Aberrant detergent-insoluble excitatory amino acid transporter 2 accumulates in Alzheimer disease.
Alzheimer disease (AD) is characterized by deposition of amyloid-beta, tau, and other specific proteins that accumulate in the brain in detergent-insoluble complexes. Alzheimer disease also involves glutamatergic neurotransmitter system disturbances. Excitatory amino acid transporter 2 (EAAT2) is the dominant glutamate transporter in cerebral cortex and hippocampus. We investigated whether accumulation of detergent-insoluble EAAT2 is related to cognitive impairment and neuropathologic changes in AD by quantifying detergent-insoluble EAAT2 levels in hippocampus and frontal cortex of cognitively normal patients, patients with clinical dementia rating of 0.5 (mildly impaired), and AD patients. Parkinson disease patients served as neurodegenerative disease controls. We found that Triton X-100-insoluble EAAT2 levels were significantly increased in patients with AD compared with controls, whereas Triton X-100-insoluble EAAT2 levels inpatients with clinical dementia rating of 0.5 were intermediately elevated between control and AD subjects. Detergent insolubility of presenilin-1, a structurally similar protein, did not differ among the groups, thus arguing that EAAT2 detergent insolubility was not caused by nonspecific cellular injury. These findings demonstrate that detergent-insoluble EAAT2 accumulation is a progressive biochemical lesion that correlates with cognitive impairment and neuropathologic changes in AD. These findings lend further support to the idea that dysregulation of the glutamatergic system may play a significant role in AD pathogenesis.
Department of Pathology, Oregon Health & Sciences Univ., Portland, Oregon, USA.
Randall L
RL
Woltjer
Kevin
K
Duerson
Joseph M
JM
Fullmer
Paramita
P
Mookherjee
Allison M
AM
Ryan
Thomas J
TJ
Montine
Jeffrey A
JA
Kaye
Joseph F
JF
Quinn
Lisa
L
Silbert
Deniz
D
Erten-Lyons
James B
JB
Leverenz
Thomas D
TD
Bird
David V
DV
Pow
Kohichi
K
Tanaka
G Stennis
GS
Watson
David G
DG
Cook
D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology*; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002853:Chromatography, Liquid / Q000379:methods; D003072:Cognition Disorders / Q000473:pathology; D003902:Detergents / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D027342:Excitatory Amino Acid Transporter 2; D005260:Female; D050491:Glutamate Plasma Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008958:Models, Molecular; D017830:Octoxynol / Q000494:pharmacology; D053764:Presenilin-1 / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods
D003902:Detergents; D027342:Excitatory Amino Acid Transporter 2; D050491:Glutamate Plasma Membrane Transport Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1; C493397:SLC1A2 protein, human; D017830:Octoxynol