Expression and function of periostin‐isoforms in bone

Abstract

Periostin was originally identified in MC3T3-E1 osteoblast-like cells. We have identified an isoform of periostin referred to as periostin-like-factor (PLF). It is homologous to other proteins such as fasciclin I (fas I), MPB70, betaIG-H3, and Algal-CAMs. All of these proteins are implicated in regulating cell adhesion. PLF and the other isoforms of periostin differ in their C-terminal sequences. PLF and periostin differ in two specific regions, between 673 and 699 amino acids (aa) and 785-812 aa. Periostin isoforms are expressed in vivo and in vitro during the stages of osteoblast differentiation and maturation. Their mRNAs are present in pre-osteoblast cells as detected by in situ hybridization, and the proteins are between 86 and 93 kD in size as determined by Western blot analysis. Antisense oligonucleotides and antibodies directed against the isoforms of periostin were used to block the activity of these proteins. In both cases, the levels of osteoblast-specific-differentiation markers were markedly reduced suggesting a role for these proteins in osteoblast differentiation.

Extracellular matrix in the trabecular meshwork

“…(Vittitow and Borras 2004;Zhao et al 2004;Chen et al 2005;Vittal et al 2005;Liton et al 2006) Periostin contains several fasciclin-like binding domains, binds several different integrins, including αVβ3, αVβ5, and affects cell adhesion and migration. (Gillan et al 2002;Litvin et al 2004) It is expressed during development and active ECM remodeling, particularly where collagen is being modified. (Litvin et al 2004;Kii et al 2006) Initially involved in osteoblast function in mineralized tissues, it appears to have other functions in other tissues, such as the TM.…”

“…(Gillan et al 2002;Litvin et al 2004) It is expressed during development and active ECM remodeling, particularly where collagen is being modified. (Litvin et al 2004;Kii et al 2006) Initially involved in osteoblast function in mineralized tissues, it appears to have other functions in other tissues, such as the TM.…”

RETRACTED: The periosteum

“…The only protein that is present in the higher amount in periosteum than in the bone is periostin. 55,72 Predominantly it is located in the preosteoblasts which secrete periostin in the extracellular matrix. The original term for this protein is OSF-2, and the highest concentration is found in the disrupted periosteum.…”

“…The synthesis of periostin is increased 4-fold during the first three days after the fracture. 72 The concentration decreases with the progression of differentiation of osteogenic progenitor cells and the activity of osteoblasts. Still the synthesis and the role of the periostin are unclear.…”

“…These significant quantitative differences in the periosteal structure in all three zones are constant despite of the region and the location on the bone and indicate persistent periosteal microanatomy. 4,72,119 Today, it is clear that morphology of the periosteum depends not only upon the species but also upon the age. Periosteal fibroblast number and fibrous layer thickness decrease with age, 127 although atrophy of the fibrous layer is less than that of the cambium layer.…”