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Role of Varp, a Rab21 exchange factor and TI‐VAMP/VAMP7 partner, in neurite growth
Author(s) -
Burgo Andrea,
Sotirakis Emmanuel,
Simmler MarieChristine,
Verraes Agathe,
Chamot Christophe,
Simpson Jeremy C,
Lanzetti Letizia,
ProuxGillardeaux Véronique,
Galli Thierry
Publication year - 2009
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/embor.2009.186
Subject(s) - morphogenesis , art history , library science , art , cognitive science , biology , computer science , psychology , gene , biochemistry
The vesicular soluble N ‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) tetanus neurotoxin‐insensitive vesicle‐associated membrane protein (TI‐VAMP/VAMP7) was previously shown to mediate an exocytic pathway involved in neurite growth, but its regulation is still largely unknown. Here we show that TI‐VAMP interacts with the Vps9 domain and ankyrin‐repeat‐containing protein (Varp), a guanine nucleotide exchange factor (GEF) of the small GTPase Rab21, through a specific domain herein called the interacting domain (ID). Varp, TI‐VAMP and Rab21 co‐localize in the perinuclear region of differentiating hippocampal neurons and transiently in transport vesicles in the shaft of neurites. Silencing the expression of Varp by RNA interference or expressing ID or a form of Varp deprived of its Vps9 domain impairs neurite growth. Furthermore, the mutant form of Rab21, defective in GTP hydrolysis, enhances neurite growth. We conclude that Varp is a positive regulator of neurite growth through both its GEF activity and its interaction with TI‐VAMP.