Open Access
Oligomeric Bax is a component of the putative cytochrome c release channel MAC, mitochondrial apoptosis-induced channel
(American Society for Cell Biology, 2005-03-16) Dejean, Laurent M.; Martínez-Caballero, Sonia; Guo, Liang; Hughes, Cynthia; Teijido Hermida, Óscar; Ducret, Thomas; Ichas, François; Korsmeyer, Stanley J.; Antonsson, Bruno; Jonas, Elizabeth A.; Kinnally, Kathleen W.; Ciencias de la Salud; Osasun Zientziak
Bcl-2 family proteins regulate apoptosis, in part, by controlling formation of the mitochondrial apoptosis-induced channel (MAC), which is a putative cytochrome c release channel induced early in the intrinsic apoptotic pathway. This channel activity was never observed in Bcl-2-overexpressing cells. Furthermore, MAC appears when Bax translocates to mitochondria and cytochrome c is released in cells dying by intrinsic apoptosis. Bax is a component of MAC of staurosporine-treated HeLa cells because MAC activity is immunodepleted by Bax antibodies. MAC is preferentially associated with oligomeric, not monomeric, Bax. The single channel behavior of recombinant oligomeric Bax and MAC is similar. Both channel activities are modified by cytochrome c, consistent with entrance of this protein into the pore. The mean conductance of patches of mitochondria isolated after green fluorescent protein-Bax translocation is significantly higher than those from untreated cells, consistent with onset of MAC activity. In contrast, the mean conductance of patches of mitochondria indicates MAC activity is present in apoptotic cells deficient in Bax but absent in apoptotic cells deficient in both Bax and Bak. These findings indicate Bax is a component of MAC in staurosporine-treated HeLa cells and suggest Bax and Bak are functionally redundant as components of MAC.
Open Access
Epigenetics of brain aging
(Academic Press, 2018) Cacabelos, Ramón; Teijido Hermida, Óscar; Ciencias de la Salud; Osasun Zientziak
The complexity of human aging and longevity results from a combination of genetic, epigenetic, and environmental factors. Epigenetic mechanisms, including DNA methylation, chromatin structure, and RNA interference, regulate gene expression and control the main metabolic pathways throughout life. This strict epigenetic management becomes progressively defective with age, which increases the risk for the onset of age-related pathologies. This chapter reviews the main alterations of the epigenetic machinery throughout life, with special focus on those affecting the aging brain, as well as the epigenetic control of life span by regulating telomere length and mitochondrial function, with special emphasis on the epigenetic interplay between nuclear and mitochondrial DNA. The last section summarizes the main epigenetic aberrations involving the most prevalent form of pathologic brain deterioration in elderly individuals, Alzheimer's disease, and novel potential epigenetic-based treatments.
Open Access
Epigenetic mechanisms in the regulation of drug metabolism and transport
(Academic Press, 2019) Teijido Hermida, Óscar; Ciencias de la Salud; Osasun Zientziak
Open Access
Pharmacoepigenomic interventions as novel potential treatments for Alzheimer's and Parkinson's diseases
(MDPI, 2018) Teijido Hermida, Óscar; Cacabelos, Ramón; Ciencias de la Salud; Osasun Zientziak
Cerebrovascular and neurodegenerative disorders affect one billion people around the world and result from a combination of genomic, epigenomic, metabolic, and environmental factors. Diagnosis at late stages of disease progression, limited knowledge of gene biomarkers and molecular mechanisms of the pathology, and conventional compounds based on symptomatic rather than mechanistic features, determine the lack of success of current treatments, including current FDA-approved conventional drugs. The epigenetic approach opens new avenues for the detection of early presymptomatic pathological events that would allow the implementation of novel strategies in order to stop or delay the pathological process. The reversibility and potential restoring of epigenetic aberrations along with their potential use as targets for pharmacological and dietary interventions sited the use of epidrugs as potential novel candidates for successful treatments of multifactorial disorders involving neurodegeneration. This manuscript includes a description of the most relevant epigenetic mechanisms involved in the most prevalent neurodegenerative disorders worldwide, as well as the main potential epigenetic-based compounds under investigation for treatment of those disorders and their limitations.
Open Access
Population-based study of risk polymorphisms associated with vascular disorders and dementia
(Bentham Science Publishers, 2017) Teijido Hermida, Óscar; Carril, Juan Carlos ; Cacabelos, Ramón; Ciencias de la Salud; Osasun Zientziak
Introduction: Cardiovascular and neurodegenerative disorders are among the major causes of mortality in the developed countries. Population studies evaluate the genetic risk, i.e. the probability of an individual carrying a specific disease-associated polymorphism. Identification of risk polymorphisms is essential for an accurate diagnosis or prognosis of a number of pathologies. Aims: The aim of this study was to characterize the influence of risk polymorphisms associated with lipid metabolism, hypertension, thrombosis, and dementia, in a large population of Spanish individuals affected by a variety of brain and vascular disorders as well as metabolic syndrome. Material & Method: We performed a cross-sectional study on 4415 individuals from a widespread regional distribution in Spain (48.15% males and 51.85% females), with mental, neurodegenerative, cerebrovascular, and metabolic disorders. We evaluated polymorphisms in 20 genes involved in obesity, vascular and cardiovascular risk, and dementia in our population and compared it with representative Spanish and European populations. Risk polymorphisms in ACE, AGT(235), IL6(573), PSEN1, and APOE (specially the APOE-ε4 allele) are representative of our population as compared to the reference data of Spanish and European individuals. Conclusion: The significantly higher distribution of risk polymorphisms in PSEN1 and APOE-ε4 is characteristic of a representative number of patients with Alzheimer’s disease; whereas polymorphisms in ACE, AGT(235), and IL6(573), are most probably related with the high number of patients with metabolic syndrome or cerebrovascular damage.
Open Access
Regulation of Bax mitochondrial localization by Bcl-2 and Bcl-xL: keep your friends close but your enemies closer
(Elsevier, 2013) Renault, Thibaud T.; Teijido Hermida, Óscar; Antonsson, Bruno; Dejean, Laurent M.; Manon, Stéphen; Ciencias de la Salud; Osasun Zientziak
Bax-induced mitochondrial outer membrane permeabilization (MOMP) is considered as one of the key control switches of apoptosis. MOMP requires Bax relocation to and insertion into the outer mitochondrial membrane to oligomerize and form pores allowing the release of apoptogenic factors such as cytochrome c. Even if these essential steps are now well-defined, it is necessary to better understand the molecular changes underlying the switch between inactive Bax and active (pore-forming) Bax. One of the ongoing issues is to determine whether Bax mitochondrial translocation is a critical step in the control of Bax activation or if this control is carried by latter regulatory steps. In this focus article we discuss recent data suggesting that although Bcl-2 and Bcl-xL block the MOMP, they can also regulate the mitochondrial Bax content. A new model in which Bax inhibition by Bcl-xL occurs at the immediate proximity of the outer mitochondrial membrane is also discussed. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.
Open Access
Current state of theoretical and experimental studies of the voltage-dependent anion channel (VDAC)
(Elsevier, 2016) Noskov, Sergei Y.; Rostovtseva, Tatiana K.; Chamberlin, Adam; Teijido Hermida, Óscar; Jiang, Wei; Bezrukov, Sergey M.; Ciencias de la Salud; Osasun Zientziak
Voltage-dependent anion channel (VDAC), the major channel of the mitochondrial outer membrane provides a controlled pathway for respiratory metabolites in and out of the mitochondria. In spite of the wealth of experimental data from structural, biochemical, and biophysical investigations, the exact mechanisms governing selective ion and metabolite transport, especially the role of titratable charged residues and interactions with soluble cytosolic proteins, remain hotly debated in the field. The computational advances hold a promise to provide a much sought-after solution to many of the scientific disputes around solute and ion transport through VDAC and hence, across the mitochondrial outer membrane. In this review, we examine how Molecular Dynamics, Free Energy, and Brownian Dynamics simulations of the large β-barrel channel, VDAC, advanced our understanding. We will provide a short overview of non-conventional techniques and also discuss examples of how the modeling excursions into VDAC biophysics prospectively aid experimental efforts.
Open Access
Pharmacogenetics of vascular risk factors in Alzheimer's disease
(MDPI, 2018-01-03) Cacabelos, Ramón; Meyyazhagan, Arun; Carril, Juan Carlos; Cacabelos, Pablo; Teijido Hermida, Óscar; Ciencias de la Salud; Osasun Zientziak
Alzheimer's disease (AD) is a polygenic/complex disorder in which genomic, epigenomic, cerebrovascular, metabolic, and environmental factors converge to define a progressive neurodegenerative phenotype. Pharmacogenetics is a major determinant of therapeutic outcome in AD. Different categories of genes are potentially involved in the pharmacogenetic network responsible for drug efficacy and safety, including pathogenic, mechanistic, metabolic, transporter, and pleiotropic genes. However, most drugs exert pleiotropic effects that are promiscuously regulated for different gene products. Only 20% of the Caucasian population are extensive metabolizers for tetragenic haplotypes integrating CYP2D6-CYP2C19-CYP2C9-CYP3A4/5 variants. Patients harboring CYP-related poor (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. Furthermore, APOE, NOS3, ACE, AGT, and CYP variants influence the therapeutic response to hypotensive drugs in AD patients with hypertension. Consequently, the implementation of pharmacogenetic procedures may optimize therapeutics in AD patients under polypharmacy regimes for the treatment of concomitant vascular disorders.
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
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.