RESUMO
OBJECTIVE: To develop a system for the culture of murine preantral ovarian follicles using Human Serum Albumin (HSA) and Human Platelet Lysate (PLTMax). METHODS: Mechanically isolated preantral follicles (N=146) were obtained from Swiss mice and cultured in DMEM:F12 medium for ten days in a 96-well plate with conical bottom. The medium was supplemented with penicillin, streptomycin, and equine chorionic gonadotropin. Additional proteins were tested in 4 test groups: G1: human serum albumin (HSA), G2: human platelet lysate (PLTM), and G3 and G4: HSA + PLTMax at lower and higher concentrations, respectively. Cellular vitality and oocyte morphology were evaluated on day 11 of culture. RESULTS: The highest follicular growth (3.4 fold) was achieved in HSA (G1), while a significantly lower (1.8 fold) growth was achieved in the presence of PLTM (G2, G4) and even further reduced (1.2 fold) when HSA and PLTM were combined (G3). Cellular vitality was close to 70-80% among the four groups, and the highest number of intact oocytes were found in G1. CONCLUSIONS: PLTM did not improve follicular development and oocyte maturation compared to HSA but preserved cell vitality.
RESUMO
A proteína prion celular (PrPC) é altamente expressa no sistema nervoso e sua. modificação estrutural está relacionada as encefalopatias espongiformes transmissíveis.. PrPC associa-se com proteínas de matriz extracelular, como a laminina (Ln) e. vitronectina (Vn) e também com a co-chaperonina stress inducible protein 1 (STI1).. Estes complexos estão envolvidos em diferentes processos relacionados ao. desenvolvimento do sistema nervoso. No desenvolvimento embrionário de camundongo. a distribuição de PrPC, Vn e STI1 é espaço-temporalmente relacionada, iniciando-se a. partir do oitavo dia embrionário para STI1 e Vn e no décimo para PrPC. As três proteínas. apresentam um padrão de expressão na medula espinhal em forma de gradiente, com. maior expressão na região ventral do tubo neural e notocorda e diminuindo na porção. dorsal, o que sugere o seu envolvimento na organização do sistema nervoso. A STI1. assim como o peptídeo da cadeia γ1 laminina (Ln-γ1), correspondente ao domínio de. ligação de PrPC, são capazes de promover axonogênese em neurônios de gânglios da raiz. dorsal. Quando combinados, Ln-γ1 e STI1 apresentam um efeito sinérgico sobre a. axonogênese através da mobilização intracelular de cálcio e pela ativação de Erk1/2. O. aumento na concentração intracelular de cálcio pela ligação de STI1 a PrPC é mediado. pela abertura de canais presentes na membrana. Por outro lado, o complexo PrPC-Ln-γ1. mobiliza cálcio a partir de estoques intracelulares. A interação PrPC-STI1 também é. importante na biologia de células tronco neurais. Precursores neurais (neuroesferas). derivados de animais deficientes para PrPC apresentam comprometimento de autorenovação. quando comparados aqueles provenientes animais tipo-selvagem. A ligação. de STI1 a PrPC promove um aumento na proliferação de precursores neurais,. desempenhado um papel chave nos mecanismos de auto-renovação destas. Portanto,. PrPC é capaz de se associar a diferentes ligantes desempenhando um papel relevante no desenvolvimento do sistema nervoso central e periférico.
The cellular prion protein (PrPC) is highly expressed in thenervous system and its structural modification is associated to transmissible espongiform encephalopathies. PrPC associates with extracellular matrix proteins, such as laminin (Ln) and vitronectin (Vn) and also to the co-chaperonin stress inducible protein 1 (STI1).These PrPC complexes are involved in to the development of the nervous system. During the mouse embryo development, PrPC , Vn and STI1 distribution is spatiotemporally related. STI1 and Vn expression became evident at embrionary day 8 (E8), while PrPC is initialy detected at E10. These three proteins present a gradient of expression in spinal cord, more abundant in the notochord and floor plate, suggesting that they can have a role in brain patterning. STI1 as well as the peptide from laminin γ1 chain (Ln-γ1), which corresponds to PrPC binding site, are able to promote axonogenesis in dorsal root ganglia neurons. When combined, STI1 and Ln-γ1 shown a synergic effect upon axonogenesis through intracellular Ca2+ mobilization and Erk1/2 activation. The increment of intracellular Ca2+ promoted by STI1 binding to PrPC is mediated by Ca2+ channels at the plasma membrane. On the other hand, the complex Ln-γ1-PrPC mobilizes Ca2+ from intracellular stores. The interaction between PrPC and STI1 is also important in neural stem cells biology. Neural precursors (neurospheres) derived from PrPC -null mice present impairment of selfrenewal compared to wild-type neuronal precursors. In addition, STI1 binding to PrPC promotes the proliferation of neural precursors, performing a key role in the self-renewal of stem cells. Thus, PrPC is able to associate with different ligands and presents a relevant role in the development of central and peripheric nervous system.
