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Evaluation of the involvement of apoptotic processes, necrotic and autophagic marrow hypoplasia in mice submitted to protein malnutrition

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Author(s):
Jackeline Soares de Oliveira Beltran
Total Authors: 1
Document type: Master's Dissertation
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
Defense date:
Examining board members:
Primavera Borelli Garcia; Joao Gustavo Pessini Amarante Mendes; Daurea Abadia de Souza
Advisor: Primavera Borelli
Abstract

Malnutrition can induce cell damage, compromising the mechanisms involved in proliferation, differentiation and cell death. Studies from our laboratory have demonstrated, in a murine model of protein malnutrition and protein-energy, marrow hypoplasia with histologic evidence of alteration of the extracellular matrix. Our objective was to evaluate the possible involvement of the processes of apoptosis, necrosis and autophagy in the development of bone marrow hypoplasia observed in this model. For this we used two groups of C57BL/6J adult male kept in metabolic gaioleiro. The control group (C) received normal protein diet containing 12% protein and undernourished group (D), fed low protein diet containing 2% protein. The protein source used was casein. The induction period of undernutrition was approximately five weeks, as defined by loss of 20 to 25% of body weight per part of group malnourished. After this period, the animals of both groups were anesthetized and held the collection of biological samples for nutritional assessment and hematology and bone marrow cells collected for evaluation of apoptosis, necrosis and autophagy. For assessment of apoptosis and necrosis of the cells were double labeled with Annexina V and PI caspase 3 were analyzed by flow cytometry. The expression of Bcl-2 was quantified by Western Blotting technique. The analysis revealed no statistical difference between the groups for these parameters. For evaluation of autophagy proteins extracted from bone marrow cells and evaluated the expression of proteins Akt and phosphorylated and total mTOR, complexes of mTOR (Raptor, and Rictor Gβl), Beclin-1 and LC3II. The results showed significant increase in overall mTOR, Raptor, and LC3II Beclin-1 and decreased phosphorylation of mTOR in cells derived from malnourished animals compared to the control group. Malnutrition did not modify the expression of Akt total, but decreased phosphorylation of Akt and decreased expression of the protein Rictor and Gβl cells analyzed. As apoptotic and autophagic processes can be difficult to detect in vivo, also redid the experiments in vitro, stimulating the cells with pro-apoptotic compounds (campotecina) and pro-autophagic (tamoxifen). In these experiments we observed that, when only stimulate cells with camptothecin malnourished, the same at 12 hours had a higher percentage of initial apoptosis compared to 0 hours, suggesting that there is a period in which cells are signaled to via malnourished being more susceptible to apoptotic stimuli. The animals starved cells stimulated after 12 h showed significant increase in apoptosis compared to control late stimulated, indicating that at that time there is an increase in apoptosis both in the initial process, both late process. Autophagy evaluated in kinetics of 0, 2, 6, 18 and 24 hours in vitro and observed a significant increase in autophagy in bone marrow cells of malnourished at 0 hours and after 18 hours stimulation with tamoxifen (20 microM) than the respective control, demonstrating that this period autophagy begins to be induced by stimulating more easily than the control. Autophagy is a major contributor to cellular metabolism, providing nutrients when they are unavailable, and therefore in our model of protein malnutrition in the marrow hypoplasia would autophagic process as a mechanism for survival and repair. (AU)

FAPESP's process: 10/13329-2 - Evaluation of the involvement of apoptotic processes, necrotic and autophagic marrow hypoplasia in mice submitted to protein malnutrition.
Grantee:Jackeline Soares de Oliveira Beltran
Support type: Scholarships in Brazil - Master