Mitochondriogenesis and brain aging

Introduction: Mitochondriogenesis is the cellular process responsible for the generation of new mitochondria and consists of the replication of mitochondrial DNA (mtDNA) and the organelle division. Several studies suggest mitochondriogenesis is regulated by oxidative stress through a molecular pathway that involves the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and the mitochondrial transcription factors A, B1 and B2 (TFAM, TFB1M, TFB2M). According to the Mitochondrial Theory of Aging, reactive oxygen species (ROS) generated in oxidative phosphorylation damage mitochondrial macromolecules, leading to mitochondrial dysfunction and signaling for cellular senescence. Since oxidative stress plays an important role in both mitochondriogenesis and aging, the amount of mitochondria in a tissue may be a biomarker of senescence and age-related diseases. Objective: The objective of the present study is to analyze the variation of mtDNA content in brain tissue with aging and how the expressions of PGC-1α, TFAM, TFB1M and TFB2M are related to this process. Methods: 60 samples of human brain were collected during autopsy procedures, as well as the clinical history of each donator. Their DNA and RNA were extracted and their mtDNA copy number and expressions of PGC-1α, TFAM, TFB1M and TFB2M were determined through quantitative polymerase chain reaction. The raw data was submitted to statistical analysis. Results: A direct correlation between mtDNA content and age was found among specimens with more than 1000 copies (p = 0,0067). In the population with less than 1000 copies, no correlation was observed. It was also found that the expressions of PGC-1α, TFAM, TFB1M and TFB2M have a good correlation among each other, but none of them correlated to mtDNA copy number or age.Discussion and conclusion: The amount of mitochondria in brain tissue varies differently with aging among population. While some individuals are prone to increase mitochondriogenesis with aging, others keep it low throughout life. It is possible that these 2 subgroups are under the influence of different factors, apart from the molecular pathway of PGC-1α, TFAM, TFB1M and TFB2M. Interestingly, individuals with propensity to mtDNA content increase also have higher body mass index and higher expression of the studied genes among diabetics. This findings suggest that metabolic disorders, besides being a risk factor for several diseases, may be also related to mitochondriogenesis increase in brain aging. Therefore, the results achieved in the present study reinforce the hypothesis that the mitochondrial content in a tissue may be a biomarker of senescence and age-related diseases

Mitochondriogenesis and brain aging

Introduction: Mitochondriogenesis is the cellular process responsible for the generation of new mitochondria and consists of the replication of mitochondrial DNA (mtDNA) and the organelle division. Several studies suggest mitochondriogenesis is regulated by oxidative stress through a molecular pathway that involves the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and the mitochondrial transcription factors A, B1 and B2 (TFAM, TFB1M, TFB2M). According to the Mitochondrial Theory of Aging, reactive oxygen species (ROS) generated in oxidative phosphorylation damage mitochondrial macromolecules, leading to mitochondrial dysfunction and signaling for cellular senescence. Since oxidative stress plays an important role in both mitochondriogenesis and aging, the amount of mitochondria in a tissue may be a biomarker of senescence and age-related diseases. Objective: The objective of the present study is to analyze the variation of mtDNA content in brain tissue with aging and how the expressions of PGC-1α, TFAM, TFB1M and TFB2M are related to this process. Methods: 60 samples of human brain were collected during autopsy procedures, as well as the clinical history of each donator. Their DNA and RNA were extracted and their mtDNA copy number and expressions of PGC-1α, TFAM, TFB1M and TFB2M were determined through quantitative polymerase chain reaction. The raw data was submitted to statistical analysis. Results: A direct correlation between mtDNA content and age was found among specimens with more than 1000 copies (p = 0,0067). In the population with less than 1000 copies, no correlation was observed. It was also found that the expressions of PGC-1α, TFAM, TFB1M and TFB2M have a good correlation among each other, but none of them correlated to mtDNA copy number or age.Discussion and conclusion: The amount of mitochondria in brain tissue varies differently with aging among population. While some individuals are prone to increase mitochondriogenesis with aging, others keep it low throughout life. It is possible that these 2 subgroups are under the influence of different factors, apart from the molecular pathway of PGC-1α, TFAM, TFB1M and TFB2M. Interestingly, individuals with propensity to mtDNA content increase also have higher body mass index and higher expression of the studied genes among diabetics. This findings suggest that metabolic disorders, besides being a risk factor for several diseases, may be also related to mitochondriogenesis increase in brain aging. Therefore, the results achieved in the present study reinforce the hypothesis that the mitochondrial content in a tissue may be a biomarker of senescence and age-related diseases

Metabolism and Brain Cancer

Cellular energy metabolism is one of the main processes affected during the transition from normal to cancer cells, and it is a crucial determinant of cell proliferation or cell death. As a support for rapid proliferation, cancer cells choose to use glycolysis even in the presence of oxygen (Warburg effect) to fuel macromolecules for the synthesis of nucleotides, fatty acids, and amino acids for the accelerated mitosis, rather than fuel the tricarboxylic acid cycle and oxidative phosphorylation. Mitochondria biogenesis is also reprogrammed in cancer cells, and the destiny of those cells is determined by the balance between energy and macromolecule supplies, and the efficiency of buffering of the cumulative radical oxygen species. In glioblastoma, the most frequent and malignant adult brain tumor, a metabolic shift toward aerobic glycolysis is observed, with regulation by well known genes as integrants of oncogenic pathways such as phosphoinositide 3-kinase/protein kinase, MYC, and hypoxia regulated gene as hypoxia induced factor 1. The expression profile of a set of genes coding for glycolysis and the tricarboxylic acid cycle in glioblastoma cases confirms this metabolic switch. An understanding of how the main metabolic pathways are modified by cancer cells and the interactions between oncogenes and tumor suppressor genes with these pathways may enlighten new strategies in cancer therapy. In the present review, the main metabolic pathways are compared in normal and cancer cells, and key regulations by the main oncogenes and tumor suppressor genes are discussed. Potential therapeutic targets of the cancer energetic metabolism are enumerated, highlighting the astrocytomas, the most common brain cancer

Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

OBJECTIVE: To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis. METHOD: In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter's criteria) and a control group consisting of four dystrophic and five Pompe's disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X). RESULTS: The mean ages at disease onset were 42.0±15.9 and 7.3±3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (

Analysis of the use of photosensitization in human glioblastoma multiforme to induce cell death

Introduction: The most frequent primary tumor of the central nervous system is the malignant glioma, being the glioblastoma (GBM), grade IV astrocytoma, the most aggressive and lethal glioma. Malignant astrocytomas are responsive for therapy targeting autophagy as temozolomide, the standard adjuvant treatment which induces autophagic cell death. Autophagy is a homeostatic intracellular process that eliminate old proteins and recycle cellular components. Mitophagy is a subtype of autophagy that regulates the removal of damaged, dysfunctional or redundant mitochondria. Parallel damage against lysosomes and mitochondria membranes using photosensitized oxidations and strong redox stress leads to activation of mitophagy and malfunction of autophagy. This mechanism of photosensitization, ultimately, causes cell death. Challenging cells with a low concentration of a photosensitizer as 1,9-dimethyl methylene blue (DMMB) combined with light- irradiation of 12 joules/cm2 have induced mitochondrial damage with activation of mitophagy and concomitant lysosome damage, in skin-derived cell lines. This experimental design was applied to U87MG GBM cells to verify if tumor cell death may be obtained with combined mitochondrial and lysosomal damages to open new therapeutic strategies for GBM and to better understand the mechanisms of mitophagy.Objectives: Our primary objective is to analyze the impact of challenging GBM cells with a low concentration of 1,9-dimethyl methylene blue (DMMB) with combined light- irradiation of 12 joules/cm2.Methodology: U87MG a human GBM cell line was used. The photodamage was performed using DMMB photosensitized by a LED with maximum emission wavelength at 630 nm providing 12 J/cm2. Cell proliferation and viability assays were performed using MTT to assess whether there was proliferation inhibition and/or alteration of cell viability after photosensitization. Quantification of cells in different stages of apoptosis, and in the various phases of the cell cycle were analyzed using flow cytometry after photosensitization. Acridine orange assay was used to assess lysosome damage. RT-PCR and Western Blotting were performed to evaluate the expression levels of the main autophagy and mitophagy genes and proteins.Partial Results: Cell proliferation and viability assays demonstrated that the concentration of DMMB to cause 50% inhibition of biological activity of cells (IC50) was 10 nM after 48h. The apoptosis and cell cycle experiments were performed in this concentration. Increase in apoptosis was observed after 24hs of photosensitization. Currently, the cell cycle flow cytometry assay has been performed, followed by the quantification of lysosomes damage by Acridine Orange assay. The genes and proteins involved in the mechanisms of autophagy and mitophagy will be determined by expression analysis through RT-PCR and Western blot assays.Discussion and Conclusion: For a future perspective, if this prove of concept is achieved, i.e. death of tumor cells by the combined approach of photosensitizer with irradiation, a new therapeutic strategy of light-activated drugs may be offered to cancer patients

Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

OBJECTIVE: To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis. METHOD: In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter's criteria) and a control group consisting of four dystrophic and five Pompe's disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X). RESULTS: The mean ages at disease onset were 42.0 +/- 15.9 and 7.3 +/- 3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (p<0.050). Moreover, a significantly higher frequency of major histocompatibility complex I (96.4% vs. 50.0%, p<0.001) compared with major histocompatibility complex II expression (14.3% vs. 53.6%, p = 0.004) was observed in juvenile dermatomyositis. Fiber damage (p = 0.006) and increased connective tissue (p<0.001) were significantly higher in adult dermatomyositis compared with the presence of perifascicular atrophy (p<0.001). The results of the histochemical and histological data did not correlate with the demographic data or with the clinical and laboratory features. CONCLUSION: The overexpression of major histocompatibility complex I was an important finding for the diagnosis of both groups, particularly for juvenile dermatomyositis, whereas there was lower levels of expression of major histocompatibility complex II than major histocompatibility complex I. This finding was particularly apparent in juvenile dermatomyositis.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico - CNPQ [300248/2008-3]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Federico FoundationFederico Foundatio

Phenotypic and immunohistochemical characterization of sarcoglycanopathies

INTRODUCTION: Limb-girdle muscular dystrophy presents with heterogeneous clinical and molecular features. The primary characteristic of this disorder is proximal muscular weakness with variable age of onset, speed of progression, and intensity of symptoms. Sarcoglycanopathies, which are a subgroup of the limb-girdle muscular dystrophies, are caused by mutations in sarcoglycan genes. Mutations in these genes cause secondary deficiencies in other proteins, due to the instability of the dystrophin-glycoprotein complex. Therefore, determining the etiology of a given sarcoglycanopathy requires costly and occasionally inaccessible molecular methods. OBJECTIVE: The aim of this study was to identify phenotypic differences among limb-girdle muscular dystrophy patients who were grouped according to the immunohistochemical phenotypes for the four sarcoglycans. METHODS: To identify phenotypic differences among patients with different types of sarcoglycanopathies, a questionnaire was used and the muscle strength and range of motion of nine joints in 45 patients recruited from the Department of Neurology - HC-FMUSP (Clinics Hospital of the Faculty of Medicine of the University of São Paulo) were evaluated. The findings obtained from these analyses were compared with the results of the immunohistochemical findings. RESULTS: The patients were divided into the following groups based on the immunohistochemical findings: a-sarcoglycanopathies (16 patients), b-sarcoglycanopathies (1 patient), y-sarcoglycanopathies (5 patients), and nonsarcoglycanopathies (23 patients). The muscle strength analysis revealed significant differences for both upper and lower limb muscles, particularly the shoulder and hip muscles, as expected. No pattern of joint contractures was found among the four groups analyzed, even within the same family. However, a high frequency of tiptoe gait was observed in patients with a-sarcoglycanopathies, while calf pseudo-hypertrophy was most common in patients with non-sarcoglycanopathies. The a-sarcoglycanopathy patients presented with more severe muscle weakness than did y-sarcoglycanopathy patients. CONCLUSION: The clinical differences observed in this study, which were associated with the immunohistochemical findings, may help to prioritize the mutational investigation of sarcoglycan genes.CNP

Polimorfismo no gene de metilenetetrahidrofolato redutase não está relacionado com o risco de doença cerebrovascular isquêmica em uma população brasileira

OBJETIVO: Os dados são conflitantes em relação a risco de acidente cerebrovascular associado a polimorfismo do gene 5,10-metilenetetrahidrofolato redutase C677T, o qual predispõe a hiperhomocisteinemia. Um estudo de meta-análise sugere que o genotipo 5,10-metilenetetrahidrofolato redutase 677TT poderia ter uma pequena influência em determinar susceptibilidade a acidente cerebrovascular. MÉTODOS: Analisamos este polimorfismo em indivíduos brasileiros com acidente cerebrovascular isquêmico, baseando-se em um estudo de caso-controle. RESULTADOS: Comparamos os genótipos 5,10-metilenetetrahidrofolato redutase em grupos de indivíduos com acidente cerebrovascular isquêmico (n=127) e controle normal (n=126), e encontramos Odds Ratio de 1,97 (IC 95% 0,84 - 4,64) em uma análise multivariada, na qual os resultados foram ajustados a características clínicas basais dos indivíduos estudados. DISCUSSÃO: Nossos estudos indicam que o genótipo 5,10-metilenetetrahidrofolato redutase C677T não é um fator de risco para acidente cerebrovascular isquêmico entre indivíduos brasileiros.PURPOSE: Data are conflicting concerning the risk for ischemic stroke associated with a common polymorphism in the gene encoding 5,10-methylenetetrahydrofolate reductase C677T, which predisposes carriers to hyperhomocysteinemia. A meta-analysis study suggested that the 5,10-methylenetetrahydrofolate reductase 677TT genotype might have a small influence in determining susceptibility to ischemic stroke. METHODS: We analyzed the 5,10-methylenetetrahydrofolate reductase 677TT genotype polymorphism in Brazilian subjects with ischemic stroke, using a case-control design. RESULTS: We compared 5,10-methylenetetrahydrofolate reductase genotypes in groups of subjects presenting ischemic stroke (n = 127) and normal control (n = 126) and found an odds ratio of 1.97 (95% CI, 0.84-4.64) in a multivariate analysis in which results were adjusted to baseline clinical characteristics of study participants. CONCLUSION: We found that the homozygous 5,10-methylenetetrahydrofolate reductase C677T genotype was not a risk factor for ischemic stroke in these Brazilian subjects

Factors associated with serum CA19-9 levels among healthy children: a cross-sectional study

Abstract\ud \ud \ud \ud Background\ud CA19-9 is a tumor marker mainly used for biliary tract, pancreas and colorectum. Since the marker applies usually for adults, the normal range of serum CA19-9 among children has been rarely reported. This is the first study reporting the distribution of serum CA19-9 levels among cancer-free children as well as their parents, taking into account the Lewis and secretor gene polymorphism and physical growth.\ud \ud \ud \ud Methods\ud Study subjects were 972 apparently healthy Japanese Brazilians including 476 children aged from 1 to 19 years.\ud \ud \ud \ud Results\ud The comparisons in five-year age groups demonstrated that the mean values of serum CA19-9 was lower in the boys than in the girls, and higher in younger age groups; 22.5 U/ml for 1–4 year-old (n=13), 17.4 U/ml for 5–9 year-old (n=36), 15.5 U/ml for 10–14 year-old (n=96) and 10.2 U/ml for 15–19 year-old (n=74) in boys, and 25.3 U/ml (n=11), 27.1 U/ml (n=50), 17.7 U/ml (n=105) and 13.5 U/ml (n=59) in girls, respectively. The difference in those geometric means was statistically significant among four age groups (p=0.006, ANOVA adjusted for sex). After Lewis and secretor genotypes, which are definitive factors of serum CA19-9, were taken into account, geometric mean of serum CA19-9 was associated with any of BMI (p<0.001), height (p<0.001) and weight (p<0.001) among children excluding those with le/le genotype. The associations were still significant when age was adjusted.\ud \ud \ud \ud Conclusions\ud Serum CA19-9 values were higher among children than among adults, and influenced by sex, height, weight, and BMI even after the adjustment for age as well as Le and Se genotypes.This study was supported in part by a Grant-in-Aid for Scientific Research on Special Priority Areas of Cancer from the Japanese Ministry of Education, Culture, Sports, Science, and Technology. We are grateful to Ms. Yoko Mitsuda and Ms. Keiko Shibata for their technical assistance