Christina Schachtler

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C7 Modulation of cellular processes and Rac/Rop (Rho) activity in Arabidopsis by Pto TTSS effector proteins

Principal investigator
Benedikt Kost

Mentor
Heinrich Sticht

Identification and functional characterization of homologous proteins to mammalian actin remodeling GTPase guanylate binding protein-1 in plants

The guanylate-binding protein-1 (GBP-1) is among the most significantly induced proteins in cells exposed to interferon (IFN)-g . It belongs to the dynamin superfamily of large GTPases. Anti-pathogen effects have been observed with mouse GBPs (mGBPs), indicating that GBPs exert conserved functions in human and rodents . In addition, GBP-1 is both necessary and sufficient for the inhibitory effects of IFN-g on cell proliferation, migration and invasion as shown in endothelial cells and epithelial tumor cells.
At the mechanistic level it has been proposed that GBP-1 might inhibit cell proliferation through the suppression of b-catenin/TCF signaling. In addition, the GTPase activity of GBP-1 is required for the up-regulation of integrin a4 and the inhibition of MMP-1 expression, leading to the inhibition of cell migration and invasion, respectively. Recently members of this team could show that GBP-1 binds to actin and via this activity is necessary and sufficient to mediate remodeling of the cellular cytoskeleton in response to IFN-g. In line with this GBP-1 has been shown to act as a downstream processor of IFN-g in T cells via interaction with plastin-2 that bundles actin fibers and spectrin β-chain, brain 1 that links the plasma membrane to the actin cytoskeleton.
In preliminary work we obtained evidence that homologous genes to the mammalian large GTPases may exist in plants and that these genes similarly as observed in mammalian cells might have impact on remodeling of the cytoskeleton as well as on cell growth and infection.
The specific goals of the project are (1) to validate the effects of large GTPases encoded by plants on remodeling of the actin cytoskeleton, cell growth and infection, (2) to investigate reciprocally the effects of plant large GTPases on the cytoskeleton, cell growth and infection in mammalian cells and (3) use bioinformatics to model structural similarities and putative active subdomain homologies of mammalian GBP-1 and homologous GTPases in plants, which subsequently will be reevaluated experimentally in the available plant and mammalian model systems.

Figure: Actin cytoskeleton.
Confocal optical section through stably transformed tobacco pollen tubes expressing the F-actin marker YFP:lifeact. Transiently co-expressed is the non-invasive marker protein GUS and a nucleus marker.

 

Publications

 

Presentations

October 2016 8th Annual Retreat, Erlangen School of Molecular Communication, Schloss Schney, Lichtenfels, Germany
”Arabidopsis homologs of HsGBP1: role in plant defense?”
Poster
     
October 2015 2nd International SFB 796 Conference: Mechanisms of microbial host cell manipulation: From plants to humans, Erlangen, Germany
Arabidopsis homologs of HsGBP1: role in plant defense?
Poster
     
July 2015 7th Annual Retreat, Erlangen School of Molecular Communication, Schloss Hirschberg, Beilngries, Germany
”Arabidopsis homologs of HsGBP1: role in plant defense?”
Poster
     
     

 

Awards

Best Poster Award

Second place

8th Annual Retreat, Erlangen School of Molecular Communication, Schloss Schney, Lichtenfels, Germany, October 2016
“Arabidopsis homologs of HsGBP1: role in plant defense?“