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Analysis of the LMNA gene and the SH3TC2 gene among Czech patients with hereditary neuropathy Charcot-Marie-Tooth type 1 and 2
Laššuthová, Petra ; Seeman, Pavel (advisor) ; Martásek, Pavel (referee) ; Fajkusová, Lenka (referee)
My PhD thesis can be devided into two parts: 1. Hereditary motor-sensory neuropathies (HMSN) 2. Selected muscle disorders The main emphasis was on the first part - hereditary motor and sensory neuropathies. Research was focused on autosomal recessive forms - demyelinating type CMT4C and axonal type CMT2B1. Most of the results obtained are related to these disorders. Data, which were obtained, are unique and were published in international journals with impact factor. Results obtained from CMT4C study are accepted for publication in Clinical Genetics. Results obtained in LMNA study (CMT2B1) were published in Journal of Human Genetics. The author performed and validated these new methods and original results, which are due to be used in genetic molecular testing of patients with hereditary neuropathies and muscle disorders: 1. Sequencing of all coding exons of the SH3TC2 gene. First mutations in the SH3TC2 gene in Czech HMSN I patients were found. 2. The prevalent mutation among Czech CMT4C patients was proven to be p.Arg954Stop. 3. Real-time PCR assay targeted at detection of the prevalent mutation p.Arg954Stop in the SH3TC2 gene was validated and is now used in our lab on a daily basis as a quick and efficient screening. 4. Molecular genetic testing of the SH3TC2 gene was introduced into the routine...
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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...
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The role of transmembrane domains in the structure and function of P2X receptors
Jindřichová, Marie ; Zemková, Hana (advisor) ; Langmeier, Miloš (referee) ; Martásek, Pavel (referee)
Purinergic P2X receptors represent a novel structural type of ligand-gated ion channels activated by extracellular ATP. So far, seven P2X receptor subunits have been found in excitable as well as non-excitable tissues. In the past ten years, the number of studies on P2X receptors has dramatically increased as investigators have begun to determine the physiological roles played by extracellular ATP and specific P2X receptor subtypes. It is already known that purinergic signaling is a key mechanism in pain sensation, brain injury, and immune processes. Little is known about their structure, mechanism of channel opening, localization and termination of ATP action by ectonucleotidases. Detailed knowledge about these events and the structure of purinergic receptor proteins evoke hope that new drugs will be developed that could prevent chronic pain and would be effective in protection against many diseases. The aim of this work is to summarize recent investigations and describe our contribution to elucidating the structure of P2X receptors. We examined the structure of transmembrane domains of the P2X4 receptor subtype, the main purinergic receptor-channel in the central nervous system, the mechanism of channel opening and closing and its sensitivity to agonists and allosteric modulator ivermectin. To...
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Eukaryotic and prokaryotic nitric oxide synthase - structure-function studies
Mikula, Ivan ; Martásek, Pavel (advisor) ; Entlicher, Gustav (referee) ; Král, Vladimír (referee)
Nitric oxide (NO) is an important signaling molecule in organisms. It plays a role in wide spectrum of physiological and pathophysiological processes, including vasodilatation, neurotransmission and host defense. The gaseous molecule of NO is produced by oxidative reaction catalyzed by proteins from the family of nitric oxide synthases (NOSs). Three NOS isoforms were identified in mammals, endothelial (eNOS), neuronal (nNOS) and inducible or immunologic (iNOS). Some bacteria harbor genes coding for proteins homologous to the mammalian NOS oxygenase domain and showing NO-producing activity in vitro. NO generated by pathologic organisms such as B. anthracis and S. aureus is supposed to play a critical role in the pathophysiological processes during the infection. Comparative study of bacterial NOS-like proteins and mammalian NOSs confirmed their principal similarity, but also revealed differences in the interactions of distinct bacterial proteins and mammalian NOS isoforms with different analogs of substrate L-arginine and various ligands. On the basis of the kinetics measurement of NO-rebinding a second NO-binding site in the active center of NOS was predicted. Further, the regulation of NO dynamic and release from the protein by the active site Hbonding network connecting the heme, the substrate and BH4...
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Inherited Disorders of Bilirubin Metabolism
Šlachtová, Lenka ; Martásek, Pavel (advisor) ; Baxová, Alice (referee)
Inherited disorders of bilirubin metabolism - hereditary hyperbilirubinemias - are metabolic disorders manifested in early childhood. Unconjugated hyperbilirubinemias result from the defect of the enzyme uridine diphosphoglucuronosyltransferase (UGT1A1). UGT1A1 mediates the conjugation of bilirubin with glucuronid acid in hepatocytes and its elimination to water soluble compound. In the next step of bilirubin degradation the transport of conjugated bilirubin from hepatocyte into the bile occure. It is caused by the ATP dependent transporters ABCC2, ATP1B1 and OATP1B3. Mutations in the genes coding the bilirubin transporters results in conjugated hyperbilirubinemia Dubin-Johnson or Rotor syndrome. This study is focused on unconjugated hyperbilirubinemia in adolescents including the non-typical manifestations and the defects of ABCC2 transporter and their phenotype in humans.
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Molecular genetic investigation of autosomal dominant demyelinating forms of Chrcot-Marie-Tooth hereditary neuropathy and in Pelizaeus-Merzbacher disease
Vyhnálková, Emílie ; Seeman, Pavel (advisor) ; Nevšímalová, Soňa (referee) ; Martásek, Pavel (referee)
We evaluated the relative frequency of each mode of inheritance in the large group of CMT fam i1ies gathered in the DNA laboratory of the Dept. of Child Neurology of the 2nd Medica! School (including famiJies wi th already detected causal mutations). The frequency of dominant and sporadic forms is approximately equal (40% of families). In a small percentage of families (2 0k'), the autosomal recessive (AR) mode of inheritance (two or more affected siblings) was recognized. In the rest of the families (18%) there are not enough reliable data on the clinical state of the family members to indicate the mode of inheritance. Further we evaJuated the rela tive frequency of inheritance modes in the "unconfirmed" group of CMT families with ou t detected causal mutation (which previously tested negative for the CMTlA / HNPP forms and / or for mlltations in some of the following CMT-associated genes - Cx32, MPZ, PMP22, EGR2, NEFL, SIMPLE). The frequency of dominant and sporadic forms in this group is somewhat different from the large cohort of families. The frequency of dominant pedigrees is low r (30%) and the frequency of sporadic cases higher (50%). This may indicate that, in general, we can expect the detection rate of CMT causes to be higher in dominant pedigrees compared to sporadic CMT cases. In this study I...
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