N-Ethylmaleimide-Sensitive Factor Is Required to Organize Functional Exocytotic Microdomains in Paramecium

Corresponding author: Jean Cohen, Centre National de la Recherche Scientifique, Ave. de la Terrasse, 91198 Gif-sur-Yvette Cedex, France., jean.cohen{at}cgm.cnrs-gif.fr (E-mail)

Communicating editor: S. L. ALLEN

In exocytosis, secretory granules contact plasma membrane at sites where microdomains can be observed, which are sometimes marked by intramembranous particle arrays. Such arrays are particularly obvious when membrane fusion is frozen at a subterminal stage, e.g., in neuromuscular junctions and ciliate exocytotic sites. In Paramecium, a genetic approach has shown that the "rosettes" of intramembranous particles are essential for stimulated exocytosis of secretory granules, the trichocysts. The identification of two genes encoding the N-ethylmaleimide-sensitive factor (NSF), a chaperone ATPase involved in organelle docking, prompted us to analyze its potential role in trichocyst exocytosis using a gene-silencing strategy. Here we show that NSF deprivation strongly interferes with rosette assembly but does not disturb the functioning of exocytotic sites already formed. We conclude that rosette organization involves ubiquitous partners of the fusion machinery and discuss where NSF could intervene in this mechanism.

This article has been cited by other articles:

				I. M. Sehring, C. Reiner, J. Mansfeld, H. Plattner, and R. Kissmehl A broad spectrum of actin paralogs in Paramecium tetraurelia cells display differential localization and function J. Cell Sci., January 1, 2007; 120(1): 177 - 190. [Abstract] [Full Text] [PDF]

				D. Gogendeau, A.-M. Keller, A. Yanagi, J. Cohen, and F. Koll Nd6p, a Novel Protein with RCC1-Like Domains Involved in Exocytosis in Paramecium tetraurelia Eukaryot. Cell, December 1, 2005; 4(12): 2129 - 2139. [Abstract] [Full Text] [PDF]

				T. Wassmer, M. Froissard, H. Plattner, R. Kissmehl, and J. Cohen The vacuolar proton-ATPase plays a major role in several membrane-bounded organelles in Paramecium J. Cell Sci., July 1, 2005; 118(13): 2813 - 2825. [Abstract] [Full Text] [PDF]

				R. D. Burgoyne and A. Morgan Secretory Granule Exocytosis Physiol Rev, April 1, 2003; 83(2): 581 - 632. [Abstract] [Full Text] [PDF]

				R. Kissmehl, M. Froissard, H. Plattner, M. Momayezi, and J. Cohen NSF regulates membrane traffic along multiple pathways in Paramecium J. Cell Sci., October 15, 2002; 115(20): 3935 - 3946. [Abstract] [Full Text] [PDF]