Periostin and transforming growth factor β‐induced protein (TGFβIp) are both expressed by osteoblasts and osteoclasts

Abstract

Periostin (Postn) and transforming growth factor β-induced protein (TGFβIp) are two closely related extracellular matrix (ECM) proteins predominantly distributed in collagen-rich connective tissues submitted to mechanical strain, including bone and more specifically the periosteum. We have investigated the expression of Postn and TGFβIp mRNA by primary osteoblasts isolated from mouse periosteum and calvaria, or by the osteoblast-like MC3T3-E1 cell line, and by osteoclasts from mouse long bones differentiated in vitro. Secretion of Postn was measured with a specific ELISA. Postn and TGFβIp mRNA were concomitantly expressed in all three osteoblast models all along the differentiation process in a time-dependent manner. Both Postn and TGFβIp transcripts appeared early in osteoblast differentiation, and their expression increased 3-10 times in mature osteoblast cells. Expression decreased after differentiation was achieved and when the cultures mineralised. ELISA for secreted Postn showed a similar pattern. When MC3T3-E1 cells were treated with TGF-β, Postn and TGFβIp mRNA expression and secretion were stimulated, whereas 1.25(OH)(2)D(3) had no detectable effect. Osteoclasts also expressed both Postn and TGFβIp during in vitro differentiation. Expression of both Postn and TGFβIp peaks in the early phases of osteoblast differentiation, and decreases later at the start of mineralisation. A novel finding is that Postn and TGFβIp are expressed by osteoclasts in vitro. Therefore Postn and TGFβIp proteins are potential biomarkers of early osteoblast differentiation and new bone formation.

Periostin expression contributes to cortical bone loss during unloading

“…Increase in MMP has been previously associated with osteocytic osteolysis, but this has been seen only in real microgravity condition (space shuttle mission) [34]. Secondly, periostin could have a direct role on osteoclasts as suggested by in vitro studies [35][36][37]; however, to our knowledge this effect has never been demonstrated in vivo. In a previous study, we did not detect an effect of periostin deficiency on osteoclast numbers, surface or markers of bone resorption either in intact or ovariectomized mice [38].…”

Serum periostin is associated with prevalent knee osteoarthritis and disease incidence/progression in women: the OFELY study

“…Moreover, POSTN is involved in regulating the Wnt signaling pathway which is an important regulator of both bone and joint metabolism 16,32 . We also showed recently that POSTN is not only expressed in osteoblasts but also in osteoclasts from mouse long bones differentiated in vitro 35 .…”

Periostin function in communication with extracellular matrices

“…However, in bone cells, periostin and βig-h3 are expressed in both osteoblasts and osteoclasts in vitro (Merie et al 2014), suggesting that both genes possibly act cooperatively in bone formation. By contrast, after myocardial inside : collagen cross-linking outside: cell migraƟon Fig.…”