Letter abstract
Nature Cell Biology 5, 1071 - 1078 (2003)
Published online: 2 November 2003 | doi:10.1038/ncb1064
Citron-N is a neuronal Rho-associated protein involved in Golgi organization through actin cytoskeleton regulation
Paola Camera1,5, Jorge Santos Da Silva2,5, Gareth Griffiths3, Maria Gabriella Giuffrida4, Luciana Ferrara1, Vanessa Schubert2, Sara Imarisio1, Lorenzo Silengo1, Carlos G. Dotti2 & Ferdinando Di Cunto1
The actin cytoskeleton is best known for its role during cellular morphogenesis. However, other evidence suggests that actin is also crucial for the organization and dynamics of membrane organelles such as endosomes and the Golgi complex1, 2, 3. As in morphogenesis, the Rho family of small GTPases are key mediators of organelle actin-driven events4, 5, although it is unclear how these ubiquitously distributed proteins are activated to regulate actin dynamics in an organelle-specific manner. Here we show that the brain-specific Rho-binding protein Citron-N6 is enriched at, and associates with, the Golgi apparatus of hippocampal neurons in culture. Suppression of the whole protein or expression of a mutant form lacking the Rho-binding activity results in dispersion of the Golgi apparatus. In contrast, high intracellular levels induce localized accumulation of RhoA and filamentous actin, protecting the Golgi from the rupture normally produced by actin depolymerization. Biochemical and functional analyses indicate that Citron-N controls actin locally by assembling together the Rho effector ROCK-II and the actin-binding, neuron-specific, protein Profilin-IIa (PIIa). Together with recent data on endosomal dynamics5, our results highlight the importance of organelle-specific Rho modulators for actin-dependent organelle organization and dynamics.
- Dipartimento di Genetica, Biologia e Biochimica, Università Degli Studi di Torino Via Santena, 5 bis, Torino, Italy.
- Cavalieri Ottolenghi Scientific Institute Università Degli Studi di Torino A.O. San Luigi Gonzaga Regione Gonzole 10, 10024 Orbassano (Torino), Italy.
- EMBL, Department of Cell Biology, Postfach 102209 Heidelberg D- 69012, Germany.
- Consiglio Nazionale delle Ricerche, Istituto Scienze Produzioni Alimentari, Bioindustry Park del Canavese, Colleretto Giacosa (Torino), Italy.
- These authors have contributed equally to this work.
Correspondence to: Carlos G. Dotti2 e-mail: carlos.dotti@unito.it
Correspondence to: Ferdinando Di Cunto1 e-mail: ferdinando.dicunto@unito.it
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