The presence of PHOSPHO1 in matrix vesicles and its developmental expression prior to skeletal mineralization.

PHOSPHO1 is a phosphoethanolamine/phosphocholine phosphatase that has previously been implicated in generating inorganic phosphate (P(i)) for matrix mineralization. In this study, we have investigated PHOSPHO1 mRNA expression during embryonic development in the chick. Whole-mount in situ hybridization indicated that PHOSPHO1 expression occurred prior to E6.

Glucocorticoid effects on chondrogenesis, differentiation and apoptosis in the murine ATDC5 chondrocyte cell line.

Glucocorticoids (GC) are used extensively in children and may cause growth retardation, which is in part due to the direct effects of GC on the growth plate. We characterised the ATDC5 chondrocyte cell line, which mimics the in vivo process of longitudinal bone growth, to examine the effects of dexamethasone (Dex) and prednisolone (Pred) during two key time points in the chondrocyte life cycle - chondrogenesis and terminal differentiation. Additionally, we studied the potential for recovery following Dex exposure.

Differences in metabolic parameters and gene expression related to osteochondrosis/osteoarthrosis in pigs fed 25-hydroxyvitamin D3.

Osteochondrosis/osteoarthrosis (OC/OA) are common terms for various joint pathologies that occur in pigs. Pathologies that may contribute to these disorders have been described, but the primary cause(s) remain unknown. We hypothesised that as OC has some similarities to dyschondroplasia, which involves a failure of growth plate chondrocytes to fully differentiate and hypertrophy, treatment with 25-hydroxyvitamin D3 (25-D) might reduce the incidence and/or severity of lesions in pigs, as it does in chickens with dyschondroplasia.

Regulation of chondrocyte terminal differentiation in the postembryonic growth plate: the role of the PTHrP-Indian hedgehog axis.

Chondrocyte differentiation during embryonic bone growth is controlled by interactions between PTHrP and Indian hedgehog. We have now determined that the major components of this signaling pathway are present in the postembryonic growth plate. PTHrP was immunolocalized throughout the growth plate, and semiquantitative RT-PCR analysis of maturationally distinct chondrocyte fractions indicated that PTHrP, Indian hedgehog, and the PTH/PTHrP receptor were expressed at similar levels throughout the growth plate.

Parathyroid hormone-related peptide expression in tibial dyschondroplasia.

Parathyroid hormone-related peptide (PTHrP) has a key role in the growth of long bones, as it is a negative regulator of growth plate chondrocyte terminal differentiation. We have examined the distribution and gene expression levels of PTHrP in the growth plates of broiler chickens with tibial dyschondroplasia (TD) in order to determine whether increased expression of PTHrP is responsible for the delayed chondrocyte differentiation that is characteristic of this skeletal disorder. PTHrP protein distribution and gene expression levels were assessed by immunocytochemistry and reverse transcriptase-polymerase chain reaction, respectively.