Acute effectors of GLUT1 glucose transporter subcellular targeting in CIT3 mouse mammary epithelial cells.
Lactogenic hormones cause intracellular targeting of glucose transporter 1 (GLUT1) for transport of glucose to the site of lactose synthesis in mammary glands. Our aim was to study the intracellular trafficking mechanisms involved in GLUT1 targeting and recycling in CIT3 mouse mammary epithelial cells. Fusion proteins of GLUT1 and enhanced green fluorescent protein (EGFP) were expressed in CIT3 cells maintained in growth medium (GM), or exposed to secretion medium (SM), containing prolactin. Agents acting on Golgi and related subcellular compartments and on GLUT1 and GLUT4 targeting in muscle and fat cells were studied. Wortmannin and staurosporine effects on internalization of GLUT1 were not specific, supporting a basal constitutive GLUT1 membrane-recycling pathway between an intracellular pool and the cell surface in CIT3 cells, which targets most GLUT1 to the plasma membrane in GM. Upon exposure to prolactin in SM, GLUT1 was specifically targeted intracellularly to a brefeldin A-sensitive compartment. Arrest of endosomal acidification by bafilomycin A1 disrupted this prolactin-induced GLUT1 intracellular trafficking with central coalescence of GLUT1-EGFP signal, suggesting that it is via endosomal pathways. This machinery offers another level of regulation of lactose synthesis by altering GLUT1 targeting within minutes to hours.
Department of Pediatrics, Section of Neonatology and ARS/USDA Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA. arik.riskin@b-zion.org.il
Arieh
A
Riskin
Veena H
VH
Nannegari
Yehudit
Y
Mond
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007774:Lactation / Q000378:metabolism*; D007785:Lactose / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011388:Prolactin / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D000077191:Wortmannin
D000730:Androstadienes; D020126:Brefeldin A; D004791:Enzyme Inhibitors; D005947:Glucose; D051272:Glucose Transporter Type 1; D049452:Green Fluorescent Proteins; D007785:Lactose; D018942:Macrolides; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011388:Prolactin; D011493:Protein Kinase C; D011500:Protein Synthesis Inhibitors; D011993:Recombinant Fusion Proteins; D019311:Staurosporine; D000077191:Wortmannin; C495678:Slc2a1 protein, mouse; C485184:enhanced green fluorescent protein; C040929:bafilomycin A1