Temporal variation of c-Fos proto-oncogene expression during osteoblast differentiation and osteogenesis in developing rat bone.
To delineate the implication of c-fos protooncogenic in the osteogenie process, we have investigated the temporal pattern of c-fos mRNA expression in fetal and neonatal rat bone during intramembranous and endochondral bone formation. Northern blot analysis of mRNA extracted from calvaria and femur showed that expression of c-fos, Histone H4, and osteocalcin mRNAs followed a temporal sequence during bone development. The levels of histone H4 mRNA, a marker of cell proliferation, were high at early stages of fetal development of calvaria and femur, and decreased until birth. In both the postnatal calvaria and femur, c-fos mRNA levels increased transiently at birth and preceded a rise in osteocalcin transcripts, a marker of the mature osteoblast phenotype. The immunohistochemical analysis showed that c-Fos protein was expressed in osteoprogenitor cells in the perichondrium and periosteum, and not in mature osteoblasts which expressed markers of differentiated osteoblasts such as type-I collagen, bone sialoprotein, and osteocalcin. Thus, the transient c-fos proto-oncogene expression during the postnatal life that precedes the osteocalcin expression may be involved in the transition from the precursor state to mature osteoblasts. These results suggest that c-fos proto-oncogene may play an important role in osteogenesis during rat postnatal life.
Machwate
M
M
INSERM Unité 349, Cell and Molecular Biology of Bone and Cartilage, Lariboisiere Hospital, Paris, France.
Jullienne
A
A
Moukhtar
M
M
Marie
P J
PJ
D000818:Animals; D000831:Animals, Newborn; D001846:Bone Development / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D005333:Fetus / Q000166:cytology / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D010012:Osteogenesis / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis / Q000235:genetics* / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger