title: Rasosomes originate from the Golgi to dispense Ras signals.
abstract: 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.
authors: Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Israel.
authors: A
authors: A
authors: Grunwald
authors: I
authors: I
authors: Gottfried
authors: A D
authors: AD
authors: Cox
authors: R
authors: R
authors: Haklai
authors: Y
authors: Y
authors: Kloog
authors: U
authors: U
authors: Ashery
mesh_terms: D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D037161:Galectins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D054878:Lipoylation; D051379:Mice; D009154:Mutation; D053758:Nanoparticles / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D059008:Time-Lapse Imaging; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D037161:Galectins; D020033:Protein Isoforms; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D048049:Extracellular Signal-Regulated MAP Kinases; D018631:ras Proteins