The effect of wortmannin on the localisation of lysosomal type I integral membrane glycoproteins suggests a role for phosphoinositide 3-kinase activity in regulating membrane traffic late in the endocytic pathway.
Addition of wortmannin to normal rat kidney cells caused a redistribution of the lysosomal type I integral membrane proteins Igp110 and Igp120 to a swollen vacuolar compartment. This compartment did not contain the cation independent mannose 6-phosphate receptor and was depleted in acid hydrolases. It was distinct from another swollen vacuolar compartment containing the cation independent mannose 6-phosphate receptor. The swollen Igp110-positive compartment was accessible to a monoclonal antibody against Igp120 added extracellularly, showing that it had the characteristics of an endosomal compartment. Wortmannin had no gross morphological effect on the trans-Golgi network or lysosomes nor any effect on the delivery to the trans-Golgi network of endocytosed antibodies against the type I membrane protein TGN38. We propose that the observed effects of wortmannin were due to inhibition of membrane traffic between cation independent mannose 6-phosphate receptor-positive late endosomes and the trans-Golgi network and to inhibition of membrane traffic between a novel Igp120-positive, cation independent mannose 6-phosphate receptor-negative late endosomal compartment and lysosomes. The effects of wortmannin suggest a function for a phosphatidylinositol 3-kinase(s) in regulating membrane traffic in the late endocytic pathway.
Reaves
B J
BJ
Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, UK.
Bright
N A
NA
Mullock
B M
BM
Luzio
J P
JP
D000730:Androstadienes / Q000494:pharmacology*; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006023:Glycoproteins; D007668:Kidney / Q000166:cytology* / Q000187:drug effects; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins; D008856:Microscopy, Fluorescence; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D051381:Rats; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D013997:Time Factors; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D000077191:Wortmannin; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
D000730:Androstadienes; D015703:Antigens, CD; D004791:Enzyme Inhibitors; D006023:Glycoproteins; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D017527:Receptor, IGF Type 2; C513045:Tgoln2 protein, rat; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D001619:beta-N-Acetylhexosaminidases; D000077191:Wortmannin