title: Impaired retrograde membrane traffic through endosomes in a mutant CHO cell defective in phosphatidylserine synthesis.
abstract: Phosphatidylserine (PS), a relatively minor constituent in the plasma membrane (PM), participates in various cellular processes such as clearance of apoptotic cells and recruitment of signaling molecules. PS also localizes in the membranes of endocytic organelles, such as recycling endosomes (REs). We recently showed that in REs, PS binds to the pleckstrin homology (PH) domain of evectin-2, thereby regulating retrograde traffic from REs to the Golgi. However, direct evidence that PS has a role in retrograde traffic is lacking. Here, we examined the contribution of PS to endosomal membrane traffic by exploiting a mutant CHO cell line (PSA-3) that is defective in PS synthesis. In PSA-3 cells, the Golgi localization of TGN38, a protein that circulates between the Golgi and the PM through endosomes by retrograde traffic, was abolished, whereas the localizations of other organelle markers remained unchanged. Increasing the cellular PS level by adding ethanolamine to the culture medium restored the Golgi localization of TGN38. Tracking the endocytic fate of cell surface TGN38 that was labeled by anti-TGN38 antibody showed that retrograde transport of TGN38 was impaired at endosomes, not at the PM. These findings provide direct evidence that intracellular PS is required for retrograde traffic through endosomes.
authors: Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.
authors: Shoken
authors: S
authors: Lee
authors: Yasunori
authors: Y
authors: Uchida
authors: Kazuo
authors: K
authors: Emoto
authors: Masato
authors: M
authors: Umeda
authors: Osamu
authors: O
authors: Kuge
authors: Tomohiko
authors: T
authors: Taguchi
authors: Hiroyuki
authors: H
authors: Arai
mesh_terms: D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D003470:Culture Media / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D019856:Ethanolamine / Q000494:pharmacology; D006056:Golgi Apparatus / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D010718:Phosphatidylserines / Q000096:biosynthesis* / Q000378:metabolism; D021381:Protein Transport; D051381:Rats; D014162:Transfection
chemical_list: D003470:Culture Media; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010718:Phosphatidylserines; C513045:Tgoln2 protein, rat; D019856:Ethanolamine