Transport of mannose-6-phosphate receptors from the trans-Golgi network to endosomes requires Rab31.
Rab31, a protein that we originally cloned from a rat oligodendrocyte cDNA library, localizes in the trans-Golgi network (TGN) and endosomes. However, its function has not yet been established. Here we show the involvement of Rab31 in the transport of mannose 6-phosphate receptors (MPRs) from TGN to endosomes. We demonstrate the specific sorting of cation-dependent-MPR (CD-MPR), but not CD63 and vesicular stomatitis virus G (VSVG) protein, to Rab31-containing trans-Golgi network carriers. CD-MPR and Rab31 containing carriers originate from extending TGN tubules that also contain clathrin and GGA1 coats. Expression of constitutively active Rab31 reduced the content of CD-MPR in the TGN relative to that of endosomes, while expression of dominant negative Rab31 triggered reciprocal changes in CD-MPR distribution. Expression of dominant negative Rab31 also inhibited the formation of carriers containing CD-MPR in the TGN, without affecting the exit of VSVG from this compartment. Importantly, siRNA-mediated depletion of endogenous Rab31 caused the collapse of the Golgi apparatus. Our observations demonstrate that Rab31 is required for transport of MPRs from TGN to endosomes and for the Golgi/TGN organization.
Rodriguez-Gabin
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Department of Neurology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA.
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D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D034622:RNA Interference; D051381:Rats; D017527:Receptor, IGF Type 2 / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D060149:Tetraspanin 30; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism* / Q000648:ultrastructure
D015703:Antigens, CD; C554586:CD63 protein, human; C554588:Cd63 protein, rat; D002966:Clathrin; C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D010980:Platelet Membrane Glycoproteins; C484190:RAB31 protein, human; C484189:Rab31 protein, rat; D017527:Receptor, IGF Type 2; D011993:Recombinant Fusion Proteins; D060149:Tetraspanin 30; D014759:Viral Envelope Proteins; D020691:rab GTP-Binding Proteins