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Non-neuronal cell outgrowth in Caenorhabditis elegans model system
Smidžárová, Lucie ; Macůrková, Marie (advisor) ; Strouhalová, Kateřina (referee)
1 Abstract Oriented cell growth is an important process for regular tissue development, in which regulated changes in cell shapes occur. An important role in this mechanism is played by remodelling of cytoskeletal elements in the growing parts of the cell, which is regulated by many extracellular and intracellular factors. This bachelor's thesis is focused on oriented non-neuronal cells growth in the model organism Caenorhabditis elegans, specifically the growth of the excretory cell and the anchor cell invasion. The growth mechanism of the excretory canal cell is in many aspects similar to growth of neurons, however it also involves a unique mechanism of growth through extension of an intracellular lumen. In case of the anchor cell the growth mechanisms support the basement membrane disruption and invasive behavior reminiscent of metastatic cancer cells. Regulation of growth of these two cells thus could serve as a good model for human pathologies such as cystic kidney disease or cancer cell metastasis, and therefore further study in this area could lead to new insights into these diseases. At the end of the thesis, other non- neuronal cells with oriented growth in the model organism C.elegans are briefly described. Key words: cell outgrowth, excretory canal cell, anchor cell, signalling, cytoskeleton
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Computational Simulation of Mechanical Behaviour of Endothelial Cells
Jakka, Veera Venkata Satya ; Gumulec, Jaromír (referee) ; Majer, Zdeněk (referee) ; Matsumoto,, Takeo (referee) ; Burša, Jiří (advisor)
Ateroskleróza je v rozvinutém světě hlavní příčinou úmrtí a finančně zatěžuje zdravotnické systémy po celém světě. Převládající hemodynamické působení spolu s lokální koncentrací mechanického napětí hrají důležitou roli v lokální povaze aterosklerózy a jejím rozvoji ve specifických oblastech lidských cév. Endotel v krevních cévách je tvořen tenkou vrstvou buněk, ležící na rozhraní mezi krevním řečištěm a cévní stěnou. Dysfunkce endoteliálních buněk se podílí na hlavních patologiích. Například ateroskleróza se rozvíjí, když jsou narušeny bariérové a protizánětlivé funkce endotelu, což umožňuje akumulaci cholesterolu a dalších materiálů v arteriální stěně. U rakoviny je klíčovým krokem v růstu nádoru jeho vaskularizace a proces migrace endoteliálních buněk. Mechanické zatížení endoteliálních buněk hraje klíčovou roli v jejich funkci a dysfunkci. Počítačové modelování může zlepšit porozumění buněčné mechanice a tím přispět k poznání vztahů mezi strukturou a funkcí různých typů buněk v různých stavech. K dosažení tohoto cíle jsou v této práci navrženy konečnoprvkové modely endoteliálních buněk, tj. model buněk plovoucích v roztoku a model buněk přilnutých k podložce, které objasňují reakci buňky na globální mechanické zatížení, jako je tah a tlak, jakož i model buňky s jeho přirozeným tvarem uvnitř endoteliální vrstvy. Zachovávají hlavní principy tensegritních struktur, jako je předpětí a spolupůsobení jednotlivých součástí, ale prvky se mohou organizovat vzájemně nezávisle. Při implementaci nedávno navržené bendo-tensegritní koncepce uvažují tyto modely namáhání mikrotubulů nejen v tahu/tlaku, ale i ohybu a také zohledňují vlnitost intermediálních filament. Modely umožňují, že jednotlivé komponenty cytoskeletu mohou změnit svůj tvar a uspořádání bez zhroucení celé buněčné struktury, dokonce i když jsou odstraněny, a umožňují nám tak vyhodnotit mechanický přínos jednotlivých cytoskeletálních složek k buněčné mechanice. Navržené modely jsou validovány porovnáním jejich křivek síla-posunutí s experimentálními výsledky. Model plovoucí buňky realisticky popisuje silově-deformační odezvu buňky při tahu a tlaku a obě reakce ilustrují nelineární zvýšení tuhosti s mechanickým zatížením. Je simulována také tlaková zkouška ploché endoteliální buňky a porovnána s testem přilnuté buňky a jeho simulací. Poté se simuluje smykový test ploché buňky, aby se vyhodnotilo její chování při smykovém zatížení vyskytujícím se v cévní stěně v důsledku proudění krve. Poté byla zkoumána mechanická odezva ploché buňky ve vrstvě endotelu za fyziologických podmínek v arteriální stěně. Později byla zkoumána buněčná odezva při odtrhování od položky během cyklických úseků pomocí 3D simulací metodou konečných prvků. Navrhované modely poskytují cenné poznatky o vzájemných souvislostech mechanických vlastností buněk, o mechanické roli jednotlivých cytoskeletálních složek i jejich synergii a o deformaci jádra za různých podmínek mechanického zatížení. Proto by práce měla přispět k lepšímu pochopení cytoskeletální mechaniky, zodpovědné za chování buněk, což může zase pomoci při zkoumání různých patologických stavů souvisejících s buněčnou mechanikou, jako je rakovina a vaskulární onemocnění.
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Molecular mechanism of mechanoreception in plants
Jelínková, Barbora ; Martinek, Jan (advisor) ; Fendrych, Matyáš (referee)
Plant, as sedentary organism, does not have many possibilities to physically escape it's unpleasant surroundings, instead it adapts oneself. One of many plant senses that are crucial for tracking environment changes is mechanoreception. Plant senses and differentiates between many mechanical cues, some of them affecting plant immunity and morphogenesis. The whole plant cell reacts to mechanical cues and many cellular structures are involved in mechanoreception. Any change in cell wall - a borderline between the cell and it's surroundings - is transduced to plasma membrane, then to the cytoskeleton and potentially to other structures. Concept of this cell wall-plasma membrane-cytoskeleton continuum and it's use as an instrument to illuminate molecular mechanisms of mechanoreception in plants are the key topics of my thesis.
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Non-traditional roles of formins besides actin nucleation
Metlička, Jáchym ; Cvrčková, Fatima (advisor) ; Opatrný, Zdeněk (referee)
Formin homology 2 (FH2) domaincontaining proteins (formins) have, since their discovery in 1990, been observed in all analyzed species of eukaryotic kingdoms. Our knowledge of structure and function of the defining FH2 domain has greatly increased over the last couple of years. Its function in nucleation, polymerization and processive capping of actin filaments designates formin protein family an important cytoskeletonremodelling factor. But FH2 domain is just one part of the puzzle additional optional conserved peptide structures surrounding it, as well as concrete variation of the FH2 domain itself, greatly influence the functional properties and cellular localization of the resultant formin protein. Formins have been implicated in variety of cellular processes, which often (but not always) involve the cytoskeleton e.g. Factin network management, crosstalk of Factin filaments and microtubules or plasma membrane. They also partake in processes integral to cell division, function in conserved signalling pathways and much more. This thesis explains the structure and function of FH2 and FH1 domains, outlines the main formin phylogenetic clades in multicellular eukaryotes and reviews various roles that formins fulfill or are thought to fulfill. Such goal, however, is very bold and (considering the...
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Cytoplasmic membrane and tonoplast dynamics during closing and opening of stomata
Röder, Matěj ; Žárský, Viktor (advisor) ; Albrechtová, Jana (referee)
Stomata are epidermal structures mediating regulated contact of plant apoplast with surrounding environment via stomatal opening. Change of turgor plays crucial part in initiation of stomatal opening or closure. During stomatal movement, guard cell undergo considerable and repetitive changes in cell volume and consequently surface area over a period of minutes. Alteration in the surface of membrane must occurs due to limited stretching capability of the plasma membrane. It can be achieved through membrane invaginations and endocytosis of small vesicles. Microscopy and electrophysiology techniques have proven that both processes are happening in guard cells. These processes are controlled and managed by complex web of signal pathways in which actin and microtubular cytoskeletons, SNARE proteins, ion channels and others molecules have crucial parts. The aim of this work is to summarize current knowledge on the processes and mechanisms of these membranes surface changes and their molecular principle.
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Role of cytoskeleton in plant cell morphogenesis
Miklánková, Pavlína ; Schwarzerová, Kateřina (advisor) ; Sekereš, Juraj (referee)
The cells are able to acquire variety of shapes, in which cytoskeleton plays an important role. Cytoskeleton influences deposition of cell wall materials, regulates vesicle movement in cell, participates in exocytosis and endocytosis. Cortical microtubules affect celulose accumulation in cell wall and determine direction of cell expansion, although the exact connection between microtubules and cellulose remains unclear. Actin promotes growth and contributes to its spatial regulation in both tip ang diffuse growing cells. Actin is important for secretion in expanding cells but its exact functions in cell growth regulation are not explained yet. Analysis of mutants, spectroscopic methods, cytoskeletal drugs, fluorescence proteins and other methods are used to better understand how actin and microtubule cytoskeleton are integrated during plant cell morphogenesis. Epidermal and trichome cells of Arabidopsis thaliana are a good model of research and they are used for most studies.
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Interactions of Mitochondria with Other Cellular Structures
Vinopalová, Martina ; Doležal, Pavel (advisor) ; Voleman, Luboš (referee)
In cells, mitochondria fulfil diverse set of roles, including a production of energy-rich molecules, which are necessary for proper functioning of the cell, calcium homeostasis, apoptosis and even biosynthesis of Fe-S centres, heme and steroids. To coordinate some of these processes with events occurring in the rest of the cell, mitochondria need to communicate with the other cellular structures through their physical contacts. Resulting intracellular platforms give rise to additional mitochondrial functions. This thesis summarizes current findings from the cells of mammalian model organisms and the budding yeast Saccharomyces cerevisiae about the interactions of this semiautonomous organelle with other cellular components and about the functions, which these interactions mediate.
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Searching for mechanisms and functions of microtubular interactions with other plant cell structures
Krtková, Jana ; Schwarzerová, Kateřina (advisor) ; Vaňková, Radomíra (referee) ; Ovečka, Miroslav (referee)
Microtubular cytoskeleton is involved in many processes in plant cells, including cell division, growth and development. Other proteins enable its functions by modulation of its dynamics and organization and by mediation of functional and structural interaction with other cell structures. Identification of the mediating proteins and the functions of these interactions under specific conditions were the main aims of the thesis. Membrane proteins interacting with microtubules were identified using biochemical methods. Surprisingly, the identified proteins co-sedimenting with microtubules were not members of the "classical" microtubule associated proteins (MAPs). There were enzymes, chaperones and plant specific proteins among them. For further studies, the identified microtubule-associated heat-shock protein 90 (Hsp90_MT) was chosen. Recombinant Hsp90_MT binds directly to microtubules and tubulin dimers in vitro. The ATP-binding pocket is not responsible for this association. In BY-2, Hsp90_MT co-localizes with phragmoplast and cortical microtubules and is involved in microtubule recovery after their depolymerization during cold treatment. In plants, Hsp90 is involved in cell cycle progression, its inhibition causes cell-cycle arrest in G1 phase. Based on literature search for animal proteins...
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Microtubule-associated proteins in plants
Benáková, Martina ; Krtková, Jana (advisor) ; Vinopal, Stanislav (referee)
1. Abstract and key words MTs are one of the basic cellular protein structure. Their features and function are influenced and modified by group of other proteins, i.e. microtubule-associated proteins (MAPs). In the last decades, an extensive research on MAPs and their wide range of functions has been carried out. Therefore we are aware of the involvement of some of the MAPs in MT dynamics, other have been shown to have rather structural function. They bundle MTs with various cell structures, such as the other MTs, proteins, organelles, actin cytoskeleton or plasma membrane. Many described MAPs are homologous in the whole eukaryotic domain, for example MAP65 or EB1 (END BINDING 1) family, therefore it is interesting to follow if and how the functions of plant MAPs differ from their animal counterparts. On the other hand, there are many specific MAPs with unique functions in plants, e.g. ATK5 or SPR1 (SPIRAL 1). This Bachelor thesis is a survey on current knowledge of plant MAPs and it makes an effort to present their characteristic and functions in plant cell and organism. Key words: cytoskeleton, microtubules, microtubule-associated proteins, plant cell, growth and development
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Mechanisms of epidermal cells polarization in plants.
Vojtíková, Zdeňka ; Žárský, Viktor (advisor) ; Soukup, Aleš (referee)
Plant epidermal cells form contact area of the plant, they protect it from impacts of surrounding environment and they mediate the communication with its neighbourhood. In the epidermis there are evenly distributed several cell types with quite specialized morphology (pavement cells, trichomes and guard cells) due to the polarization mechanisms. The cytoskeleton and signal molecules of ROP GTPase family promote the polarized growth. Thanks to polarized growth the cells reach their shapes. The cytoskeleton responds to the signal by expanding the cell, helps with targeting of the secretion to the sites of active growth and mediates polarized formation of the cell wall. On the upper side of the epidermis the cuticle and layer of epicuticular waxex is secreted. The secretion of cuticular components is baso-apicaly polarized. This work summarizes the mechanisms of the polarization in plant epidermal cells discoverd untill now.
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