Interference with cellular differentiation by D-serine through antagonism at N-methyl-D-aspartate receptors composed of NR1 and NR3A subunits in chondrocytes

Takeshi Takarada, Yoshifumi Takahata, Mika Iemata, Eiichi Hinoi, Kyosuke Uno, Takao Hirai, Tomomi Yamamoto, Yukio Yoneda

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Serine racemase (SR) is responsible for the biosynthesis of D-serine (D-Ser), an endogenous co-agonist for the glycine (Gly)-binding site on N-methyl-D-aspartate (NMDA) receptors, from L-Ser in the brain. We have previously demonstrated high expression of SR by chondrocytes in cartilage. In this study, we attempted to elucidate the possible functional role of D-Ser in chondrogenesis. Expression of mRNA and corresponding protein was seen for SR in cultured rat costal chondrocytes, while the addition of L-Ser significantly increased intracellular and extracellular levels of D-Ser. In organotypic cultured mouse embryonic metatarsals isolated before vascularization, SR mRNA was highly localized in hypertrophic and calcified chondrocytes. Exposure to D-Ser not only suppressed several chondrocytic maturation markers, including alkaline phosphatase (ALP) activity, Ca2+ accumulation, nodule formation, and osteopontin expression, in rat chondrocytes, but also delayed chondral mineralization in mouse metatarsals. Either NMDA or Gly alone significantly increased Ca2+ accumulation in cultured chondrocytes, whereas D-Ser significantly prevented Ca2+ accumulation by Gly, but not by NMDA. Gly alone also significantly increased gene transactivation by the introduction of runt-related transcription factor-2 (Runx2) in COS7 cells transfected with NR1 and NR3A subunits, while D-Ser significantly prevented the increase by Gly without affecting the promoter activity of Runx2. In both cultured chondrocytes and metatarsals from NR1-null mice, significant decreases were seen in ALP activity and chondral mineralization, respectively. These results suggest that D-Ser may negatively regulate cellular differentiation through inhibiting NMDA receptors composed of NR1 and NR3A subunits in a manner related to Runx2 transcriptional activity in chondrocytes.

Original languageEnglish
Pages (from-to)756-764
Number of pages9
JournalJournal of cellular physiology
Issue number3
Publication statusPublished - Sept 1 2009
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Cell Biology


Dive into the research topics of 'Interference with cellular differentiation by D-serine through antagonism at N-methyl-D-aspartate receptors composed of NR1 and NR3A subunits in chondrocytes'. Together they form a unique fingerprint.

Cite this