Navegando por Palavras-chave "Cell Cycle"
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- ItemSomente MetadadadosA atuação conjunta de SWI4 e SWI6 na ativação ciclo-celular dependente da expressão do gene HO em Saccharomyces cerevisiae(Universidade Federal de São Paulo (UNIFESP), 1992) Taba, Maria Rita Miyagusko [UNIFESP]
- ItemSomente MetadadadosImunoespressão de p53, p21Waf1/Cip1, p27 Kip1, Bcl2, caspase-3-clivada e Hsp27 em neoplasias intraepiteliais e cânceres invasivos cérvicas(Universidade Federal de São Paulo (UNIFESP), 2007) Dobo, Cristine [UNIFESP]; Oshima, Celina Tizuko Fujiyama [UNIFESP]
- ItemAcesso aberto (Open Access)Papel da caspase-3 na quiescência dos gonócitos de ratos(Universidade Federal de São Paulo (UNIFESP), 2019-01-31) Santos, Marina Nunes Dos [UNIFESP]; Teixeira, Taiza Stumpp [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)The germ cell lineage arises from a progenitor cell population in the epiblast called primordial germ cells (PGC). These cells erase their somatic program and enter a germ cell program after what they migrate to the gonads through the gut endoderm and their dorsal mesentery. During their migration and just after they enter the gonadal ridges, the male PGC proliferate for a short period and then enter in quiescence. These cells are then called gonocytes. Because gonocytes are quiescent cells, very few studies about them are available, so that the mechanisms of the quiescence establishment and regulation are not well known. Studies by our group showed that rat gonocytes are mitotic until 18 days post coitum (dpc) and enter in quiescence at 19dpc. During this period, they stay arrested in G0/G1 and no death or proliferation is observed. Our group also showed very abundant and intense caspase-3 (Casp3) labeling in the cytoplasm of all gonocytes, suggesting that this enzyme may play a non-apoptotic role during rat gonocyte quiescence. In addition, there is evidence that Casp3 cleaves the pluripotent marker NANOG in embryonic stem cells, which is also expressed by the male germ cells. Aim: The aim of this study was to investigate if Casp3 and NANOG interact and whether the inhibition of Casp3 activity leads to alterations of the expression of cell cycle genes in the quiescent gonocyte. Methods: For this, 19dpc testis were collected, dissociated and the isolated gonocytes were incubated in vitro with Casp3 inhibitor for 24h. The expression of cell cycle, apoptosis and pluripotency markers was analyzed by qPCR. Gonocyte viability was investigated by propidium iodide and flow cytometry. Protein extraction was performed from whole 19dpc testes for the investigation of Casp3 and NANOG protein expression. Results: The analysis of gonocyte viability showed that the cultures treated with Casp3 inhibitor presented more dead gonocytes than the control cultures. The inhibition of Casp3 also lead to an increase of Pcna expression as well as a decrease of p21cip, p27kip, Bcl2 and Kras expression. When compared with gonocytes that were not maintained in culture for 24h, the cultured gonocytes showed an increase of p21cip expression in control and treated cultures and of p27kip in the control cultures. The expression of Sox2 and Nanog was not detected in the cultured gonocytes, although Sox2 have been detected in non-cultured gonocytes. Casp3 protein was detected in 19dpc testis extract, although NANOG protein was not detected. Conclusion: The results obtained here lead us to conclude that Casp3 inhibition affects the expression of classical cell cycle markers, suggesting that this enzyme plays a non-apoptotic role in male germ cell development by controlling the cell cycle.
- ItemSomente MetadadadosTrypanosoma cruzi: Uma nova visão de um velho conhecido(Universidade Federal de São Paulo (UNIFESP), 2010-08-25) Ramos, Thiago Cesar Prata [UNIFESP]; Schenkman, Sergio [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Trypanosoma cruzi is the protozoan that causes Chagas’ disease. It divides in the insect vector gut or in the cytosol of an infected mammalian cell. Although the protozoan ultrastructure has been extensively described, little is known about how it changes at the ultrastructural level during the cell division cycle. T. cruzi has one mitochondrion one Golgi complex, one flagellum and one cytostoma. To better understand how the organelles are distributed during its cell cycle, here we provide 3D reconstructions based on images obtained from serial sections on electron microcopy of these parasites at different stages of cell cycle. The parasites were fixed in a mixture of formaldehyde e glutaraldehyde, post-fixed in osmium tetroxide, contrasted with a solution of uranyl acetate membrane contrast enhancement, dehydrated in ethanol and embedded in Epon resin. Ultrathin serial sections of parasites were obtained, analyzed and photographed in a transmission electron microscope JEOL, model, JEM1200EX2. "Reconstruct" software was used for alignment and mounting stacks for the production of a representative 3D models. Subsequently, models of certain structures were merged with the "Blender 3D" modeling software. The localization and distribution of organelles were evaluated and attributed to specific morphological patterns as deduced by distribution of markers by immunofluorescence analysis. We observed an interconnected heterochromatin G1 to G2 phases. The disk shaped kinetoplast, which is the mitochondrial DNA, duplicates at G2 phase, and its division starts from the interior, when the new flagellum is present. The kinetoplast is accommodated within the unique and highly branched mitochondrion, with similar shapes in cells before and after entry into G2. There is an increase in the size and number of intracellular vesicles. The single Golgi complex, localized in the anterior part of the cell, enlarges before division. There is a progressive retraction of the cytostome relative to the nucleus probably to allow formation of a new endocytic structures. This study provides new informations about the parasite anatomy during different stages of the cell division cycle.