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The search for novel interaction partners of SH3 domain of an adaptor protein p130Cas
Gemperle, Jakub ; Rösel, Daniel (advisor) ; Forstová, Jitka (referee)
Protein p130Cas is the major tyrosine phosphorylated protein in cells transformed by v-crk and v-src oncogenes. P130Cas plays an important role in invasiveness and metastasis of Src-transformed cells. In breast cancer patients, high p130Cas levels are associated with higher recurrence of disease, poor response to tamoxifen treatment and lower overall survival. In non-transformed cells, after the stimulation of integrins, protein p130Cas is phosphorylated in substrate domain affecting cell migration and cytoskeletal dynamics. For this signalling is the SH3 domain of p130Cas indispensable. In this thesis, was for the first time using the Phage display method analysed and subsequently characterized the binding motif of SH3 domain of p130Cas. Based on this high-affinity motif [AP]-P-[APMS]-K-P-[LPST]-[LR]- [LPST], we predicted new interaction partners of protein p130Cas and subsequently confirmed the interaction with the Ser/Thr kinase PKN3. This kinase colocalizes with p130Cas in the nucleus and perinuclear region and could phosphorylate p130Cas. In this thesis, we also analysed the effect of phosphomimicking mutation of tyrosine from sequence ALYD, which is conserved in the sequence of SH3 domains, on ability of these domains to bind ligands. This mutation reduced binding by about 3 orders of...
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Adaptor domains in signalling proteins: phosphorylation analysis and a role in mechanosensing
Tatárová, Zuzana ; Novotný, Marian (advisor) ; Doležal, Pavel (referee)
P130Cas (Crk-associated substrate, CAS) is a multiadaptor protein important in integrin signalling where it positively regulates cell motility, invasion, proliferation and survival. CAS lacks enzymatic activity, but its binding to other signalling proteins could lead to the change of phosphorylation status of its substrate domain, which is the main mode, through which CAS takes part in regulating cell behavior. Local tensions in focal adhesions lead to an extension of CAS substrate domain, leaving phosphorylation sites more accessible for kinases, which subsequently leads to an increased CAS substrate domain phosphorylation. The CAS anchorage in focal adhesions is mediated by its SH3 domain, probably through the interactions with FAK, and also by C-terminal domain, where interaction partners are not known. The aim of my project is to find out, which proteins mediate the CAS anchorage to the focal adhesions. The elucidation of CAS anchorage to focal adhesions will contribute to the understanding of mechanosensory function of CAS. Experimental data suggest that tyrosine phosphorylation of the CAS SH3 domain plays an important role in the regulation of its binding properties. Another goal of my diploma project was to analyze the significance of tyrosine phosphorylation within SH3 domain and other...
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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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The biological importance of CAS SH3 domain tyrosine phosphorylation
Janoštiak, Radoslav ; Brábek, Jan (advisor) ; Dvořák, Michal (referee)
Protein CAS is a major tyrosine-phosphorylated protein in cells transformed by v-crk and v-src oncogenes. It is a multidomain adaptor protein, which serves as a scaffold for assembly of signalling complexes which are important for migration and invasiveness of Src-transformed cells. A novel phosphorylation site in N-terminal SH3 domain was identified - tyrosine 12 located on binding surface of CAS SH3 domain. To study biological importance of tyrosine 12 phosphorylation, non-phosphorylable (Y12F) and phosphomimicking ( Y12E) mutant of CAS were prepared. We found that phosphomimicking mutation Y12E leads to decreased interaction of CAS SH domain with kinase FAK a phosphatase PTP-PEST and also reduce tyrosine phosphorylation of FAK. Using GFP-tagged CAS protein, we show that Y12E mutation caused delocalization of CAS from focal adhesion but has no effect on localization of CAS to podosome-type adhesion. Non-phosphorylable mutation Y12F cause hyperphosphorylation of CAS substrate domain and decrease turnover of focal adhesion and associated cell migration of mouse embryonal fibroblasts (MEFs) independent to integrin singalling. Analogically to migration, CAS Y12F decrease invasiveness of Src-transformed MEF. The results of this diploma thesis show that phosphorylation of Tyr12 in CAS SH3 domain is...
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A comparison of SH3 domains' tyrosine phosporylation influence on their binding capacity
Tatárová, Zuzana ; Novotný, Marian (advisor) ; Kuthan, Martin (referee)
Understanding the impact of protein phosphorylation is very important for the formation of dynamic biological processes such as gene silencing, cell growth, differentiation or apoptosis. This work deals with the phosphorylation of a protein-interaction module known as SH3 domain and the influence of phosphorylation on its ligand-binding capacity. SH3 domain is a part of a large number of enzymes directly involved in signal transduction as well as adapter proteins without enzymatic activity. Many studies have shown the importance of tyrosine sites within SH3 domain in regulatory mechanisms of proteins by using either mutants that cannot be phosphorylated, mutants mimicking the negative charges created by phosphorylation or by evidence of in vivo phosphorylation. The work also includes bioinformatic analysis, which further expand our knowledge of SH3 phosphorylated proteins and confirms that phosphorylation of the tyrosine sites is conserved among proteins containing the SH3 domain.
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