Validation of an in vitro assay to evaluate drugs effects on synaptic functioning and plasticity

• Research unit: EU RFP
• Project number: 95.0836

Key words (English)

Growth cones; SNARES; syntaxin; vesicles

Alternative project number (English)

EU project number: BMH4CT951406

Research programs (English)

EU-programme: 4. Frame Research Programme - 4.2 Agriculture and agroindustry

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise:
Université de Lausanne
Faculté de Médecine
Institut de Biologie cellulaire et de Morphologie

Partners and International Organizations (English)

A. Malgaroli, Milan, J. Bockaert, Monpellier

Abstract (English)

In our investigation on membrane trafficking during neurite outgrowth, we have identified in developing brain syntaxin13 in a complex with SNAP-25. Syntaxin13 is implicated in the early endosomal recycling pathway where it localizes to early endosomes, but can also be detected on the plasma membrane. Syntaxin13 enhances neurite outgrowth in PC12 cells, while it has no effect on regulated secretion.
In order to better understand the role of syntaxin13 and early endosomal recycling in neurite elongation, we analyzing putative syntaxin13-binding proteins. Moreover, we have expressed GFP-tagged syntaxin13 under the control of an inducible promoter during NGF-differentiation. We found that the protein is found in distrete organelles which are targeted to growth cones of neurites.
In a second project we have analyzed nSec1 during differentiation of PC12 cells. This is a syntaxin1-binding protein proposed to regulate the formation of the SNARE complex syntaxin1/SNAP-25/VAMP-2 during exocytosis. Since SNARE proteins have been shown to be essential for axonal elongation, we hypothesized that nSec1 might also be involved in membrane trafficking during neurite outgrowth. We showed on fixed as well as living cells using nSec1-GFP that the protein is targeted into neurites and to their growth cones. Moreover, overexpression of the protein inhibits regulated secretion in PC12 cells as well as an insulin-secreting b-cell line. Finally, expression of nSec1 reduces the rate of neurite outgrowth in PC12 cells. This effect is further enhanced with a nSec1 mutant which has an increased binding to syntaxin 1. This suggests that nSec1 regulates SNARE complex formation not only in regulated exocytosis, but also in membrane dynamics during neurite outgrowth.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 95.0836