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A top-down approach to uncover the hidden ligandome of low-density lipoprotein receptor-related protein 1 in cartilage

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  • Kazuhiro Yamamoto, University of Liverpool
  • ,
  • Carsten Scavenius
  • Maria M. Meschis, University of Liverpool
  • ,
  • Abdulrahman M.E. Gremida, University of Liverpool
  • ,
  • Emilie H. Mogensen
  • ,
  • Ida B. Thøgersen
  • Simone Bonelli, IRCCS Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (ISMETT) - Palermo
  • ,
  • Simone D. Scilabra, IRCCS Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (ISMETT) - Palermo
  • ,
  • Anders Jensen, University of Liverpool
  • ,
  • Salvatore Santamaria, Imperial College London
  • ,
  • Josefin Ahnström, Imperial College London
  • ,
  • George Bou-Gharios, University of Liverpool
  • ,
  • Jan J. Enghild
  • Hideaki Nagase, University of Oxford

The low-density lipoprotein receptor-related protein 1 (LRP1) is a cell-surface receptor ubiquitously expressed in various tissues. It plays tissue-specific roles by mediating endocytosis of a diverse range of extracellular molecules. Dysregulation of LRP1 is involved in multiple conditions including osteoarthritis (OA) but little information is available about the specific profile of direct binding partners of LRP1 (ligandome) for each tissue, which would lead to a better understanding of its role in disease states. Here, we investigated adult articular cartilage where impaired LRP1-mediated endocytosis leads to tissue destruction. We used a top-down approach involving proteomic analysis of the LRP1 interactome in human chondrocytes, direct binding assays using purified LRP1 and ligand candidates, and validation in LRP1-deficient fibroblasts and human chondrocytes, as well as a novel Lrp1 conditional knockout (KO) mouse model. We found that inhibition of LRP1 and ligand interaction results in cell death, alteration of the entire secretome and transcriptional modulations in human chondrocytes. We identified a chondrocyte-specific LRP1 ligandome consisting of more than 50 novel ligand candidates. Surprisingly, 23 previously reported LRP1 ligands were not regulated by LRP1-mediated endocytosis in human chondrocytes. We confirmed direct LRP1 binding of HGFAC, HMGB1, HMGB2, CEMIP, SLIT2, ADAMTS1, TSG6, IGFBP7, SPARC and LIF, correlation between their affinity for LRP1 and the rate of endocytosis, and some of their intracellular localization. Moreover, a conditional LRP1 KO mouse model demonstrated a critical role of LRP1 in regulating the high-affinity ligands in cartilage in vivo. This systematic approach revealed the specificity and the extent of the chondrocyte LRP1 ligandome and identified potential novel therapeutic targets for OA.

Original languageEnglish
JournalMatrix Biology
Volume112
Pages (from-to)190-218
Number of pages29
ISSN0945-053X
DOIs
Publication statusPublished - Sep 2022

Bibliographical note

Publisher Copyright:
© 2022

    Research areas

  • Cartilage, Chondrocyte, Endocytosis, Extracellular matrix, Interactome, LRP1, Osteoarthritis

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