Browsing by Subject "Cytokinesis"

Now showing 1 - 4 of 4
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    MAPK‑dependent control of mitotic progression in S. pombe
    (BioMed Central, 2024-03-25) Iglesias Romero, Ana Belén; Soto Pino, Teresa; Flor Parra, Ignacio; Salas Pino, Silvia; Ruiz Romero, Gabriel; Gould, Kathleen L.; Cansado Vizoso, José; Daga, Rafael R.; Genética y Microbiología; Facultades de la UMU::Facultad de Biología
    Background: Mitogen-activated protein kinases (MAPKs) preserve cell homeostasis by transducing physicochemical fluctuations of the environment into multiple adaptive responses. These responses involve transcriptional rewiring and the regulation of cell cycle transitions, among others. However, how stress conditions impinge mitotic progression is largely unknown. The mitotic checkpoint is a surveillance mechanism that inhibits mitotic exit in situations of defective chromosome capture, thus preventing the generation of aneuploidies. In this study, we investigate the role of MAPK Pmk1 in the regulation of mitotic exit upon stress. Results: We show that Schizosaccharomyces pombe cells lacking Pmk1, the MAP kinase effector of the cell integrity pathway (CIP), are hypersensitive to microtubule damage and defective in maintaining a metaphase arrest. Epistasis analysis suggests that Pmk1 is involved in maintaining spindle assembly checkpoint (SAC) signaling, and its deletion is additive to the lack of core SAC components such as Mad2 and Mad3. Strikingly, pmk1Δ cells show up to twofold increased levels of the anaphase-promoting complex (APC/C) activator Cdc20Slp1 during unperturbed growth. We demonstrate that Pmk1 physically interacts with Cdc20Slp1 N-terminus through a canonical MAPK docking site. Most important, the Cdc20Slp1 pool is rapidly degraded in stressed cells undergoing mitosis through a mechanism that requires MAPK activity, Mad3, and the proteasome, thus resulting in a delayed mitotic exit. Conclusions: Our data reveal a novel function of MAPK in preventing mitotic exit and activation of cytokinesis in response to stress. The regulation of Cdc20Slp1 turnover by MAPK Pmk1 provides a key mechanism by which the timing of mitotic exit can be adjusted relative to environmental conditions.
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    Metabolic control of cytokinesis by glucose cAMP–PKA signaling in fission yeast
    (Elsevier, 2025-09-19) Marín Castillo, Antonio; León Zaragoza, Sergio; Franco Sánchez, Alejandro; Vicente Soler, Jerónima; Núñez Hernández, Andrés; Soto Pino, Teresa; Madrid Mateo, María Isabel; Cansado Vizoso, José; Genética y Microbiología; Facultades de la UMU::Facultad de Biología
    Cytokinesis, the final step of cell division, must be precisely coordinated with the cellular metabolic status, yet the underlying regulatory mechanisms remain poorly understood. Here we show that in Schizosaccharomyces pombe, glucose signaling promotes cytokinesis via the evolutionarily conserved cAMP–PKA signaling pathway. Loss of the Pka1 catalytic subunit delays assembly and constriction of the contractile actomyosin ring (CAR), whereas constitutive PKA activation enhances CAR integrity and accelerates cytokinesis. Mechanistically, Pka1 downregulates the basal activity of the stress-activated MAPK Sty1 under glucose-rich conditions, thereby stabilizing the formin For3 and its nucleated actin cables, which collaborate to regulate CAR dynamics. Remarkably, cAMP–PKA signaling also facilitates cytokinesis through a parallel, actin cable–independent mechanism. Additionally, mitochondrial respiration contributes to cytokinesis in the presence of glucose through a PKA-independent pathway. These findings reveal a multilayered network that links carbon source metabolism to cytoskeletal organization and underscore the importance of tight PKA activity control for robust cell division.
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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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    Polarized endocytic transport ,The roles of Rab11 and Rab11-FIPs in regulating cell polarity
    (Murcia : F. Hernández, 2009) Jing, Jian; Prekeris, Rytis
    Endocytic transport plays a vital role in the establishment and maintenance of cell polarity. Many studies have demonstrated that endosome-dependent protein targeting is required for polarization of epithelial cells and neurons. Endocytic transport regulates several highly polarized cellular events, such as cell motility and division. Rab11 GTPase has been shown to be a master regulator of protein transport via recycling endosomes, and many recent studies have focused on the molecular machinery that mediates Rab11-dependent endocytic protein transport in polarized cells. This mini-review describes the recent advances in identifying and characterizing the role of Rab11 and its effector proteins that play important roles in polarized endocytic sorting and transport.