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Phycocyanin protects INS-1E pancreatic beta cells against human islet amyloid polypeptide-induced apoptosis through attenuating oxidative stress and mitochondrial dysfunction. / CUHK electronic theses & dissertations collectionJanuary 2010 (has links)
Additionally, cyclosporin A, an inhibitor of the mitochondrial permeability transition (MPT) pore, failed to prevent hIAPP-induced DeltaPsim collapse, cytochrome c and AIF release and caspase-3 activation, indicating that the MPT pore was not involved in hIAPP-induced apoptosis. On the other hand, potential crosstalk between the extrinsic and intrinsic apoptotic pathways was demonstrated by cleavage of Bid by caspase-8 in the apoptotic process triggered by hIAPP. / It is widely accepted that human islet amyloid polypeptide (hIAPP) aggregation plays an important role in the loss of insulin-producing pancreatic beta cells. Insulin secretion impairment and cell apoptosis can be due to mitochondrial dysfunction in pancreatic beta cells. hIAPP-induced cytotoxicity is mediated by the generation of reactive oxygen species (ROS). Phycocyanin (PC) is a natural compound from blue-green algae that is widely used as food supplement. Currently, little information is available about the effect of hIAPP on mitochondrial function of beta cells and protection of PC against hIAPP-induced cytotoxicity. In this thesis, I hypothesize that hIAPP may impair beta cell function with the involvement of mitochrondrial dysfunction, and this effects could be attenuated by PC. Therefore, the aim of this study was to investigate the role of mitochondria in hIAPP-induced apoptosis, the in vitro protective effects of PC and explore the underlying mechanisms. / It was found that hIAPP induced apoptosis in INS-1E cells with the disruption of mitochondrial function, as evidenced by ATP depletion, mitochondrial mass reduction, mitochondrial fragmentation and loss of mitochondrial membrane potential (DeltaPsim). Further molecular analysis showed that hIAPP induced changes in the expression of Bcl-2 family members, release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria into cytosol, activation of caspases and cleavage of poly (ADP-ribose) polymerase. Interestingly, the hIAPP-induced mitochondrial dysfunction in INS1-E cells was effectively restored by co-treatment with PC. / Our results showed that hIAPP inhibited the INS-1E cell growth in a dose-dependent manner. However, cytotoxicity of hIAPP was significantly attenuated by co-incubation of the cells with PC. hIAPP induced DNA fragmentation and chromatin condensation, which were key characteristics of cell apoptosis. These changes were inhibited by PC as examined by TUNEL assay and DAPI staining. Moreover, PC significantly prevented the hIAPP-induced overproduction of intracellular ROS and malonaldehyde (MDA), as well as changes of activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzymes. Furthermore, hIAPP triggered the activation of mitogen-activated protein kinases (MAPKs) such as c-Jun N-terminal kinase (JNK) and p38 kinase, and these effects were effectively suppressed by PC. / Taken together, I have demonstrated for the first time the involvement of mitochondrial dysfunction in hIAPP-induced INS-1E cell apoptosis, which was attenuated by PC through attenuating oxidative stress, modulating JNK and p38 pathways and reducing mitochondrial dysfunction. / Li, Xiaoling. / Adviser: Juliana Chung Ngor Chan. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 150-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
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Expressão de tireotrofina humana em células de embrião de rim humano (HEK293) / Human tryrotropin expression in human embrionic kidney cells (HEK293)SANTANA, PATRICIA M. 22 December 2016 (has links)
Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-12-22T16:39:39Z
No. of bitstreams: 0 / Made available in DSpace on 2016-12-22T16:39:39Z (GMT). No. of bitstreams: 0 / Neste trabalho foi transfectada uma linhagem de células embrionárias de rim humano (HEK293) com os genes das subunidades α e β da tireotrofina humana (hTSH), hormônio glicoproteico secretado pela hipófise. Após 5 dias de cultivo obteve-se uma concentração de hTSH no meio condicionado de 0,95μg/mL. O material foi concentrado e purificado utilizando uma estratégia envolvendo duas etapas, uma cromatografia de troca catiônica e uma cromatografia líquida de alta eficiência (HPLC) de fase reversa, que permitiu uma recuperação de 55% e uma pureza >90%. O produto purificado (hTSH-HEK) foi analisado e comparado a uma preparação comercial obtida em células CHO (hTSH-CHO) e a uma preparação hipofisária (hTSH-Pit). A identidade e a pureza do hTSH-HEK foram avaliadas por métodos físicoquímicos e imunológico (espectrometria de massa MALDI-TOF, HPLC de exclusão molecular e de fase reversa, SDS-PAGE e ensaio imunoradiométrico). A porção glicídica do hTSH-HEK foi avaliada pela análise do perfil dos N-glicanos e o comportamento biológico deste hormônio foi avaliado por bioensaio in vivo e estudo farmacocinético. As 3 preparações apresentaram pureza equivalente (97%) e a massa molecular relativa do hTSH-HEK foi 2,1% menor do que a do hTSH-CHO e 2,7% maior do que a do hTSH-Pit. A maior hidrofobicidade relativa, avaliada por RP-HPLC, foi a do hTSH-HEK. Os N-glicanos identificados no hTSH-HEK foram do tipo complexo, apresentando predominantemente estruturas tri-antenárias, enquanto no hTSH-CHO e no hTSH-Pit as estruturas bi-antenárias foram predominantes. Foram detectadas diferenças significativas relacionadas à composição dos carboidratos para estas preparações, um teor muito menor de ácido siálico e muito maior de fucose foram observados no hTSHHEK. Foi confirmada a atividade biológica das 3 preparações, sendo a bioatividade do hTSHHEK 39% e 16% inferior à do hTSH-CHO e hTSH-Pit, respectivamente. A meia-vida circulatória do hTSH-HEK foi menor (1,5 X) que a do hTSH-CHO e a do hTSH-Pit (1,2 X). De acordo com esses resultados o hTSH-HEK pode ser considerado uma alternativa viável para aplicações clínicas especialmente por sua origem humana e composição de carboidratos. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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