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Cytoskeletal orchestration of early mammalian development
Novotný, Jan ; Libusová, Lenka (advisor) ; Mašek, Jan (referee)
Structures of the cytoskeleton play a critical role in early mammalian development. Microtubules, intermediate filaments and actin microfilaments provide structural and mechanical basis for major developmental transitions of preimplantation development. Microvilli supported by bundles of actin filaments become restricted to one pole of the blastomere during the process of polarisation. All components of the cytoskeleton network undergo apparent reorganisation in embryo compaction. Cells flatten and adhere to each other thanks to the formation of cytoskeleton-linked intercellular junctions and oscillatory contractions generated by actomyosin complexes. Filopodia, actin based protrusions, are debated for their potential role in blastomere apposition and cell signalling. The first process of cell line specification in mammalian development is that which defines outer cells of morula as presumptive trophectoderm and inner cells as presumptive inner cell mass. Proteins and structures of cytoskeleton are asymmetrically distributed between these two populations helping to determine the fate of each blastomere. The aim of the thesis is to summarise the roles of cytoskeleton in blastomere polarisation, embryo compaction and specification of inner and outer cell populations in mammalian preimplantation...
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Protein composition of the cytoskeleton of protists
Švagr, Eva ; Hampl, Vladimír (advisor) ; Pánek, Tomáš (referee)
While we have a good understanding of the roles of actin and tubulin filaments in the cell cytoskeleton, intermediate filaments (IFs) are often overlooked. However, the importance of IFs becomes quite apparent, as proteins similar to IF proteins have been identified in many protist cells. This holds particularly for the cells of protists, where even the functions of some members of the of actin and tubulin superfamilies remain unclear. Intermediate filaments are still not well established as components of protist cytoskeletons, in contrast to their more thoroughly studied counterparts in Metazoa. Protist and metazoan IF proteins are dissimilar in their sequence; however, they share similarities in structure, and they assemble autonomously into analogous filaments. IF-like proteins have been localized to striated fibers or unique cytoskeletal components in several organisms, even though not much is known about the protein composition of these striated fibers to date. This suggests that IF-like proteins might be a universally present component of these striated fibers often seen in protist cells. Keywords: Protists, cytoskeleton, microtubules, microfilaments, intermediate filaments, fibrils, protein composition
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