Induction of autophagy causes dramatic changes in the subcellular distribution of GFP-Rab24.
Rab GTPases comprises a large family of proteins, with more than 50 gene products localized in distinct subcellular compartments. Rab24 is a member of this family whose function is not presently known. In order to elucidate the role of this protein we have generated a GFP-tagged Rab24 and studied the distribution of this chimera by fluorescence microscopy. GFP-Rab24 showed a perinuclear reticular localization that often encircled the nucleus. This reticular pattern partially overlapped with ER markers, cis-Golgi, and the ER-Golgi intermediate compartment. Surprisingly, when GFP-Rab24-transfected cells were starved to induce autophagy the distribution of the protein changed dramatically. GFP-Rab24 localized in large dots, cup-shaped structures and ring-shaped vesicles. Some of these vesicles were labeled with monodansylcadaverine, a specific autophagosome marker. In the presence of vinblastine, an agent that induces the formation of very large autophagic vesicles, GFP-Rab24 accumulated in the large vacuoles that were also labeled by monodansylcadaverine. Furthermore, Rab24 colocalized with LC3, a mammalian homolog of the yeast protein Apg8/Aut7, an essential gene for autophagy. This is the first report indicating that Rab24 localizes on autophagosomes, suggesting that this Rab protein is involved in the autophagic pathway.
Munafó
Daniela B
DB
Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, CONICET, Mendoza 5500, Argentina.
Colombo
María I
MI
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000187:drug effects / Q000502:physiology*; D016466:CHO Cells; D002103:Cadaverine / Q000031:analogs & derivatives* / Q000378:metabolism; D006224:Cricetinae; D005033:Ethylmaleimide / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism; D000077191:Wortmannin; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
D000730:Androstadienes; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; C086224:Rab24 protein, mouse; D020691:rab GTP-Binding Proteins; C008542:monodansylcadaverine; D002103:Cadaverine; D005033:Ethylmaleimide; D000077191:Wortmannin