Research article

Actin polymerisation at the cytoplasmic face of eukaryotic nuclei

Sylvia Münter^1,2 , Jost Enninga³ , Rafael Vazquez-Martinez^4,5 , Erwan Delbarre⁶ , Brigitte David-Watine¹ , Ulf Nehrbass¹ and Spencer L Shorte⁷

¹  Unité de Biologie Cellulaire du Noyau, CNRS URA 2582, Département de Biologie Cellulaire et Infection, Institut Pasteur; 25, Rue du Docteur Roux, 75724 Paris Cedex 15, France

²  Current address: Department of Parasitology, Heidelberg University School of Medicine, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany

³  Unité de Pathogénie Microbienne Moléculaire, U389 INSERM Institut Pasteur; 28, Rue du Docteur Roux, 75724 Paris Cedex 15, France

⁴  Unité de Embryologie Moléculaire, Institut Pasteur; 25, Rue du Docteur Roux, 75724 Paris Cedex 15, France

⁵  Current address: Department of Cell Biology, University of Cordoba, 14014-Cordoba, Spain

⁶  Département de Biologie Cellulaire, Institut Jacques Monod, CNRS, Universités Paris 6 and 7, 75251 Paris Cedex 05, France

⁷  Plate-Forme d'Imagerie Dynamique (PFID), Département de Biologie Cellulaire et Infection, Institut Pasteur; 25, Rue du Docteur Roux, 75724 Paris Cedex 15, France

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BMC Cell Biology 2006, 7:23doi:10.1186/1471-2121-7-23

Published:	23 May 2006

Abstract

Background

There exists abundant molecular and ultra-structural evidence to suggest that cytoplasmic actin can physically interact with the nuclear envelope (NE) membrane system. However, this interaction has yet to be characterised in living interphase cells.

Results

Using a fluorescent conjugate of the actin binding drug cytochalasin D (CD-BODIPY) we provide evidence that polymerising actin accumulates in vicinity to the NE. In addition, both transiently expressed fluorescent actin and cytoplasmic micro-injection of fluorescent actin resulted in accumulation of actin at the NE-membrane. Consistent with the idea that the cytoplasmic phase of NE-membranes can support this novel pool of perinuclear actin polymerisation we show that isolated, intact, differentiated primary hepatocyte nuclei support actin polymerisation in vitro. Further this phenomenon was inhibited by treatments hindering steric access to outer-nuclear-membrane proteins (e.g. wheat germ agglutinin, anti-nesprin and anti-nucleoporin antibodies).

Conclusion

We conclude that actin polymerisation occurs around interphase nuclei of living cells at the cytoplasmic phase of NE-membranes.