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Effect of amyloid β on the function of endosomes and lysosomes
Tmějová, Monika ; Rudajev, Vladimír (advisor) ; Čočková, Zuzana (referee)
Alzheimer's disease is progressive neurodegenerative disease characterized by accumulation of amyloid β aggregates in brain tissue. Understanding the mechanisms of amyloid β pathogenesis and neuronal cell destruction is still not clear. The most toxic form of amyloid β are 42 aminoacids long oligomers that tends to cumulate and speed up disease progression. Membrane dynamics which affect protein degradation and recycling within the cell plays a criticale role in maintaining homeostasis. Vesicular trafficking plays fundamental role in balancing physiological level of amyloid β. Disruption of endolysosomal complex leads to cycle of disruptions within the cell which results in neuronal cell death. The main aim of this thesis was to look through different ways how amyloid β42 affects endolysosomal compartment. Results of our work confirmed toxic effect of amyloid on SH-SY5Y cell line and its ability to damage functions of lysosomes. We were not able to confirm amyloid β toxicity on endosomal function. Key words: amyloid β, Alzheimer disease, oligomers, plasma membrane, endocytosis, endosome, lysosome, neurotoxicity
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Analysis of WASH complex member strumpellin
Pácalt, Ondřej ; Libusová, Lenka (advisor) ; Cvrčková, Fatima (referee)
Actin polymerization facilitated by the Arp2/3 complex plays a critical role in a wide range of cellular processes such as motility, endocytosis and cargo recycling. Activation and appropriate localization of the Arp2/3 complex is mediated by an interaction with the nucleation-promoting factor (NPF). WASH complex is the major endosomal NPF which plays a crucial role in the cargo recycling back to the trans-Golgi network (TGN) or plasma membrane. It is composed of five subunits: WASH1, SWIP, FAM21, CCDC53 and strumpellin. While WASH1 and FAM21 have been extensively studied, much less is known about strumpellin, a protein causally implicated in the onset of hereditary spastic paraplegia (HSP). This work focuses on strumpellin function in the cells, showing that only full-length protein incorporates into the WASH complex. In a strumpellin knock out cell line, we demonstrated that loss of strumpellin resulted in destabilization of the other WASH complex subunits. Still, an incomplete WASH complex without strumpellin was assembled. Cells also displayed enlarged endosomal subdomains and WASH complex nucleation activity on endosomes was largely diminished as assessed by loss of the actin patches. Finally, the absence of strumpellin was also accompanied by the accumulation of glucose transporter 1 (GLUT1)...
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Analysis of WASH complex member strumpellin
Pácalt, Ondřej ; Libusová, Lenka (advisor) ; Cvrčková, Fatima (referee)
Actin polymerization facilitated by the Arp2/3 complex plays a critical role in a wide range of cellular processes such as motility, endocytosis and cargo recycling. Activation and appropriate localization of the Arp2/3 complex is mediated by an interaction with the nucleation-promoting factor (NPF). WASH complex is the major endosomal NPF which plays a crucial role in the cargo recycling back to the trans-Golgi network (TGN) or plasma membrane. It is composed of five subunits: WASH1, SWIP, FAM21, CCDC53 and strumpellin. While WASH1 and FAM21 have been extensively studied, much less is known about strumpellin, a protein causally implicated in the onset of hereditary spastic paraplegia (HSP). This work focuses on strumpellin function in the cells, showing that only full-length protein incorporates into the WASH complex. In a strumpellin knock out cell line, we demonstrated that loss of strumpellin resulted in destabilization of the other WASH complex subunits. Still, an incomplete WASH complex without strumpellin was assembled. Cells also displayed enlarged endosomal subdomains and WASH complex nucleation activity on endosomes was largely diminished as assessed by loss of the actin patches. Finally, the absence of strumpellin was also accompanied by the accumulation of glucose transporter 1 (GLUT1)...
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Exosomes, their biogenesis, composition and role
Hyka, Lukáš ; Forstová, Jitka (advisor) ; Motlová, Lucia (referee)
Exosomes are a subtype of extracellular vesicles. Exosomes are distinguishable from other extracellular vesicles by their endosomal origin and their typical cup-shaped morphology. The biogenesis of exosomes begins in the early endosomes by inward budding. The endosomal sorting complex required for transport sorts ubiquitinylated proteins into the vesicles. The small volume of cytosol is also encapsulated during budding. These vesicles are called intraluminal vesicles and the whole body is called multivesicular body. Multivesicular body fuses with the plasma membrane and vesicles are released as exosomes into the extracellular space. Exosomes are present in all bodily fluids and are secreted by a high number of cells. Exosomes present antigens on their surface to trigger immunity or serve in the cellular communication by the transfer of small RNAs.
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Endocytic transport in cytokinesis
Koudelová, Kristina ; Libusová, Lenka (advisor) ; Vosolsobě, Stanislav (referee)
Cytokinesis represents a very complex and highly orchestrated process. For many years, the mechanism of animal cell cytokinesis was described as a result of actomyosin ring constriction. By contrast, in plant cells the division was seen as an outcome of vesicle fusion at the cell plate region between two daughter cells. Recent studies, however, uncover the involvement of vesicular trafficking in animal cell cytokinesis. This thesis aims to highlight the importance of endocytic transport and the necessity of its proper regulation. At first, the origin of vesicles is debated. Afterwards, three main types of endocytic vesicles are examined - Rab11/FIP3 endosomes, Rab35-endosomes and PI(3)P-enriched endosomes, along with their function and interacting partners. Finally, the attention is given to the mechanism of abscission and midbody inheritance. Ongoing processes are accompanied by changes in membrane composition, cytoskeleton reorganization and targeted delivery of distinct cargo molecules. Failure in cytokinesis has been implicated in the etiology of many diseases, such as cancer. Therefore, better understanding of associated endocytic trafficking may provide us with new therapeutic strategies.
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The role of cytoskeleton in endosomal fusion and fission
Získalová, Tereza ; Libusová, Lenka (advisor) ; Tolde, Ondřej (referee)
Cytoskeleton plays a key role in endocytic process. Vesicules move along microtubules to target membranes. Microtubules also partake in the formation of endosomal tubules, from which recyclated vesicules are splitted off. Actin network has in endocytosis multi-ple effect as well. In the case of membrane fusion is its role both, positive and negative, for it creates mechanical force which facilitates the fusion in last stage. By contrast, in the first stage, it acts as a physical barrier, which needs to be removed. Actin also actively participates in fission of vesicules. Actin network and microtubules are thus interconnected with endocytic pathway in time and space. Right functional connection of the cytoskeleton with dynamics of endocytic vesicles is driven by many regulatory proteins. Among important regulators of actin network belong for example proteins of Arp2/3, WASH complex, WASP or Rab and Rho proteins. Powered by TCPDF (www.tcpdf.org)
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