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The effect of variations in GRIN genes on the biogenesis and functional properties of the NMDA receptor
Kuchtiak, Viktor ; Balík, Aleš (advisor) ; Rozbeský, Daniel (referee) ; Ladislav, Marek (referee)
The expression and activity of ionotropic glutamate receptors control signal transduction at the excitatory synapses in the central nervous system. The major class are the calcium-permeable NMDA receptors that are fundamental for the various forms of synaptic plasticity, a key mechanism in the process of learning and memory formation. NMDA receptors are heterotetrameric and are represented by three types of subunits: GluN1, GluN2A-D, and GluN3A-B. Each subunit consists of four domains, with the intracellular C-terminal domain accounting for up to half of the entire NMDA receptor subunit (GluN2A/2B). A body of evidence indicates that the hypofunction of the NMDA receptor plays an important role in the pathogenesis of several neuropsychiatric disorders, including schizophrenia. Schizophrenia is characterised by a high degree of heritability, but its genetic background is not yet fully understood. Previous studies have identified in the human genome several individual loci that contribute to disease susceptibility, including the GRIN genes encoding NMDA receptors. Using a sequencing approach, we identified and annotated genetic variations across all GRIN genes in a cohort of schizophrenia patients and control subjects. The submitted doctoral thesis focuses on the functional analysis of the genetic...
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The role of RNA demethylase FTO in differentiation, regulation of energy metabolism and sensitivity to streptozotocin of neuronal and glial cell models
Čočková, Zuzana ; Novotný, Jiří (advisor) ; Horák, Martin (referee) ; Balík, Aleš (referee)
Fat mass and obesity associated (FTO) demethylase is responsible for erasure of the most abundant epitranscriptomic mark in eukaryotic mRNA, the N6-methyladenosine (m6A) residue. Together with other m6A erasers, writers (methyltransferases) and readers it forms an m6A regulatory pathway that controls the amount, location and biological effect of m6A. The dynamic regulation of the brain's m6A methylome during neurodevelopment is essential for maintaining cerebral functions. In addition, preclinical research suggests that the m6A regulatory pathway regulates energy balance in a tissue- and cell type-specific manner. The FTO gene has been associated with lifelong risks of obesity and metabolic syndrome as well as regulation of total body energy intake and expenditure. However, little is understood about the function of the m6A pathway in control of brain energy metabolism. That is of interest in pursuit of understanding Alzheimer's disease, as this illness is characterized by profound disruptions in cerebral energy metabolism and mounting evidence suggests that disrupted brain bioenergetics may play a role in the disease's early genesis, before the appearance of clinical symptoms. In the present thesis we aimed to investigate the role of FTO in models of two brain cell types, neurons and astrocytes....
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Spontaneous calcium permeability of ionic channel of P2X receptor after substitution ofconserved tyrosine in the 1st transmembrae domajn
Rupert, Marian ; Zemková, Hana (advisor) ; Balík, Aleš (referee)
Purinergic receptors are membrane ion channels that are activated by extracellular ATP. In vertebrates, seven genes encode subunits of P2X receptors. The subunits, designated P2X1-7, are 40 - 50% identical in amino acid sequences. P2X receptors are composed of three subunits and are found as homo- and heterotrimers in tissues of vertebrates. P2X receptors have a wide distribution in the organism, functional receptors are found in neurons, glial cells, muscle cells and also in nonexcitable tissues as epithelial, endothelial, and in hemopoietic tissue. Purinergic signalling plays an important role in pain transmission, at CNS injury and immune processes. P2X receptor subunit consists of two transmembrane domains, extracellular domain and intracellular N-and C-termini. Each transmembrane domain contains two amino acids conserved across all P2X subunits. In the first transmembrane domain receptor P2X2 are that Gly30 and Tyr43. In previous experiments performed on P2X2 receptor, electrophysiological measurements demonstrated that substitution of conserved Tyr43 in the first transmembrane domain with alanine prolongs the deactivation time of ion channel after agonist wash out. This work is focused on clarifying the role of conserved tyrosine in the process of opening and closing of ion channel of P2X...
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Alzheimer's disease-related changes in phosphorylation of collapsin response mediator protein 2 (CRMP2) and their effect on neuronal function
Škrlantová, Alice ; Balaštík, Martin (advisor) ; Balík, Aleš (referee)
CRMP2 was first identified in 1995 as a mediator of Sema3A signalization pathway which leads to axon growth cone collapse. Since then CRMP2 was designated as an essential cue during neuronal polarity estabilishment and neuronal growth in embryonic life. CRMP2 was also found hyperphosphorylated in NFT's and this finding led to further research of CRMP2 function in the pathogenesis of AD. The activity and proper function of CRMP2 is regulated by phosphorylation and a deeper look into the mechanism of this modification is necessary for understanding how CRMP2 influences the function of neural cells. In this thesis I focus on signaling pathways, kinases and interaction partners of CRMP2 and describe how aberrant regulation of these interactions leads to Alzheimerʼs disease development.
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Zebrafish as a model to study the glutamate receptor mediated excitatory neurotrasmission
Chumchal, Lukáš ; Balík, Aleš (advisor) ; Pangrácová, Marie (referee)
Glutamate is the most prominent excitatory neurotransmitter in the vertebrate brain and is used by most synaptic connections in the cortex. Signal transduction on these neurons is mediated by ionotropic glutamate receptors, including the NMDA receptor family. With the development of molecular biological methods and the advent of genomics, genetic changes found in ionotropic glutamate receptors were tested, as well as substances that modulate their activity. Since a large number of genetic changes found, rodents have ceased to be a sufficiently robust system for some, for example, behavioural studies. In these types of studies, the model organism Danio rerio could replace rodents. The use of this model organism could thus expand knowledge about the evolution and physiology of glutamate receptors. This work aims to summarize the current knowledge about the use of Dania rerio in the research of glutamate receptors, especially NMDA type in the central nervous system. This work also focuses on the description of specific behavioural tests available for the analysis of these receptors.
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Molecular mechanisms of regulation of trafficking and function of different subtypes of NMDA receptors in hippocampal neurons
Skřenková, Kristýna ; Horák, Martin (advisor) ; Balík, Aleš (referee) ; Bendová, Zdeňka (referee)
of Ph.D. thesis Molecular mechanisms of regulation of trafficking and function of different subtypes of NMDA receptors in hippocampal neurons Mgr. Kristýna Skřenková N-methyl-D-aspartate (NMDA) receptors are ionotropic glutamate receptors that play a key role in the mammalian central nervous system. Under physiological conditions, these receptors are important for excitatory synaptic transmission and memory formation. However, under pathological conditions, their abnormal regulation or activation may lead to many neurological and psychiatric disorders, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy or schizophrenia. Previous studies have shown that the number and type of NMDA receptors on the cell surface are regulated at multiple levels, including their synthesis, folding, internalization or degradation. During the trafficking of NMDA receptors to the cell surface membrane, both the agonist binding and receptor activation are examined. Moreover, NMDA receptors undergo many posttranslational modifications such as palmitoylation, phosphorylation or N-glycosylation. In this thesis, we studied the molecular mechanisms that may affect the trafficking and functional properties of NMDA receptors in mammalian cells and rat hippocampal neurons. Specifically, we studied i)...
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Intracellular domain of glutamate ion channels and its role in the emergence of pathophysiological states
Sadílková, Lucie ; Balík, Aleš (advisor) ; Kolář, David (referee)
Glutamate mediates most of the excitatory neurotransmissions in the central nervous system of mammals. Its effect depends on the presence of glutamate receptors on postsynaptic neurons. NMDA receptors are class of the ionotropic glutamate receptors and are necessary for normal brain function such as synaptic plasticity, learning, memory and correct development of neu- rons. NMDA receptors are also involved in the pathophysiology of many neurodevelopmental and neuropsychiatric diseases. The aim of this work is to evaluate the current knowledge of the role of the intracellular part of NMDA receptors for their function, particularly with respect to the regulation of their localization at excitatory synapses. In addition, it also provides an over- view of the genetic changes found in this part of the receptor, their effect on the functional properties of the receptor and then also a possible link to specific disease.
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Iontropic glutamate receptors and their RNA processing in the mammalian suprachaismatic nuclei
Kuchtiak, Viktor ; Balík, Aleš (advisor) ; Sládek, Martin (referee)
Suprachiasmatic nuclei (SCN) are primary center of mammalian circadian rhythms. To maintain a 24 hour period of its rhythms, SCN are synchronized with phase of external environment. Regular changes of light and darkness are known to be the main external synchronizer that determines the period of SCN rhythms. Information about light is being transferred from retina to the ventrolateral region of SCN through excitatory synapses where ionotropic glutamate receptors (iGluRs) play a primary role in the signal transduction. Posttranscriptional modifications of RNA can alter the functional properties of iGluRs, thus this process contributes to synaptic plasticity. The extent of posttranscriptional modifications of iGluRs can be in vitro affected by neuronal activity altered by pharmacological manipulation. The aim of this study was to determine possible changes of posttranscriptional modifications of iGluRs in in vivo rat SCN model and how this process can be regulated. RNA posttranscriptional modifications of GluA2 subunit of AMPA receptor (AMPAR) and GluK2 subunit of kainate receptor were assessed using PCR and subsequent sequencing of amplified DNA. Using quantitative PCR, we also determined mRNA expression of GluA1 and GluA2 subunits of AMPAR and the editing enzyme ADAR2 in SCN. Our results showed...
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The analysis of structural details of the NMDA receptor
Radilová, Kateřina ; Balík, Aleš (advisor) ; Jakubík, Jan (referee)
NMDA receptor is necessary for excitatory transmission in the central nervous system. Altered funtion of the NMDA receptors is associated with many neurodegenerative and neuropsychiatric diseases. All available crystal structures of the NMDAR meant great shift towards our understanding of details of the receptor and its function. Unfortunately, these up- to-date available structures present only certain functional states of receptors and also a few structural data are still missing. For complete comprehension of the process of activation and deactivation of NMDA receptors, we need to supplement the current information with more data. The aim of this thesis was to employ a combination of different approaches (computational modelling, cloning, biochemistry, protein expression and purification and mass spectrometry) to obtain new structural data, by which we would be able to fill in the gaps in current receptor models, especially at various functional states of the receptor. Key words: NMDA receptor, glutamate receptor, computational modelling, structure, cloning, protein expression
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