Structure and biological function
PERIOSTIN (UniProtKB - Q15063), also known as osteoblast specific factor 2 (OSF-2), is a cell adhesion protein belonging to the fasciclin domain-containing protein family. It consists of 836 amino acids (aa) starting with a 21 aa long signaling sequence, followed by an Emilin-like domain rich in cysteine, four repeated fasiclin 1 and a C-terminal variable domain, which is different among the 7 splice variants (isoforms) in humans. PERIOSTIN is expressed during ontogenesis and especially in adult connective tissues submitted to mechanical stress such as bone, tendons, heart valves, skin and the periodontal ligaments. Further, it is widely expressed in aorta, stomach, lower gastrointestinal tract, placenta, uterus, thyroid and breast tissue. In bone, PERIOSTIN directly interacts with collagen type I, fibronectin, Notch 1, tenascin-C and BMP-1, resulting in enhanced proteolytic activation of lysyl oxidase for collagen cross-linking, thus stabilising the bone matrix. Next to its role in developing, maintaining and repairing of tissue, PERIOSTIN plays a vital role in tumorigenesis by interacting with various cell-surface receptors and signaling pathways e.g. resulting in inactivation of integrin- mediated signaling, leading to promoting cell adhesion and motility which is of relevance for tumor progression and metastasis.
Involvement in diseases :
A variety of studies have shown the value of PERIOSTIN as a Biomarker for diagnosis, therapy monitoring and patient stratification for respiratory tract diseases.
The use of PERIOSTIN as a prognostic marker for widely spread cancers (e.g. mamma- or colon-carcinoma) has been demonstrated. PERIOSTIN can be used as stand-alone marker or in combination with established markers to improve clinical prognosis.
PERIOSTIN seems to enhance inflammatory processes in osteoarthritic tissue, thus contributing to the progression of the disease.
PERIOSTIN serum levels change in presence of bone fractures and during their healing. Therefore, PERIOSTIN levels can be used for monitoring healing of fractures, however it has to be taken into account when interpreting serum levels for other diseases.