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Human metallothioneins 2 and 3 differentially affect amyloid‐beta binding by transthyretin
Author(s) -
Martinho Ana,
Gonçalves Isabel,
Cardoso Isabel,
Almeida Maria R.,
Quintela Telma,
Saraiva Maria J.,
Santos Cecília R. A.
Publication year - 2010
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2010.07749.x
Subject(s) - transthyretin , gene isoform , binding site , amyloid beta , plasma protein binding , chemistry , amyloid (mycology) , biochemistry , intracellular , biophysics , biology , endocrinology , peptide , gene , inorganic chemistry
Transthyretin (TTR), an amyloid‐beta (Aβ) scavenger protein, and metallothioneins 2 and 3 (MT2 and MT3), low molecular weight metal‐binding proteins, have recognized impacts in Aβ metabolism. Because TTR binds MT2, an ubiquitous isoform of the MTs, we investigated whether it also interacts with MT3, an isoform of the MTs predominantly expressed in the brain, and studied the role of MT2 and MT3 in human TTR–Aβ binding. The TTR–MT3 interaction was characterized by yeast two‐hybrid assays, saturation‐binding assays, co‐immunolocalization and co‐immunoprecipitation. The effect of MT2 and MT3 on TTR–Aβ binding was assessed by competition‐binding assays. The results obtained clearly demonstrate that TTR interacts with MT3 with a K d of 373.7 ± 60.2 n m . Competition‐binding assays demonstrated that MT2 diminishes TTR–Aβ binding, whereas MT3 has the opposite effect. In addition to identifying a novel ligand for TTR that improves human TTR–Aβ binding, the present study highlights the need to clarify whether the effects of MT2 and MT3 in human TTR–Aβ binding observed in vitro have a relevant impact on Aβ deposition in animal models of Alzheimer’s disease. Structured digital abstract• MINT‐7905930 : Amyloid beta (uniprotkb: P05067 ) physically interacts ( MI:0915 ) with Ttr (uniprotkb: P02767 ) by saturation binding ( MI:0440 ) • MINT‐7905857 : MT3 (uniprotkb: P25713 ) binds ( MI:0407 ) to TTR (uniprotkb: P02766 ) by saturation binding ( MI:0440 ) • MINT‐7905838 : TTR (uniprotkb: P02766 ) physically interacts ( MI:0915 ) with MT3 (uniprotkb: P25713 ) by two hybrid ( MI:0018 ) • MINT‐7905914 : Ttr (uniprotkb: P02766 ) physically interacts ( MI:0915 ) with Mt3 (uniprotkb: P25713 ) by anti tag coimmunoprecipitation ( MI:0007 ) • MINT‐7905895 : TTR (uniprotkb: P02767 ) and Mt3 (uniprotkb: P37361 ) colocalize ( MI:0403 ) by fluorescence microscopy ( MI:0416 )