Estudio de los antígenos de histocompatibilidad en los espermatozoides humanos

Tesis Univ. Complutense de Madrid, 1982.Depto. de Biología CelularFac. de Ciencias BiológicasTRUEProQuestpu

Increased Endoplasmic Reticulum Stress and Decreased Proteasomal Function in Lafora Disease Models Lacking the Phosphatase Laforin

12 pages, 6 figures, 1 table.-- PMID: 19529779 [PubMed].[Background] Lafora progressive myoclonus epilepsy (Lafora disease; LD) is a fatal autosomal recessive neurodegenerative disorder caused by loss-of-function mutations in either the EPM2A gene, encoding the dual specificity phosphatase laforin, or the EPM2B gene, encoding the E3-ubiquitin ligase malin. Previously, we and others have shown that both proteins form a functional complex that regulates glycogen synthesis by a novel mechanism involving ubiquitination and proteasomal degradation of at least two proteins, glycogen synthase and R5/PTG. Since laforin and malin localized at the endoplasmic reticulum (ER) and their regulatory role likely extend to other proteins unrelated to glycogen metabolism, we postulated that their absence may also affect the ER-unfolded protein response pathway.[Methodology/Principal Findings] Here, we demonstrate that siRNA silencing of laforin in Hek293 and SH-SY5Y cells increases their sensitivity to agents triggering ER-stress, which correlates with impairment of the ubiquitin-proteasomal pathway and increased apoptosis. Consistent with these findings, analysis of tissue samples from a LD patient lacking laforin, and from a laforin knockout (Epm2a-/-) mouse model of LD, demonstrates constitutive high expression levels of ERstress markers BIP/Grp78, CHOP and PDI, among others.[Conclusions/Significance] We demonstrate that, in addition to regulating glycogen synthesis, laforin and malin play a role protecting cells from ER-stress, likely contributing to the elimination of unfolded proteins. These data suggest that proteasomal dysfunction and ER-stress play an important role in the pathogenesis of LD, which may offer novel therapeutic approaches for this fatal neurodegenerative disorder.This work was supported by grants from the Fundación Marató TV3, the Fundación La Caixa, the Spanish Ministry of Education and Science (SAF2008-01907) and the European Commission (LSHM-CT-2004-005272).Peer reviewe

The Antimicrobials Anacardic Acid and Curcumin Are Not-Competitive Inhibitors of Gram-Positive Bacterial Pathogenic Glyceraldehyde-3-Phosphate Dehydrogenase by a Mechanism Unrelated to Human C5a Anaphylatoxin Binding

The ubiquitous and highly abundant glycolytic enzyme D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is pivotal for the energy and carbon metabolism of most organisms, including human pathogenic bacteria. For bacteria that depend mostly on glycolysis for survival, GAPDH is an attractive target for inhibitor discovery. The availability of high-resolution structures of GAPDH from various pathogenic bacteria is central to the discovery of new antibacterial compounds. We have determined the X-ray crystal structures of two new GAPDH enzymes from Gram-positive bacterial pathogens, Streptococcus pyogenes and Clostridium perfringens. These two structures, and the recent structure of Atopobium vaginae GAPDH, reveal details in the active site that can be exploited for the design of novel inhibitors based on naturally occurring molecules. Two such molecules, anacardic acid and curcumin, have been found to counter bacterial infection in clinical settings, although the cellular targets responsible for their antimicrobial properties remain unknown. We show that both anacardic acid and curcumin inhibit GAPDH from two bacterial pathogens through uncompetitive and non-competitive mechanisms, suggesting GAPDH as a relevant pharmaceutical target for antibacterial development. Inhibition of GAPDH by anacardic acid and curcumin seems to be unrelated to the immune evasion function of pathogenic bacterial GAPDH, since neither natural compound interfere with binding to the human C5a anaphylatoxin

Laforin, a dual specificity protein phosphatase involved in Lafora disease, is phosphorylated at Ser25 by AMP-activated protein kinase

Carlos Romá-Mateo et alt.Lafora progressive myoclonus epilepsy [LD (Lafora disease)] is a fatal autosomal recessive neurodegenerative disorder caused by loss-of-function mutations in either the EPM2A gene, encoding the dual-specificity phosphatase laforin, or the EPM2B gene, encoding the E3-ubiquitin ligase malin. Previously, we and others showed that laforin and malin form a functional complex that regulates multiple aspects of glycogen metabolism, and that the interaction between laforin and malin is enhanced by conditions activating AMPK (AMP-activated protein kinase). In the present study, we demonstrate that laforin is a phosphoprotein, as indicated by two-dimensional electrophoresis, and we identify Ser25 as the residue involved in this modification. We also show that Ser25 is phosphorylated both in vitro and in vivo by AMPK. Lastly, we demonstrate that this residue plays a critical role for both the phosphatase activity and the ability of laforin to interact with itself and with previously established binding partners. The results of the present study suggest that phosphorylation of laforin-Ser25 by AMPK provides a mechanism to modulate the interaction between laforin and malin. Regulation of this complex is necessary to maintain normal glycogen metabolism. Importantly, Ser25 is mutated in some LD patients (S25P), and our results begin to elucidate the mechanism of disease in these patientsThis work was supported the Spanish Ministry of Education and Science [grant number SAF2008-01907 (to P.S.)]; the Generalitat Valenciana [grant number Prometeo 2009/051 (to P.S.)]; the National Institutes of Health [grant numbers R00NS061803, P20RR020171, R01NS070899 (to M.S.G.)]; and the University of Kentucky College of Medicine startup funds (to M.S.G.)Peer reviewe

The structure of Leptospira interrogans GAPDH sheds light into an immunoevasion factor that can target the anaphylatoxin C5a of innate immunity

Leptospirosis is a neglected worldwide zoonosis involving farm animals and domestic pets caused by the Gram-negative spirochete Leptospira interrogans. This bacterium deploys a variety of immune evasive mechanisms, some of them targeted at the complement system of the host’s innate immunity. In this work, we have solved the X-ray crystallographic structure of L. interrogans glyceraldehyde-3-phosphate dehydrogenase (GAPDH) to 2.37-Å resolution, a glycolytic enzyme that has been shown to exhibit moonlighting functions that potentiate infectivity and immune evasion in various pathogenic organisms. Besides, we have characterized the enzyme’s kinetic parameters toward the cognate substrates and have proven that the two natural products anacardic acid and curcumin are able to inhibit L. interrogans GAPDH at micromolar concentration through a noncompetitive inhibition modality. Furthermore, we have established that L. interrogans GAPDH can interact with the anaphylatoxin C5a of human innate immunity in vitro using bio-layer interferometry and a short-range cross-linking reagent that tethers free thiol groups in protein complexes. To shed light into the interaction between L. interrogans GAPDH and C5a, we have also carried out cross-link guided protein-protein docking. These results suggest that L. interrogans could be placed in the growing list of bacterial pathogens that exploit glycolytic enzymes as extracellular immune evasive factors. Analysis of the docking results indicates a low affinity interaction that is consistent with previous evidence, including known binding modes of other α-helical proteins with GAPDH. These findings allow us to propose L. interrogans GAPDH as a potential immune evasive factor targeting the complement system

Actualización en síndrome hemolítico urémico atípico: diagnóstico y tratamiento. Documento de consenso

Trobareu una actualització (2015) d'aquest document a: http://hdl.handle.net/2445/99427Haemolytic uraemic syndrome (HUS) is a clinical entity defined as the triad of nonimmune haemolytic anaemia, thrombocytopenia, and acute renal failure, in which the underlying lesions are mediated by systemic thrombotic microangiopathy (TMA). Atypical HUS (aHUS) is a sub-type of HUS in which the TMA phenomena are the consequence of decreased regulation of the alternative complement pathway on cell surfaces due to a genetic cause. aHUS is an extremely rare disease that, despite the administration of standard treatment with plasma therapy, often progresses to terminal chronic renal failure with a high associated rate of mortality. In recent years, research has established the key role that the complement system plays in the induction of endothelial damage in patients with aHUS, through the characterisation of multiple mutations and polymorphisms in the genes that code for certain complement factors. Eculizumab is a monoclonal antibody that inhibits the terminal fraction of the complement protein, blocking the formation of a cell membrane attack complex. In prospective studies in patients with aHUS, administering eculizumab produces a rapid and sustained interruption in the TMA process, with significant improvements in long-term renal function and an important decrease in the need for dialysis or plasma therapy. In this document, we review and bring up to date the important aspects of this disease, with special emphasis on how recent advancements in diagnostic and therapeutic processes can modify the treatment of patients with aHUS

Hepatic disease as the first manifestation of progressive myoclonus epilepsy of Lafora

5 páginas, 2 figuras -- PAGS nros. 1369-1373Background: Lafora disease (LD; progressive myoclonus epilepsy type 2; EPM2) is an autosomal recessive disorder caused by mutations in the EPM2A and EPM2B genes. LD is characterized by the presence of strongly PAS-positive intracellular inclusions (Lafora bodies) in several tissues. Glycogen storage disease type IV (GSD-IV; Andersen disease) is an autosomal recessive disorder characterized by cirrhosis leading to severe liver failure. GSD-IV has been associated with mutations in the glycogen branching enzyme gene (GBE). Histopathologic changes of the liver in both diseases show an identical appearance, although cirrhosis has never been described in patients with LD. We report a LD family in which the proband presented severe liver failure at onset of the disease. Methods: Clinical histories, physical and neurologic examination, laboratory tests, EEGs, MRI of the brain, and liver or axillary skin biopsies were performed in the two affected siblings. The diagnosis was confirmed by molecular genetic analysis of the EPM2A, EPM2B, and GBE genes and loci. Results: During the first decade of life, abnormalities in liver function tests were detected in the two affected siblings. The proband's liver dysfunction was severe enough to require liver transplantation. Subsequently, both sibs developed LD. Mutation analysis of EPM2A revealed a homozygous Arg241stop mutation in both patients. Conclusions: This is the first description of severe hepatic dysfunction as the initial clinical manifestation of LD. The phenotypic differences between the two affected siblings suggest that modifier genes must condition clinical expression of the disease outside the CNSPeer reviewe

Pleiotropic effects of cell wall amidase LytA on Streptococcus pneumoniae sensitivity to the host immune response

The complement system is a key component of the host immune response for the recognition and clearance of Streptococcus pneumoniae. In this study, we demonstrate that the amidase LytA, the main pneumococcal autolysin, inhibits complement-mediated immunity independently of effects on pneumolysin by a complex process of impaired complement activation, increased binding of complement regulators, and direct degradation of complement C3. The use of human sera depleted of either C1q or factor B confirmed that LytA prevented activation of both the classical and alternative pathways, whereas pneumolysin inhibited only the classical pathway. LytA prevented binding of C1q and the acute-phase protein C-reactive protein to S. pneumoniae, thereby reducing activation of the classical pathway on the bacterial surface. In addition, LytA increased recruitment of the complement downregulators C4BP and factor H to the pneumococcal cell wall and directly cleaved C3b and iC3b to generate degradation products. As a consequence, C3b deposition and phagocytosis increased in the absence of LytA and were markedly enhanced for the lytA ply double mutant, confirming that a combination of LytA and Ply is essential for the establishment of pneumococcal pneumonia and sepsis in a murine model of infection. These data demonstrate that LytA has pleiotropic effects on complement activation, a finding which, in combination with the effects of pneumolysin on complement to assist with pneumococcal complement evasion, confirms a major role of both proteins for the full virulence of the microorganism during septicemia.This work was supported by grant SAF2012-39444-C01/02 from MINECO. The Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES) and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) are initiatives of ISCIII. E.R.-S. was supported by an FPU fellowship from MINECO.S

Extravascular hemolysis and complement consumption in Paroxysmal Nocturnal Hemoglobinuria patients undergoing eculizumab treatment

Los datos asociados con este artículo están disponibles en: http://dx.doi.org/10.1016/j.imbio.2016.09.002.Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia characterized by complement-mediated intravascular hemolysis that is effectively treated with eculizumab. However, treatment responses are reported heterogeneous with some patients presenting residual hemolysis and requiring RBC transfusions. Recent reports have shown that both extravascular hemolysis and incomplete C5 blockade can explain these suboptimal hematological responses. Here we have tested our eculizumab-treated PNH patients (n = 12) for signs of hemolysis and assessed complement biomarkers. Patients were also genotyped for complement receptor 1 (CR1, CD35) and C5 polymorphisms and evaluated for free eculizumab in plasma. We report that 10 patients (83%) present parameters suggesting persistent hemolysis, although they did not require additional transfusions. Seven of them (58%) become direct Coombs-test positive as a consequence of treatment, including all patients carrying the low-expression CR1-L allele. CH50 and sC5b-9 assays demonstrate that the persistent low-level hemolysis identified in our treated patients is not a consequence of incomplete C5 blockade, supporting that this hemolysis, as has been suggested previously, results from the extravascular removal of C3 opsonized PNH erythrocytes. We also show that continuous alternative pathway activation in eculizumab-treated individuals carrying the CR1-L allele results in abnormally decreased levels of C3 in plasma that could, potentially, increase their susceptibility to bacterial infections. Finally, we encourage a routine evaluation of free eculizumab levels and terminal pathway activity to personalize eculizumab administrationIn this study S.R de C. is supported by the Spanish “Ministerio de Economía y Competitividad” (SAF2011-26583) and the Autonomous Region of Madrid (S2010/BMD-2316