Browsing by Subject "Fission yeast"

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    Activation of the cell integrity pathway is channelled through diverse signalling elements in fission yeast
    (ELSEVIER, 2008-01-04) Barba, Gregorio; Soto, Teresa; Madrid, Marisa; Núñez, Andrés; Vicente, Jero; Gacto, Mariano; Cansado Vizoso, José; Genética y Microbiología
    MAPK Pmk1p is the central element of a cascade involved in the maintenance of cell integrity and other functions in Schizosaccharomyces pombe. Pmk1p becomes activated by multiple stressing situations and also during cell separation. GTPase Rho2p acts upstream of the protein kinase C homolog Pck2p to activate the Pmk1 signalling pathway through direct interaction with MAPKKK Mkh1p. In this work we analyzed the functional significance of both Rho2p and Pck2p in the transduction of various stress signals by the cell integrity pathway. The results indicate that basal Pmk1p activity can be positively regulated by alternative mechanisms which are independent on the control by Rho2p and/or Pck2p. Unexpectedly, Pck1p, another protein kinase C homolog, negatively modulates Pmk1p basal activity by an unknown mechanism. Moreover, different elements appear to regulate the stress-induced activation of Pmk1p depending on the nature of the triggering stimuli. Whereas Pmk1p activation induced by hyper- or hypotonic stresses is channeled through Rho2p–Pck2p, other stressors, like glucose deprivation or cell wall disturbance, are transduced via other pathways in addition to that of Rho2p–Pck2p. On the contrary, Pmk1p activation observed during cell separation or after treatment with hydrogen peroxide does not involve Rho2p–Pck2p. Finally, Pck2p function is critical to maintain a Pmk1p basal activity that allows Pmk1p activation induced by heat stress. These data demonstrate the existence of a complex signalling network modulating Pmk1p activation in response to a variety of stresses in fission yeast.
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    Myosin II regulatory light chain phosphorylation and formin availability modulate cytokinesis upon changes in carbohydrate metabolism.
    (eLife Sciences Publications, 2023-03-10) Prieto Ruiz, Francisco; Gómez Gil, Elisa; Martín García, Rebeca; Pérez Díaz, Armando J.; Vicente Soler, Jero; Franco, Alejandro; Soto, Teresa; Pérez, Pilar; Madrid, Marisa; Cansado Vizoso, José; Genética y Microbiología
    Cytokinesis, which achieves the separation of daughter cells after mitosis completion, relies in animal cells on a contractile actomyosin ring (CAR), made of actin and class II myosins, whose activity is heavily influenced by regulatory light chain (RLC) phosphorylation. However, in simple eukaryotes such as fission yeast Schizosaccharomyces pombe, regulation of CAR dynamics by RLC phosphorylation seems dispensable. We found that redundant phosphorylation at Ser35 of the S. pombe RLC homolog Rlc1 by the p21-activated kinases Pak1 and Pak2, modulates Myosin II Myo2 activity and becomes essential for cytokinesis and cell growth during respiration. Previously, we showed that the Stress Activated Protein Kinase Pathway (SAPK) MAPK Sty1 controls fission yeast CAR integrity by downregulating formin For3 levels (Gomez-Gil et al.,2020). Here we report that reduced availability of formin For3-nucleated actin filaments for the CAR is the main reason for the required control of myosin II contractile activity by RLC phosphorylation during respiration-induced oxidative stress. Hence, recovery of For3 levels with antioxidants bypasses the control of Myosin II function regulated by RLC phosphorylation to allow cytokinesis and cell proliferation during respiration. Therefore, a fine-tuned interplay between Myosin II function by Rlc1 phosphorylation and environmentally controlled actin filament availability is critical for a successful cytokinesis in response to a switch to a respiratory carbohydrate metabolism.
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    Specific functional features of the cell integrity MAP Kinase pathway in the dimorphic fission yeast Schizosaccharomyces japonicus
    (MDPI, 2021-06-14) Gómez Gil, Elisa; Franco Sánchez, Alejandro; Vázquez Marín, Beatriz; Prieto Ruiz, Francisco; Pérez Díaz, Armando Jesús; Vicente Soler, Jerónima; Madrid Mateo, María Isabel; Soto Pino, Teresa; Cansado Vizoso, José; Genética y Microbiología; Facultades de la UMU::Facultad de Biología
    Mitogen activated protein kinase (MAPK) signaling pathways execute essential functions in eu-karyotic organisms by transducing extracellular stimuli into adaptive cellular responses. In the fis-sion yeast model Schizosaccharomyces pombe the cell integrity pathway (CIP) and its core effector, MAPK Pmk1, play a key role during regulation of cell integrity, cytokinesis, and ionic homeostasis. Schizosaccharomyces japonicus, another fission yeast species, shows remarkable differences with re-spect to S. pombe, including a robust yeast to hyphae dimorphism in response to environmental changes. We show that the CIP MAPK module architecture and its upstream regulators, PKC orthologs Pck1 and Pck2, are conserved in both fission yeast species. However, some of S. pombe’s CIP-related functions, such as cytokinetic control and response to glucose availability, are regulated differently in S. japonicus. Moreover, Pck1 and Pck2 antagonistically regulate S. japonicus hyphal differentiation through fine-tuning of Pmk1 activity. Chimeric MAPK-swapping experiments re-vealed that S. japonicus Pmk1 is fully functional in S. pombe, whereas S. pombe Pmk1 shows a limited ability to execute CIP functions and promote S. japonicus mycelial development. Our findings also suggest that a modified N-lobe domain secondary structure within S. japonicus Pmk1 has a major influence on the CIP signaling features of this evolutionarily diverged fission yeast.2021
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    Transduction of centrifugation-induced gravity forces through mitogen-activated protein kinase pathways in the fission yeast Schizosaccharomyces pombe
    (Microbiology Society, 2007-05-01) Soto, Teresa; Núñez, Andrés; Madrid, Marisa; Vicente, Jero; Gacto, Mariano; Cansado Vizoso, José; Genética y Microbiología
    Centrifugation of cells of Schizosaccharomyces pombe in liquid medium prompted a marked activation of Sty1 and Pmk1, which are the effector mitogen-activated protein kinases (MAPKs) of the stress-activated protein kinase pathway and the cell-integrity pathway, respectively. Transduction of the centrifugation signals showed a sensitivity threshold above which the response was dependent on time and temperature. Centrifugation-induced phosphorylation of Sty1 and Pmk1 required the presence of the main functional components of the respective signalling cascades, i.e. Wak1 or Win1 plus Wis1, and Mkh1 plus Pek1. The transcription factor Atf1 also became phosphorylated in a Sty1-dependent way upon centrifugation. Hypergravity was an important factor in the activation of Sty1 induced by centrifugation, whilst activation of Pmk1 was mostly due to gravity-associated shear forces. Centrifugation did not increase cell survival against other stresses. Rather, the increased gravitational forces produced a delay in the cell cycle, probably related to alterations in the actin-polarization pattern. Phosphorylation of the MAPK Sty1 was needed for the depolarization of actin patches induced by the centrifugation stress.