Expression of TAU in insulin-secreting cells and its interaction with the calcium-binding protein secretagogin

Maj, Magdalena and Gartner, Wolfgang and Ilhan, Aysegul and Neziri, Dashurie and Attems, Johannes and Wagner, Ludwig (2010) Expression of TAU in insulin-secreting cells and its interaction with the calcium-binding protein secretagogin. Journal of Endocrinology, 205. pp. 25-36.

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Abstract

Tauopathies have been associated with Alzheimer’s disease (AD), which frequently manifests together with diabetes mellitus type 2. Calcium-binding proteins such as the recently identified secretagogin (SCGN) might exert protective effects. As pancreatic b-cells and neurons share common electrophysiological properties, we investigated the appearance of TAU (listed as MAPT in the HUGO and MGI Databases) protein at the islets of Langerhans and b-cellderived cell lines which highly express the neuroendocrinespecific protein SCGN. Six predominant TAU isoforms could be identified by immunoblotting, which formed TAU deposits detectable by immunofluorescence and sarkosylinsoluble pellets. Using GST–SCGN pull-down assays, a calcium-dependent SCGN–TAU interaction was found. In this line, sucrose density gradient fractionation and differential ultracentrifugation studies of TAU and SCGN revealed co-appearance of both proteins. Co-localization of TAU and SCGN within insulinoma cells and islets of Langerhans mainly restricted to insulin-positive b-cells was demonstrated by confocal microscopy. Motivated by these findings, we looked if SCGN overexpression could exert protective function on Rin-5F cells, which showed differences in TAU levels. Testing the vulnerability of Rin-5F clones by MTT assay, we revealed that high TAU levels going along with highest TAU aggregates could not be antagonized by high levels of SCGN protein. Our findings demonstrated for the first time the association of TAU and the calcium-binding protein SCGN and support earlier results implicating that b-cells might represent an extra cerebral site of tauopathy

Item Type: Article
Subjects: Medical and Health Sciences > Basic medicine
Medical and Health Sciences > Clinical medicine
Medical and Health Sciences > Other medical sciences
Divisions: Faculty of Medical Science
Depositing User: Biljana Kosturanova
Date Deposited: 05 Mar 2013 15:27
Last Modified: 05 Mar 2013 15:27
URI: http://eprints.ugd.edu.mk/id/eprint/5741

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