Open Access
Pharmacogenetic considerations in the treatment of Alzheimer's disease
(Taylor & Francis, 2016) Cacabelos, Ramón; Torrellas, Clara; Teijido Hermida, Óscar; Carril, Juan Carlos ; Ciencias de la Salud; Osasun Zientziak
The practical pharmacogenetics of Alzheimer’s disease (AD) is circumscribed to acetylcholinesterase inhibitors (AChEIs) and memantine. However, pharmacogenetic procedures should be applied to novel strategies in AD therapeutics including: novel AChEIs and neurotransmitter regulators, anti-Aβ treatments, anti-tau treatments, pleiotropic products, epigenetic drugs and combination therapies. Genes involved in the pharmacogenetic network are under the influence of the epigenetic machinery which regulates gene expression transcriptionally and post-transcriptionally, configuring the fundamentals of pharmacoepigenomics. Over 60% of AD patients present concomitant pathologies demanding additional treatments which increase the likelihood of drug–drug interactions. Lipid metabolism dysfunction is a pathogenic mechanism inherent to AD neurodegeneration. The therapeutic response to hypolipidemic compounds is influenced by the APOE and CYP genotypes. The development of novel compounds and the use of combination/multifactorial treatments require the implantation of pharmacogenomic procedures for the avoidance of ADRs and the optimization of therapeutics.
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
Epigenetic drug discovery for alzheimer's disease
(Academic Press, 2018) Cacabelos, Ramón; Teijido Hermida, Óscar; Ciencias de la Salud; Osasun Zientziak
Alzheimer's disease (AD) is the most important neurodegenerative disorder in Western countries. Pathological phenotypes of neurodegeneration result from a combination of genomic, epigenomic, metabolic, and environmental factors, which hinders their treatment. Current FDA-approved conventional drugs are purely symptomatic but incapable to halt or, at least, delay the progression of the disease. The epigenetic approach allows the identification of key pathological targets in complex disorders that cannot be explained by conventional genetics. Many of these epigenetic targets may be detected in early asymptomatic stages of the disease. Furthermore, the reversibility and potential restoring of epigenetic aberrations, unlike genetic mutations, sited epigenetic-based therapy as a promising tool to treat those complex disorders. This chapter reviews the main potential epigenetic-based compounds that have been used for preclinical studies during the last decade and those currently submitted to clinical trials for the treatment of AD.
Open Access
Vacuolating megalencephalic leukoencephalopathy with subcortical cysts: functional studies of novel variants in MLC1
(Wiley, 2006-02-08) Montagna, Giorgia; Teijido Hermida, Óscar; Eymard-Pierre, Eleonore; Muraki, Koutarou; Cohen, Bruce; Loizzo, Annalivia; Grosso, Pietro; Tedeschi, Gioacchino; Palacín, Manuel; Boespflug-Tanguy, Odile; Bertini, Enrico; Santorelli, Filippo M.; Estévez, Raúl; Ciencias de la Salud; Osasun Zientziak
Nine new unrelated patients presenting vacuolating myelinopathy with subcortical cysts were identified and analyzed for variations in the MLC1 gene. We detected 12 mutations (p.Leu37fs, p.Met80Val, p.Leu83Phe, p.Pro92Ser, p.Ser93Leu, p.Ile108fs, p.Gly130Arg, p.Cys171fs, p.Glu202Lys, p.Ser269Tyr, p.Ala275Asn, and p.Leu310_311insLeu) of which nine were novel. In one patient we did not detect mutations. Using a heterologous system, three new missense variants (p.Glu202Lys, p.Ser269Tyr, and p.Ala275Asn) and a single leucine insertion (p.Leu310insLeu) - lying in a stretch of seven leucines - were functionally assayed by determining total protein levels and mutant protein expression at the plasma membrane. No correlation was observed between mutation, clinical features, and plasma membrane expression of mutant protein.
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
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
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
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.