Dissertation (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2008. / Vita. Bibliography: p.116-143

Thesis (Ph. D.)--University of Washington, 2007. / Includes bibliographical references (leaves 79-99).

Charles University Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Bc. Etela Kouklíková Supervisor: RNDr. Eva Novotná, Ph.D. Title of diploma thesis: Study of the effect of cyclin-dependent kinase inhibitors on the expression of selected AKR and CBR enzymes in human cell lines Cyclin-dependent kinase inhibitors (CDKi) are considered as a suitable treatment especially in patients with wrong prognosis or advanced stage of cancer. It has only recently been discovered that CDKi are able to influence the activity of some enzymes from aldo-keto reductase (AKR) and short-chain dehydrogenase/reductase (SDR) superfamilies. AKR and SDR enzymes belong to a group of carbonyl reducing enzymes that are involved in the metabolism of endobiotics and xenobiotics. An important group of drugs that are metabolized by these enzymes to less efficient compounds are anthracyclines. The aim of this diploma thesis was to find out whether purvalanol A, roscovitin, dinaciclib, AZD5438 and R547 can affect the expression of the most important anthracycline reductases (AKR1A1, AKR1B10, AKR1C3, AKR7A2 and CBR1) in human HepG2 and HL-60 cell lines. Expression of anthracycline reductases in cells exposed to CDKi was evaluated at mRNA level by RT-qPCR and at protein level by Western blotting. The...

Macrophage-conditioned medium (MacCM) inhibits the differentiation of rodent and human preadipocytes. Previous studies report that murine J774A.1-MacCM inhibits clonal expansion (early required phase of adipogenesis), including Rb phosphorylation. I hypothesized that MacCM induced alterations in cyclins and/or cyclin-dependent kinases (CDKs) were responsible for impairing Rb phosphorylation. My first objective was to assess the effect of J774A.1-MacCM on CDK4, CDK2, and their regulatory cyclins. Murine 3T3-L1 preadipocytes were differentiated with control medium or J774A.1-MacCM. Expression of cyclin D and A was inhibited by J774A.1-MacCM. Inhibition of cyclin A expression was associated with reduced differentiation-induced CDK2 activity. My second objective was to assess the expression patterns of cell cycle proteins in differentiating human abdominal subcutaneous preadipocytes, which do not undergo clonal expansion in culture. Cyclin E expression increased with differentiation. THP-1-MacCM (a human macrophage cell line) further enhanced this increase. My studies suggest MacCM leads to alterations in cyclin/CDK regulation during adipogenesis in murine and human preadipocyte models.

In cell culture, entry into mitosis of many adherent mammalian cells is accompanied by substantial changes in cellular architecture. Flat, spread-out interphase cells detach from the extracellular matrix and become more spherical. These changes in cell shape are mediated by rearrangements in the actin cytoskeleton, a dynamic network of actin filaments that are organized by actin-binding proteins. Filamin A (FLNa) is a 280 kD actin-binding protein that crosslinks actin filaments into parallel bundles or three-dimensional orthogonal networks. We previously identified FLNa as an in vitro substrate of cyclin-dependent kinase 1 (Cdk1), a kinase that regulates entry into mitosis, and hypothesized that Cdk1 phosphorylation of FLNa regulates mitotic actin remodelling. Using mass spectrometry and a p-FLNa antibody, we show that FLNa is phosphorylated in vivo in HeLa cells on multiple Cdk1 sites, including serines 1084, 1459 and 1533. All three sites match the phosphorylation consensus sequence of Cdk1. We further show that p-FLNa is almost fully dephosphorylated by anaphase, consistent with it being a cell cycle-regulated substrate. Using a phospho-specific antibody, we find that p-FLNa has decreased cortical actin localization compared to total FLNa in mitotic cells. To investigate the functional role of mitotic FLNa phosphorylation, we mutated serines 1084, 1459 and 1533 to nonphosphorylatable alanine and expressed this FLNa mutant (FLNa-S1084A, S1459A, S1533A, referred to as “FLNa-AAA GFP”) in FLNa-deficient human M2 melanoma cells. FLNa-AAA GFP-expressing cells have enhanced FLNa-AAA GFP localization at sites of contact between daughter cells and this correlates with defects in cell division and impaired cell migration. Therefore, mitotic delocalization of cortical FLNa is critical for successful cell division and interphase cell behaviour.

This thesis comprises three separate studies that investigate the consequences of supernumary centrosomes, the effect of centrosome loss, and a control mechanism for regulating CDK2/cyclin E activity in centrosome duplication. The centrosome is the major microtubule-organizing center of the cell. When the cell enters mitosis, it is of critical importance that the cell has exactly two centrosomes in order to properly segregate the chromosomes to two daughter cells. Supernumary centrosomes are a problem for the cell in that they increase the incidence of chromosomal instability. Aberrant centrosome numbers are seen in a number of cancers, and there has been a proposed connection between the loss of function of p53 and multiple centrosomes. We investigated the consequences of multiple centrosomes in p53-null mouse embryonic fibroblasts (MEFs) to determine how cells with multiple centrosomes can continue to propagate and become cancer. We found that even in the face of extra centrosomes, p53-null MEFs are able to divide in a bipolar fashion by bundling extra centrosomes into two spindle poles. The centrosome has also been proposed to play a role in cell cycle control. We followed up on a previous study, which had suggested that centrosome loss causes a G1 arrest. We found that cells did not arrest in G1 due to centrosome removal as previously reported, but instead the arrest was viii dependent on additional stressors, namely the incident light used for our long-term live-cell observations. Our study showed that centrosome loss is a detectable stress that, in conjunction with additional stresses, can contribute to cell cycle arrest. It is known that CDK2/cyclin E activity is required to promote centrosome duplication. But with the discovery of a centrosomal localization sequence (CLS) in cyclin E, we wanted to know if centrosome duplication required a specific sub-cellular localization of CDK2 kinase activity. We found that centrosome duplication in Xenopus extract was dependent on CLS-mediated centrosomal localization of cyclin E, in complex with CDK2. Our results point to a mechanism for regulating centrosome duplication in the face of high cytoplasmic CDK2/cyclin E kinase activity.

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京都大学 / 新制・課程博士 / 博士(医学) / 甲第25176号 / 医博第5062号 / 新制||医||1071(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 武藤 学, 教授 萩原 正敏, 教授 永井 純正 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser.

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