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Role of cAMP signaling in phagocyte migration
Dáňová, Klára ; Paňková, Daniela (referee) ; Kamanová, Jana (advisor)
Cell migration plays a key role in a wide diversity of biological processes. Migration enables phagocytic cells to localize into the site of inflammation and to lymph nodes, thereby leading to initiation of innate and adaptive immune responses, respectively. The signal transduction that coordinates phagocyte migration consist of diverse signaling proteins, being often under control of 3'-5'-cyclic adenosine monophosphate (cAMP) and its two effectors, protein kinase A (PKA) and Epac (exchange protein activated by cAMP). Small GTPase Rap is activated by Epac and controls phagocyte migration via activation of RAPL and RIAM proteins. On the other hand, PKA regulates cell migration via modulation of activity of other proteins, which comprise actin, integrins, small GTPases Rho, Rac, Cdc42 as well as protein VASP. A prominent feature of cAMP signalization is its spatio-temporal organization. Therefore, besides description of cAMP-regulated signaling cascades in cell migration, this bachelor thesis also depicts how changes of activity of cAMP effectors in time and place are involved in regulation of cell movement.
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Signalization of adenylate cyclase toxin of Bordetella pertussis in macrophages.
Černý, Ondřej ; Kuthan, Martin (referee) ; Kamanová, Jana (advisor)
Adenylate cyclase toxin (CyaA) is a key virulence factor of Bordetella pertussis, the causative agent of whooping cough. The toxin targets primarily myeloid phagocytes expressing CD11b/CD18 (αMβ2, CR3, Mac-1) and by elevation of cytosolic cAMP levels it paralyses their macropinocytic and opsono-phagocytic functions. Here, we dissected the cAMP-regulated pathway responsible for the block of macrophage macropinocytosis and characterized the capacity of CyaA-treated macrophages to shut- down Akt (protein kinase B, PKB) signaling; that controls nitric oxide (NO) production by macrophages. By using specific activators of protein kinase A (PKA) and for the exchange protein activated by cAMP (Epac), we show that activation of the cAMP effector Epac inhibits macropinocytosis in macrophages. Moreover, upon transfection of macrophages by the constitutively active and dominant negative variants of a downstream effector of Epac, the small GTPase Rap1, inhibition or upregulation of macrophage macropinocytosis was observed, respectively. It was reported previously that the Epac/Rap1 pathway regulates activity of tyrosin phosphatase SHP-1 as well as of protein phosphatase 2 A (PP2A). We show that inhibition of both tyrosin phosphatases and PP2A interferes with CyaA-mediated block of macropinocytosis. These...
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Role of bacteria and mucosal immune system and their interaction in the pathogenesis of inflammatory bowel disease
Du, Zhengyu ; Hudcovic, Tomáš (advisor) ; Prokešová, Ludmila (referee) ; Kamanová, Jana (referee)
Although the etiology and pathogenesis of inflammatory bowel disease (IBD) is not fully understood, it is generally accepted that the inflammation results from aberrant immune responses to antigens of gut microbiota in genetically susceptible individuals (Sartor et al., 2006). Alteration in intestinal microbiota has been found in IBD patients with increased abundance of certain bacteria and decreased abundance of others. Due to the complexity of the disease, multifaceted interactions between genetic factors, host immune response, gut microbiota and environment factors need to be taken into account. In this thesis, the pathogenesis of IBD was first reviewed in respect with the four factors mentioned above. Then we concentrated on the interaction between IBD-associated bacteria and mucosal immune system. We investigated the ability of mucosal-associated bacteria (MAB) from IBD patients to induce spontaneous colitis in germ-free (GF) mice and the impact of those bacteria on the development of dextran sulfate sodium (DSS)-colitis. Together with the analysis of the composition of gut microbiota of MAB colonized mice, we demonstrated the potential deleterious microbes were able to increase the susceptibility to DSS-colitis once they found a suitable niche. We revealed the mechanism of an E.coli strain...
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