Role of Resveratrol and Selenium on Oxidative Stress and Expression of Antioxidant and Anti-Aging Genes in Immortalized Lymphocytes from Alzheimer's Disease Patients

Oxidative damage is involved in the pathophysiology of age-related ailments, including Alzheimer's disease (AD). Studies have shown that the brain tissue and also lymphocytes from AD patients present increased oxidative stress compared to healthy controls (HCs). Here, we use lymphoblastoid cell lines (LCLs) from AD patients and HCs to investigate the role of resveratrol (RV) and selenium (Se) in the reduction of reactive oxygen species (ROS) generated after an oxidative injury. We also studied whether these compounds elicited expression changes in genes involved in the antioxidant cell response and other aging-related mechanisms. AD LCLs showed higher ROS levels than those from HCs in response to H2O2 and FeSO4 oxidative insults. RV triggered a protective response against ROS under control and oxidizing conditions, whereas Se exerted antioxidant effects only in AD LCLs under oxidizing conditions. RV increased the expression of genes encoding known antioxidants (catalase, copper chaperone for superoxide dismutase 1, glutathione S-transferase zeta 1) and anti-aging factors (sirtuin 1 and sirtuin 3) in both AD and HC LCLs. Our findings support RV as a candidate for inducing resilience and protection against AD, and reinforce the value of LCLs as a feasible peripheral cell model for understanding the protective mechanisms of nutraceuticals against oxidative stress in aging and AD

Epigenetic alterations in hippocampus of SAMP8 senescent mice and modulation by voluntary physical exercise

The senescence-accelerated SAMP8 mouse model displays features of cognitive decline and Alzheimer's disease. With the purpose of identifying potential epigenetic markers involved in aging and neurodegeneration, here we analyzed the expression of 84 mature miRNAs, the expression of histone-acetylation regulatory genes and the global histone acetylation in the hippocampus of 8-month-old SAMP8 mice, using SAMR1 mice as control. We also examined the modulation of these parameters by 8 weeks of voluntary exercise. Twenty-one miRNAs were differentially expressed between sedentary SAMP8 and SAMR1 mice and seven miRNAs were responsive to exercise in both strains. SAMP8 mice showed alterations in genes involved in protein acetylation homeostasis such as Sirt1 and Hdac6 and modulation of Hdac3 and Hdac5 gene expression by exercise. Global histone H3 acetylation levels were reduced in SAMP8 compared with SAMR1 mice and reached control levels in response to exercise. In sum, data presented here provide new candidate epigenetic markers for aging and neurodegeneration and suggest that exercise training may prevent or delay some epigenetic alterations associated with accelerated aging

Rcor2 underexpression in senescent mice: a target for inflammaging?

BACKGROUND: Aging is characterized by a low-grade systemic inflammation that contributes to the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). However, little knowledge is currently available on the molecular processes leading to chronic neuroinflammation. In this context, recent studies have described the role of chromatin regulators in inflammation and longevity including the REST corepressor (Rcor)-2 factor, which seems to be involved in an inflammatory suppressive program. METHODS: To assess the impact of Rcor2 in age-related inflammation, gene expression levels were quantified in different tissues and ages of the spontaneous senescence-accelerated P8 mouse (P8) using the SAMR1 mouse (R1) as a control. Specific siRNA transfection in P8 and R1 astrocyte cultures was used to determine Rcor2 involvement in the modulation of neuroinflammation. The effect of lipopolysaccharide (LPS) treatment on Rcor2 levels and neuroinflammation was analyzed both in vivo and in vitro. RESULTS: P8 mice presented a dramatic decrease in Rcor2 gene expression compared with R1 controls in splenocytes, an alteration also observed in the brain cortex, hippocampus and primary astrocytes of these mice. Rcor2 reduction in astrocytes was accompanied by an increased basal expression of the interleukin (Il)-6 gene. Strikingly, intraperitoneal LPS injection in R1 mice downregulated Rcor2 in the hippocampus, with a concomitant upregulation of tumor necrosis factor (Tnf-α), Il1-β and Il6 genes. A negative correlation between Rcor2 and Il6 gene expression was also verified in LPS-treated C6 glioma cells. Knock down of Rcor2 by siRNA transfection (siRcor2) in R1 astrocytes upregulated Il6 gene expression while siRcor2 further increased Il6 expression in P8 astrocytes. Moreover, LPS activation provoked a further downregulation of Rcor2 and an amplified induction of Il6 in siRcor2-tranfected astrocytes. CONCLUSIONS: Data presented here show interplay between Rcor2 downregulation and increased inflammation and suggest that Rcor2 may be a key regulator of inflammagin

Temporal Integrative Analysis of mRNA and microRNAs Expression Profiles and Epigenetic Alterations in Female SAMP8, a Model of Age-Related Cognitive Decline

A growing body of research shows that epigenetic mechanisms are critically involved in normal and pathological aging. The Senescence-Accelerated Mouse Prone 8 (SAMP8) can be considered a useful tool to better understand the dynamics of the global epigenetic landscape during the aging process since its phenotype is not fully explained by genetic factors. Here we investigated dysfunctional age-related transcriptional profiles and epigenetic programming enzymes in the hippocampus of 2- and 9-month-old SAMP8 female mice using the Senescent-Accelerated Resistant 1 (SAMR1) mouse strain as control. SAMP8 mice presented 1,062 genes dysregulated at 2 months of age, and 1,033 genes at 9 months, with 92 genes concurrently dysregulated at both ages compared to age-matched SAMR1. SAMP8 mice showed a significant decrease in global DNA methylation (5-mC) at 2 months while hydroxymethylation (5-hmC) levels were increased in SAMP8 mice at 2 and 9 months of age compared to SAMR1. These changes were accompanied by changes in the expression of several enzymes that regulate 5-mC and methylcytosine oxidation. Acetylated H3 and H4 histone levels were significantly diminished in SAMP8 mice at 2-month-old compared to SAMR1 and altered Histone DeACetylase (HDACs) profiles were detected in both young and old SAMP8 mice. We analyzed 84 different mouse miRNAs known to be altered in neurological diseases or involved in neuronal development. Compared with SAMR1, SAMP8 mice showed 28 and 17 miRNAs differentially expressed at 2 and 9 months of age, respectively; 6 of these miRNAs overlapped at both ages. We used several bioinformatic approaches to integrate our data in mRNA:miRNA regulatory networks and functional predictions for young and aged animals. In sum, our study reveals interplay between epigenetic mechanisms and gene networks that seems to be relevant for the progression toward a pathological aging and provides several potential markers and therapeutic candidates for Alzheimer's Disease (AD) and age-related cognitive impairment

Characterization of epigenetic and transcriptional changes in aging and Alzheimer’s disease

[eng] Epigenetic changes are currently recognized as part of the aging process and have been implicated in many age-related chronic diseases such as Alzheimer’s disease (AD). The term epigenetics includes a variety of processes known to regulate gene expression in a stable and potentially reversible way, without altering the primary DNA sequence. The molecular mechanisms that mediate epigenetic regulation are principally DNA methylation, post-translational modifications of histones, and regulation by non-coding RNAs. Research on age-related disorders have recently focused in epigenetic mechanisms since they allow for the integration of long-lasting non-genetic inputs on specific genetic backgrounds, and a growing number of epigenetic alterations in AD have been described recently. Interestingly, it has been estimated that about one-third of AD dementia cases worldwide might be attributable to modifiable risk factors including depression, midlife hypertension, midlife obesity, diabetes, physical inactivity, smoking, and low education; whereas investigations like the FINGER study, a two-year landmark randomized controlled trial, show that a multicomponent approach targeting several vascular and lifestyle-related risk factors simultaneously in elderly people at risk of dementia can improve or maintain cognitive functioning. In fact, many nutrients or dietary compounds (including folate, vitamin B-12, curcumin, resveratrol, selenium, etc.) are described to exert a favorable or unfavorable effect regarding AD onset and progression through epigenetic mechanisms. Similarly, several studies have described a modulation of these mechanisms by physical exercise on different animal peripheral systems and central nervous system, highlighting beneficial epigenetic exercise-induced effects. Within this context, this thesis comprises three studies aiming to better understand the epigenetic contribution to pathological aging, the potential utility of epigenetic changes as early biomarkers of AD, and their role in orchestrating physical exercise and folate deficiency effects on brain health. In the first study we measured plasma miRNA levels in samples from AD patients, AD preclinical subjects (patients with intact cognitive abilities but β-amyloid levels <500pg/mL in cerebrospinal fluid), and healthy elderly controls. We found that plasma miR-34a and miR-545-3p showed good diagnostic values in our first cohort and so they could constitute good early peripheral biomarkers for AD. However, contradictory results regarding a second cohort highlights possible sources of variability in miRNA analysis (e.g. age or environmental factors), which currently prevents their use as reliable clinical tools and warrants further research on the topic. In the second study, we found alterations on twenty-one microRNAs (previously reported to be involved in aging and neurodegeneration), histone-acetylation regulatory genes (histone deacetylases HDAC5, HDAC6, and SIRT1), and global histone H3 acetylation levels in the hippocampus of 10-month-old SAMP8 mice (a senescence-accelerated mouse model resembling features of AD), compared to SAMR1 control mice. We also observed that some of these parameters were modulated by 8 weeks of voluntary exercise; particularly, seven microRNAs (involved in the regulation of signaling pathways previously reported to be modulated in the brain by exercise), histone deacetylases HDAC3, HDAC5, and histone H3 acetylation levels. In fact, acetylation levels of histone H3, which have been described to positively correlate with cognitive function, were reduced in SAMP8 hippocampus, and the physical exercise intervention was able to restore its levels. Finally, in the last study we characterized epigenetic and transcriptional changes associated with folate metabolism disruption on 10-month old mice, and its potential impact on brain neurodegeneration and cognition. We found that dietary and/or genetic folate metabolism disruption leads to alterations on short-term recognition memory, brain gene expression of APP-processing enzymes, neurotrophic factors, histone-acetylation and DNA methylation regulatory enzymes. Particularly, dysregulation of both the neurotrophic factor Bdnf and the APP-processing enzyme Psen1, seems to be associated with changes on DNA methylation levels at their gene promoters. We concluded that this signature may be contributing to the higher neurodegeneration risk reported in dietary and genetic folate-deficiencies.[spa] Los cambios epigenéticos son reconocidos como parte del proceso de envejecimiento y están implicados en muchas enfermedades relacionadas con la edad, como la enfermedad de Alzheimer (EA). Estos mecanismos regulan la expresión génica de una manera estable y potencialmente reversible, sin alterar la secuencia primaria del ADN. Incluyen principalmente la metilación del ADN, modificaciones post-traduccionales de histonas, y ARNs no codificantes. Por otro lado, se ha estimado que alrededor de 1/3 de los casos de EA podría ser atribuible a factores de riesgo relacionados con el estilo de vida. De hecho, se ha reportado que muchos nutrientes ejercen un efecto favorable o desfavorable por lo que respecta al desarrollo o progresión de la EA a través de mecanismos epigenéticos. Del mismo modo, también se ha descrito una modulación de estos mecanismos por el ejercicio físico en el sistema nervioso central, destacando sus beneficios. En este contexto, la siguiente tesis contiene tres estudios que tienen como objetivo mejorar la comprensión de la contribución de estos mecanismos al envejecimiento patológico y la EA, estudiar su papel en la orquestación de los efectos inducidos por el ejercicio físico y una deficiencia en folatos en la salud del cerebro, y su potencial como biomarcadores precoces de la EA. En el primer estudio se midieron los niveles plasmáticos de microARNs en muestras de pacientes con EA, sujetos preclínicos de la enfermedad (con capacidades cognitivas intactas, pero niveles alterados de beta-amiloide en líquido cefalorraquídeo) y controles sanos de edad avanzada. Los microARNs miR-34a-5p y miR-545-3p destacaron como posibles biomarcadores tempranos de la EA. En el segundo estudio, se detectaron alteraciones en microARNs, genes reguladores de acetilación de histonas y niveles globales de acetilación de histona 3 en hipocampo de ratones SAMP8 de 10 meses de edad (un modelo de ratón de senescencia acelerada con características similares a la EA). Además, se observó que algunos de estos parámetros fueron modulados, y en algunos casos restaurados, por una intervención de 8 semanas de ejercicio voluntario. En el último estudio se caracterizaron cambios de comportamiento, epigenéticos, y transcripcionales, asociados a una deficiencia en folatos en ratones de 10 meses. En consecuencia, se planteó su posible relación con el mayor riesgo de neurodegeneración observado en este tipo de deficiencias

Temporal Integrative Analysis of mRNA and microRNAs Expression Profiles and Epigenetic Alterations in Female SAMP8, a Model of Age-Related Cognitive Decline

A growing body of research shows that epigenetic mechanisms are critically involved in normal and pathological aging. The Senescence-Accelerated Mouse Prone 8 (SAMP8) can be considered a useful tool to better understand the dynamics of the global epigenetic landscape during the aging process since its phenotype is not fully explained by genetic factors. Here we investigated dysfunctional age-related transcriptional profiles and epigenetic programming enzymes in the hippocampus of 2- and 9-month-old SAMP8 female mice using the Senescent-Accelerated Resistant 1 (SAMR1) mouse strain as control. SAMP8 mice presented 1,062 genes dysregulated at 2 months of age, and 1,033 genes at 9 months, with 92 genes concurrently dysregulated at both ages compared to age-matched SAMR1. SAMP8 mice showed a significant decrease in global DNA methylation (5-mC) at 2 months while hydroxymethylation (5-hmC) levels were increased in SAMP8 mice at 2 and 9 months of age compared to SAMR1. These changes were accompanied by changes in the expression of several enzymes that regulate 5-mC and methylcytosine oxidation. Acetylated H3 and H4 histone levels were significantly diminished in SAMP8 mice at 2-month-old compared to SAMR1 and altered Histone DeACetylase (HDACs) profiles were detected in both young and old SAMP8 mice. We analyzed 84 different mouse miRNAs known to be altered in neurological diseases or involved in neuronal development. Compared with SAMR1, SAMP8 mice showed 28 and 17 miRNAs differentially expressed at 2 and 9 months of age, respectively; 6 of these miRNAs overlapped at both ages. We used several bioinformatic approaches to integrate our data in mRNA:miRNA regulatory networks and functional predictions for young and aged animals. In sum, our study reveals interplay between epigenetic mechanisms and gene networks that seems to be relevant for the progression toward a pathological aging and provides several potential markers and therapeutic candidates for Alzheimer's Disease (AD) and age-related cognitive impairment

Epigenetic alterations in hippocampus of SAMP8 senescent mice and modulation by voluntary physical exercise

The senescence-accelerated SAMP8 mouse model displays features of cognitive decline and Alzheimer's disease. With the purpose of identifying potential epigenetic markers involved in aging and neurodegeneration, here we analyzed the expression of 84 mature miRNAs, the expression of histone-acetylation regulatory genes and the global histone acetylation in the hippocampus of 8-month-old SAMP8 mice, using SAMR1 mice as control. We also examined the modulation of these parameters by 8 weeks of voluntary exercise. Twenty-one miRNAs were differentially expressed between sedentary SAMP8 and SAMR1 mice and seven miRNAs were responsive to exercise in both strains. SAMP8 mice showed alterations in genes involved in protein acetylation homeostasis such as Sirt1 and Hdac6 and modulation of Hdac3 and Hdac5 gene expression by exercise. Global histone H3 acetylation levels were reduced in SAMP8 compared with SAMR1 mice and reached control levels in response to exercise. In sum, data presented here provide new candidate epigenetic markers for aging and neurodegeneration and suggest that exercise training may prevent or delay some epigenetic alterations associated with accelerated aging

Epigenetic alterations in hippocampus of SAMP8 senescent mice and modulation by voluntary physical exercise

The senescence-accelerated SAMP8 mouse model displays features of cognitive decline and Alzheimer's disease. With the purpose of identifying potential epigenetic markers involved in aging and neurodegeneration, here we analyzed the expression of 84 mature miRNAs, the expression of histone-acetylation regulatory genes and the global histone acetylation in the hippocampus of 8-month-old SAMP8 mice, using SAMR1 mice as control. We also examined the modulation of these parameters by 8 weeks of voluntary exercise. Twenty-one miRNAs were differentially expressed between sedentary SAMP8 and SAMR1 mice and seven miRNAs were responsive to exercise in both strains. SAMP8 mice showed alterations in genes involved in protein acetylation homeostasis such as Sirt1 and Hdac6 and modulation of Hdac3 and Hdac5 gene expression by exercise. Global histone H3 acetylation levels were reduced in SAMP8 compared with SAMR1 mice and reached control levels in response to exercise. In sum, data presented here provide new candidate epigenetic markers for aging and neurodegeneration and suggest that exercise training may prevent or delay some epigenetic alterations associated with accelerated aging

Rcor2 underexpression in senescent mice: a target for inflammaging?

BACKGROUND: Aging is characterized by a low-grade systemic inflammation that contributes to the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). However, little knowledge is currently available on the molecular processes leading to chronic neuroinflammation. In this context, recent studies have described the role of chromatin regulators in inflammation and longevity including the REST corepressor (Rcor)-2 factor, which seems to be involved in an inflammatory suppressive program. METHODS: To assess the impact of Rcor2 in age-related inflammation, gene expression levels were quantified in different tissues and ages of the spontaneous senescence-accelerated P8 mouse (P8) using the SAMR1 mouse (R1) as a control. Specific siRNA transfection in P8 and R1 astrocyte cultures was used to determine Rcor2 involvement in the modulation of neuroinflammation. The effect of lipopolysaccharide (LPS) treatment on Rcor2 levels and neuroinflammation was analyzed both in vivo and in vitro. RESULTS: P8 mice presented a dramatic decrease in Rcor2 gene expression compared with R1 controls in splenocytes, an alteration also observed in the brain cortex, hippocampus and primary astrocytes of these mice. Rcor2 reduction in astrocytes was accompanied by an increased basal expression of the interleukin (Il)-6 gene. Strikingly, intraperitoneal LPS injection in R1 mice downregulated Rcor2 in the hippocampus, with a concomitant upregulation of tumor necrosis factor (Tnf-α), Il1-β and Il6 genes. A negative correlation between Rcor2 and Il6 gene expression was also verified in LPS-treated C6 glioma cells. Knock down of Rcor2 by siRNA transfection (siRcor2) in R1 astrocytes upregulated Il6 gene expression while siRcor2 further increased Il6 expression in P8 astrocytes. Moreover, LPS activation provoked a further downregulation of Rcor2 and an amplified induction of Il6 in siRcor2-tranfected astrocytes. CONCLUSIONS: Data presented here show interplay between Rcor2 downregulation and increased inflammation and suggest that Rcor2 may be a key regulator of inflammagin