Clathrin-dependent APP endocytosis and Abeta secretion are highly sensitive to the level of plasma membrane cholesterol.
Several lines of evidence support a strong relationship between cholesterol and Alzheimer's disease pathogenesis. Membrane cholesterol is known to modulate amyloid precursor protein (APP) endocytosis and amyloid-beta (Abeta) secretion. Here we show in a human cell line model of endocytosis (HEK293 cells) that cholesterol exerts these effects in a dose-dependent and linear manner, over a wide range of concentrations (-40% to +40% variations of plasma membrane cholesterol induced by methyl-beta-cyclodextrin (MBCD) and MBCD-cholesterol complex respectively). We found that the gradual effect of cholesterol is inhibited by small interference RNA-mediated downregulation of clathrin. Modulation of clathrin-mediated APP endocytosis by cholesterol was further demonstrated using mutants of proteins involved in the formation of early endosomes (dynamin2, Eps15 and Rab5). Importantly we show that membrane proteins other than APP are not affected by cholesterol to the same extent. Indeed clathrin-dependent endocytosis of transferrin and cannabinoid1 receptors as well as internalization of surface proteins labelled with a biotin derivative (sulfo-NHS-SS-biotin) were not sensitive to variations of plasma membrane cholesterol from -40% to 40%. In conclusion clathrin-dependent APP endocytosis appears to be very sensitive to the levels of membrane cholesterol. These results suggest that cholesterol increase in AD could be responsible for the enhanced internalization of clathrin-, dynamin2-, Eps15- and Rab5-dependent endocytosis of APP and the ensuing overproduction of Abeta.
Cossec
Jack-Christophe
JC
Centre de Recherche de l'Institut du Cerveau et de la Moelle, CNRS UMRS7225 INSERM UMRS975 UPMC, Hôpital de La Salpêtrière, 75651, Paris Cedex 13, France.
Simon
Anne
A
Marquer
Catherine
C
Moldrich
Randal X
RX
Leterrier
Christophe
C
Rossier
Jean
J
Duyckaerts
Charles
C
Lenkei
Zsolt
Z
Potier
Marie-Claude
MC
D048868:Adaptor Proteins, Signal Transducing; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D002966:Clathrin / Q000378:metabolism / Q000502:physiology; D022163:Clathrin-Coated Vesicles / Q000378:metabolism*; D034285:Dynamin II / Q000378:metabolism / Q000502:physiology; D004705:Endocytosis / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism / Q000502:physiology; D055571:Secretory Pathway / Q000187:drug effects; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D002135:Calcium-Binding Proteins; D002966:Clathrin; C486206:EPS15 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D002784:Cholesterol; D020696:rab5 GTP-Binding Proteins; D034285:Dynamin II