title: HIV-1 protein gp120 crosses the blood-brain barrier: role of adsorptive endocytosis.
abstract: HIV-1 infects the brain and leads to AIDS dementia complex. The viral coat glycoprotein, gp120, may facilitate the passage of HIV-1 and HIV-infected immune cells across the blood-brain barrier (BBB). Since the endothelial cells of the BBB do not possess the CD4 or galactosylceramide binding sites used by gp120 to induce HIV-1 uptake into other cell types, how gp120 mediates entry into brain is unknown. We postulate that gp120 crosses the BBB and does so by acting as a weak lectin to induce adsorptive endocytosis (AE) in a fashion similar to other glycoproteins like wheatgerm agglutinin (WGA). We found in vivo that gp120 crosses the BBB and its passage is enhanced 18.7-fold by WGA. In vitro studies confirm that WGA enhances uptake of gp120 by brain endothelia; most of the uptake is membrane-associated, as expected in AE. Uptake is not dependent on clatharin, caveolae, calcium channels, or endosomal acidification. Our results suggest that gp120 crosses the BBB and does so by acting as a lectin to induce AE.
authors.affiliation: Veterans Affairs Medical Center and Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70146, USA. bbbpts@mailhost.tcs.tulane.edu
authors.forename: W A
authors.initials: WA
authors.lastname: Banks
authors.forename: A J
authors.initials: AJ
authors.lastname: Kastin
authors.forename: V
authors.initials: V
authors.lastname: Akerstrom
mesh_terms: D000327:Adsorption; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D004727:Endothelium / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D051379:Mice; D014909:Wheat Germ Agglutinins / Q000494:pharmacology
chemical_list: D015699:HIV Envelope Protein gp120; D014909:Wheat Germ Agglutinins