Skeletal Unloading Induces Biphasic Changes in Insulin-Like Growth Factor-I mRNA Levels and Osteoblast Activity
| Autor: | E. Zerath, H. Drissi, Abderrahim Lomri, Pierre J. Marie, F. Lasmoles, X. Holy |
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| Rok vydání: | 1999 |
| Předmět: |
Male
medicine.medical_specialty medicine.medical_treatment Skeletal Unloading Hindlimb Protein Serine-Threonine Kinases Receptor IGF Type 1 Weight-Bearing Insulin-like growth factor Transforming Growth Factor beta Internal medicine medicine Animals Femur RNA Messenger Insulin-Like Growth Factor I Rats Wistar Receptor Osteoblasts Tibia biology Growth factor Receptor Transforming Growth Factor-beta Type II Cell Differentiation Osteoblast Organ Size Cell Biology Transforming growth factor beta Antigens Differentiation Rats Endocrinology medicine.anatomical_structure biology.protein Osteocalcin Receptors Transforming Growth Factor beta |
| Zdroj: | Experimental Cell Research. 251:275-284 |
| ISSN: | 0014-4827 |
| DOI: | 10.1006/excr.1999.4539 |
| Popis: | To determine the local mechanisms involved in the effects of skeletal unloading on bone formation, we studied the temporal pattern of mRNA levels for insulin-like growth factor-I (IGF-I), IGF-I receptor type I (IGF-IR), and transforming growth factor beta receptor type II (TGF-betaRII) in relation to osteoblast phenotypic markers and osteoblast activity in hindlimb suspended rats. Skeletal unloading decreased bone volume and the mineralizing and osteoblastic surfaces at 4, 7, and 14 days in the tibial metaphysis, whereas the mineral appositional rate returned to normal at 14 days of suspension. RT-PCR analysis showed that skeletal unloading decreased type 1 collagen (Col 1) and osteocalcin (OC) mRNA levels in metaphyseal bone at days 4 and 7, and the levels returned to normal at 14 days of suspension. Unloading also decreased mRNA levels for IGF-I, IGF-IR, and TGF-betaRII at 4-7 days in the metaphyseal bone. However, IGF-I and IGF-IR levels rose above normal at 14 days of suspension. The biphasic changes in IGF-I mRNA levels were strongly correlated with Col 1 and OC mRNA levels. The associated biphasic pattern of IGF-I/IGF-IR expression, osteoblast markers, and osteoblast activity strongly suggests an important role for IGF-I signaling in the local effect of skeletal unloading on metaphyseal bone formation. |
| Databáze: | OpenAIRE |
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