ApoE promotes the proteolytic degradation of Abeta.
Apolipoprotein E is associated with age-related risk for Alzheimer's disease and plays critical roles in Abeta homeostasis. We report that ApoE plays a role in facilitating the proteolytic clearance of soluble Abeta from the brain. The endolytic degradation of Abeta peptides within microglia by neprilysin and related enzymes is dramatically enhanced by ApoE. Similarly, Abeta degradation extracellularly by insulin-degrading enzyme is facilitated by ApoE. The capacity of ApoE to promote Abeta degradation is dependent upon the ApoE isoform and its lipidation status. The enhanced expression of lipidated ApoE, through the activation of liver X receptors, stimulates Abeta degradation. Indeed, aged Tg2576 mice treated with the LXR agonist GW3965 exhibited a dramatic reduction in brain Abeta load. GW3965 treatment also reversed contextual memory deficits. These data demonstrate a mechanism through which ApoE facilitates the clearance of Abeta from the brain and suggest that LXR agonists may represent a novel therapy for AD.
Jiang
Qingguang
Q
Alzheimer Research Laboratory, Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
Lee
C Y Daniel
CY
Mandrekar
Shweta
S
Wilkinson
Brandy
B
Cramer
Paige
P
Zelcer
Noam
N
Mann
Karen
K
Lamb
Bruce
B
Willson
Timothy M
TM
Collins
Jon L
JL
Richardson
Jill C
JC
Smith
Jonathan D
JD
Comery
Thomas A
TA
Riddell
David
D
Holtzman
David M
DM
Tontonoz
Peter
P
Landreth
Gary E
GE
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000375:Aging; D000544:Alzheimer Disease / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001057:Apolipoproteins E / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D001565:Benzoates / Q000494:pharmacology; D001596:Benzylamines / Q000494:pharmacology; D001921:Brain / Q000473:pathology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D000071518:Liver X Receptors; D008568:Memory / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D057093:Orphan Nuclear Receptors; D010446:Peptide Fragments / Q000378:metabolism; D058225:Plaque, Amyloid / Q000187:drug effects; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D013997:Time Factors
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D016229:Amyloid beta-Peptides; D001057:Apolipoproteins E; D001565:Benzoates; D001596:Benzylamines; D004268:DNA-Binding Proteins; C473027:GW 3965; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D010446:Peptide Fragments; D018160:Receptors, Cytoplasmic and Nuclear; C075222:amyloid beta-protein (1-42)