disturbed, is able to promote a senescent phenotype, possibly through a mechanism that involves over- or under-licensing of DNA replication.

Made available in DSpace on 2014-12-17T14:13:21Z (GMT). No. of bitstreams: 1 PatriciaFM_tese.pdf: 303057 bytes, checksum: d3d1e5a21de3ce58bcfe65ef800c8734 (MD5) Previous issue date: 2008-05-13 / The uses of radiobiocomplexes labeled with technetium-99m contributed to health science advances. Stannous chloride (SnCl2) has been used as a reducing agent for the labeling process. Cytotoxic and genotoxic effect of the SnCl2 have been described in several studies and with this experimental models alterations in molecular and cellular level can be evaluated. In the last years the physicals therapists acquired new devices which emits electromagnetic radiation such us Extremely Low Frequency Pulsated Electromagnetic Fields (E.L.F. P.E.M.F.), radiofrequency, Intense Pulsed Light (I.P.L.) and others which emits sonic waves such us Biorresonance. Scientific evidence of the effects and dosage is important to protect public health and to reach exposition levels that result in significant biological effects. The aim of this project is to verify the effects of these physical agents in plasmid DNA and E. coli AB1157 cultures in presence or absence of SnCl2 and the effects in blood constituents labeled with technetium-99m. Wistar rats blood was exposed to the cited sources and the labelling of blood constituents with 99mTc was carried through. Cultures of E. coli AB1157 and plasmidial samples DNA had been also exposed the physical agents. The results suggest that these agents are capable of altering neither the survival of E. coli cells or plasmid DNA electrophoresis mobility. The multidiscipline character was clearly in this study due the interaction between Nuclear Medicine department of the UERJ and the Laboratory of Physical Agents of the Maimonides University in Argentina until the union between the teacher (biomedical and physiotherapist) and student (physiotherapist), besides collaborators of the area of Physics and Biology, promoting new ideas and perspectives and also adding the knowledge of different areas and origins / O uso de radiobiocomplexos marcados com 99mtecn?cio tem contribu?do para avan?os em Ci?ncias da Sa?de. Na marca??o desses radiobiocomplexos utiliza-se o redutor cloreto estanoso (SnCl2). Efeitos citot?xicos e genot?xicos do SnCl2 t?m sido descritos. Atrav?s de modelos experimentais em n?vel molecular, celular e sist?mico estas altera??es podem ser avaliadas. Entre os novos agentes f?sicos sugeridos para a pr?tica da Fisioterapia Dermato-Funcional, h? os que s?o de natureza eletromagn?tica (campos eletromagn?ticos pulsados, a radiofreq??ncia e a luz intensa pulsada) e os de natureza mec?nica (ondas s?nicas). A literatura a respeito dos agentes f?sicos gera d?vidas quanto aos seus efeitos. Seu uso correto ? importante n?o s? para proteger a sa?de p?blica, mas tamb?m para justificar n?veis de exposi??o que resultem em efeitos biol?gicos significativos. Dessa forma, o objetivo desse estudo ? verificar os poss?veis efeitos destes agentes f?sicos em plasm?dios bacterianos e em culturas bacterianas na presen?a e na aus?ncia de cloreto estanoso e na marca??o de elementos sang??neos com o 99mtecn?cio. Sangue de ratos Wistar foi exposto ?s fontes citadas e a marca??o de c?lulas sangu?neas com 99mtecn?cio foi realizada. Culturas de E. coli AB1157 e amostras DNA plasmidial tamb?m foram expostas aos agentes f?sicos. As consequ?ncias biol?gicas associadas a esses agentes n?o foram capazes de interferir em algumas propriedades dos constituintes sangu?neos, nem na sobreviv?ncia de E. coli ou na mobilidade eletrofor?tica do DNA plasmidial. O car?ter multidisciplinar ficou claro neste estudo desde a intera??o entre o Setor de Medicina Nuclear da UERJ e o Laborat?rio de Agentes F?sicos da Universidade Maimonides na Argentina at? a uni?o entre um orientador (biom?dico e fisioterapeuta) e uma orientanda (fisioterapeuta), contando com colaboradores da ?rea de F?sica e Biologia, possibilitando novas id?ias e perspectivas, agregando o conhecimento de diferentes ?reas

The green tea is considered a functional food with antioxidant activity, and this delays the process of old age and helps in the prevention of chronicle and degenerative diseases, such as cancer and heart affections. Of catechins, present in green tea, may is extremely important in the inactivation of free radicals, which provoke damages to the DNA molecules and to the cell membranes prevent the cytotoxicity induced by the oxidative stress in different tissues, by actuating in the process of chemoprevention. In this study two crosses, ST and HB aimed at evaluating the protective effects of green tea in three different concentrations (25, 50 e 75mg/mL), combined with the antitumor agent, doxorrubicin (DXR), of the genotoxic action; by the of wing spot test (SMART) of Drosophila melanogaster. The results obtained demonstrated that in MH descendants there was not a statistically significant increase in the frequencies of spots, in the individuals treated with green tea, in standard cross (ST) as well as in the high bioactivation cross (HB - characterized by a high constitutive level of cytochrome P450) . However we could observe a statistically significant decrease in the sum of mutant spots, in MH descendants of both crossings (ST and HB), in all concentrations of green tea associated to DXR. These results suggest that green tea does not present genotoxic effect, but presents protective affect against the mutagenic and recombinagenic action of DXR in the somatic cells of D. melanogaster, in the experimental concentrations used in this study. / O chá verde (CV) é considerado um alimento funcional com atividade antioxidante, que retarda o processo de envelhecimento e auxilia na prevenção de doenças crônicas e degenerativas, como o câncer e doenças cardiovasculares. As catequinas, presentes neste chá, podem inativar os radicais livres que causam danos na molécula de DNA e dessa maneira, prevenir a citotoxicidade induzida pelo estresse oxidativo, em diferentes tecidos, atuando no processo de quimioprevenção. Neste estudo dois diferentes cruzamentos, ST e HB foram utilizados para avaliar o efeito do CV em três diferentes concentrações (25, 50 e 75mg/mL) combinados com um agente tumoral, doxorrubicina (DXR), de comprovada ação genotóxica; através do teste para detecção de manchas (SMART) na asa de Drosophila melanogaster. Os resultados obtidos demonstram que para os descendentes MH não houve aumento, estatisticamente significativo, nas freqüências de manchas, nos indivíduos tratados apenas com CV, tanto no cruzamento padrão (ST) quanto no cruzamento de alta bioativação (HB - caracterizado pelo alto nível constitutivo de citocromo 450). Contudo, foi observada uma redução, estatisticamente significativa, no total de manchas mutantes, nos descendentes MH, de ambos os cruzamentos (ST e HB), em todas as concentrações do CV quando associadas com a DXR. Estes resultados sugerem que o CV não possui efeito genotóxico, e, apresenta efeito protetor contra a ação mutagênica e recombinogênica induzida pela DXR em células somáticas de D. melanogaster, nas concentrações experimentais utilizadas neste estudo. / Mestre em Genética e Bioquímica