Human neuroblastoma SH-SY5Y cells treated with okadaic acid express phosphorylated high molecular weight tau-immunoreactive protein species

Scientific paper - Original scientific paper

• Author: Mirta Boban
• Author: Mirjana Babić Leko
• Author: Terezija Miškić
• Author: Patrick R. Hof
• Author: Goran Šimić
• Author's institution: University of Zagreb; School of Medicine
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Basic Medical Sciences

Abstract (english)

Background: Early stages of Alzheimer's disease (AD) are characterized by high phosphorylation of microtubule-associated protein tau, which may result from the downregulation of protein phosphatases. -----
New method: In order to model phosphatase downregulation and analyze its effect on tau aggregation in vitro, we treated neuroblastoma SH-SY5Y cells with okadaic acid (OA), a protein phosphatase inhibitor, and examined high molecular weight phospho-tau species. -----
Results and comparison with existing methods: OA treatment led to the appearance of heat-stable protein species with apparent molecular weight around 100 kDa, which were immunoreactive to anti-tau antibodies against phosphorylated Ser202 and Ser396. As these high molecular weight tau-immunoreactive proteins (HMW-TIPs) corresponded to the predicted size of two tau monomers, we considered the possibility that they represent phosphorylation-induced tau oligomers. We attempted to dissociate HMW-TIPs by urea and guanidine, as well as by alkaline phosphatase treatment, but HMW-TIPs were stable under all conditions tested. These characteristics resemble properties of certain sodium dodecyl sulfate (SDS)-resistant tau oligomers from AD brains. The absence of HMW-TIPs detection by anti-total tau antibodies Tau46, CP27 and Tau13 may be a consequence of epitope masking and protein truncation. Alternatively, HMW-TIPs may represent previously unreported phosphoproteins cross-reacting with tau. -----
Conclusions: Taken together, our data provide a novel characterization of an OA-based cell culture model in which OA induces the appearance of HMW-TIPs. These findings have implications for further studies of tau under the conditions of protein phosphatase downregulation, aiming to explain mechanisms involved in early events leading to AD.

• Keywords (english): Alzheimer Disease / enzymology; Antibodies; Cell Line, Tumor; Enzyme Inhibitors / administration & dosage; Humans; Models, Biological; Okadaic Acid / administration & dosage; Phosphoprotein Phosphatases / antagonists & inhibitors; Phosphoprotein Phosphatases / metabolism; Phosphorylation; Radioimmunoprecipitation Assay; tau Proteins / immunology; tau Proteins / metabolism
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review
• Publication version: Accepted version
• Journal title: Journal of Neuroscience Methods
• Numbering: vol. 319, pp. 60-68
• p-ISSN: 0165-0270
• DOI: https://doi.org/10.1016/j.jneumeth.2018.09.030
• URN:NBN: urn:nbn:hr:105:362312
• Publication: 2019-05-01
• Document URL: http://doi.org/10.1016/j.jneumeth.2018.09.030
• Type of resource: Text
• Access conditions: Open access
• Created on: 2024-03-28 10:42:07