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A novel monoclonal antibody DC63 reveals that inhibitor 1 of protein phosphatase 2A is preferentially nuclearly localised in human brain
Author(s) -
Kovacech Branislav,
Kontsekova Eva,
Zilka Norbert,
Novak Pavol,
Skrabana Rostislav,
Filipcik Peter,
Iqbal Khalid,
Novak Michal
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.01.015
Subject(s) - phosphorylation , phosphatase , biology , western blot , tau protein , monoclonal antibody , microbiology and biotechnology , human brain , protein phosphatase 1 , phosphoprotein , cerebellum , protein phosphatase 2 , kinase , antibody , alzheimer's disease , biochemistry , neuroscience , pathology , immunology , medicine , disease , gene
Abnormal phosphorylation of tau protein represents one of the major candidate pathological mechanisms leading to Alzheimer's disease (AD) and related tauopathies. Altered phosphorylation status of neuronal tau protein may result from upregulation of tau‐specific kinases or from inhibition of tau‐specific phosphatases. Increased expression of the protein inhibitor 1 of protein phosphatase 2A (I1PP2A) could therefore indirectly regulate the phosphorylation status of tau. As an important step towards elucidation of the role of I1PP2A in the physiology and pathology of tau phosphorylation, we developed a novel monoclonal antibody, DC63, which recognizes I1PP2A. Specificity of the antibody was examined by mass spectrometry and Western blot. This analysis supports the conclusion that the antibody does not recognize any of the other proteins of the 9‐member leucine‐rich acidic nuclear phosphoprotein family to which I1PP2A belongs. Immunoblot detection revealed that the inhibitor I1PP2A is expressed throughout the brain, including the hippocampus, temporal cortex, parietal cortex, subcortical nuclei and brain stem. The cerebellum displayed significantly higher levels of expression of I1PP2A than was seen elsewhere in the brain. Imunohistochemical analysis of normal human brain showed that I1PP2A is expressed in both neurons and glial cells and that the protein is preferentially localized to the nucleus. We conclude that the novel monoclonal antibody DC63 could be successfully employed as a mass spectrometry‐validated molecular probe that may be used for in vitro and in vivo qualitative and quantitative studies of physiological and pathological pathways involving I1PP2A.