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Neurobiol Dis. 2014 Nov;71:53-61. doi: 10.1016/j.nbd.2014.07.011. Epub 2014 Aug 1.

Intracellular amyloid and the neuronal origin of Alzheimer neuritic plaques.

Author information

1
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. Electronic address: apensalfini@NKI.RFMH.ORG.
2
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
3
Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697, USA.
4
Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697, USA; Department of Neurology, University of California, Irvine, CA 92697, USA.
5
Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697, USA; Department of Neurology, University of California, Irvine, CA 92697, USA; Department of Neurobiology & Behavior, University of California, Irvine, CA 92697, USA.
6
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA; Biochemistry Department and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.

Abstract

Genetic analysis of familial forms of Alzheimer's disease (AD) causally links the proteolytic processing of the amyloid precursor protein (APP) and AD. However, the specific type of amyloid and mechanisms of amyloid pathogenesis remain unclear. We conducted a detailed analysis of intracellular amyloid with an aggregation specific conformation dependent monoclonal antibody, M78, raised against fibrillar Aß42. M78 immunoreactivity colocalizes with Aß and the carboxyl terminus of APP (APP-CTF) immunoreactivities in perinuclear compartments at intermediate times in 10month 3XTg-AD mice, indicating that this represents misfolded and aggregated protein rather than normally folded APP. At 12months, M78 immunoreactivity also accumulates in the nucleus. Neuritic plaques at 12months display the same spatial organization of centrally colocalized M78, diffuse chromatin and neuronal nuclear NeuN staining surrounded by peripheral M78 and APP-CTF immunoreactivity as observed in neurons, indicating that neuritic plaques arise from degenerating neurons with intracellular amyloid immunoreactivity. The same staining pattern was observed in neuritic plaques in human AD brains, showing elevated intracellular M78 immunoreactivity at intermediate stages of amyloid pathology (Braak A and B) compared to no amyloid pathology and late stage amyloid pathology (Braak 0 and C, respectively). These results indicate that intraneuronal protein aggregation and amyloid accumulation is an early event in AD and that neuritic plaques are initiated by the degeneration and death of neurons by a mechanism that may be related to the formation of extracellular traps by neutrophils.

KEYWORDS:

Alzheimer; Intracellular amyloid; Neuritic plaques; Nuclear pathology

PMID:
25092575
PMCID:
PMC4179983
DOI:
10.1016/j.nbd.2014.07.011
[Indexed for MEDLINE]
Free PMC Article

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