Cartilage oligomeric matrix protein (COMP) induction in periodontal ligament fibroblasts

Cartilage oligomeric matrix protein (COMP), a pentameric member of the thrombospondin family of extracellular matrix proteins, is expressed in a variety of tissues including articular cartilage, synovium, tendon, and ligament.  The role of COMP in the periodontal ligament (PDL) has not yet been investigated.  Mutations in the COMP gene cause two skeletal dysplasias, pseudoachondroplasia and multiple epiphyseal dysplasia.  COMP is upregulated by transforming growth factor -beta 1 (TGF-β) in articular chondrocytes, dermal fibroblasts, and bone marrow derived stem cells.  Activation of latent TGF-β1 occurs by multiple mechanisms, including binding to thrombospondin-1 (TSP-1).

Objective: The aim of this study was to investigate whether COMP is expressed by PDL cells and how its expression might be regulated by factors that control TGF-β activity.  Based on gene array data, we hypothesize that TSP-1 increases TGF-β activity and COMP expression in PDL cells.

Method: Human PDL cells were treated with TSP-1 (10-100nM) and TGF-β1 (200pM) for 2 to 72 hours.  Quantitative RT-PCR analyses were performed using COMP and S9 (housekeeping gene control) primers.

Result: Both TSP-1 and TGF-β1 treatment of PDL cells increased COMP mRNA as measured by RTq-PCR.  Further studies are being conducted to determine whether TSP-1 stimulation of COMP occurs through TSP-1-dependent TGF-β activation or by direct stimulation.

Conclusion: This is the first report of COMP regulation by TSP-1 and of TGF-β1 regulation of COMP mRNA in PDL cells.  These data suggest a novel pathway for COMP regulation and suggest that COMP might play a role in periodontal ligament function, regeneration and repair.

This work is supported by NIDCR F30 DE018259.