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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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Glutamate Receptors and Endoplasmic Reticulum Quality Control
Tachezy, Ruth ; Horák, Martin (advisor) ; Adámek, Pavel (referee)
Quality control (QC) is a collection of processes taking part in the biogenesis and architecture of proteins. The objective of this thesis is to describe these processes in detail. QC takes place on many different levels in various compartments of the cell. The focus is on the endoplasmic reticulum (ER) QC interconnected with cytosolic QC. There are multiple steps involved in ERQC: several types of protein translocation to the ER lumen, glycosylation, disulfide bond formation via protein disulfide isomerase, chaperones that assist to achieve a correct conformation, and ER- associated degradation pathway for retranslocation of misfolded proteins back to the cytoplasm, where they are degraded. Cytosolic QC is interconnected with the ERQC through various ways of translocation of proteins to the ER membrane or lumen. Proteins that are retranslocated from ER to the cytosol are ubiquitinated and subsequently degraded in the proteasome. Ubiquitination is a process of targeting a protein for degradation. Cytosolic chaperones and other cellular structures, such as aggresomes, juxtanuclear compartments, and insoluble protein deposits, take part in the ubiquitination. Calcium dysregulation that is linked to QC and correct protein folding in ER is also described. Some of the possible consequences of protein...
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