Transient and localized expression of bone morphogenetic protein 4 messenger RNA during fracture healing.
Temporal and spatial distribution of a gene encoding murine bone morphogenetic protein 4 (mBMP-4) during fracture repair were investigated in mice by RT-PCR and in situ hybridization. For in situ hybridization, fractured ribs and surrounding tissues were decalcified and hybridized with a mBMP-4-specific complementary RNA probe labeled with digoxigenin-11 UTP. mBMP-4 messenger RNA (mRNA) was not detected in ribs without fracture, whereas it was detected only in the early phase of fracture from 12 to 72 h after the onset of fracture before new cartilage or bone formation. The mBMP-4 mRNAs were present in cells distributed in three distinct regions, namely, the proliferating periosteum, the medullary cavity, and the muscles near the fracture site. These BMP-4-positive cells did not express bone gla protein mRNA, which is a marker of the mature osteogenic cell. RT-PCR also showed a transient increase in the level of BMP-4 mRNA in the early phase of fracture repair. The findings provide us with some new information. (1) The BMP-4 gene is produced by less differentiated osteoprogenitor cells, not by differentiated osteoblasts. (2) The BMP-4 gene is enhanced by the impact of fracture and localized in callus-forming tissue before callus formation. Together with the activities of BMP-4, as was previously described, our results suggest that newly produced BMP-4 gene product is one of the local contributing factors in callus formation in the early phase of fracture healing.
Nakase
T
T
Department of Orthopaedic Surgery, Osaka University Medical School, Suita, Japan.
Nomura
S
S
Yoshikawa
H
H
Hashimoto
J
J
Hirota
S
S
Kitamura
Y
Y
Oikawa
S
S
Ono
K
K
Takaoka
K
K
D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D019485:Bone Morphogenetic Proteins; D002454:Cell Differentiation / Q000235:genetics; D003856:Deoxyuracil Nucleotides; D004076:Digoxigenin / Q000031:analogs & derivatives; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D017102:Fracture Healing / Q000235:genetics*; D006133:Growth Substances / Q000096:biosynthesis / Q000235:genetics; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D012253:Rib Fractures / Q000378:metabolism / Q000473:pathology; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
D019485:Bone Morphogenetic Proteins; D003856:Deoxyuracil Nucleotides; D006133:Growth Substances; D011506:Proteins; D012333:RNA, Messenger; C070202:digoxigenin-11-deoxyuridine triphosphate; D004076:Digoxigenin