Upregulation of select rab GTPases in cholinergic basal forebrain neurons in mild cognitive impairment and Alzheimer's disease

• Published in: Journal of chemical neuroanatomy Vol. 42; no. 2; pp. 102 - 110
• Main Authors: Ginsberg, Stephen D., Mufson, Elliott J., Alldred, Melissa J., Counts, Scott E., Wuu, Joanne, Nixon, Ralph A., Che, Shaoli
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2011
• Subjects: Aged; Aged, 80 and over; Alzheimer Disease - enzymology; Alzheimer Disease - physiopathology; Basal Nucleus of Meynert - enzymology; Basal Nucleus of Meynert - physiopathology; Cholinergic Neurons - enzymology; Cognitive decline; Cognitive Dysfunction - enzymology; Cognitive Dysfunction - physiopathology; Endosome; Female; Humans; Male; Microarray; Mild cognitive impairment; qPCR; rab GTP-Binding Proteins - biosynthesis; rab GTP-Binding Proteins - genetics; rab27 GTP-Binding Proteins; rab4 GTP-Binding Proteins - biosynthesis; rab4 GTP-Binding Proteins - genetics; rab5; rab5 GTP-Binding Proteins - biosynthesis; rab5 GTP-Binding Proteins - genetics; rab7 GTP-Binding Proteins; Up-Regulation - physiology; Cognitive decline; qPCR; Microarray; Mild cognitive impairment; Endosome; rab5
• ISSN: 0891-0618; 1873-6300; 1873-6300
• DOI: 10.1016/j.jchemneu.2011.05.012

► Microarrays, qPCR, and immunoblotting assessed CBF neurons in NCI, MCI and AD. ► Upregulation of select rab GTPases was seen in MCI and AD versus NCI CBF neurons. ► Upregulation of rab4, rab5, rab7 and rab27 was validated via qPCR in basal forebrain. ► rab GTPase defects correlated with antemortem cognitive decline and neuropathology. Endocytic system dysfunction is one of the earliest disturbances that occur in Alzheimer's disease (AD), and may underlie the selective vulnerability of cholinergic basal forebrain (CBF) neurons during the progression of dementia. Herein we report that genes regulating early and late endosomes are selectively upregulated within CBF neurons in mild cognitive impairment (MCI) and AD. Specifically, upregulation of rab4, rab5, rab7, and rab27 was observed in CBF neurons microdissected from postmortem brains of individuals with MCI and AD compared to age-matched control subjects with no cognitive impairment (NCI). Upregulated expression of rab4, rab5, rab7, and rab27 correlated with antemortem measures of cognitive decline in individuals with MCI and AD. qPCR validated upregulation of these select rab GTPases within microdissected samples of the basal forebrain. Moreover, quantitative immunoblot analysis demonstrated upregulation of rab5 protein expression in the basal forebrain of subjects with MCI and AD. The elevation of rab4, rab5, and rab7 expression is consistent with our recent observations in CA1 pyramidal neurons in MCI and AD. These findings provide further support that endosomal pathology accelerates endocytosis and endosome recycling, which may promote aberrant endosomal signaling and neurodegeneration throughout the progression of AD.