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Temporal Changes of mRNA Expression of Matrix Proteins and Parathyroid Hormone and Parathyroid Hormone–Related Protein (PTH/PTHrP) Receptor in Bone Development
Author(s) -
Kondo Hisatomo,
Ohyama Takashi,
Ohya Keiichi,
Kasugai Shohei
Publication year - 1997
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1997.12.12.2089
Subject(s) - parathyroid hormone , medicine , endocrinology , calvaria , osteocalcin , osteopontin , bone sialoprotein , osteoblast , alkaline phosphatase , parathyroid hormone receptor , chemistry , parathyroid hormone related protein , biology , hormone receptor , calcium , in vitro , biochemistry , enzyme , cancer , breast cancer
Expression of parathyroid hormone and parathyroid hormone–related protein (PTH/PTHrP) receptor is one of the osteoblastic phenotypes; however, it has not been clear whether this phenotype expression is a marker of immature or mature osteoblasts. We examined the temporal expression pattern of PTH/PTHrP receptor in bone development in vivo and in vitro compared with the expression of other osteoblastic phenotypes: osteopontin (OPN), bone sialoprotein (BSP) and osteocalcin (OC), alkaline phosphatase (ALP), and mineralization. Total RNA was extracted from rat calvariae, and cell culture of rat bone marrow at different developmental stages and then Northern blot hybridization were performed. Mineralization was detected with contact microradiography (CMR) in calvaria or with Alizarin Red S staining in bone marrow cell culture. Both in calvaria and in marrow cell culture, extensive expression of OPN, BSP, type I collagen (COL I), and ALP coincided with the onset of mineralization, and OC expression was observed after mineralized tissue formation. Notably, PTH/PTHrP receptor was expressed at an early developmental stage (prenatal day 14 in calvaria, day 5 in culture) when mineralized tissue was not formed and other osteoblastic phenotypes were scarcely detected. Further study in cell culture revealed that the fold increase in cyclic adenosine monophosphate (cAMP) in response to PTH was elevated with the advance in the culture stage. These results indicate that mRNA expression of PTH/PTHrP receptor could be the early differentiation marker in osteoblastic lineage and that the levels of cAMP production in response to PTH represent the stage of osteoblastic differentiation.