Megalin binds and internalizes angiotensin-(1-7)

Am J Physiol Renal Physiol. 2006 May;290(5):F1270-5. doi: 10.1152/ajprenal.00164.2005. Epub 2005 Dec 27.

Abstract

Megalin is a multiligand receptor heavily involved in protein endocytosis. We recently demonstrated that megalin binds and mediates internalization of ANG II. Although there is a strong structural resemblance between ANG II and ANG-(1-7), their physiological actions and their affinity for the angiotensin type 1 receptor (AT(1)R) are dissimilar. Therefore, the hypothesis of the present work was to test whether megalin binds and internalizes ANG-(1-7). The uptake of ANG-(1-7) was determined by exposure of confluent monolayers of BN/MSV cells (a model representative of the yolk sac epithelium) to fluorescently labeled ANG-(1-7) (100 nM) and measurement of the amount of cell-associated fluorescence after 4 h by flow cytometry. Anti-megalin antisera and an AT(1)R blocker (olmesartan) were used to interfere with uptake via megalin and the AT(1)R, respectively. ANG-(1-7) uptake was prevented by anti-megalin antisera (63%) to a higher degree than olmesartan (13%) (P < 0.001). In analysis by flow cytometry of binding experiments performed in brush-border membrane vesicles isolated from kidneys of CD-1 mice, anti-megalin antisera interfered with ANG-(1-7) binding more strongly than olmesartan (P < 0.05 against positive control). Interactions of megalin with ANG-(1-7) at a molecular level were studied by surface plasmon resonance, demonstrating that ANG-(1-7) binds megalin dose and time dependently and with an affinity similar to ANG II. These results show that the scavenger receptor megalin binds and internalizes ANG-(1-7).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin I / metabolism*
  • Antihypertensive Agents / metabolism*
  • Cell Culture Techniques
  • Epithelium
  • Flow Cytometry
  • Humans
  • Kidney / physiology
  • Low Density Lipoprotein Receptor-Related Protein-2 / physiology*
  • Peptide Fragments / metabolism*
  • Renin-Angiotensin System / physiology
  • Yolk Sac / cytology

Substances

  • Antihypertensive Agents
  • Low Density Lipoprotein Receptor-Related Protein-2
  • Peptide Fragments
  • Angiotensin I
  • angiotensin I (1-7)