http://hdl.handle.net/10366/4605 2026-04-21T00:19:48Z 2026-04-21T00:19:48Z Urdiales, José Luis Becker, Elena Andrieu, Muriel Thomas, Annie Jullien, Jérôme van Grunsven, Leo A. Menut, Sophie Evan, Gerard I. Martı́n-Zanca, Dionisio Rudkin, Brian B. http://hdl.handle.net/10366/146279 2025-04-30T20:51:21Z 1998-01-01T00:00:00Z

[EN]Expression of the nerve growth factor (NGF) receptors TrkA and p75NTR was found to vary at the surface of PC12 cells in a cell cycle phase-specific manner. This was evidenced by using flow cytometric and microscopic analysis of cell populations labeled with antibodies to the extracellular domains of both receptors. Differential expression of these receptors also was evidenced by biotinylation of surface proteins and Western analysis, using antibodies specific for the extracellular domains of TrkA and p75NTR. TrkA is expressed most strongly at the cell surface in M and early G1 phases, whereas p75NTR is expressed mainly in late G1, S, and G2 phases. This expression reflects the molecular and cellular responses to NGF in specific phases of the cell cycle; in the G1 phase NGF elicits both the anti-mitogenic effect, i.e., inhibition of the G1 to S transition, and the differentiation response whereas a survival effect is provoked elsewhere in the cell cycle. A model is proposed relating these responses to the surface expression of the two receptors. These observations open the way for novel approaches to the investigation of the mechanism of NGF signal transduction.

1998-01-01T00:00:00Z Jiménez García, Alberto Lisa Santamaría, Patricia García Marino, Matilde Escribano Bailón, María Teresa Rivas Gonzalo, Julián C. Revuelta Doval, José Luis http://hdl.handle.net/10366/141137 2025-04-30T20:41:49Z 2010-01-01T00:00:00Z

[EN] Polyphenols are considered to be responsible for some of the health benefits derived from the consumption of red wine. These protective effects might probably be explained in the context of the xenohormesis theory that considers plant metabolites as interspecific chemical signals. However, the complexity of the polyphenolic constituents of different wines makes it difficult to clarify the specific contribution of polyphenols to such effects. In the present work, we fractionated the polyphenols of a red wine and evaluated the effect of each polyphenolic fraction on the growth pattern of the yeast Saccharomyces cerevisiae. We observed a different contribution of the phenolic fractions to the xenohormetic response of S. cerevisiae, the fractions that were enriched with red pigments being the most protective against oxidative insults. Moreover, we found that red wine phenolic fractions exert their biological activity through the activation of the Yap1 and Msn2 stress-responsive regulators. Above all, the anthocyanins delphinidin 3- glucoside and petunidin 3-glucoside were found to improve significantly the growth rate of S. cerevisiae in an Msn2-, Msn4-dependent manner, indicating that the stress regulators Msn2 and Msn4 participate in the xenohormetic activity of the wine polyphenols delphinidin and petunidin.

2010-01-01T00:00:00Z Cortés, Juan Carlos G. Carnero, Elena Ishiguro, Junpei Sánchez, Yolanda Durán, Angel Ribas, Juan Carlos http://hdl.handle.net/10366/125259 2025-04-30T20:51:22Z 2005-01-01T00:00:00Z

[EN]Schizosaccharomyces pombe contains four putative (1,3)β-D-glucan synthase (GS) catalytic subunits, Bgs1p to Bgs4p. In this work, we cloned bgs4+ and show that Bgs4p is the only subunit 1) essential for maintaining cell integrity during both cytokinesis and polarized growth, and 2) found to be part of the GS enzyme. Here we show that bgs4+, cwg1+ (cwg1-1 shows reduced cell-wall β-glucan and GS catalytic activity) and orb11+ (orb11-59 is defective in cell morphogenesis) are the same gene. bgs4+ is essential during spore germination. bgs4+ shut-off produces cell lysis at growing poles and mainly at the septum prior to cytokinesis, suggesting that Bgs4p is essential for cell wall growth and for compensating an excess of cell wall degradation during cytokinesis. Shut-off and overexpression analysis suggest that 1) Bgs4p forms part of a GS catalytic multiprotein complex, and 2) Bgs4p-promoted cell-wall β-glucan alterations induce compensatory mechanisms from other Bgs subunits and (1,3)α-D-glucan synthase. Physiological localization studies showed that Bgs4p localizes to the growing ends, the medial ring and septum, and in each process of wall synthesis or remodeling that occurs during sexual differentiation: mating, zygote and spore formation, and spore germination. Bgs4p timing and requirements for proper positioning during cytokinesis and its localization pattern during spore maturation differ from those of Bgs1p. Bgs4p localizes overlapping the contractile ring once Bgs1p is present and a Calcofluor white-stained septum material is detected, suggesting that Bgs4p is involved in a late process of secondary or general septum synthesis. Unlike Bgs1p, Bgs4p needs the medial ring but not the Septation Initiation Network proteins to localize with the other septation components. Furthermore, Bgs4p localization depends on the polarity establishment proteins. Finally, F-actin is necessary for Bgs4p delocalization from and relocalization to the growing regions, but it is not needed for its stable maintenance at the growing sites, poles and septum. All these data show for the first time an essential role for a Bgs subunit in the synthesis of a (1,3)β-D-glucan necessary to preserve cell integrity when cell wall synthesis or repair are needed.

2005-01-01T00:00:00Z Cortés, Juan Carlos G. Ishiguro, Junpei Durán, Angel Ribas, Juan Carlos http://hdl.handle.net/10366/125258 2025-04-30T20:51:22Z 2002-08-01T00:00:00Z

[EN]Schizosaccharomyces pombe Bgs1p/Cps1p has been identified as a putative (1,3)β-Dglucan synthase (GS) catalytic subunit with a possible function during cytokinesis and polarized growth. To study this possibility, double mutants of cps1-12 and cdc septation mutants, were made. The double mutants displayed several hypersensitive phenotypes and altered actin distribution. Epistasis analysis showed mutations prior to septum synthesis were dominant over cps1-12, while cps1-12 was dominant over the end of septation mutant cdc16-116, suggesting Bgs1p is involved in septum cell-wall (1,3)β-D-glucan synthesis at cytokinesis. We have studied the in vivo physiological localization of Bgs1p in a bgs1Δ strain containing a functional GFP-bgs1+ gene (integrated single copy and expressed under its own promoter). During vegetative growth, Bgs1p always localizes to the growing zones: one or both ends during cell growth, and contractile ring and septum during cytokinesis. Bgs1p localization in cdc septation mutants indicates that Bgs1p needs the medial ring and septation initiation network (SIN) proteins to localize properly with the rest of septation components. Bgs1p localization in the actin mutant cps8-188 shows it depends on actin localization. In addition, Bgs1p remains polarized in the mislocalized growing poles and septa of tea1-1 and tea2-1 mutants. During the meiotic process of the life cycle, Bgs1p localizes to the mating projection, to the cell-to-cell contact zone during cell fusion and to the neck area during zygote formation. Also, Bgs1p localization suggests it collaborates in forespore and spore wall synthesis. During spore germination, Bgs1p localizes first around the spore during isotropic growth, then to the zone of polarized growth and finally, to the medial ring and septum. At the end of spore-cell division, the Bgs1p displacement to the old end only occurs in the new cell. All these data shows Bgs1p is localized to the areas of polarized cell wall growth and according to that, we propose it might be involved in synthesizing the lineal (1,3)β-D-glucan of the primary septum, as well as a similar lineal (1,3)β-D-glucan when other processes of cell wall growth or repair are needed.

2002-08-01T00:00:00Z Moreno, María Belén Durán, Angel Ribas, Juan Carlos http://hdl.handle.net/10366/125257 2025-04-30T20:51:22Z 2000-02-17T00:00:00Z

[EN]A series of thiamine-repressible shuttle vectors has been constructed to allow a more efficient DNA manipulation in Schizosaccharomyces pombe. These high-copy-number vectors with regulatable expression (pJR) are based on the backbone of the pREP-3X, pREP-41X and pREP-81X plasmids. The pJR vectors are all uniform in structure, containing i) sequences for replication (ori) and selection (AmpR) in Escherichia coli, ii) the f1 ori sequence of the phage f1 for packaging of ssDNA, making them suitable for site-directed mutagenesis, and iii) the ars1 sequence for replication in S. pombe. The pJR vectors differ among them in i) the selectable marker (Saccharomyces cerevisiae LEU 2 gene, that complements S. pombe leu1- gene, and S. pombe ura4+ and his3+ genes); ii) the thiaminerepressible nmt1 promoter (3X, 41X and 81X with extremely high, moderate or low transcription efficiency, respectively); and iii) the multiple cloning site (two multiple cloning sites, with twelve restriction sites each). The expression level of the pJR vectors has been analyzed using the β-galactosidase gene as reporter. Three levels of expression for each nmt1 promoter version, with any selectable marker and for either repressed or induced conditions, have been found. The expression is dependent on the distance to the initiation codon, varying from 0.001 to 15 times the activity characterized for the pREP plasmids. Also, the gene expression has been found to be extremely sensitive to the nucleotide sequence prior to the initiation codon, being up to 50 fold higher with an A/T sequence than with a G/C sequence. Finally, the β-galactosidase mRNA levels were found to be similar in each nmt1 series, suggesting a translational effect on gene expression. As a result, any of these eighteen new vectors allow performing gene expression in fission yeast as well as a more versatile cloning, sequencing and mutagenesis directly in the plasmid without the need for subcloning into intermediary vectors.

2000-02-17T00:00:00Z Cortés, Juan Carlos G. Konomi, Mami Martins, Ivone M. Muñoz, Javier Moreno, María Belén Osumi, Masako Durán, Angel Ribas, Juan Carlos http://hdl.handle.net/10366/125256 2025-04-30T20:51:22Z 2007-07-01T00:00:00Z

[EN]Cytokinesis is a crucial event in the cell cycle of all living cells. In fungal cells, it requires coordinated contraction of an actomyosin ring and synthesis of both plasmatic membrane and a septum structure that will constitute the new cell wall end. Schizosaccharomyces pombe contains four essential putative (1,3)β-D-glucan synthase catalytic subunits, Bgs1p to Bgs4p. Here we examined the function of Bgs1p in septation by studying the lethal phenotypes of bgs1 + shut-off and bgs1 Δ cells and demonstrated that Bgs1p is responsible and essential for linear (1,3)β-D-glucan and primary septum formation. bgs1 + shut-off generates a more than 300-fold Bgs1p reduction, but the septa still present large amounts of disorganized linear (1,3)β-D-glucan and partial primary septa. Conversely, both structures are absent in bgs1 Δ cells, where there is no Bgs1p. The septum analysis of bgs1+-repressed cells indicates that linear (1,3)β-D-glucan is necessary but not sufficient for primary septum formation. Linear (1,3)β-D-glucan is the polysaccharide that specifically interacts with the fluorochrome Calcofluor white in fission yeast. We also show that in the absence of Bgs1p abnormal septa are formed, but the cells cannot separate and eventually die.

2007-07-01T00:00:00Z