Dynamics of Rac1 GTPases and their role in the regulation of cell polarity in Dictyostelium discoideum

Marinović, Maja (2015) Dynamics of Rac1 GTPases and their role in the regulation of cell polarity in Dictyostelium discoideum. Doctoral thesis, Faculty of Science > Department of Biology.

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Abstract

Rac proteins are the only members of the Rho family of small GTPases present in Dictyostelium discoideum. It has been shown that Rac1 proteins play a dual role in the regulation of actin polymerization, which is the key determinant of cell polarity. At the front end of a cell Rac1A activates the Scar/WAVE complex and stimulates Arp2/3-mediated actin polymerization, while it simultaneously regulates stability of the rear end by initiating formation of a complex containing one of the IQGAP-related proteins, DGAP1 or GAPA, and the cortexillin heterodimer. To gain more insight into the roles of three highly homologous Rac1 proteins in D. discoideum, Rac1A, 1B and 1C, we developed an improved probe for active Rac1 GTPases. The probe consists of the GBD domain from DPAKa fused with the yellow fluorescent protein. We monitored localization of the DPAKa_GBD probe, and it's colocalization with probes for other proteins involved in organization of the actin cytoskeleton, to obtain information about spatio-temporal relations between main components of this dynamic system in live cells. Functional analysis of D. discoideum Rac1B/1C-deficient strain revealed that, although three Rac1 proteins are highly homologous, their roles are not completely redundant.

Item Type: Thesis (Doctoral thesis)
Keywords: Rho GTPases, Rac1, actin cytoskeleton, cell polarization, Dictyostelium
Supervisor: Weber, Igor
Date: 2015
Number of Pages: 132
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 06 Jul 2015 08:48
Last Modified: 06 Jul 2015 09:02
URI: http://digre.pmf.unizg.hr/id/eprint/4088

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