Browsing by Subject "cell cycle"

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    Fission Yeast Receptor of Activated C Kinase (RACK1) Ortholog Cpc2 Regulates Mitotic Commitment through Wee1 Kinase
    (American Society for Biochemistry and Molecular Biology, 2010-10-25) Núñez, Andrés; Franco, Alejandro; Soto, Teresa; Vicente, Jero; Cansado Vizoso, José; Genética y Microbiología
    In the fission yeast Schizosaccharomyces pombe, Wee1-dependent inhibitory phosphorylation of the highly conserved Cdc2/Cdk1 kinase determines the mitotic onset when cells have reached a defined size. The receptor of activated C kinase (RACK1) is a scaffolding protein strongly conserved among eukaryotes which binds to other proteins to regulate multiple processes in mammalian cells, including the modulation of cell cycle progression during G1/S transition. We have recently described that Cpc2, the fission yeast ortholog to RACK1, controls from the ribosome the activation of MAPK cascades and the cellular defense against oxidative stress by positively regulating the translation of specific genes whose products participate in the above processes. Intriguingly, mutants lacking Cpc2 display an increased cell size at division, suggesting the existence of a specific cell cycle defect at the G2/M transition. In this work we show that protein levels of Wee1 mitotic inhibitor are increased in cells devoid of Cpc2, whereas the levels of Cdr2, a Wee1 inhibitor, are down-regulated in the above mutant. On the contrary, the kinetics of G1/S transition was virtually identical both in control and Cpc2-less strains. Thus, our results suggest that in fission yeast Cpc2/RACK1 positively regulates from the ribosome the mitotic onset by modulating both the protein levels and the activity of Wee1. This novel mechanism of translational control of cell cycle progression might be conserved in higher eukaryotes.
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    Sub-lethal doses of polybrominated diphenyl ethers affect some biomarkers involved in energy balance and cell cycle, via oxidative stress in the marine fish cell line SAF-1
    (Elsevier, 2019-02-19) Espinosa Ruiz, Cristóbal; Manuguerra, Simona; Santulli, Andrea; Messina, Concetta M.; Cuesta Peñafiel, Alberto; Esteban Abad, María de los Ángeles; Biología Celular e Histología
    Polybrominated diphenyl ethers (PBDEs) are a class of persistent contaminants which are found all over the world in the marine environment. Sparus aurata fibroblast cell line (SAF-1) was exposed to increasing concentrations of PBDEs 47 and 99, until 72 hours to evaluate the cytotoxicity, reactive oxygen species (ROS) production and the expression of some selected molecular markers related to cell cycle, cell signaling, energetic balance and oxidative stress (p53, erk-1, hif-1α and nrf-2), by real-time PCR. Furthermore, SAF-1 cells were exposed for 7 and 15 days to sub-lethal concentrations, in order to evaluate the response of some biomarkers by immunoblotting (p53,ERK-1, AMPK, HIF-1α and NRF-2). After 48 and 72 hours, the cells showed a significant decrease of cell vitality as well as an increase of intracellular ROS production. Gene expression analysis showed that sub-lethal concentrations of BDE-99 and 47, after 72 hours, up-regulated cell cycle and oxidative stress biomarkers, although exposure to 100μmol L-1 down-regulated the selected markers related to cell cycle, cell signaling, energetic balance. After 7 and 15 days of sub-lethal doses exposure, all the analyzed markers resulted affected by the contaminants. Our results suggest that PBDEs influence the cells homeostasis first of all via oxidative stress, reducing the cell response and defense capacity and affecting its energetic levels. This situation of stress and energy imbalance could represents a condition that, modifying some of the analyzed biochemical pathways, would predispose to cellular transformation.