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Megalin mediates renal uptake of heavy metal metallothionein complexes.

Publication ,  Journal Article
Klassen, RB; Crenshaw, K; Kozyraki, R; Verroust, PJ; Tio, L; Atrian, S; Allen, PL; Hammond, TG
Published in: Am J Physiol Renal Physiol
September 2004

Although several heavy metal toxins are delivered to the kidney on the carrier protein metallothionein (MT), uncertainty as to how MT enters proximal tubular cells limits treatment strategies. Prompted by reports that MT-I interferes with renal uptake of the megalin ligand beta(2)-microglobulin in conscious rats, we tested the hypothesis that megalin binds MT and mediates its uptake. Three lines of evidence suggest that binding of MT to megalin is critical in renal proximal tubular uptake of MT-bound heavy metals. First, MT binds megalin, but not cubilin, in direct surface plasmon resonance studies. Binding of MT occurs at a single site with a K(d) approximately 10(-4) and, as with other megalin ligands, depends on divalent cations. Second, antisera and various known megalin ligands inhibit the uptake of fluorescently labeled MT in model cell systems. Anti-megalin antisera, but not control sera, displace >90% bound MT from rat renal brush-border membranes. Megalin ligands including beta(2)-microglobulin and also recombinant MT fragments compete for uptake by megalin-expressing rat yolk sac BN-16 cells. Third, megalin and fluorescently labeled MT colocalize in BN-16 cells, as shown by fluorescent microscopic techniques. Follow-up surface plasmon resonance and flow cytometry studies using overlapping MT peptides and recombinant MT fragments identify the hinge SCKKSCC region of MT as a critical site for megalin binding. These findings suggest that disruption of the SCKKSCC motif can inhibit proximal tubular MT uptake and thereby eliminate much of the renal accumulation and toxicity of heavy metals such as cadmium, gold, copper, and cisplatinum.

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Published In

Am J Physiol Renal Physiol

DOI

ISSN

1931-857X

Publication Date

September 2004

Volume

287

Issue

3

Start / End Page

F393 / F403

Location

United States

Related Subject Headings

  • Urology & Nephrology
  • Surface Plasmon Resonance
  • Receptors, Cell Surface
  • Rats, Sprague-Dawley
  • Rats
  • Protein Structure, Tertiary
  • Molecular Sequence Data
  • Microscopy, Fluorescence
  • Metallothionein
  • Male
 

Citation

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MLA
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Klassen, R. B., Crenshaw, K., Kozyraki, R., Verroust, P. J., Tio, L., Atrian, S., … Hammond, T. G. (2004). Megalin mediates renal uptake of heavy metal metallothionein complexes. Am J Physiol Renal Physiol, 287(3), F393–F403. https://doi.org/10.1152/ajprenal.00233.2003
Klassen, R Bryan, Kimberly Crenshaw, Renata Kozyraki, Pierre J. Verroust, Laura Tio, Sílvia Atrian, Patricia L. Allen, and Timothy G. Hammond. “Megalin mediates renal uptake of heavy metal metallothionein complexes.Am J Physiol Renal Physiol 287, no. 3 (September 2004): F393–403. https://doi.org/10.1152/ajprenal.00233.2003.
Klassen RB, Crenshaw K, Kozyraki R, Verroust PJ, Tio L, Atrian S, et al. Megalin mediates renal uptake of heavy metal metallothionein complexes. Am J Physiol Renal Physiol. 2004 Sep;287(3):F393–403.
Klassen, R. Bryan, et al. “Megalin mediates renal uptake of heavy metal metallothionein complexes.Am J Physiol Renal Physiol, vol. 287, no. 3, Sept. 2004, pp. F393–403. Pubmed, doi:10.1152/ajprenal.00233.2003.
Klassen RB, Crenshaw K, Kozyraki R, Verroust PJ, Tio L, Atrian S, Allen PL, Hammond TG. Megalin mediates renal uptake of heavy metal metallothionein complexes. Am J Physiol Renal Physiol. 2004 Sep;287(3):F393–F403.

Published In

Am J Physiol Renal Physiol

DOI

ISSN

1931-857X

Publication Date

September 2004

Volume

287

Issue

3

Start / End Page

F393 / F403

Location

United States

Related Subject Headings

  • Urology & Nephrology
  • Surface Plasmon Resonance
  • Receptors, Cell Surface
  • Rats, Sprague-Dawley
  • Rats
  • Protein Structure, Tertiary
  • Molecular Sequence Data
  • Microscopy, Fluorescence
  • Metallothionein
  • Male