Insulin-like growth factor binding protein-4 inhibits both basal and IGF-mediated chick pelvic cartilage growth in vitro
| Autor: | Patric M. Schiltz, David J. Baylink, Subburaman Mohan |
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| Rok vydání: | 2009 |
| Předmět: |
medicine.medical_specialty
Endocrinology Diabetes and Metabolism medicine.medical_treatment Chick Embryo Insulin-like growth factor-binding protein chemistry.chemical_compound Organ Culture Techniques Somatomedins Internal medicine Bone cell medicine Animals Orthopedics and Sports Medicine Pelvic Bones biology Cartilage Growth factor Radioimmunoassay In vitro medicine.anatomical_structure Endocrinology Insulin-Like Growth Factor Binding Protein 4 chemistry Insulin-like growth factor 2 biology.protein Carrier Proteins Thymidine |
| Zdroj: | Journal of Bone and Mineral Research. 8:391-396 |
| ISSN: | 0884-0431 |
| Popis: | This laboratory has purified a unique insulin-like growth factor binding protein (IGFBP-4) that was previously demonstrated to be inhibitory to bone cell proliferation. In this study, the hypothesis that IGFBP-4 is inhibitory to insulin-like growth factor (IGF) actions on cartilage was tested using the pelvic cartilages of 10-day-old chick embryos as an in vitro model system. Pelvic leaflets were incubated in serum-free medium for 18 h with effectors (BSA, IGF-I, IGF-II, IGFBP-4, or a combination of IGF and IGFBP-4). After the first 8 h, 1.5 μCi [3H]thymidine per well was added. Cartilage growth was assayed by TCA-insoluble [3H]thymidine incorporation into DNA. Additional experiments were conducted under similar conditions to assess the actions of the effectors on cartilage dry weight over a 72 h time period. In separate experiments, serum-free medium conditioned by chick pelvic cartilages for 72 h was assayed for IGF-II by radioreceptorassay, IGF-I by radioimmunoassay, and IGFBP by western ligand analysis. Exogenous IGF addition increased [3H]thymidine incorporation and dry weight of cartilages compared to controls. IGFBP-4 decreased both parameters in basal cartilage growth and also inhibited IGF-mediated cartilage growth. Pelvic cartilages secreted in vitro both IGF-I and IGF-II and a 32–34 kD IGFBP. In conclusion, the IGFs are stimulatory to cartilage growth in vitro and embryonic chick cartilage in vitro produces both IGF-I and II as well as an IGFBP. Exogenous IGFBP-4 inhibits both the basal and IGF-mediated growth of chick cartilage, suggesting that IGFBP-4 acts to downregulate the growth-promoting effects of IGFs on cartilage growth. |
| Databáze: | OpenAIRE |
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