Hepatoma-derived growth factor (HDGF) is a nucleus-targeting mitogen for various types of cells. Besides, HDGF overexpression is associated with tumor progression and poor survival outcome in patients with hepatocellular carcinoma (HCC) and lung cancer. HDGF is capable of promoting the proliferation and migration in various types of cells. HDGF is composed of 240 amino acids and contains 2 putative bipartite nuclear localization signals (NLSs). By dividing HDGF into two deletion domains: PWWP (residues 1-100) and C140 (residues 101-240), we found that both PWWP and C140 domains are capable of promoting nuclear localization, However, only C140 domain promoted cell proliferation and migration as HDGF. Mutation in NLS domains abrogated the nuclear localization and growth-promoting function, but not the migratory potential of HDGF. Beside, Ser165 was predicted as putative cdc2 phosphorylation site. In vitro kinase assay indicated that Ser165 of HDGF is the phosphorylated site of cdc2 kinase. We also demonstrated that mutations in cdc2 phoshprylation site did not affect the nuclear localization, proliferation-stimulating activities of HDGF but enhance migration-stimulating abilities of HDGF. Recently, the HDGF domain containing residues 81 to 100 is shown to be responsible for binding to membrane receptor in NIH3T3 cells. Besides, Lys96 plays a pivotal role for receptor binding. By generation of HDGF Lys96A mutant protein, we found that mutation of Lys96 indeed caused a prominent reduction in cellular binding affinity of HDGF to NIH3T3 cells and affect cell migration. In summary, the NLSs are essential for the mitogenic effect of HDGF, but not required for migration. And the cdc2 phoshorylation site is important for NIH3T3 migration. The Lys96 of HDGF play an important role of membrane receptor binding and cell migration.

Les cellules T folliculaires helper (Tfh) jouent un rôle central dans la mise en place de réponses humorales efficaces. En effet, les Tfh participent à la sélection des lymphocytes B permettant le développement de lymphocytes B mémoires et d’anticorps de haute affinité. Les Tfh représentent ainsi une cible prometteuse pour la mise en place de nouvelles stratégies thérapeutiques, notamment pour augmenter l’efficacité de la vaccination. Ainsi, il apparaît crucial de mieux comprendre les étapes menant à leur développement, en particulier chez l’Homme. L’initiation de la polarisation Tfh se déroule dans les organes lymphoïdes secondaires et met en jeu les cellules myéloïdes mononucléaires (MMC). Les MMC présentes dans les organes lymphoïdes comprennent les macrophages résidents et trois sous populations de DC résidentes : les cDC1 (CD141+), les cDC2 (CD1c+) et les pDC. Nous nous sommes plus particulièrement intéressés au rôle respectif des sous populations de MMC humaines dans l’induction de la polarisation Tfh. Ainsi, les travaux effectués au cours de ma thèse avaient pour objectifs dans un premier temps d’analyser la capacité des différentes populations de MMC à induire la polarisation Tfh, afin de mettre en évidence de potentielles spécialisations fonctionnelles. Dans un second temps, nous nous sommes concentrés sur les mécanismes moléculaires impliqués dans l’induction par les MMC de la polarisation Tfh. Nous avons montré une spécialisation fonctionnelle des cDC2 et des macrophages des amygdales pour la polarisation Tfh. Toutefois, des différences ont été observées entre les cDC2 et macrophages, puisque les macrophages induisent la sécrétion par les lymphocytes T d’une grande quantité de CXCL13 par rapport au cDC2, qui sont plus efficaces pour induire la production d’IL21. Nous avons pu également montrer que les cDC2 et macrophages sécrétaient des cytokines précédemment identifiées comme ayant un rôle dans l’induction des Tfh telles que IL12p70, ActivinA et TGFβ. Afin de confirmer le rôle de ces cytokines dans la polarisation induite par les MMC d’amygdales, nous avons utilisé des anticorps bloquants dans nos expériences de polarisation T helper. Ainsi, nous avons confirmé le rôle de l’IL12p70, de l’Activin A et du TGFβ dans l’induction des Tfh humains. Nos résultats suggèrent également un rôle de l’Activin A et de TGFβ dans l’induction de la sécrétion de CXCL13, alors que l’IL12p70 serait impliqué dans l’induction de la sécrétion d’IL21. Nos résultats suggèrent aussi l’existence de deux sous populations de Tfh caractérisées soit par l’expression d’IL21 soit par l’expression de CXCL13. Les travaux réalisés au cours de ma thèse enrichissent ainsi les connaissances sur la spécialisation fonctionnelle des sous populations de DC et des macrophages humains, et apportent de nouveaux éléments pour la compréhension de la différenciation des Tfh humains. / T follicular helper cells (Tfh) play a key role in the establishment of efficient humoral responses. Indeed, Tfh are involved in B lymphocyte selection allowing the development of high affinity memory B cells and antibodies. Tfh are promising targets for new therapeutic strategies, especially to increase the effectiveness of vaccination. Thus, it is crucial to better understand the stages leading to their development, especially in human. Initiation of Tfh polarisation occurs in secondary lymphoid organs and involves mononuclear myeloid cells (MMC). MMC from secondary lymphoid organs include resident macrophages and three subsets of resident Dendritic Cells (DC): cDC1 (CD141+), cDC2 (CD1c+) and pDC. We were particularly interested in human MMC subsets respective roles in the induction of Tfh polarisation. Thus, the work carried out during my thesis aimed first at analysing the ability of different populations of MMC to induce Tfh polarisation, in order to highlight potential functional specialisations. In a second step, we focused on the molecular mechanisms involved in Tfh polarisation by MMC. We have shown a functional specialisation of cDC2 and tonsillar macrophages for Tfh polarisation. However, differences have been observed between cDC2 and macrophages, since macrophages induce secretion by T cells of a large amount of CXCL13 compared to cDC2, which are more effective in inducing IL21 production. We have also been able to show that cDC2 and macrophages secreted cytokines previously shown to play a role in Tfh induction such as IL12p70, ActivinA and TGFβ. In order to confirm the role of these cytokines in Tfh polarisation induced by tonsil MMCs, we used blocking antibodies in our T helper polarisation experiments. Thereby, we confirmed the role of IL12p70, Activin A and TGFβ in the induction of human Tfh. Our results also suggest a role for Activin A and TGFβ in inducing secretion of CXCL13, whereas IL12p70 would be involved in the induction of IL21 secretion. Besides, our results suggest the existence of two Tfh subsets characterised by expression of either IL21 or CXCL13. The work performed during my thesis broadens the knowledge on the functional specialisation of human DC subsets and macrophages, and provides new insight into the differentiation of human Tfh.

Orientador: Patrícia de Oliveira Prada / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-21T14:12:45Z (GMT). No. of bitstreams: 1 Quaresma_PaulaGabrieleFernandes_M.pdf: 949361 bytes, checksum: 237d0acc0b5bc5358adba045381b4a92 (MD5) Previous issue date: 2012 / Resumo: O hipotálamo é um órgão crucial na regulação do balanço energético por integrar sinais hormonais e nutricionais de órgão periféricos. O hormônio produzido pelo pâncreas - insulina - e o hormônio derivado de células adiposas - leptina- reconhecidamente, agem no SNC controlando a ingestão alimentar e o gasto energético. Recentemente foi demonstrado que a fosforilação em treonina 343 da proteina Cdc2-like kinase 2 (Clk2) é induzida pela sinalização de PI3-q/Akt no fígado. Esta regulação envolve a repressão de genes que controlam a gliconeogênese e produção de glicose hepática, levando a hipoglicemia. Porém, não há informações de que a insulina ou a leptina podem regular a Clk2 no hipotálamo in vivo. Camundongos das linhagens Swiss, db/db e C57/BL6J com oito semanas de idade foram utilizados nos experimentos. Nossos resultados mostraram que a Clk2 é expressa e regulada por insulina e leptina em hipotálamo e também que a inibição da Clk2 causou aumento da adiposidade e ingestão alimentar, diminuição do gasto energético e alterações na expressão de neuropeptídeos e do metabolismo de glicose. Além disso, a fosforilação no sítio treonina 343 da Clk2 está diminuída em animais com obesidade induzida por dieta e geneticamente obesos (db/db). A avaliação da gliconeogênese hepática em animais com a proteína Clk2 inibida via ICV mostrou uma tendência ao aumento da produção hepática de glicose, revelando uma possível participação da proteína Clk2 no controle hipotalâmico da gliconeogênese hepática. Sendo assim, podemos sugerir que a Clk2 hipotalâmica é importante no controle do balanço energético pois sua inibição acarreta obesidade acompanhada por aumento da ingestão alimentar e diminuição do gasto energético, e também podemos sugerir um papel no controle hipotalâmico da produção hepática de glicose / Abstract: The hypothalamus plays an important role in the regulation of whole-body energy balance by integrating nutrients and hormones signals from peripheral inputs. The pancreatic hormone - insulin - and the adipocyte hormone - leptin - are known to act in the CNS controlling food intake and energy expenditure. Leptin and insulin signaling regulate anorexigenic neuropeptide expression. Recently, it was shown that Cdc2-like kinase 2 (Clk2) threonine 343 phosphorylation is induced by PI3K/Akt signaling in the liver. This regulation is involved in the repression of gluconeogenic gene expression and hepatic glucose output leading to hypoglycemia. Thus, it was not shown if insulin or leptin are able to regulate Clk2 threonine 343 phosphorylation in the hypothalamus in vivo. Swiss, db/db and C57/BL6J mice eight-weeks-old were used to proceed the experiments. Our data show that Clk2 is expressed and regulated by insulin and leptin in hypothalamus and hypothalamic Clk2 inhibition increased adiposity and food intake, decreased energy expenditure and disrupted neuropeptides expressions and glucose metabolism. Indeed, Clk2 threonine 343 phosphorylation is impaired in the hypothalamus of DIO and db/db mice. Hepatic gluconeogenesis was evaluated and showed increase in ICV inhibited Clk2 mice, it is plausible that Clk2 participates of hypothalamic control of hepatic gluconeogenesis. We suggest that hypothalamic Clk2 is crucial to control energy balance because its inhibition triggers obesity accompanied by increased food intake, decreased energy expenditure and increased hepatic gluconeogenesis / Mestrado / Clinica Medica / Mestra em Ciências

Several cell cycle events require specific forms of the cyclin-CDK complexes. It has been known for some time that cyclins not only contribute by activating the CDK but also by choosing substrates and/or specifying the location of the CDK holoenzyme. There are several examples of B-type cyclins identifying certain peptide motifs in their specific substrates through a conserved region in their structure. Such interactions were not known for the G1 class of cyclins, which are instrumental in helping the cell decide whether or not to commit to a new cell cycle, a function that is non-redundant with B-type cylins in budding yeast. In this dissertation, I have presented evidence that some G1 cyclins in budding yeast, Cln1/2, specifically identify substrates by interacting with a leucine-proline rich sequence different from the ones used by B-type cyclins. These “LP” type docking motifs determine cyclin specificity, promote phosphorylation of suboptimal CDK sites and multi-site phosphorylation of substrates both in vivo and in vitro. Subsequently, we have discovered the substrate-binding region in Cln2 and further showed that this region is highly conserved amongst a variety of fungal G1 cyclins from budding yeasts to molds and mushrooms, thus suggesting a conserved function across fungal evolution. Interestingly, this region is close to but not same as the one implicated in B-type cyclins to binding substrates. We discovered that the main effect of obliterating this interaction is to delay cell cycle entry in budding yeast, such that cells begin DNA replication and budding only at a larger than normal cell size, possibly resulting from incomplete multi-site phosphorylation of several key substrates. The docking-deficient Cln2 was also defective in promoting polarized bud morphogenesis. Quite interestingly, we found that a CDK inhibitor, Far1, could regulate the Cln2-CDK1 activity partly by inhibiting the Cln2-substrate interaction, thus demonstrating that docking interactions can be targets of regulation. Finally, by studying many fungal cyclins exogenously expressed in budding yeast, we discovered that some have the ability to make the CDK hyper-potent, which suggests that these cyclins confer special properties to the CDK. My work provides mechanistic clues for cyclinspecific events during the cell cycle, demonstrates the usefulness of synthetic strategies in problem solving and also possibly resolves long-standing uncertainties regarding functions of some cell cycle proteins.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 170-189.

2-Methoxyestradiol (2ME) is an endogenous estrogen metabolite with antiproliferative and antiangiogenic properties. 2ME also plays an active role in the induction of apoptosis, especially in cancerous cells. These properties have been confirmed by various in vitro and in vivo studies and render 2ME a potential antitumor agent. The mechanism of action of 2ME, however, is not yet fully elucidated and it is believed that multiple mechanisms are involved that may be dependent on cell type. The aim of this study was to investigate the differential effects of 2ME on cell growth, morphology and spindle formation in the non-tumorigenic MCF-12A breast cell line and the tumorigenic MCF-7 breast cell line. In dose-dependent studies, cell growth was determined spectrophotometrically. Light microscopy was used to investigate the morphological changes induced by 2ME and its effect on spindle formation was investigated by means of indirect immunofluorescence. The estrogen receptor status of the MCF-12A cells was confirmed with immunocytochemistry. In order to investigate the effect of 2ME on the length of the cell cycle, cells were blocked in early S-phase with hydroxyurea, then allowed to continue through the cell cycle and mitotic indices determined at regular time intervals. Checkpoint kinase and Cdc2 kinase assays were used to determine the effect of 2ME on relevant cell cycle kinases. Although 2ME inhibited cell growth in both cell lines, the MCF-7 cells were inhibited from much lower concentrations and growth inhibition was more pronounced than in the MCF-12A cells. Treated MCF-7 cells showed abnormal metaphase cells, membrane blebbing, apoptotic cells and disrupted spindle formation. These observations were either absent, or not as prominent in the MCF-12A cells. Therefore, differential mechanism(s) of growth inhibition are evident between the normal and tumorigenic cells. Although the two cell lines differ in their estrogen receptor status, this could not explain the differential effects, for 2ME has a very low affinity for the estrogen receptor. 2ME had no effect on the length of the cell cycle, but blocked MCF-7 cells in mitosis. There were no significant alterations in the phosphorylation status of Cdc25C after 2ME treatment. However, Cdc2 activity was increased to a greater extend in the MCF-7 cells than in the MCF-12A cells. Therefore, it is suggested that exposure to 2ME disrupts mitotic spindle formation and enhances Cdc2 kinase activity, leading to persistence of the spindle checkpoint and thus prolonged metaphase arrest, which may result in the induction of apoptosis. The tumorigenic MCF-7 cells are especially sensitive to 2ME treatment compared to the normal MCF-12A cells. 2ME shows potential for the treatment of breast cancer. Selecting the concentration of 2ME that has maximum inhibitory effect on tumorigenic, but minimal effect on normal cells is crucial in its possible application as antitumor agent. Furthermore, research concerning the differential action mechanisms of 2ME is essential to create a better understanding regarding the treatment of cancer and may possibly contribute to the development and/or improvement of novel chemotherapeutic agents. / Dissertation (MSc (Physiology))--University of Pretoria, 2008. / Physiology / unrestricted

The dichotomy between type 1 and 2 conventional DCs under steady-state conditions is well defined. Bosteels et al. demonstrate that, upon inflammation, cDC2s acquire a hybrid inf-cDC2 phenotype, sharing phenotype, gene expression, and function with cDC1s and monocyte-derived cells, to optimally boost CD4 and CD8 immunity via Fc receptors.

Activation of the MAPK cascade during mitosis is critical for spindle assembly and normal mitotic progression. The underlying regulatory mechanisms that control activation of the MEK/MAPK cascade during mitosis are poorly understood. The goal of my dissertation research is to identify the MEK kinase responsible for activation of the MAPK cascade during mitosis and to elucidate the biochemical mechanisms that regulate its activity. In the described herein work I purified and characterized the MEK kinase activity present in M-phase arrested Xenopus egg extracts. I demonstrate that B-Raf is the critical MEK kinase required for activation of the MAPK pathway at mitosis. Consistent with this, I show that B-Raf is activated in an M-phase dependent manner. Further, I provide data linking Cdk1/cyclin B to mitotic activation of B-Raf. Cdk1/cyclin B associates with and phosphorylates B-Raf in M-phase arrested extracts and directly targets Xenopus B-Raf in vitro at a conserved Ser-144 residue. Phosphorylation at Ser-144 is critical for M-phase dependent activation of B-Raf and for B-Raf's ability to trigger activation of the MAPK cascade at mitosis. Finally, I demonstrate that mitotic B-Raf undergoes feedback phosphorylation by MAPK at its conserved C-terminal SPKTP motif. Mutation of both phosphorylation sites within the SPKTP sequence to alanines increases activity of mitotic B-Raf. Further, inhibition or over-activation of MAPK during mitosis enhances or diminishes B-Raf activity, respectively. These results indicate that MAPK-mediated feedback phosphorylation negatively regulates B-Raf activity. Additionally, I show that active mitotic B-Raf exists in large multi-protein complex(s). By utilizing a proteomics approach I identify a set of proteins, which potentially associate with B-Raf at M-phase. Future studies are necessary to elucidate the involvement of these proteins in regulating B-Raf mitotic functions. In summary, my dissertation studies demonstrate that B-Raf activates MAPK signaling at mitosis and undergoes an M-phase dependent regulation. I propose that B-Raf has important functions at mitosis that contributes to its overall role in promoting cell proliferation.

Dissertation (Ph.D.)--University of South Florida, 2006. / Includes vita. Includes bibliographical references (leaves 166-187). Also available online.

The proper transmission of genetic materials into progeny cells is crucial for maintenance of genetic integrity in eukaryotes and fundamental for reproduction of organisms. To achieve this goal, chromosomes must be attached to microtubules emanating from opposite poles in a bi-oriented manner at metaphase, and then should be separated equally through proper spindle elongation in anaphase. Failure to do so leads to aneuploidy, which is often associated with cancer. Despite the presence of a safety device called the spindle assembly checkpoint (SAC) to monitor chromosome bi-orientation, mammalian cells frequently possess merotelic kinetochore orientation, in which a single kinetochore binds microtubules emanating from both poles. Merotelically attached kinetochores escape from the surveillance mechanism of the SAC and when cells proceed to anaphase cause lagging chromosomes, which are a leading cause of aneuploidy in mammalian tissue cultured cells. The fission yeast monopolin complex functions in prevention of mal-orientation of kinetochores including merotelic attachments during mitosis. Despite the known importance of Cdk1 activity during mitosis, it has been unclear how oscillations in Cdk1 activity drive the dramatic changes in chromosome behavior and spindle dynamics that occur at the metaphase/anaphase transition. In two separate studies, we show how dynamic Cdk1 phosphorylation regulates chromosome segregation. First, we demonstrate that sequential phosphorylation and dephosphorylation of monopolin by Cdk1 and Cdc14 phosphatase respectively helps ensure the orderly execution of two discrete steps in mitosis, namely sister kinetochore bi-orientation at metaphase and spindle elongation in anaphase. Second, we show that elevated Cdk1 activity is crucial for correction of merotelic kinetochores produced in monopolin and heterochromatin mutants.