Development and assessment of sensitive immuno-PCR assays for the quantification of cerebrospinal fluid three- and four-repeat tau isoforms in tauopathies.

Abstract

Characteristic tau isoform composition of the insoluble fibrillar tau inclusions define tauopathies, including Alzheimer's disease (AD), progressive supranuclear palsy (PSP) and frontotemporal dementia with parkinsonism linked to chromosome 17/frontotemporal lobar degeneration-tau (FTDP-17/FTLD-tau). Exon 10 splicing mutations in the tau gene, MAPT, in familial FTDP-17 cause elevation of tau isoforms with four microtubule-binding repeat domains (4R-tau) compared to those with three repeats (3R-tau). On the basis of two well-characterised monoclonal antibodies against 3R- and 4R-tau, we developed novel, sensitive immuno-PCR assays for measuring the trace amounts of these isoforms in CSF. This was with the aim of assessing if CSF tau isoform changes reflect the pathological changes in tau isoform homeostasis in the degenerative brain and if these would be relevant for differential clinical diagnosis. Initial analysis of clinical CSF samples of PSP (n = 46), corticobasal syndrome (CBS; n = 22), AD (n = 11), Parkinson's disease with dementia (PDD; n = 16) and 35 controls revealed selective decreases of immunoreactive 4R-tau in CSF of PSP and AD patients compared with controls, and lower 4R-tau levels in AD compared with PDD. These decreases could be related to the disease-specific conformational masking of the RD4-binding epitope because of abnormal folding and/or aggregation of the 4R-tau isoforms in tauopathies or increased sequestration of the 4R-tau isoforms in brain tau pathology.

• Authors: Connie Luk, Yaroslau Compta, Nadia Magdalinou, Maria José Martí, Geshanthi Hondhamuni, Henrik Zetterberg, Kaj Blennow, Radu Constantinescu, Yolande Pijnenburg, Brit Mollenhauer, Claudia Trenkwalder, John Van Swieten, Wan Zheng Chiu, Barbara Borroni, Ana Cámara, Perdita Cheshire, David R Williams, Andrew J Lees, Rohan de Silva
• Journal: Journal of neurochemistry (J Neurochem) Vol. 123 Issue 3 Pg. 396-405 (Nov 2012) ISSN: 1471-4159 [Electronic] England
• PMID: 22862741 (Publication Type: Controlled Clinical Trial, Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)
• Copyright: © 2012 The Authors Journal of Neurochemistry © 2012 International Society for Neurochemistry.

Chemical References

• Protein Isoforms
• tau Proteins

Topics

• Aged
• Cohort Studies
• Homeostasis (genetics, immunology)
• Humans
• Immunoassay (methods, standards)
• Middle Aged
• Polymerase Chain Reaction (methods, standards)
• Protein Isoforms (cerebrospinal fluid, genetics, immunology)
• Repetitive Sequences, Amino Acid (genetics, immunology)
• Reproducibility of Results
• Tauopathies (cerebrospinal fluid, genetics, metabolism)
• tau Proteins (cerebrospinal fluid, genetics, immunology)