Volume 15, Issue 2-3 p. 508-519
Research Article

Quantitative phosphoproteomics of Alzheimer's disease reveals cross-talk between kinases and small heat shock proteins

Eric B. Dammer

Eric B. Dammer

Department of Biochemistry, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

These authors contributed equally to this work.

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Andrew K. Lee

Andrew K. Lee

Department of Biochemistry, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

These authors contributed equally to this work.

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Duc M. Duong

Duc M. Duong

Department of Biochemistry, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

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Marla Gearing

Marla Gearing

Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

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James J. Lah

James J. Lah

Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

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Allan I. Levey

Allan I. Levey

Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

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Nicholas T. Seyfried

Corresponding Author

Nicholas T. Seyfried

Department of Biochemistry, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

Department of Neurology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA, USA

Correspondence: Dr. Nicholas T. Seyfried, Departments of Biochemistry and Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA

E-mail: [email protected]

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First published: 21 October 2014
Citations: 58

Colour Online: See the article online to view Fig. 2 in colour.

Abstract

Abnormal phosphorylation contributes to the formation of neurofibrillary tangles in Alzheimer's disease (AD), but may play other signaling roles during AD pathogenesis. In this study, we employed IMAC followed by LC-MS/MS to identify phosphopeptides from eight individual AD and eight age-matched control postmortem human brain tissues. Using this approach, we identified 5569 phosphopeptides in frontal cortex across all 16 cases in which phosphopeptides represented 80% of all peptide spectral counts collected following IMAC enrichment. Marker selection identified 253 significantly altered phosphopeptides by precursor intensity, changed by at least 1.75-fold relative to controls, with an empirical false discovery rate below 7%. Approximately 21% of all significantly altered phosphopeptides in AD tissue were derived from tau. Of the other 142 proteins hyperphosphorylated in AD, membrane, synapse, cell junction, and alternatively spliced proteins were overrepresented. Of these, we validated differential phosphorylation of HSP 27 (HSPB1) and crystallin-alpha-B (CRYAB) as hyperphosphorylated by Western blotting. We further identified a network of phosphorylated kinases, which coenriched with phosphorylated small HSPs. This supports a hypothesis that a number of kinases are regulating and/or regulated by the small HSP folding network.