Cellular uptake of proMMP-2:TIMP-2 complexes by the endocytic receptor megalin/LRP-2

Sci Rep. 2017 Jun 28;7(1):4328. doi: 10.1038/s41598-017-04648-y.

Abstract

Matrix metalloproteinases (MMPs) are regulated at multiple transcriptional and post-transcriptional levels, among which receptor-mediated endocytic clearance. We previously showed that low-density lipoprotein receptor-related protein-1 (LRP-1) mediates the clearance of a complex between the zymogen form of MMP-2 (proMMP-2) and tissue inhibitor of metalloproteinases, TIMP-2, in HT1080 human fibrosarcoma cells. Here we show that, in BN16 rat yolk sac cells, proMMP-2:TIMP-2 complex is endocytosed through a distinct LRP member, megalin/LRP-2. Addition of receptor-associated protein (RAP), a natural LRP antagonist, caused accumulation of endogenous proMMP-2 and TIMP-2 in conditioned media. Incubation with RAP also inhibited membrane binding and cellular uptake of exogenous iodinated proMMP-2:TIMP-2. Moreover, antibodies against megalin/LRP-2, but not against LRP-1, inhibited binding of proMMP-2:TIMP-2 to BN16 cell surface. BIAcore analysis confirmed direct interaction between the complex and megalin/LRP-2. Conditional renal invalidation of megalin/LRP-2 in mice resulted in accumulation of proMMP-2 and TIMP-2 in their urine, highlighting the physiological relevance of the binding. We conclude that megalin/LRP-2 can efficiently mediate cell-surface binding and endocytosis of proMMP-2:TIMP-2 complex. Therefore megalin/LRP-2 can be considered as a new actor in regulation of MMP-2 activity, an enzyme crucially involved in many pathological processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cell Membrane / metabolism
  • Culture Media, Conditioned
  • Enzyme Precursors / metabolism*
  • Enzyme Precursors / urine
  • Gelatinases / metabolism*
  • Gelatinases / urine
  • Kidney / metabolism
  • Low Density Lipoprotein Receptor-Related Protein-2
  • Matrix Metalloproteinase 2 / metabolism*
  • Matrix Metalloproteinase 2 / urine
  • Mice
  • Mice, Transgenic
  • Multiprotein Complexes / metabolism
  • Protein Binding
  • Protein Transport
  • Rats
  • Tissue Inhibitor of Metalloproteinase-2 / metabolism

Substances

  • Culture Media, Conditioned
  • Enzyme Precursors
  • Low Density Lipoprotein Receptor-Related Protein-2
  • Multiprotein Complexes
  • Tissue Inhibitor of Metalloproteinase-2
  • Gelatinases
  • progelatinase
  • Matrix Metalloproteinase 2