Production of insulin-like growth factor binding-proteins by bovine adrenomedullary cells: differential regulation by IGF-I and dexamethasone
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- 作者：Grø ; nning ; Mona ; Serck-Hanssen ; Guldborg
- 关键词：Adrenal medulla ; Autocrine/paracrine modulation ; Bovine chromaffin cells ; Cell culture ; Cycloheximide ; Dexamethasone ; Endocrine modulation ; IGF binding-proteins ; IGF-I ; Insulin-like growth factor I ; Sympathetic tissue
- 刊名：Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology
- 出版年：2003
- 出版时间：April, 2003
- 年：2003
- 卷：134
- 期：4
- 页码：727-738
- 全文大小：971 K
文摘
In the present study we examined the production of insulin-like growth factor binding proteins (IGFBPs), in chromaffin cells, a model system for sympathetic neurons. Four IGFBPs of 
27, 31, 36 and a doublet of 45–50 kDa, detected in Western ligand blots of conditioned medium, were identified in Western immunoblots as IGFBP-4, IGFBP-5, IGFBP-2 and IGFBP-3, respectively. In ligand blots IGFBP-3 and IGFBP-4 appeared as the most prominent species. IGF-I (1 nM) enhanced release of IGFBP-3 while dexamethasone (1 nM) diminished release of IGFBP-4. No significant proteolytic degradation of the IGFBPs was demonstrated. Cycloheximide completely attenuated release of the IGFBPs, indicating dependency on new synthesis of the proteins. These findings are consistent with autocrine modulation of the IGF system in bovine adrenomedullary chromaffin cells by IGFBPs. Furthermore, the specific stimulatory and inhibitory effects of IGF-I and dexamethasone, respectively, on release of the predominant species of IGFBP-3 and IGFBP-4, suggested that IGFBP production may be selectively modulated in a positive and negative manner.
27, 31, 36 and a doublet of 45–50 kDa, detected in Western ligand blots of conditioned medium, were identified in Western immunoblots as IGFBP-4, IGFBP-5, IGFBP-2 and IGFBP-3, respectively. In ligand blots IGFBP-3 and IGFBP-4 appeared as the most prominent species. IGF-I (1 nM) enhanced release of IGFBP-3 while dexamethasone (1 nM) diminished release of IGFBP-4. No significant proteolytic degradation of the IGFBPs was demonstrated. Cycloheximide completely attenuated release of the IGFBPs, indicating dependency on new synthesis of the proteins. These findings are consistent with autocrine modulation of the IGF system in bovine adrenomedullary chromaffin cells by IGFBPs. Furthermore, the specific stimulatory and inhibitory effects of IGF-I and dexamethasone, respectively, on release of the predominant species of IGFBP-3 and IGFBP-4, suggested that IGFBP production may be selectively modulated in a positive and negative manner.