Osteoclasts’ ability to generate trenches rather than pits depends on high levels of active cathepsin K and efficient clearance of resorption products

Xenia Goldberg Borggaard*, Dinisha Cyril Pirapaharan, Jean-Marie Delaissé, Kent Søe*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Until recently, it was well-accepted that osteoclasts resorb bone according to the resorption cycle model. This model is based on the assumption that osteoclasts are immobile during bone erosion, allowing the actin ring to be firmly attached and thereby provide an effective seal encircling the resorptive compartment. However, through time-lapse, it was recently documented that osteoclasts making elongated resorption cavities and trenches move across the bone surface while efficiently resorbing bone. However, it was also shown that osteoclasts making rounded cavities and pits indeed resorb bone while they are immobile. Only little is known about what distinguishes these two different resorption modes. This is of both basic and clinical interest because these resorption modes are differently sensitive to drugs and are affected by the gender as well as age of the donor. In the present manuscript we show that: 1. levels of active cathepsin K determine the switch from pit to trench mode; 2. pit and trench mode depend on clathrin-mediated endocytosis; and 3. a mechanism integrating release of resorption products and membrane/integrin recycling is required for prolongation of trench mode. Our study therefore contributes to an improved understanding of the molecular and cellular determinants for the two osteoclastic bone resorption modes.

Original languageEnglish
Article number5924
JournalInternational Journal of Molecular Sciences
Volume21
Issue number16
Number of pages18
ISSN1661-6596
DOIs
Publication statusPublished - 18. Aug 2020

Keywords

  • Bone resorption
  • Cathepsin K
  • Chloroquine
  • Clathrin
  • Functional secretory domain
  • Lysosome
  • Osteoclast
  • Pit
  • Transcytosis
  • Trench

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