Preservation of cortical sortilin protein levels in MCI and Alzheimer's disease

Document Type

Article

Abstract

The nerve growth factor (NGF) precursor protein proNGF is the predominant NGF moiety found in the human neocortex and exhibits pro-apoptotic properties when bound to the p75NTR neurotrophin receptor in the presence of sortilin, a Vps10p domain trafficking protein. Recently studies have shown that proNGF levels increase in the cortex of people who died with early stage Alzheimer's disease (AD) or with mild cognitive impairment (MCI), a putative prodromal AD stage. In contrast, cortical levels of the high-affinity, pro-survival NGF receptor TrkA are reduced in AD despite stable levels of p75NTR. These data suggest a stoichiometric shift in proNGF and its receptors which favors proNGF binding of p75NTR. Whether cortical levels of sortilin are altered during the progression of AD remains unknown. Therefore, we measured sortilin protein levels in postmortem superior frontal and superior temporal cortical tissues derived from Religious Orders Study subjects clinically diagnosed antemortem with no cognitive impairment (NCI), MCI or AD. No changes in frontal or temporal cortical sortilin protein levels occurred across the clinical groups. There was no association between sortilin levels and antemortem cognitive test scores. However, there was a positive association between temporal cortex sortilin levels and severity of neuropathology by Braak and NIA-Reagan diagnoses. The stability of cortical sortilin levels in the face of stable p75NTR, increased proNGF, and reduced TrkA levels may favor pro-apoptotic proNGF:p75NTR:sortilin trimeric interactions within the cortex during the earliest stages of AD. These findings are relevant to the development of NGF drug therapy for the treatment of dementia. © 2010 Elsevier Ireland Ltd. All rights reserved.

Keywords

Alzheimer's disease, Mild cognitive impairment, proNGF, Receptors, Sortilin

Publication Date

3-8-2010

Publication Title

Neuroscience Letters

ISSN

03043940

Volume

471

Issue

3

First Page

129

Last Page

133

PubMed ID

20085800

Digital Object Identifier (DOI)

10.1016/j.neulet.2010.01.023

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