Periostin‐like‐factor in osteogenesis

Abstract

Periostin-like-factor (PLF), an isoform related to Periostin, is expressed in bone, heart, and vascular smooth muscle cells. PLF was detected by immunostaining in mesenchymal cells in the periosteum and in osteoblasts lining trabecular bone, suggesting that PLF has a role in osteogenesis. PLF has a signal peptide and is also secreted from osteoblasts in vitro. To study the function of PLF in osteogenesis, we assessed the effect of PLF on osteoblast proliferation and differentiation in vitro and bone formation in vivo. First, to examine whether PLF regulates osteoblast proliferation in vitro, the CyQUANT cell proliferation assay was performed. PLF over-expression by adenovirus resulted in a significantly higher rate of cell proliferation compared to controls. This finding suggests that PLF promotes osteoblast proliferation in vitro. Second, to test whether PLF mediates osteoblast differentiation in vitro, differentiation markers of osteoblasts, were assessed, including alkaline phosphatase staining and activity, von Kossa staining and calcium deposition. Over-expression of PLF resulted in higher expression and activity of alkaline phosphatase and higher amounts of mineralization and calcium deposition compared to controls. These data suggest that PLF promotes osteoblast differentiation in vitro. Third, to investigate the role of PLF in bone formation in vivo, PLF adenovirus was injected into 6-week-old rat femur bone marrow. Over-expression of PLF resulted in increased bone formation within the marrow cavity. Lastly, in a model of fracture healing, PLF expression is robustly upregulated in callus osteoblasts at post-fracture days 7 and 14. Taken together, these findings suggests that PLF induces bone formation in vivo. We conclude that PLF stimulates bone formation in vivo possibly by promoting osteoblast proliferation and differentiation.

The Matricellular Protein Periostin Is Required for Sost Inhibition and the Anabolic Response to Mechanical Loading and Physical Activity

“…Although we attempted to improve their feeding and growth rate by giving them a soft diet from birth, Postn Ϫ/Ϫ mice still exhibited a slower growth rate with a continuous increase of BV/TV up to 16 -18 (49,50). In addition, in 6-week-old rats, Postn overexpression increased bone formation and bone mass, as evaluated by microCT and histomorphometry (51). In vitro, overexpression of Postn results in a significant increase in primary osteoblast cell proliferation and differentiation (51).…”

“…In addition, in 6-week-old rats, Postn overexpression increased bone formation and bone mass, as evaluated by microCT and histomorphometry (51). In vitro, overexpression of Postn results in a significant increase in primary osteoblast cell proliferation and differentiation (51). Conversely, deletion of Postn induces a defect in the attachment of bone cells, which affects their differentiation and mineralization processes (16).…”

The multiple facets of periostin in bone metabolism

“…As in embryonic bone, multiple protein variants of periostin are expressed, but to a lesser extent, in neonates, young, and adult rodents bone [3,9,16,24]. Periostin protein (at least isoform 3) was detected in mesenchymal cells and alkaline phosphatase expressing cells, that is, preosteoblasts and osteoblasts of the periosteum and in the osteoblasts lining trabecular bone [3,24,25].…”

Characterization of a Novel Periodontal Ligament-specific Periostin Isoform

“…A heart-specific isoform of mouse periostin plays important roles in the regeneration of heart tissue (Shimazaki et al, 2008), while periostin-like factor (PLF), another isoform of mouse periostin, is expressed in bone, heart, and vascular smooth muscle (Litvin et al, 2004(Litvin et al, , 2005Zhu et al, 2009). These reports suggest that tissue-specific isoforms of periostin play important roles in the regulation of tissue-specific functions.…”