Open Access
Molecular pathogenesis of megalencephalic leukoencephalopathy with subcortical cysts: mutations in MLC1 cause folding defects
(IRL Press at Oxford University Press, 2008-08-30) Duarri, Anna; Teijido Hermida, Óscar; López-Hernández, Tania; Scheper, Gert C.; Barriere, Herve; Boor, Ilja; Aguado, Fernando; Zorzano, Antonio; Palacín, Manuel; Martínez, Albert; Lukacs, Gergely L.; Van der Knaap, Marjo S.; Nunes, Virginia; Estévez, Raúl; Ciencias de la Salud; Osasun Zientziak
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of leukodystrophy, most often caused by mutations in the MLC1 gene. MLC1 is an oligomeric plasma membrane (PM) protein of unknown function expressed mainly in glial cells and neurons. Most disease-causing missense mutations dramatically reduced the total and PM MLC1 expression levels in Xenopus oocytes and mammalian cells. The impaired expression of the mutants was verified in primary cultures of rat astrocytes, as well as human monocytes, cell types that endogenously express MLC1, demonstrating the relevance of the tissue culture models. Using a combination of biochemical, pharmacological and imaging methods, we also demonstrated that increased endoplasmatic reticulum-associated degradation and endo-lysosomal-associated degradation can contribute to the cell surface expression defect of the mutants. Based on these results, we suggest that MLC1 mutations reduce protein levels in vivo. Since the expression defect of the mutants could be rescued by exposing the mutant-protein expressing cells to low temperature and glycerol, a chemical chaperone, we propose that MLC belongs to the class of conformational diseases. Therefore, we suggest the use of pharmacological strategies that improve MLC1 expression to treat MLC patients.
Open Access
The cytosolic domain of human Tom22 modulates human Bax mitochondrial translocation and conformation in yeast
(Elsevier, 2012) Renault, Thibaud T.; Grandier-Vazeille, Xavier; Arokium, Hubert; Velours, Gisèle; Camougrand, Nadine; Priault, Muriel; Teijido Hermida, Óscar; Dejean, Laurent M.; Manon, Stéphen; Ciencias de la Salud; Osasun Zientziak
The role of the mitochondrial protein receptor Tom22p in the interaction of pro-apoptotic protein Bax with yeast mitochondria was investigated. Co-immunoprecipitation assays showed that human Bax interacted with different TOM subunits, including Tom22p. Expression of the cytosolic receptor domain of human Tom22 increased Bax mitochondrial localization, but decreased the proportion of active Bax. BN-PAGE showed that the cytosolic domain of Tom22 interfered with the oligomerization of Bax. These data suggest that the interaction with the cytosolic domain of Tom22 helps Bax to acquire a conformation able to interact with the outer mitochondrial membrane.
Open Access
Characterization of the common genetic variation in the spanish population of Navarre
(MDPI, 2024) Maíllo Ruiz de Infante, Alberto; Huergo, Estefanía; Apellániz Ruiz, María Valvanera; Urrutia Lafuente, Edurne; Miranda, María; Salgado Garrido, Josefa; Pasalodos Sánchez, Sara; Delgado-Mora, Luna; Teijido Hermida, Óscar; Goicoechea, Ibai; Carmona, Rosario; Pérez-Florido, Javier; Aquino, Virginia; López-López, Daniel; Peña-Chilet, María; Beltrán, Sergi; Dopazo, Joaquín; Lasa Uzcudun, Íñigo; Beloqui, Juan José; NAGEN-Scheme; Alonso Sánchez, Ángel Miguel; Gómez-Cabrero, David; Ciencias de la Salud; Osasun Zientziak
Large-scale genomic studies have significantly increased our knowledge of genetic variability across populations. Regional genetic profiling is essential for distinguishing common benign variants from disease-causing ones. To this end, we conducted a comprehensive characterization of exonic variants in the population of Navarre (Spain), utilizing whole genome sequencing data from 358 unrelated individuals of Spanish origin. Our analysis revealed 61,410 biallelic single nucleotide variants (SNV) within the Navarrese cohort, with 35% classified as common (MAF > 1%). By comparing allele frequency data from 1000 Genome Project (excluding the Iberian cohort of Spain, IBS), Genome Aggregation Database, and a Spanish cohort (including IBS individuals and data from Medical Genome Project), we identified 1069 SNVs common in Navarre but rare (MAF ≤ 1%) in all other populations. We further corroborated this observation with a second regional cohort of 239 unrelated exomes, which confirmed 676 of the 1069 SNVs as common in Navarre. In conclusion, this study highlights the importance of population-specific characterization of genetic variation to improve allele frequency filtering in sequencing data analysis to identify disease-causing variants.
Open Access
Conductance hysteresis in the voltage-dependent anion channel
(Springer, 2015) Rappaport, Shay M.; Teijido Hermida, Óscar; Hoogerheide, David P.; Rostovtseva, Tatiana K.; Berezhkovskii, Alexander M.; Bezrukov, Sergey M.; Ciencias de la Salud; Osasun Zientziak
Open Access
Can cloud-based tools accelerate Alzheimer's disease drug discovery?
(Taylor & Francis, 2016) Cacabelos, Ramón; Teijido Hermida, Óscar; Carril, Juan Carlos; Ciencias de la Salud; Osasun Zientziak
Open Access
Lipid dynamics and protein-lipid interactions in 2D crystals formed with the beta-barrel integral membrane protein VDAC1
(American Chemical Society, 2012) Eddy, Matthew T.; Ong, Ta-Chung; Clark, Lindsay; Teijido Hermida, Óscar; Van der Wel, Patrick C. A.; Garces, Robert; Wagner, Gerhard; Rostovtseva, Tatiana K.; Griffin, Robert G.; Ciencias de la Salud; Osasun Zientziak
We employ a combination of 13C/15N magic angle spinning (MAS) NMR and 2H NMR to study the structural and functional consequences of different membrane environments on VDAC1 and, conversely, the effect of VDAC1 on the structure of the lipid bilayer. MAS spectra reveal a well-structured VDAC1 in 2D crystals of dimyristoylphosphatidylcholine (DMPC) and diphytanoylphosphatidylcholine (DPhPC), and their temperature dependence suggests that the VDAC structure does not change conformation above and below the lipid phase transition temperature. The same data show that the N-terminus remains structured at both low and high temperatures. Importantly, functional studies based on electrophysiological measurements on these same samples show fully functional channels, even without the presence of Triton X-100 that has been found necessary for in vitro-refolded channels. 2H solid-state NMR and differential scanning calorimetry were used to investigate the dynamics and phase behavior of the lipids within the VDAC1 2D crystals. 2H NMR spectra indicate that the presence of protein in DMPC results in a broad lipid phase transition that is shifted from 19 to -27 °C and show the existence of different lipid populations, consistent with the presence of both annular and bulk lipids in the functionally and structurally homogeneous samples.
Open Access
Magic angle spinning nuclear magnetic resonance characterization of voltage-dependent anion channel gating in two-dimensional lipid crystalline bilayers
(American Chemical Society, 2014-12-29) Eddy, Matthew T.; Andreas, Loren; Teijido Hermida, Óscar; Su, Yongchao; Clark, Lindsay; Noskov, Sergei Y.; Wagner, Gerhard; Rostovtseva, Tatiana K.; Griffin, Robert G.; Ciencias de la Salud; Osasun Zientziak
The N-terminus of the voltage-dependent anion channel (VDAC) has been proposed to contain the mechanistically important gating helices that modulate channel opening and closing. In this study, we utilize magic angle spinning nuclear magnetic resonance (MAS NMR) to determine the location and structure of the N-terminus for functional channels in lipid bilayers by measuring long-range 13C–13C distances between residues in the N-terminus and other domains of VDAC reconstituted into DMPC lipid bilayers. Our structural studies show that the distance between A14 Cβ in the N-terminal helix and S193 Cβ is ∼4–6 Å. Furthermore, VDAC phosphorylation by a mitochondrial kinase at residue S193 has been claimed to delay mitochondrial cell death by causing a conformational change that closes the channel, and a VDAC-Ser193Glu mutant has been reported to show properties very similar to those of phosphorylated VDAC in a cellular context. We expressed VDAC-S193E and reconstituted it into DMPC lipid bilayers. Two-dimensional 13C–13C correlation experiments showed chemical shift perturbations for residues located in the N-terminus, indicating possible structural perturbations to that region. However, electrophysiological data recorded on VDAC-S193E showed that channel characteristics were identical to those of wild type samples, indicating that phosphorylation of S193 does not directly affect channel gating. The combination of NMR and electrophysiological results allows us to discuss the validity of proposed gating models.
Open Access
Epigenomics and proteomics of brain disorders
(SciTech Central, 2017-11-30) Cacabelos, Ramón; Meyyazhagan, Arun; Carril, Juan Carlos; Teijido Hermida, Óscar; Ciencias de la Salud; Osasun Zientziak
Epigenomic mechanisms (DNA methylation, chromatin remodeling/histone modifications, miRNA regulation) are involved in the transcriptional and post-translational regulation of genes in physiological and pathological conditions leading to potentially reversible phenotypes. Mutations in the genes encoding elements of the epigenetic machinery cause epigenetic Mendelian disorders. Epigenetic aberrations contribute to the pathogenesis of neurodevelopmental, imprinting, neuropsychiatric, and age-related neurodegenerative disorders. Some brain disorders exhibit proteoepigenomic changes resulting from primary genomic traits and/or secondary epigenetic events which induce pathogenic (structural, functional, conformational) changes in key proteins. Proteomic biomarkers and epigenomic signatures may help in the prediction, early diagnosis, and prognosis of CNS disorders. Epigenetic drug discovery, application of pharmacoepigenomic procedures for personalized therapeutics, novel approaches to decode and resolve drug resistance, and targeting miRNAs in prevention and treatment of brain disorders are promising areas of future development.
Open Access
Pharmacogenomics of Alzheimer's disease: genetic determinants of phenotypic variation and therapeutic outcome
(SciTech Central, 2016-11-16) Cacabelos, Ramón; Carril, Juan Carlos; Cacabelos, Pablo; Teijido Hermida, Óscar; Goldgaber, Dmitry; Ciencias de la Salud; Osasun Zientziak
Alzheimer's disease is a polygenic/complex disorder in which genomic, epigenomic, cerebrovascular, metabolic, and environmental factors converge to define a progressive neurodegenerative phenotype. Conventional anti-dementia drugs are not cost-effective, and pharmacological breakthroughs have not been achieved for the past 10 years. Major determinants of therapeutic outcome in Alzheimer's disease (AD) include age- and sex-related factors, pathogenic phenotype, concomitant disorders, treatment modality and polypharmacy, and pharmacogenetics. Different categories of genes are potentially involved in the pharmacogenetic network responsible for drug efficacy and safety. Pathogenic, mechanistic, metabolic, transporter, and pleiotropic genes represent the major genetic determinants of response to treatment in AD. In pharmacogenetic studies, APOE-4 carriers are the worst responders and APOE-3 carriers are the best responders to conventional treatments. Patients harboring a large (L) number of poly T repeats in intrón 6 of the TOMM40 gene (L/L or S/L genotypes) in haplotypes associated with APOE-4 are the worst responders whereas patients with short (S) TOMM40 poly T variants (S/S genotype), and to a lesser extent S/VL and VL/VL carriers, in haplotypes with APOE-3 are the best responders to treatment. Only 25% of the Caucasian population are extensive metabolizers for trigenic haplotypes integrating CYP2D6- CYP2C19-CYP2C9 variants. Patients harboring CYP-related por (PM) and/or ultra-rapid (UM) geno-phenotypes display more irregular profiles in drug metabolism than extensive (EM) or intermediate (IM) metabolizers. Among 111 pentagenic (APOE-APOB-APOC3-CETP-LPL) haplotypes associated with lipid metabolism, carriers of the H26 haplotype (23-TT-CG- AG-CC) exhibit the lowest cholesterol levels and patients with the H104 haplotype (44-CC-CC-AA-CC) are severely hypercholesterolemic. Epigenetic aberrations (DNA methylation, histone modifications, miRNA dysregulation) in genes configuring the pharmacoepigenetic cascade also influence the response/resistance to drugs. Consequently, novel strategies in drug development, either preventive or therapeutic, for AD should take into consideration these pharmacogenetic determinants for treatment optimization.
Open Access
Genetic polymorphisms of CYP2C19 in Ecuadorian population: an interethnic approach
(Elsevier, 2024) Alonso Llorente, Alba; Salgado Garrido, Josefa; Teijido Hermida, Óscar; González Andrade, Fabricio; Valiente Martín, Alberto; Fanlo Villacampa, Ana; Vicente Romero, Jorge; Ciencias de la Salud; Osasun Zientziak
Introduction: CYP2C19 is a highly polymorphic gene responsible for metabolizing commonly used drugs. CYP2C192,3 (loss of activity alleles) and 17 (increased activity allele) are the principal alleles included in clinical guidelines, however their prevalence varies among different ethnicities. Ecuadorian population is formed by Mestizos, Afrodescendants and Native Americans and frequency of CYP2C19 alleles could be different among them. The objective of this study was to establish the frequency of these variants in the different populations of Ecuador and to compare them with other populations. Materials and methods: DNA from 105 Afrodescendants, 75 Native Americans of the Kichwa ethnicity, and 33 Mestizos Ecuadorians was analyzed by nested-PCR to identify CYP2C1917 carriers. CYP2C192 allele was analyzed in DNA from 78 Afrodescendants, 29 Native Americans of the Kichwa, and 16 Mestizos by TaqMan Allelic Discrimination Assay. CYP2C193 was analyzed in 33 Afrodescendants by nested-PCR. Results: The global frequencies of the alternate alleles were 14.22% (CYP2C192) and 2.10% (CYP2C1917). No differences (p > 0.05) were observed among the subgroups. No CYP2C193 carrier was identified. CYP2C192 frequencies in Ecuador were similar to the ones reported in Europe, Africa and Middle East countries and to some American populations. Low CYP2C1917 frequencies, like the ones in our population, were also observed in East and South Asia and in Native American groups. Discussion: Absence of differences in the ethnic groups in Ecuador for CYP2C192 and 17 could be due to either a bias in sample selection (ethnic group was assed by self-identification) or to a high interethnic admixture in the Ecuadorian population that would had diluted genetic differences. In addition, CYP2C192, *3, and *17 alleles frequencies in our study suggest that Ecuadorians ancestry is mostly of Native American origin.