Rasosomes originate from the Golgi to dispense Ras signals

• Published in: Cell death & disease Vol. 4; no. 2; p. e496
• Main Authors: Grunwald, A, Gottfried, I, Cox, A D, Haklai, R, Kloog, Y, Ashery, U
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2013; Springer Nature B.V; Nature Publishing Group
• Subjects: 631/45/612/1243; 631/80/313/1525; 631/80/86; Animals; Antibodies; Biochemistry; Biomedical and Life Sciences; Cell Biology; Cell Culture; Cell Line; Cell Membrane - metabolism; Cercopithecus aethiops; COS Cells; Extracellular Signal-Regulated MAP Kinases - metabolism; Galectins - deficiency; Galectins - genetics; Galectins - metabolism; Golgi Apparatus - genetics; Golgi Apparatus - metabolism; Guanosine Diphosphate - metabolism; Guanosine Triphosphate - metabolism; Immunology; Life Sciences; Lipoylation; Mice; Mutation; Nanoparticles - chemistry; Original; original-article; Phosphorylation; Protein Binding; Protein Isoforms - genetics; Protein Isoforms - metabolism; ras Proteins - metabolism; Signal Transduction; Time-Lapse Imaging; Transfection; Brownian motion; Golgi budding; signaling; trafficking; rasosomes
• ISSN: 2041-4889; 2041-4889
• DOI: 10.1038/cddis.2013.16

Ras proteins undergo an incompletely understood trafficking process in the cell. Rasosomes are protein nanoparticles of 80–100 nm diameter that carry lipidated Ras isoforms (H-Ras and N-Ras) as well as their effectors through the cytoplasm and near the plasma membrane (PM). In this study, we identified the subcellular origin of rasosomes and how they spread Ras proteins through the cell. We found no dependency of rasosome formation on galectins, or on the GDP-/GTP-bound state of Ras. We found that significantly more rasosomes are associated with forms of Ras that are localized to the Golgi, namely N-Ras or the singly palmitoylated H-Ras mutant (C181S). To explore the possibility that rasosome originate from the Golgi, we used photoactivatable (PA)-GFP-H-Ras mutants and showed that rasosomes bud from the Golgi in a two-step mechanism. Newly released rasosomes first move in an energy-dependent directed fashion and then convert to randomly diffusing rasosomes. Dual fluorescence time-lapse imaging revealed the appearance of dually labeled rasosomes, indicating a dynamic exchange of cytoplasmic and PM-associated Ras with rasosome-associated Ras. Finally, higher levels of rasosomes correlate with higher levels of ERK phosphorylation, a key marker of Ras downstream signaling. We suggest that H-Ras and N-Ras proteins exchange with rasosomes that can function as carriers of palmitoylated Ras and its signals.