Iron metabolism in oligodendrocytes and astrocytes: friend or foe?

Recent reports show that astrocytes (AST) are able to create a permissive environment for remyelination through their action on oligodendrocyte (OLG) precursor migration, proliferation, and differentiation. When disrupted, iron homeostasis negatively impacts OLG differentiation and impairs myelination. We demonstrate that iron deficiency (ID) affects not only OLG maturation but also AST. Using gestational iron deprivation, we studied OLG requirements for their progression to a mature myelinating state and energy metabolism in primary cultures of OLG and AST from newly born control and ID pups. In particular, oxygen consumption and extracellular acidification rates were measured using a Seahorse extracellular flux analyzer. Both ID AST and OLG exhibited decreased spare respiratory capacity, which indicates that maternal ID effectively induces mitochondrial dysfunction. Absence of glycogen granules was observed in ID AST and an increase in ROS production was detected in ID OLG. Mitochondrial fission was increased in ID AST, while fusion was prevalent in ID OLG. Electron microscopy also showed abnormal cristae in ID mitochondria in OLG as well as in AST. These findings further prove that the regulation of cell metabolism may impact cell fate decisions and maturation. An additional model of ID was developed by knocking down the divalent metal transporter 1 (DMT1), a multi-metal transporter with a primary role in iron transport and present in AST and OLG. OLG maturation was compromised in primary OPC cultures treated with conditioned medium from DMT1-silenced AST, which suggests that molecules secreted by AST may be affected.Fil: Pasquini, Juana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Rosato Siri, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Martino Adami, Pamela Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Guitart, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Marcora, Maria Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Morelli, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Correale, Jorge. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaLXVI Reunión anual de la Sociedad Argentina de Investigación Clínica; LXIX Reunión Anual de la Sociedad Argentina de Inmunología; LIII Reunión Anual de la Asociación Argentina de Farmacología Experimental y XI Reunión Anual de la Asociación Argentina de NanomedicinasArgentinaSociedad Argentina de Investigación ClínicaSociedad Argentina de InmunologíaAsociación Argentina de Farmacología ExperimentalAsociación Argentina de Nanomedicina

Genome-wide association analysis of dementia and its clinical endophenotypes reveal novel loci associated with Alzheimer's disease and three causality networks : The GR@ACE project

Introduction: Large variability among Alzheimer's disease (AD) cases might impact genetic discoveries and complicate dissection of underlying biological pathways. Methods: Genome Research at Fundacio ACE (GR@ACE) is a genome-wide study of dementia and its clinical endophenotypes, defined based on AD's clinical certainty and vascular burden. We assessed the impact of known AD loci across endophenotypes to generate loci categories. We incorporated gene coexpression data and conducted pathway analysis per category. Finally, to evaluate the effect of heterogeneity in genetic studies, GR@ACE series were meta-analyzed with additional genome-wide association study data sets. Results: We classified known AD loci into three categories, which might reflect the disease clinical heterogeneity. Vascular processes were only detected as a causal mechanism in probable AD. The meta-analysis strategy revealed the ANKRD31-rs4704171 and NDUFAF6-rs10098778 and confirmed SCIMP-rs7225151 and CD33-rs3865444. Discussion: The regulation of vasculature is a prominent causal component of probable AD. GR@ACE meta-analysis revealed novel AD genetic signals, strongly driven by the presence of clinical heterogeneity in the AD series

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

Microplate assay for endo-polygalacturonase activity determination based on ruthenium red method

Endo-polygalacturonase (endo-PGase) activity determinations generally rely on viscosity changes or reducing sugar ends produced by this activity over polygalacturonic acid. Torres and coworkers [Enzyme Microb. Technol. 48 (2011) 123–128] showed that ruthenium red (RR) is useful for endo-PGase determination. In this article, we present a high-throughput liquid-based endo-PGase assay based on the RR method and compare it with the viscosity determination method. The reduced assay uses a small volume of enzyme solution, 40 μg of polygalacturonic acid, and 45 μg of RR for each sample determination. Furthermore, we obtained an interconversion factor for RR and viscosity activities.Fil: Ortiz, Gastón Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Guitart, María Eugenia. Universitat Bremen. School of Enigineerring and Science Jacobs; AlemaniaFil: Alberto, Edgardo Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Fernandez Lahore, Hector. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universitat Bremen. School of Enigineerring and Science Jacobs; AlemaniaFil: Blasco, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin

Iron Availability Compromises Not Only Oligodendrocytes But Also Astrocytes and Microglial Cells

When disrupted, iron homeostasis negatively impacts oligodendrocyte (OLG) differentiation and impairs myelination. To better understand myelin formation and OLG maturation, in vivo and in vitro studies were conducted to evaluate the effect of iron deficiency (ID) not only on OLG maturation but also on astrocytes (AST) and microglial cells (MG). In vivo experiments in an ID model were carried out to describe maturational events during OLG and AST development and the reactive profile of MG during myelination when iron availability is lower than normal. In turn, in vitro assays were conducted to explore proliferating and maturational states of each glial cell type derived from control or ID conditions. Studies targeted NG2, PDGFRα, CNPAse, CC1, and MBP expression in OLG, GFAP and S100 expression in AST, and CD11b, ED1, and cytokine expression in MG, as well as BrDU incorporation in the three cell types. Our results show that ID affected OLG development at early stages, not only reducing their maturation capacity but also increasing their proliferation and affecting their morphological complexity. AST ID proliferated more than control ones and were more immature, much like OLG. Cytokine expression in ID animals reflected an anti-inflammatory state which probably influenced OLG maturation. These results show that ID conditions alter all glial cells and may impact myelin formation, which could be regulated by a mechanism involving a cross talk between AST, MG, and oligodendrocyte progenitors (OPC).Fil: Rosato Siri, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Marziali, Leandro Nazareno. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Guitart, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Badaracco, María Elvira. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Puntel, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Pitossi, Fernando Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Correale, Jorge. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Pasquini, Juana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentin

Characterization, optimization, and scale-up of cellulases production by trichoderma reesei cbs 836.91 in solid-state fermentation using agro-industrial products

The application of cellulases in saccharification processes is restricted by its production cost. Consequently, new fungal strains able to elaborate higher cellulases titers and with special activity profiles are required to make the process economical. The aim of this investigation was to find a promising wild-type Trichoderma strain for cellulases production. The Trichoderma reesei strain 938 (CBS 836.91) was selected among twenty strains on the basis of cellulase-agar-plate screening. Evaluation of the selected strain on six solid substrates indicated the highest activities to be obtained from wheat bran. Statistical analyses of the experimental design indicated a significant effect of pH and moisture on the generation of endoglucanase (EGA) and filter-paper (FPA) activity. Furthermore, a central-composite design-based optimization revealed that pH values between 6.4 and 6.6 and moisture from 74 to 94 % were optimal for cellulases production. Under these conditions, 8?10 IU gds-1 of FPA and 15.6?17.8 IU gds-1 of EGA were obtained. In addition, cultivation in a rotating-drum reactor under optimal conditions gave 8.2 IU gds-1 FPA and 13.5 IU gds-1 EGA. Biochemical characterization of T. reesei 938 cellulases indicated a substantially higher resistance to 4 mM Fe?2 and a slightly greater tolerance to alkaline pH in comparison to Celluclast. These results suggest that T. reesei 938 could be a promising candidate for improved cellulases production through direct-evolution strategies.Fil: Ortiz, Gastón Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentina. Universitat Bremen. School Of Enigineerring And Science Jacobs; AlemaniaFil: Guitart, María Eugenia. Universitat Bremen. School Of Enigineerring And Science Jacobs; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Cavalitto, Sebastian Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; ArgentinaFil: Alberto, Edgardo Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Fernandez Lahore, Marcelo. Universitat Bremen. School Of Enigineerring And Science Jacobs; AlemaniaFil: Blasco, Martín. Instituto Nacional de Tecnología Industrial. Centro de Investigación y Desarrollo en Biotecnología Industrial; Argentin

Glial Cell Metabolic Profile Upon Iron Deficiency: Oligodendroglial and Astroglial Casualties of Bioenergetic Adjustments

Iron deficiency (ID) represents one of the most prevalent nutritional deficits, affecting almost two billion people worldwide. Gestational iron deprivation induces hypomyelination due to oligodendroglial maturation deficiencies and is thus a useful experimental model to analyze oligodendrocyte (OLG) requirements to progress to a mature myelinating state. A previous proteomic study in the adult ID brain by our group demonstrated a pattern of dysregulated proteins involved in the tricarboxylic acid cycle and mitochondrial dysfunction. The aim of the present report was to assess bioenergetics metabolism in primary cultures of OLGs and astrocytes (ASTs) from control and ID newborns, on the hypothesis that the regulation of cell metabolism correlates with cell maturation. Oxygen consumption and extracellular acidification rates were measured using a Seahorse extracellular flux analyzer. ID OLGs and ASTs both exhibited decreased spare respiratory capacity, which indicates that ID effectively induces mitochondrial dysfunction. A decrease in glycogen granules was observed in ID ASTs, and an increase in ROS production was detected in ID OLGs. Immunolabeling of structural proteins showed that mitochondrial number and size were increased in ID OLGs, while an increased number of smaller mitochondria was observed in ID ASTs. These results reflect an unfavorable bioenergetic scenario in which ID OLGs fail to progress to a myelinating state, and indicate that the regulation of cell metabolism may impact cell fate decisions and maturation.Fil: Rosato Siri, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Martino Adami, Pamela Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Guitart, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Verstraeten, Sandra Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; ArgentinaFil: Morelli, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Correale, Jorge. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Pasquini, Juana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas "Prof. Alejandro C. Paladini". Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Físico-Química Biológicas; Argentin

X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern