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Doctoral Thesis
DOI
10.11606/T.5.2018.tde-09042018-095856
Document
Author
Full name
Helena Passarelli Giroud Joaquim
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2018
Supervisor
Committee
Gattaz, Wagner Farid (President)
Carvalho, Valdemir Melechco
Forlenza, Orestes Vicente
Sallet, Paulo Clemente
Zanata, Silvio Marques
Title in Portuguese
Proteômica da esquizofrenia: busca por biomarcadores em plaquetas
Keywords in Portuguese
Biomarcadores
Esquizofrenia
Plaquetas
Proteômica
Transtorno bipolar
Transtornos psicóticos
Abstract in Portuguese
Esquizofrenia é um transtorno psiquiátrico complexo que afeta cerca de 1% da população mundial. Apesar de progressos consideráveis nos últimos anos, a etiologia da doença ainda não foi elucidada principalmente pela heterogeneidade tanto do início quanto da progressão da doença. Frequentemente os sintomas dos pacientes são comuns a outras desordens neuropsiquiátricas, dificultando a diferenciação por meio de métodos essencialmente clínicos. Por isso, pesquisadores têm tentado identificar medidas baseadas em características moleculares que justifiquem e expliquem a etiologia da esquizofrenia. Já há alguns estudos com marcadores no cérebro, mas por esse ser um material com disponibilidade limitada, os esforços tem se concentrado em encontrar biomarcadores periféricos. Este estudo visou traçar um perfil proteico, em plaquetas, de pacientes drug-naïve com diagnóstico de esquizofrenia. Para tanto, comparamos este grupo com controles saudáveis e com controles psiquiátricos. Utilizamos duas abordagens proteômicas complementares para análise: a primeira, uma ferramenta clássica utilizando eletroforese bidimensional com posterior identificação dos spots por espectrometria de massas; e a segunda, uma abordagem de identificação em larga escala por shotgun label-free. Foram analisadas amostras de 16 controles saudáveis, de 11 pacientes com esquizofrenia e de 8 pacientes com transtornos do humor (controle psiquiátrico). Com a eletroforese bidimensional foram identificados 110 spots comuns nos géis de controles saudáveis, 83 spots comuns aos géis de pacientes com esquizofrenia e 80 spots comuns aos géis de pacientes com diagnóstico de transtornos do humor. Foram encontrados 27 spots exclusivos do grupo controle, não sendo detectados em nenhum dos dois grupos de pacientes. Esses spots foram recortados e analisados por espectrometria de massas revelando proteínas relacionadas com: neurotransmissão, sinapse, neurodesenvolvimento, homeostase celular, sinalização de cálcio, apoptose, resposta imune, e estresse oxidativo. Para verificação dos resultados, escolhemos proteínas de acordo com sua função já descrita na literatura e ineditismo na matriz e na casuística estudadas. Por meio da técnica de western blotting, encontramos diminuições significantes nos níveis de anexina A3 e peroxirredoxina 6 nos dois grupos de pacientes. Ambas proteínas diferentemente expressas nos pacientes já foram relacionadas à fosfolipase A2, que é a principal enzima responsável pelo metabolismo de fosfolípides de membrana e tem sido associada à desordens neuropsiquiátricas, inclusive à esquizofrenia. Ainda há algumas abordagens analíticas e bioinformáticas a serem realizadas na busca por candidatos a biomarcadores de esquizofrenia em plaquetas. Os resultados obtidos por shotgun necessitam de uma análise mais aprofundada além da verificação e validação em coortes maiores. A casuística utilizada para este trabalho é bastante valiosa já que permitirá a elucidação de alterações proteômicas já no primeiro episódio psicótico
Title in English
Proteomic of schizophrenia: research in biomarkers in platelets
Keywords in English
Biomarkers
Bipolar disorder
Platelets
Proteomics
Psychotic disorders
Schizophrenia
Abstract in English
Schizophrenia is a mulfatorial psychiatric disorder that affects about 1% of the world's population. Despite considerable progress in recent years, the etiology of the disease has not yet been elucidated mainly because the heterogeneity of disease onset and progression. Often the symptoms overlap to other neuropsychiatric disorders, which turns difficult to differentiate through essentially clinical methods. The researchers have focused in identify mesureable molecular characteristics that can help to elucidate schizophrenia etiology. There are already important findings regarding markers in the brain, but recent efforts have focused on finding peripheral biomarkers. This study aimed to find a protein profile in platelets of schizophrenia drug-naïve patients. For comparision we recruited two more groups: healthy controls and psychiatric control. We used two complementary proteomic approaches for analysis: a classic tool using two-dimensional electrophoresis with subsequent identification of the spots by mass spectrometry; and a large-scale label-free shotgun identification approach. The sample comprised 11 schizophrenic patients, 8 patients with mood disorders (psychiatric control and 16 healthy controls. 2-DE profiles of each sample were generated in triplicate. 110 proteins spots were identified in most gels of control group, 83 in most gels of schizophrenia group, and 80 proteins spots in most gels of bipolar disorder patients. Among these proteins spots, 76 were common to all three groups; 5 to controls and schizophrenia group; 2 common to controls and bipolar disorders groups; 2 exclusive of bipolar disorder patients and 27 proteins spots were identified exclusively in the control group. The 27 exclusive protein spots of control group were identified by LC-MS/MS. Proteins related to neurotransmission, synapse, neurodevelopment, cellular homeostasis, calcium signaling, apoptosis, immune response, and oxidative stress were identified. To verify the results, we chose proteins according to their function already described in the literature and novelty in platelets and first onset psychosis patients research. By western blotting we verified the difference in levels of annexin A3 and peroxiredoxin 6 between groups, but not of glutathione S-transferase pi 1 or 78-kDa glucose-regulated protein. Both proteins differentially expressed have already been related to phospholipase A2, which is the main enzyme responsible for the membrane phospholipids metabolism and has been associated with neuropsychiatric disorders, including schizophrenia. Despite the good and promising results presented and published, there are still some analytical and bioinformatic approaches to be performed in search for candidates for platelet schizophrenia biomarkers. The data from shotgun approach require further analysis, as well as verification and validation in larger cohorts. The sample enrroled in this study is greatly important and certainly informed us much about the proteomic alterations still in the first onset psychosis
 
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Publishing Date
2018-04-09
 
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