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Role of the serotonin receptor type 7 (5-HT7) in autoimmune disease
NUßBAUMER, Mia
Serotonin receptor type 7 (5-HT7) displays immunomodulatory functions and is overexpressed in individuals with Crohn's disease. Here, we set out to determine 5-HT7 mode of interaction with its cognate proteins Gs and G12. A unique type of coupling, termed 'inverse coupling' is known to occur between the 5-HT7 receptor and the Gs protein. The aim of our research was to determine whether G12 can also undergo this kind of coupling. We found that the G12 protein has a surprisingly lower mobility than Gs implying a specific interaction with a membrane domain or another membrane-localized protein. For both G proteins, we were unable to detect their inverse coupling with the 5-HT7 receptor at room temperature. Our findings indicate peculiar differences in G protein mobility and emphasize the importance of temperature for studies of interactions between G proteins and G protein-coupled receptors.
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Cell signalling and molecular complexes of the TRH receptor
Drastichová, Zdeňka
The first part of this thesis is preoccupied with the identification of protein alterations in the membrane fraction of HEK293-E2M11 cells after prolonged TRH treatment. The isolated membrane fraction enriched in plasma membranes contained high amounts of Na+ ,K+ -ATPase, TRH receptor and G-proteins compared to the postnuclear supernatant. By using 2D electrophoresis and mass spectrometry, the levels of 42 proteins were identified to be altered in samples of PM-enriched fractions from TRH-treated (16 h; 10 μM) cells. Out of these proteins only ezrin and stomatin-like 2 are known to be localized in the plasma membrane. Five proteins (mitofilin, MTHSP75, prohibitin, stomatin like-2, peroxiredoxin III) whose levels were increased after the prolonged TRH treatment represent proteins localized in mitochondria. All of them are important for proper structure and function of mitochondria. The ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax was markedly higher in cells treated with TRH compared to control cells. Hence, it can be concluded that prolonged TRH treatment may significantly affect mitochondrial membrane and function of mitochondria. The second part of this thesis deals with the identification of molecular protein complexes of TRH-R and/or Gq/11 protein. The presumed effects of TRH on the...
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The expression and regulation of Dexras1 in the rat brain under development
Kyclerová, Hana ; Bendová, Zdeňka (advisor) ; Jelínková, Dana (referee)
The Dexras1 gene was identified after induction by glucocorticoid dexamethasone in pituitary tumor cells. Dexras1 has also been found in other brain regions and in the peripheral organs but its expression is rhythmic only in the suprachiasmatic nuclei of the hypothalamus (SCN), where the mammalian main circadian pacemaker is located. Dexras1 expression was also affected by stress, amphetamine or prenatal alcohol exposure. Its role in cells has not yet been explained. Dexras1 GTPase activity has been determined to be dependent on the NMDA receptor stimulation. Dexras1 acts as an activator of G protein signaling in cells. Its role has been detected in neuronal iron homeostasis or in the regulation of main circadian pacemaker sensitivity to photic and nonphotic synchronization cues during the day. The aim of our study was to describe the Dexras1 mRNA expression in the rat brain during ontogeny and during development after visual sensory deprivation by in situ hybridization. The earliest Dexras1 expression was detected on embryonic day 20, in the rat SCN and the ventral posteromedial thalamic nucleus. Postnatally, its expression also appeared in other sensory areas, motor thalamic areas, hypothalamic areas involved in the regulation of water homeostasis, or in limbic system. Our results further show...
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Beta-adrenergic receptors and their desensitization
Biriczová, Lilla ; Novotný, Jiří (advisor) ; Kolář, David (referee)
β-Adrenergic receptors (β-ARs) are G-protein-coupled receptors (GPCR), widely present in the animal organism and mediate catecholamine pathways leading to diverse physiological responses. The family of β-ARs consists of β1-AR, β2-AR and β3-AR, which are distinguished by their affinity to adrenaline and noradrenaline. A typical model of β-AR signalling includes binding of the ligand, G-protein coupling, activation of adenylyl cyclase (AC) resulting in production of the second messenger cAMP and activation of protein kinase A (PKA) that phosphorylates downstream proteins leading to physiological responses. Beacause excessive catecholamine signalling can cause undesirable consequences, a mechanism has evolved, which attenuates the function of β-ARs in spite of further stimulation, so called desensitization. The classic course of desensitization consists of characteristic steps including phosphorylation of the receptor, β-arrestin attachement and uncoupling of the G-protein from β-AR. Restoration of the signalling ability is allowed through resensitization of β-AR when the receptor is sequestrated and dephosphorylated. Given that β-ARs are structurally and genetically different, it is reasonable to consider that each step of the desenstization process may happen differently among the different subtypes...
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Role of the 14-3-3 protein in the regulation of G-protein signaling
Řežábková, Lenka ; Obšil, Tomáš (advisor) ; Konvalinka, Jan (referee) ; Bařinka, Cyril (referee)
Univerzita Karlova v Praze Přírodovědecká fakulta Studijní program: Fyzikální chemie Mgr. Lenka Řežábková Studium úlohy proteinů 14-3-3 v regulaci G-proteinové signalizace Role of the 14-3-3 proteins in the regulation of G-protein signaling Disertační práce Školitel: doc. RNDr. Tomáš Obšil, Ph.D. Konzultanti: doc. RNDr. Petr Heřman, CSc. doc. RNDr. Jaroslav Večeř, CSc. Praha, 2012 Abstract The 14-3-3 family of phosphoserine/phosphothreonine-binding proteins dynamically regulates the activity of their binding partners in various signaling pathways that control diverse physiological and pathological processes such as signal transduction, metabolic pathways, cell cycle and apoptosis. More than 300 different cellular proteins from diverse eukaryotic organisms have been described as binding partners for the 14-3-3 proteins. During my Ph.D., I was particularly interested in the role of 14-3-3 proteins in the regulation of G protein signaling pathway. The 14-3-3 proteins affect the G protein signaling via the interaction with negative regulators of G protein cascade - the RGS proteins and phosducin. I employed both biochemical and biophysical approaches to understand how the activity and function of RGS3/14-3-3 and phosducin/14-3-3 complexes are regulated. I solved the low-resolution solution structure of...
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Cell signalling and molecular complexes of the TRH receptor
Drastichová, Zdeňka
The first part of this thesis is preoccupied with the identification of protein alterations in the membrane fraction of HEK293-E2M11 cells after prolonged TRH treatment. The isolated membrane fraction enriched in plasma membranes contained high amounts of Na+ ,K+ -ATPase, TRH receptor and G-proteins compared to the postnuclear supernatant. By using 2D electrophoresis and mass spectrometry, the levels of 42 proteins were identified to be altered in samples of PM-enriched fractions from TRH-treated (16 h; 10 μM) cells. Out of these proteins only ezrin and stomatin-like 2 are known to be localized in the plasma membrane. Five proteins (mitofilin, MTHSP75, prohibitin, stomatin like-2, peroxiredoxin III) whose levels were increased after the prolonged TRH treatment represent proteins localized in mitochondria. All of them are important for proper structure and function of mitochondria. The ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax was markedly higher in cells treated with TRH compared to control cells. Hence, it can be concluded that prolonged TRH treatment may significantly affect mitochondrial membrane and function of mitochondria. The second part of this thesis deals with the identification of molecular protein complexes of TRH-R and/or Gq/11 protein. The presumed effects of TRH on the...
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Cell signalling and molecular complexes of the TRH receptor
Drastichová, Zdeňka ; Novotný, Jiří (advisor) ; Hodný, Zdeněk (referee) ; Říčný, Jan (referee)
1 Summary The first part of this thesis is preoccupied with the identification of protein alterations in the membrane fraction of HEK293-E2M11 cells after prolonged TRH treatment. The isolated membrane fraction enriched in plasma membranes contained markedly increased the amount of Na,K-ATPase, TRH receptor and G-proteins compared to the postnuclear supernatant. By using 2D electrophoresis and mass spectrometry, the levels of 42 proteins were identified to be altered in samples of PM- enriched fractions from TRH-treated (16 h; 10 μM) cells. Out of these proteins only ezrin and stomatin-like 2 are known to be localized in the plasma membrane. Five proteins (mitofilin, MTHSP75, prohibitin, stomatin like-2, peroxiredoxin III) whose levels were increased after the prolonged TRH treatment represent proteins localized in mitochondria. All of them are important for proper structure and function of mitochondria. The ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax was markedly higher in cells treated with TRH than in control untreated cells. Hence, it can be concluded that prolonged TRH treatment may significantly affect mitochondrial membrane and function of mitochondria. The second part of this thesis deals with the identification of molecular protein complexes of TRH-R and/or Gq/11 protein. The presumed...
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The study of membrane receptors by radioligands binding
Rejhová, Alexandra ; Hudeček, Jiří (advisor) ; Hejnová, Lucie (referee)
Drug addiction, opiates respectively, is a social problem which seriousness is currently on the rise. One of key elements causing addiction is tolerance to increasing doses of drug causing abstinence syndrome during withdrawal and craving. Opioid receptors are members of a large group of receptors coupled with heterotrimeric G-proteins (GPCR), whose properties can be investigated using agonist- stimulated binding [35 S] GTPγS. Many extracellular signals are transferred into a cell through GPCR. Opioid receptor agonists inhibit the activity of adenylyl cyclase and are coupled with G-protein group Gi/Go. This work is devoted to the study of changes in isolated plasma membranes of rat forebrain containing opioid receptors of healthy subjects with membranes acquired from morphine addicted subjects. The rats were long-term morphine treated in increasing doses, to develop the dependency. The comparison is done firstly by binding of [3 H]ouabain to Na,K-ATPase, which proves to be a negative standard of changes, secondly by binding [35 S]GTPγS to G-proteins, thereby providing the functional activity of G-protein in stimulating the binding by the agonist of δ-opioid receptors DADLE or agonist of µ-opioid receptors DAMGO. Furthermore, it has been studied the influence of prostaglandin E1 on binding [35...
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