|
| |
|
|
A study of the modulation of recombinant and native NMDA receptors by physical and chemical factors
Cais, Ondřej ; Vyklický, Ladislav (advisor) ; Blahoš, Jaroslav (referee) ; Chvátal, Alexandr (referee) ; Šťastný, František (referee)
Excitatory synaptic transmission in mammalian CNS is mostly mediated by ionotropic glutamate receptors. NMDA receptors, one of three subclasses of this ligand-activated ion channels family, are involved in memory formation and learning and also play a role in the pathogenesis of various neurodegenerative diseases. Current knowledge about NMDA receptors function is predominantly based upon results of in vitro experiments conducted at room temperature, far from physiological. The aim of this PhD thesis was to describe the temperature dependence of NMDA receptors. We determined the rate constants that characterise each step in the mechanism of recombinant NR1/NR2B receptors activation in the temperature range 25-45řC. The receptor desensitization, resensitization and glutamate unbinding turned out to be the most temperature sensitive of these processes. In addition to that, we described the temperature dependence of deactivation kinetics in various experimental models of NMDA receptors (both recombinant and native). The second part of the thesis focused on the modulation of NMDA receptors function by steroid compounds derived from pregnanolone sulfate, an endogenously occuring neurosteroid. We tested 21 steroids that showed various degree of ability to inhibit (or, in one case, potentiate) the current...
|
|
|
Study of Structure-Function Relationship of Temperature-Gated TRP Channels
Benedikt, Jan ; Vlachová, Viktorie (advisor) ; Kršiak, Miloslav (referee) ; Blahoš, Jaroslav (referee)
Sensory physiology research was heavily influenced by molecular identification of transient receptor potential (TRP) ion channel family. Discovery of these unique family of membrane receptors allowed detailed study of their structure-function relationship. TRP channel expression in sensory neurons, but also apparently in keratinocytes provides living organisms with the ability to fast and accurately detect noxious thermal and chemical stimuli and to transmit this noxious signaling to higher nervous system structures. Despite recent efforts to elucidate molecular mechanisms of temperature or chemical activation of these non-selective cation channels, there is still no unifying hypothesis that is able to explain complex behaviour of these receptors. This dissertation aims to investigate three aspects of the TRP channel function: 1. Molecular characterization of acute desensitization of vanilloid receptor TRPV1 and investigation of the role of phosphorylation sites for calmodulin kinase II. 2. To characterize mechanisms of etanol-induced inhibition of menthol receptor TRPM8 and to find out possible physiological consequences of this inhibition. 3. To explore the role of inner pore region in activation gating of ankyrin receptor TRPA1 and identify amino acids involved in this process. Our findings contribute to...
|
|
| |
|
|
Metabotropic glutamate receptors: mechanism of activation
Hlaváčková, Veronika ; Blahoš, Jaroslav (advisor) ; Vyklický, Ladislav (referee) ; Martásek, Pavel (referee) ; Konvalinka, Jan (referee)
Any living organism receives constantly many signals that have to be evaluated and weighted to respond in an appropriate way. To perform all functions needed for precise control of homeostasis and for communication with the surrounding environment, signals coming from the outside are recognized and transferred into modulation of intracellular signaling cascades. These mediate response to the extracellular stimulus as well as intercellular communication. Cell communication is mediated by several types of receptors, located either intracellularly (including nuclear receptors) that modulate gene transcription and receptors localized on plasma membrane. Cell membrane receptors are transmembrane proteins that are divided into three superfamilies according to their structure and principles of signal transduction. These are ion channel-linked receptors, enzyme-linked receptors and G-protein-coupled receptors (GPCRs). GPCRs comprise the biggest family of membrane receptors and are one of the largest gene families in general. They are encoded by about 1% of genes in mammals. Many of them bind sensory ligands (rhodopsin, taste and olfactory receptors), but others also recognize ions, amino acids, nucleotides, peptides and large glycoproteins (1). They play a crucial role in such distant physiological functions as...
|
|
| |
|
| |
|
| |
|
| |
|
| |
guest ::
