Extracellular Ca(2+)-sensing receptors modulate matrix production and mineralization in chondrogenic RCJ3.1C5.18 cells

Endocrinology. 2002 Apr;143(4):1467-74. doi: 10.1210/endo.143.4.8709.


Previous studies in chondrogenic RCJ3.1C5.18 (C5.18) cells showed that growth of these cells at high extracellular Ca(2+) concentrations ([Ca(2+)](o)) reduced the expression of markers of early chondrocyte differentiation. These studies addressed whether raising [Ca(2+)](o) accelerates C5.18 cell differentiation and whether Ca(2+) receptors (CaRs) are involved in coupling changes in [Ca(2+)](o) to cellular responses. We found that high [Ca(2+)](o) increased expression of osteopontin (OP), osteonectin, and osteocalcin, all markers of terminal differentiation, in C5.18 cells and increased the production of matrix mineral. Overexpression of wild-type CaR cDNA in C5.18 cells suppressed proteoglycan synthesis and aggrecan RNA, two early differentiation markers, and increased OP expression. The sensitivity of these parameters to changes in [Ca(2+)](o) was significantly increased, as indicated by left-shifted dose-responses. In contrast, stable expression of a signaling-defective CaR mutant (Phe707Trp CaR) in C5.18 cells, presumably through dominant-negative inhibition of endogenous CaRs, blocked the suppression of aggrecan RNA levels and proteoglycan accumulation and the enhancement of OP expression by high [Ca(2+)](o). These data support a role for CaRs in mediating high [Ca(2+)](o)-induced differentiation of C5.18 cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoviridae / genetics
  • Aggrecans
  • Animals
  • Blotting, Northern
  • Calcification, Physiologic / physiology*
  • Calcium / pharmacology
  • Cartilage / drug effects
  • Cartilage / metabolism
  • Cell Differentiation / physiology
  • Cell Line
  • Chondrocytes / metabolism*
  • Chondroitin / biosynthesis*
  • Coloring Agents
  • Extracellular Matrix / physiology*
  • Extracellular Matrix Proteins*
  • Immunoblotting
  • Lectins, C-Type
  • Osteopontin
  • Proteoglycans / biosynthesis
  • Proteoglycans / metabolism
  • RNA, Messenger / biosynthesis
  • Rats
  • Receptors, Calcium-Sensing
  • Receptors, Cell Surface / physiology*
  • Sialoglycoproteins / biosynthesis
  • Transfection


  • Acan protein, rat
  • Aggrecans
  • Coloring Agents
  • Extracellular Matrix Proteins
  • Lectins, C-Type
  • Proteoglycans
  • RNA, Messenger
  • Receptors, Calcium-Sensing
  • Receptors, Cell Surface
  • Sialoglycoproteins
  • Spp1 protein, rat
  • extracellular calcium cation-sensing receptor, rat
  • Osteopontin
  • Chondroitin
  • Calcium