Navegando por Palavras-chave "Phospholipase"

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    HPV-16 E7 expression up-regulates phospholipase D activity and promotes rapamycin resistance in a pRB-dependent manner
    (Biomed Central Ltd, 2018) Rabachini, Tatiana; Boccardo, Enrique; Andrade, Rubiana; Perez, Katia Regina [UNIFESP]; Nonogaki, Suely; Cuccovia, Iolanda Midea; Villa, Luisa Lina
    Background: Human Papillomavirus (HPV) infection is the main risk factor for the development and progression of cervical cancer. HPV-16 E6 and E7 expression is essential for induction and maintenance of the transformed phenotype. These oncoproteins interfere with the function of several intracellular proteins, including those controlling the PI3K/AKT/mTOR pathway in which Phospolipase D (PLD) and Phosphatidic acid (PA) play a critical role. Methods: PLD activity was measured in primary human keratinocytes transduced with retroviruses expressing HPV-16 E6, E7 or E7 mutants. The cytostatic effect of rapamycin, a well-known mTOR inhibitor with potential clinical applications, was evaluated in monolayer and organotypic cultures. Results: HPV-16 E7 expression in primary human keratinocytes leads to an increase in PLD expression and activity. Moreover, this activation is dependent on the ability of HPV-16 E7 to induce retinoblastoma protein (pRb) degradation. We also show that cells expressing HPV-16 E7 or silenced for pRb acquire resistance to the antiproliferative effect of rapamycin. Conclusion: This is the first indication that HPV oncoproteins can affect PLD activity. Since PA can interfere with the ability of rapamycin to bind mTOR, the use of combined strategies to target mTOR and PLD activity might be considered to treat HPV-related malignancies.
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    Papel regulatório das vias 5- e 12- lipoxigenases e do citocromo p450 sobre a degeneração e a regeneração muscular esquelética, induzidas por miotoxina de serpente em camundongos
    (Universidade Federal de São Paulo (UNIFESP), 2021) Damico, Marcio Vinicius [UNIFESP]; Moreira, Vanessa [UNIFESP]; Universidade Federal de São Paulo
    Introduction: Skeletal muscle regeneration begins with a degenerative phase followed by a tissue regenerative phase. Depending on the nature and intensity of the injury, tissue regeneration will be successful with recovery of function, or deficient with fibrosis formation and impairment of muscle function. Different mediators participate in this process, and lipid mediators synthesized from AA, synthesized by the action of the lipoxygenase (LOX), 5- and 12-LOX and cytochrome P450 (CYP450) pathways emerge as new possible targets. Rare in vivo studies have demonstrated the possible role of these mediators in muscle regeneration. Objective: to evaluate the regulatory role of lipid mediators from the 5-,12-LOX and CYP450 pathways in the phases of muscle degeneration and regeneration induced by a phospholipase A2. Material and Methods: Male Swiss mice (20 g) were injected intramuscularly (im) in the right gastrocnemius muscle with phospholipase A2, from Crotalus durissus terrificus snake venom, crotoxin B (CB - 7.5 μg/animal /50 μL) or saline solution. After 30 min and 48 h of injection, mice received orally: MK-886 (5-LOX inhibitor - 3 mg/kg/100 μL), baicalein (12-LOX inhibitor - 20 mg/kg/100 μL), SKF-525A (CYP450 inhibitor – 25 mg/kg/100 μL) or 1% carboxymethyl cellulose (1% CMC). After 6 and 24 h or 3, 7, 14 and 21 d of i.m. injection, histological, functional and molecular analyzes were performed. The statistical tests One or Two-Way ANOVA and Tukey were applied as post test. Results: Expressions of 5- LOX and CYP450 proteins increased in animals injected with CB at 6 h (for 5-LOX) and 24 h and 3 d (for 5-LOX and CYP450), while 12-LOX expression decreased at 6 h in animals injected with CB. Inhibition of the 5-LOX pathway decreased the % of injured fibers (FLs), basophilic fibers (FBs) and central core fibers (CNFs). Its inhibition kept small-caliber fibers and muscle more resistant to fatigue during muscle regeneration. For the 12-LOX pathway, there was a decrease in the % of FLs and did not change the % of FBs and FNCs. This inhibition generated fibers of greater caliber and muscles that are less resistant to fatigue. Inhibition of the CYP450 pathway increased the % of FLs and FBs. Its inhibition generated fibers of greater caliber and muscles less resistant to fatigue. Conclusion: these data suggest that at the beginning of regeneration, the 5-LOX and CYP450 pathways have pro and anti-proliferative actions, respectively. The data suggest that lipid mediators derived from 12-LOX and CYP450 are responsible for the development of slow fibers.