Other articles by Mercedes Pardo on PubMed

• [Premature Death from Infectious Diseases in Spain, 1908-1995] Revista Panamericana De Salud Publica = Pan American Journal of Public Health. Oct, 2002  |   Pubmed ID: 12431358 Infectious diseases have traditionally been one of the leading causes of death in developed countries. The objectives of this research were to: 1) quantify the importance of infectious diseases as a cause of premature mortality in Spain between 1908 and 1995, and 2) determine the frequency and distribution of the infectious diseases with the greatest impact on premature death.
• Synthesis and Cytotoxic Activity of N,N-bis-(3-[N-(4-chlorobenzo[g]-phthalazin-1-yl)]aminopropyl)-N-methylamine: a New Potential DNA Bisintercalator Bioorganic & Medicinal Chemistry. May, 2003  |   Pubmed ID: 12713823 The synthesis of a new series of mono- and dinuclear 1-alkylamino-4-chlorobenzo[g]phthalazine derivatives 7-10 containing flexible polyaminic chains is reported. It has been achieved by the reaction of 1,4-dichlorobenzo[g]phthalazine with the corresponding polyamines. In vitro antitumoral activity against HT-29 human colon carcinoma cells was evaluated and showed best results for compound 10, in which two heteroaromatic units are linked by a N-methylsubstituted polyaminic chain. Molecular modelling of the complexes of 9 and 10 with DNA strongly suggests the possibility of bisintercalation, and also that the N-methyl group of 10 plays an important role in the formation of a specially stable DNA complex.
• Equatorial Retention of the Contractile Actin Ring by Microtubules During Cytokinesis Science (New York, N.Y.). Jun, 2003  |   Pubmed ID: 12791993 In most eukaryotes cytokinesis is brought about by a contractile actin ring located at the division plane. Here, in fission yeast the actin ring was found to be required to generate late-mitotic microtubular structures located at the division plane, and these in turn maintained the medial position of the actin ring. When these microtubular structures were disrupted, the actin ring migrated away from the cell middle in a membrane traffic-dependent manner, resulting in asymmetrical cell divisions that led to genomic instability. We propose that these microtubular structures contribute to a checkpoint control that retains the equatorial position of the ring when progression through cytokinesis is delayed.
• PST1 and ECM33 Encode Two Yeast Cell Surface GPI Proteins Important for Cell Wall Integrity Microbiology (Reading, England). Dec, 2004  |   Pubmed ID: 15583168 Pst1p was previously identified as a protein secreted by yeast regenerating protoplasts, which suggests a role in cell wall construction. ECM33 encodes a protein homologous to Pst1p, and both of them display typical features of GPI-anchored proteins and a characteristic receptor L-domain. Pst1p and Ecm33p are both localized to the cell surface, Pst1p being at the cell membrane and possibly also in the periplasmic space. Here, the characterization of pst1Delta, ecm33Delta and pst1Delta ecm33Delta mutants is described. Deletion of ECM33 leads to a weakened cell wall, and this defect is further aggravated by simultaneous deletion of PST1. As a result, the ecm33Delta mutant displays increased levels of activated Slt2p, the MAP kinase of the cell integrity pathway, and relies on a functional Slt2-mediated cell integrity pathway to ensure viability. Analyses of model glycosylated proteins show glycosylation defects in the ecm33Delta mutant. Ecm33p is also important for proper cell wall ultrastructure organization and, furthermore, for the correct assembly of the mannoprotein outer layer of the cell wall. Pst1p seems to act in the compensatory mechanism activated upon cell wall damage and, in these conditions, may partially substitute for Ecm33p.
• Cystic Adenomatoid Malformation of the Lung Presenting in Adulthood The Annals of Thoracic Surgery. Jan, 2005  |   Pubmed ID: 15620971 Cystic adenomatoid malformation is an uncommon embryonic developmental abnormality usually diagnosed in neonates and infants. Its presentation in adulthood is rare, with only 27 cases reported up to now. Due to its rarity, it is seldom suspected and adult physicians are not familiar with its clinical and radiologic features. We report two cases of cystic adenomatoid malformation presenting in adults, one as a recurrent pneumonia, and another as a coincidental finding on a chest roentgenogram. We describe the clinical features, radiologic and computed tomographic findings, and the histopathologic characteristics in this article, along with a review of the literature.
• The Nuclear Rim Protein Amo1 is Required for Proper Microtubule Cytoskeleton Organisation in Fission Yeast Journal of Cell Science. Apr, 2005  |   Pubmed ID: 15797925 Microtubules have a central role in cell division and cell polarity in eukaryotic cells. The fission yeast is a useful organism for studying microtubule regulation owing to the highly organised nature of its microtubular arrays. To better understand microtubule dynamics and organisation we carried out a screen that identified over 30 genes whose overexpression resulted in microtubule cytoskeleton abnormalities. Here we describe a novel nucleoporin-like protein, Amo1, identified in this screen. Amo1 localises to the nuclear rim in a punctate pattern that does not overlap with nuclear pore complex components. Amo1Delta cells are bent, and they have fewer microtubule bundles that curl around the cell ends. The microtubules in amo1Delta cells have longer dwelling times at the cell tips, and grow in an uncoordinated fashion. Lack of Amo1 also causes a polarity defect. Amo1 is not required for the microtubule loading of several factors affecting microtubule dynamics, and does not seem to be required for nuclear pore function.
• Genetic and Proteomic Evidences Support the Localization of Yeast Enolase in the Cell Surface Proteomics. Apr, 2006  |   Pubmed ID: 16544286 Although enolase, other glycolytic enzymes, and a variety of cytoplasmic proteins lacking an N-terminal secretion signal have been widely described as located at the cell surface in yeast and in mammalian cells, their presence in this external location is still controversial. Here, we report that different experimental approaches (genetics, cellular biology and proteomics) show that yeast enolase can reach the cell surface and describe the protein regions involved in its cell surface targeting. Hybrid enolase truncates, fused at their C terminus with the yeast internal invertase or green fluorescent protein (GFP) as reporter proteins, proved that the 169 N-terminal amino acids are sufficient to target the protein to the cell surface. Furthermore, the enolase-GFP fusion co-localized with a plasma membrane marker. Enolase was also identified among membrane proteins obtained by a purification protocol that includes sodium carbonate to prevent cytoplasmic contamination. These proteins were analyzed by SDS-PAGE, trypsin digestion and LC-MS/MS for peptide identification. Elongation factors, mitochondrial membrane proteins and a mannosyltransferase involved in cell wall mannan biosynthesis were also identified in this fraction.
• 1,4-Bis(alkylamino)benzo[g]phthalazines Able to Form Dinuclear Complexes of Cu(II) Which As Free Ligands Behave As SOD Inhibitors and Show Efficient in Vitro Activity Against Trypanosoma Cruzi Bioorganic & Medicinal Chemistry. Mar, 2007  |   Pubmed ID: 17222558 The synthesis of a new series of 1,4-bis(alkylamino)benzo[g]phthalazines 1-3 is reported, and their ability to form dinuclear complexes with Cu(II) assayed. The geometry of the complexes is dependent on the nature of the electron-donor sites at the sidechains. Compounds 1 and 2, that contain sp3 or sp2 nitrogens at the end of the alkylamino groups, originate monopodal dinuclear complexes which seem to include endogenous OH bridges, and the sidechains seem to actively participate in complexation. However, the substitution of nitrogen by oxygen in 3 leads to a tripodal dinuclear complex in which the sidechains are not involved. The in vitro antiparasitic activity on Trypanosoma cruzi epimastigotes and amastigotes and the SOD activity inhibition have been evaluated for compounds 1-3, and, as expected, 1 and 2 show in all cases relevant results, whereas 3 is always the less active among the three substrates tested.
• Molecular Characterization of the Salmonella Enterica Serovar Typhi Vi-typing Bacteriophage E1 Journal of Bacteriology. Apr, 2008  |   Pubmed ID: 18192390 Some bacteriophages target potentially pathogenic bacteria by exploiting surface-associated virulence factors as receptors. For example, phage have been identified that exhibit specificity for Vi capsule producing Salmonella enterica serovar Typhi. Here we have characterized the Vi-associated E1-typing bacteriophage using a number of molecular approaches. The absolute requirement for Vi capsule expression for infectivity was demonstrated using different Vi-negative S. enterica derivatives. The phage particles were shown to have an icosahedral head and a long noncontractile tail structure. The genome is 45,362 bp in length with defined capsid and tail regions that exhibit significant homology to the S. enterica transducing phage ES18. Mass spectrometry was used to confirm the presence of a number of hypothetical proteins in the Vi phage E1 particle and demonstrate that a number of phage proteins are modified posttranslationally. The genome of the Vi phage E1 is significantly related to other bacteriophages belonging to the same serovar Typhi phage-typing set, and we demonstrate a role for phage DNA modification in determining host specificity.
• Efficient Inhibition of Iron Superoxide Dismutase and of Trypanosoma Cruzi Growth by Benzo[g]phthalazine Derivatives Functionalized with One or Two Imidazole Rings Journal of Medicinal Chemistry. Mar, 2008  |   Pubmed ID: 18293910 The synthesis and trypanosomatic behavior of a new series of 1,4-bis(alkylamino)benzo[g]phthalazines 1- 4 containing the biologically significant imidazole ring are reported. In vitro antiparasitic activity against Trypanosoma cruzi epimastigotes is remarkable, especially for compound 2, whereas toxicity against Vero cells is very low. Conversion of epimastigotes to metacyclic forms in the presence of the tested compounds causes significant decreases in the amastigote and trypomastigote numbers. Fe-SOD inhibition is noteworthy, whereas effect on human Cu/Zn-SOD is negligible.
• [The Halo Sign in Computed Tomography Images: Differential Diagnosis and Correlation with Pathology Findings] Archivos De Bronconeumologia. Jul, 2008  |   Pubmed ID: 18727892 The halo sign is a circular area of ground-glass attenuation that is seen around pulmonary nodules at computed tomography (CT). Although the sign is most often an indication of pulmonary hemorrhage, it may also accompany other lesions associated with different disease processes. Examples are hemorrhagic nodules of infectious origin (mucormycosis, candidiasis, tuberculosis, viral pneumonia, and invasive aspergillosis--the last being the most common cause of the CT halo sign); hemorrhagic nodules of noninfectious origin (Wegener granulomatosis, Kaposi sarcoma, and hemorrhagic metastases); tumor cell infiltration (bronchioloalveolar carcinoma, lymphoma, and metastasis with intra-alveolar tumor growth); and nonhemorrhagic lesions (sarcoidosis and organizing pneumonia). Diagnosis must therefore be based on careful consideration of all the CT chest findings within the context of the patient's clinical state. The aim of this review was to describe and illustrate different disease processes that appear as a halo sign on CT scans, to analyze the value of this diagnostic tool, and to assess its correlation with pathology findings.
• An Expanded Oct4 Interaction Network: Implications for Stem Cell Biology, Development, and Disease Cell Stem Cell. Apr, 2010  |   Pubmed ID: 20362542 The transcription factor Oct4 is key in embryonic stem cell identity and reprogramming. Insight into its partners should illuminate how the pluripotent state is established and regulated. Here, we identify a considerably expanded set of Oct4-binding proteins in mouse embryonic stem cells. We find that Oct4 associates with a varied set of proteins including regulators of gene expression and modulators of Oct4 function. Half of its partners are transcriptionally regulated by Oct4 itself or other stem cell transcription factors, whereas one-third display a significant change in expression upon cell differentiation. The majority of Oct4-associated proteins studied to date show an early lethal phenotype when mutated. A fraction of the human orthologs is associated with inherited developmental disorders or causative of cancer. The Oct4 interactome provides a resource for dissecting mechanisms of Oct4 function, enlightening the basis of pluripotency and development, and identifying potential additional reprogramming factors.
• Prmt5 is Essential for Early Mouse Development and Acts in the Cytoplasm to Maintain ES Cell Pluripotency Genes & Development. Dec, 2010  |   Pubmed ID: 21159818 Prmt5, an arginine methyltransferase, has multiple roles in germ cells, and possibly in pluripotency. Here we show that loss of Prmt5 function is early embryonic-lethal due to the abrogation of pluripotent cells in blastocysts. Prmt5 is also up-regulated in the cytoplasm during the derivation of embryonic stem (ES) cells together with Stat3, where they persist to maintain pluripotency. Prmt5 in association with Mep50 methylates cytosolic histone H2A (H2AR3me2s) to repress differentiation genes in ES cells. Loss of Prmt5 or Mep50 results in derepression of differentiation genes, indicating the significance of the Prmt5/Mep50 complex for pluripotency, which may occur in conjunction with the leukemia inhibitory factor (LIF)/Stat3 pathway.
• Assignment of Protein Interactions from Affinity Purification/mass Spectrometry Data Journal of Proteome Research. Mar, 2012  |   Pubmed ID: 22283744 The combination of affinity purification with mass spectrometry analysis has become the method of choice for protein complex characterization. With the improved performance of mass spectrometry technology, the sensitivity of the analyses is increasing, probing deeper into molecular interactions and yielding longer lists of proteins. These identify not only core complex subunits but also the more inaccessible proteins that interact weakly or transiently. Alongside them, contaminant proteins, which are often abundant proteins in the cell, tend to be recovered in affinity experiments because they bind nonspecifically and with low affinity to matrix, tag, and/or antibody. The challenge now lies in discriminating nonspecific binders from true interactors, particularly at the low level and in a larger scale. This review aims to summarize the variety of methods that have been used to distinguish contaminants from specific interactions in the past few years, ranging from manual elimination using heuristic rules to more sophisticated probabilistic scoring approaches. We aim to give awareness on the processing that takes place before an interaction list is reported and on the different types of list curation approaches suited to the different experiments.
• Nuclear Receptor Binding Protein 1 Regulates Intestinal Progenitor Cell Homeostasis and Tumour Formation The EMBO Journal. May, 2012  |   Pubmed ID: 22510880 Genetic screens in simple model organisms have identified many of the key components of the conserved signal transduction pathways that are oncogenic when misregulated. Here, we identify H37N21.1 as a gene that regulates vulval induction in let-60(n1046gf), a strain with a gain-of-function mutation in the Caenorhabditis elegans Ras orthologue, and show that somatic deletion of Nrbp1, the mouse orthologue of this gene, results in an intestinal progenitor cell phenotype that leads to profound changes in the proliferation and differentiation of all intestinal cell lineages. We show that Nrbp1 interacts with key components of the ubiquitination machinery and that loss of Nrbp1 in the intestine results in the accumulation of Sall4, a key mediator of stem cell fate, and of Tsc22d2. We also reveal that somatic loss of Nrbp1 results in tumourigenesis, with haematological and intestinal tumours predominating, and that nuclear receptor binding protein 1 (NRBP1) is downregulated in a range of human tumours, where low expression correlates with a poor prognosis. Thus NRBP1 is a conserved regulator of cell fate, that plays an important role in tumour suppression.
• Mechanisms Controlling the Temporal Degradation of Nek2A and Kif18A by the APC/C-Cdc20 Complex The EMBO Journal. Jan, 2013  |   Pubmed ID: 23288039 The Anaphase Promoting Complex/Cyclosome (APC/C) in complex with its co-activator Cdc20 is responsible for targeting proteins for ubiquitin-mediated degradation during mitosis. The activity of APC/C-Cdc20 is inhibited during prometaphase by the Spindle Assembly Checkpoint (SAC) yet certain substrates escape this inhibition. Nek2A degradation during prometaphase depends on direct binding of Nek2A to the APC/C via a C-terminal MR dipeptide but whether this motif alone is sufficient is not clear. Here, we identify Kif18A as a novel APC/C-Cdc20 substrate and show that Kif18A degradation depends on a C-terminal LR motif. However in contrast to Nek2A, Kif18A is not degraded until anaphase showing that additional mechanisms contribute to Nek2A degradation. We find that dimerization via the leucine zipper, in combination with the MR motif, is required for stable Nek2A binding to and ubiquitination by the APC/C. Nek2A and the mitotic checkpoint complex (MCC) have an overlap in APC/C subunit requirements for binding and we propose that Nek2A binds with high affinity to apo-APC/C and is degraded by the pool of Cdc20 that avoids inhibition by the SAC.
• P53 Mediates Loss of Hematopoietic Stem Cell Function and Lymphopenia in Mysm1 Deficiency Blood. Apr, 2015  |   Pubmed ID: 25710881 MYSM1 is a chromatin-binding transcriptional cofactor that deubiquitinates histone H2A. Studies of Mysm1-deficient mice have shown that it is essential for hematopoietic stem cell (HSC) function and lymphopoiesis. Human carriers of a rare MYSM1-inactivating mutation display similar lymphopoietic deficiencies. However, the mechanism by which MYSM1 regulates hematopoietic homeostasis remains unclear. Here, we show that Mysm1-deficiency results in p53 protein elevation in many hematopoietic cell types. p53 is a central regulator of cellular stress responses and HSC homeostasis. We thus generated double-knockout mice to assess a potential genetic interaction between Mysm1 and p53 in hematopoiesis. Mysm1(-/-)p53(-/-) mouse characterization showed a full rescue of Mysm1(-/-) developmental and hematopoietic defects. This included restoration of lymphopoiesis, and HSC numbers and functions. These results establish p53 activation as the driving mechanism for hematopoietic abnormalities in Mysm1 deficiency. Our findings may advance the understanding of p53 regulation in hematopoiesis and implicate MYSM1 as a potential p53 cofactor.
• Characterization of Two Distinct Nucleosome Remodeling and Deacetylase (NuRD) Complex Assemblies in Embryonic Stem Cells Molecular & Cellular Proteomics : MCP. Mar, 2016  |   Pubmed ID: 26714524 Pluripotency and self-renewal, the defining properties of embryonic stem cells, are brought about by transcriptional programs involving an intricate network of transcription factors and chromatin remodeling complexes. The Nucleosome Remodeling and Deacetylase (NuRD) complex plays a crucial and dynamic role in the regulation of stemness and differentiation. Several NuRD-associated factors have been reported but how they are organized has not been investigated in detail. Here, we have combined affinity purification and blue native polyacrylamide gel electrophoresis followed by protein identification by mass spectrometry and protein correlation profiling to characterize the topology of the NuRD complex. Our data show that in mouse embryonic stem cells the NuRD complex is present as two distinct assemblies of differing topology with different binding partners. Cell cycle regulator Cdk2ap1 and transcription factor Sall4 associate only with the higher mass NuRD assembly. We further establish that only isoform Sall4a, and not Sall4b, associates with NuRD. By contrast, Suz12, a component of the PRC2 Polycomb repressor complex, associates with the lower mass entity. In addition, we identify and validate a novel NuRD-associated protein, Wdr5, a regulatory subunit of the MLL histone methyltransferase complex, which associates with both NuRD entities. Bioinformatic analyses of published target gene sets of these chromatin binding proteins are in agreement with these structural observations. In summary, this study provides an interesting insight into mechanistic aspects of NuRD function in stem cell biology. The relevance of our work has broader implications because of the ubiquitous nature of the NuRD complex. The strategy described here can be more broadly applicable to investigate the topology of the multiple complexes an individual protein can participate in.