Binding of rat thyroglobulin to heparan sulfate proteoglycans

M. Marino, David Andrews, R. T. McCluskey

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

We previously showed that rat thyroglobulin (Tg) is a heparin-binding protein and that heparin inhibits Tg binding to megalin (gp330), an endocytic Tg receptor found on the apical surface of thyrocytes. Cooperation between cell surface receptors and heparin-like molecules, namely heparan sulfate proteoglycans (HSPGs), can facilitate cell surface binding of some heparin-binding proteins. Based on our previous findings indicating that heparin and megalin-binding sites of rat Tg are functionally related, here we investigated whether rat Tg binds to HSPGs, which are expressed by thyroid cells. We showed in solid phase assays that unlabeled rat Tg binds to a heparan sulfate (HS) preparation in a dose-dependent, saturable manner, with moderately high affinity (K(d) ~ 19 nM, K(i) ~ 25 nM). Binding was inhibited by heparin and by HS itself. We then studied the role of HSPGs in Tg binding to FRTL-5 cells, a differentiated Fisher rat thyroid cell line. As previously reported, after incubation of FRTL-5 cells with unlabeled rat Tg at 4°C, heparin released virtually all the cell-bound Tg. Co-incubation of Tg with HS or with a preparation of HSPGs resulted in a reduction of binding by 35%-40%. When FRTL-5 cells were preincubated with heparitinase or heparinase I, which released 20%-30% of cell surface HSPGs, Tg binding was reduced to a similar extent. An antibody against a Tg heparin-binding site functionally related to a major megalin-binding site virtually abolished Tg binding to HS and to FRTL-5 cells, supporting the hypothesis that combined interactions of Tg with HSPGs and with megalin are involved in Tg binding to rat thyroid cells.

Original languageEnglish
Pages (from-to)551-559
Number of pages9
JournalThyroid
Volume10
Issue number7
StatePublished - Sep 14 2000
Externally publishedYes

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Heparan Sulfate Proteoglycans
Thyroglobulin
Low Density Lipoprotein Receptor-Related Protein-2
Heparin
Heparitin Sulfate
Thyroid Gland
Binding Sites
heparitinsulfate lyase
Heparin Lyase
Cell Surface Receptors

ASJC Scopus subject areas

  • Endocrinology

Cite this

Marino, M., Andrews, D., & McCluskey, R. T. (2000). Binding of rat thyroglobulin to heparan sulfate proteoglycans. Thyroid, 10(7), 551-559.

Binding of rat thyroglobulin to heparan sulfate proteoglycans. / Marino, M.; Andrews, David; McCluskey, R. T.

In: Thyroid, Vol. 10, No. 7, 14.09.2000, p. 551-559.

Research output: Contribution to journalArticle

Marino, M, Andrews, D & McCluskey, RT 2000, 'Binding of rat thyroglobulin to heparan sulfate proteoglycans', Thyroid, vol. 10, no. 7, pp. 551-559.
Marino M, Andrews D, McCluskey RT. Binding of rat thyroglobulin to heparan sulfate proteoglycans. Thyroid. 2000 Sep 14;10(7):551-559.
Marino, M. ; Andrews, David ; McCluskey, R. T. / Binding of rat thyroglobulin to heparan sulfate proteoglycans. In: Thyroid. 2000 ; Vol. 10, No. 7. pp. 551-559.
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