Characterization of Insulin-Like Growth Factor-I and Its Receptor and Binding Proteins in Transected Nerves and Cultured Schwann Cells
| Autor: | Douglas Yee, Gihan I. Tennekoon, Patrick Delafontaine, Ann Randolph, Eva L. Feldman, Hsin Lin Cheng |
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| Rok vydání: | 2002 |
| Předmět: |
Male
medicine.medical_specialty medicine.medical_treatment Gene Expression Schwann cell Biology Biochemistry Insulin-like growth factor-binding protein Rats Sprague-Dawley Cellular and Molecular Neuroscience Insulin-like growth factor Internal medicine Gene expression medicine Animals Humans Insulin-Like Growth Factor I Receptor Cells Cultured Receptors Somatomedin Nerve injury Denervation Sciatic Nerve Rats Cell biology Insulin-Like Growth Factor Binding Proteins medicine.anatomical_structure Endocrinology Culture Media Conditioned biology.protein Neuroglia Schwann Cells Sciatic nerve medicine.symptom Insulin-Like Growth Factor Binding Protein 5 Cell Division Peptide Hydrolases |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1471-4159 0022-3042 |
| Popis: | The insulin-like growth factors (IGFs) are trophic factors whose growth-promoting actions are mediated via the IGF-I receptor and modulated by six IGF binding proteins (IGFBPs). In this study, we observed increased transcripts of both IGF-I and IGF-I receptor after rat sciatic nerve transection. Schwann cells (SCs) were the main source of IGF-I and IGFBP-5 immunoreactivity until 7 days after nerve transection, when invading macrophages in the distal nerve stumps were strongly IGF-I positive. In vitro, IGF-I promoted SC mitogenesis. Northern analysis revealed that SCs expressed IGF-I receptor and IGFBP-5. IGF-I treatment increased the intensity of IGFBP-5 without affecting gene expression. Des(1-3)IGF-I, an IGF-I analogue with low affinity for IGFBP, had no such effect. Incubation of recombinant human IGFBP-5 with SC conditioned media revealed IGF-I protection of IGFBP-5 from proteolysis, implying the presence of an IGFBP-5 protease in SC conditioned media. Collectively, these data support the concept that, in response to nerve injury, invading macrophages produce IGF-I and SC express the IGF-I receptor, to facilitate regeneration. This regenerative process may be augmented further by the ability of SC to secrete IGFBPs, which in turn may increase local IGF-I bioavailability. |
| Databáze: | OpenAIRE |
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