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Sequestration and secretion of insulin‐like growth factor‐I by bovine aortic endothelial cells
Author(s) -
Gajdusek Corinne M.,
Luo Zhengyu,
Mayberg Marc R.
Publication year - 1993
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041540122
Subject(s) - incubation , in vitro , biology , growth factor , radioimmunoassay , secretion , northern blot , medicine , cell culture , insulin like growth factor , endocrinology , endothelial stem cell , microbiology and biotechnology , messenger rna , biochemistry , receptor , gene , genetics
Endothelial cells elaborate growth promoting activities in culture medium that support limited smooth muscle cell and fibroblast growth in vitro in the absence of serum. We investigated whether insulin‐like growth factor‐I (IGF‐I) was synthesized and secreted by bovine aortic endothelial cells in vitro. Subconfluent endothelial cell cultures in serum‐free medium secreted severalfold higher IGF‐I levels than confluent cultures by acid‐sizing chromatography and IGF‐I radioimmunoassay. The IGF‐I secretory level was not sustained during a second serum‐free incubation. In contrast, secretion of IGF binding proteins persisted and was maintained at constant levels throughout the same observation periods. Analysis of poly (A + )RNA by northern blots revealed hybridization of an IGF‐I cDNA to a 7.5‐ to 7.0‐kb transcript and superinduction of the 7.5–7.0‐kb mRNA by the translational inhibitor, cyclohexamide. However, no endogenously labeled IGF‐I was detected in conditioned media after incubation of cultures with [ 35 S]cysteine or [ 3 H]leucine. When cultures were incubated in the presence of serum supplemented with IGF‐I, subconfluent cultures sequestered and released more IGF‐I than confluent cultures. We concluded that the majority of IGF‐I secreted in vitro was sequestered from serum. © 1993 Wiley‐Liss, Inc.