title: Heparan sulfate/heparin promotes transthyretin fibrillization through selective binding to a basic motif in the protein.
abstract: Transthyretin (TTR) is a homotetrameric protein that transports thyroxine and retinol. Tetramer destabilization and misfolding of the released monomers result in TTR aggregation, leading to its deposition as amyloid primarily in the heart and peripheral nervous system. Over 100 mutations of TTR have been linked to familial forms of TTR amyloidosis. Considerable effort has been devoted to the study of TTR aggregation of these mutants, although the majority of TTR-related amyloidosis is represented by sporadic cases due to the aggregation and deposition of the otherwise stable wild-type (WT) protein. Heparan sulfate (HS) has been found as a pertinent component in a number of amyloid deposits, suggesting its participation in amyloidogenesis. This study aimed to investigate possible roles of HS in TTR aggregation. Examination of heart tissue from an elderly cardiomyopathic patient revealed substantial accumulation of HS associated with the TTR amyloid deposits. Studies demonstrated that heparin/HS promoted TTR fibrillization through selective interaction with a basic motif of TTR. The importance of HS for TTR fibrillization was illustrated in a cell model; TTR incubated with WT Chinese hamster ovary cells resulted in fibrillization of the protein, but not with HS-deficient cells (pgsD-677). The effect of heparin on TTR fibril formation was further demonstrated in a Drosophila model that overexpresses TTR. Heparin was colocalized with TTR deposits in the head of the flies reared on heparin-supplemented medium, whereas no heparin was detected in the nontreated flies. Heparin of low molecular weight (Klexane) did not demonstrate this effect.
authors.affiliation: Department of Medical Biochemistry and Microbiology, The Biomedical Center, Uppsala University, Husargatan 3, Box 582, 751 23 Uppsala, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Noborn
authors.forename: Paul
authors.initials: P
authors.lastname: O'Callaghan
authors.forename: Erik
authors.initials: E
authors.lastname: Hermansson
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhang
authors.forename: John B
authors.initials: JB
authors.lastname: Ancsin
authors.forename: Ana M
authors.initials: AM
authors.lastname: Damas
authors.forename: Ingrid
authors.initials: I
authors.lastname: Dacklin
authors.forename: Jenny
authors.initials: J
authors.lastname: Presto
authors.forename: Jan
authors.initials: J
authors.lastname: Johansson
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Saraiva
authors.forename: Erik
authors.initials: E
authors.lastname: Lundgren
authors.forename: Robert
authors.initials: R
authors.lastname: Kisilevsky
authors.forename: Per
authors.initials: P
authors.lastname: Westermark
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Li
mesh_terms: D000682:Amyloid / Q000096:biosynthesis*; D028226:Amyloidosis, Familial / Q000209:etiology / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004331:Drosophila melanogaster; D006493:Heparin / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D011228:Prealbumin / Q000378:metabolism*
chemical_list: D000682:Amyloid; D006493:Heparin; D006497:Heparan Sulfate; D011228:Prealbumin