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Ena/VASP proteins: focus on interaction partners and Enah splice variants

Sylvie Veniere UGent (2010)
abstract
Actin (de)polymerization and reorganization of supramolecular actin structures are driving forces for cellular migration. Key factors in these processes are numerous actin binding proteins for example Ena/VASP proteins and profilins that are also partner proteins. Ena/VASP proteins bind to profilin via their central proline-rich region. N-terminal to this region is the EVH1 domain that interacts with the adaptor protein lamellipodin. Although already the subject of several studies, the functional significance of the interaction between Ena/VASP proteins and profilin is still not fully understood. In the first part of this thesis, we designed a sensitive quantitative assay to study the interaction between profilin and proline-rich sequences. Via this assay, we showed that the interaction between the Ena/VASP protein EVL and the poly-L-proline docking ligands profilin and SH3 domains either occurs via competition or via ternary complex formation. In addition, we identified two new profilin ligands: Shootin1 and lamellipodin. As lamellipodin is a known Ena/VASP ligand, we explored the interaction between lamellipodin and profilin more in detail. We demonstrated that lamellipodin binds profilin IIa via at least four proline-rich sites that show somewhat different binding characteristics for profilin IIa and that the interaction between lamellipodin and profilin IIa is differentially regulated via lamellipodin phosphorylation by Abl kinase. Additionally, we investigated the cellular role of the interaction between profilin and EVL. Our results show that the proline-rich region of EVL is essential for EVL function in a scratch wound assay which suggests a function for the EVL-profilin complex in the latter. In a final part of this thesis we mapped the splice variants of the Ena/VASP protein ENAH. The mouse Enah gene has four extra alternatively included exons of which one encodes an extra proline-rich sequence. Via an in silico analysis and a reverse transcription-polymerase chain reaction screen we identified at least eight and maximally sixteen different Enah transcripts. We show that all identified Enah transcripts are expressed during mouse development and in adult mouse tissues. Also cell lines display specific expression profiles of these different transcripts. Our results indicate complex regulation mechanisms of Ena/VASP protein function both via differential expression of Enah alternative transcripts as via multiple ligand binding.
Please use this url to cite or link to this publication:
author
promoter
UGent
organization
year
type
dissertation (monograph)
subject
pages
176 pages
publisher
Ghent University. Faculty of Medicine and Health Sciences
place of publication
Ghent, Belgium
defense location
Gent : Rommelaere Institute (auditorium 1.39)
defense date
2010-10-20 16:00
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted materials
copyright statement
I have transferred the copyright for this publication to the publisher
id
1070505
handle
http://hdl.handle.net/1854/LU-1070505
date created
2010-11-05 09:52:57
date last changed
2013-01-30 09:41:35
@phdthesis{1070505,
  abstract     = {Actin (de)polymerization and reorganization of supramolecular actin structures are driving forces for cellular migration. Key factors in these processes are numerous actin binding proteins for example Ena/VASP proteins and profilins that are also partner proteins. Ena/VASP proteins bind to profilin via their central proline-rich region. N-terminal to this region is the EVH1 domain that interacts with the adaptor protein lamellipodin. Although already the subject of several studies, the functional significance of the interaction between Ena/VASP proteins and profilin is still not fully understood.
In the first part of this thesis, we designed a sensitive quantitative assay to study the interaction between profilin and proline-rich sequences. Via this assay, we showed that the interaction between the Ena/VASP protein EVL and the poly-L-proline docking ligands profilin and SH3 domains either occurs via competition or via ternary complex formation. In addition, we identified two new profilin ligands: Shootin1 and lamellipodin. As lamellipodin is a known Ena/VASP ligand, we explored the interaction between lamellipodin and profilin more in detail. We demonstrated that lamellipodin binds profilin IIa via at least four proline-rich sites that show somewhat different binding characteristics for profilin IIa and that the interaction between lamellipodin and profilin IIa is differentially regulated via lamellipodin phosphorylation by Abl kinase. Additionally, we investigated the cellular role of the interaction between profilin and EVL. Our results show that the proline-rich region of EVL is essential for EVL function in a scratch wound assay which suggests a function for the EVL-profilin complex in the latter.
In a final part of this thesis we mapped the splice variants of the Ena/VASP protein ENAH. The mouse Enah gene has four extra alternatively included exons of which one encodes an extra proline-rich sequence. Via an in silico analysis and a reverse transcription-polymerase chain reaction screen we identified at least eight and maximally sixteen different Enah transcripts. We show that all identified Enah transcripts are expressed during mouse development and in adult mouse tissues. Also cell lines display specific expression profiles of these different transcripts.
Our results indicate complex regulation mechanisms of Ena/VASP protein function both via differential expression of Enah alternative transcripts as via multiple ligand binding.},
  author       = {Veniere, Sylvie},
  language     = {eng},
  pages        = {176},
  publisher    = {Ghent University. Faculty of Medicine and Health Sciences},
  school       = {Ghent University},
  title        = {Ena/VASP proteins: focus on interaction partners and Enah splice variants},
  year         = {2010},
}

Chicago
Veniere, Sylvie. 2010. “Ena/VASP Proteins: Focus on Interaction Partners and Enah Splice Variants”. Ghent, Belgium: Ghent University. Faculty of Medicine and Health Sciences.
APA
Veniere, S. (2010). Ena/VASP proteins: focus on interaction partners and Enah splice variants. Ghent University. Faculty of Medicine and Health Sciences, Ghent, Belgium.
Vancouver
1.
Veniere S. Ena/VASP proteins: focus on interaction partners and Enah splice variants. [Ghent, Belgium]: Ghent University. Faculty of Medicine and Health Sciences; 2010.
MLA
Veniere, Sylvie. “Ena/VASP Proteins: Focus on Interaction Partners and Enah Splice Variants.” 2010 : n. pag. Print.