Transport of insulin-like growth factor-I across endothelial cell monolayers and its binding to the subendothelial matrix

Experimental and Clinical Endocrinology & Diabetes : Official Journal, German Society of Endocrinology [and] German Diabetes Association
J Grulich-HennK T Preissner

Abstract

Cultured human umbilical vein endothelial cells (HUVEC) were used as a model to study transendothelial IGF-I transport, and its deposition into the extracellular matrix (ECM). Specific binding of (125)I-IGF-I to HUVEC monolayers was demonstrated, which was inhibited by aIR-3, a specific antibody directed against the IGF-I receptor. ECM-associated (125)I-IGF-I was approximately 10% of cell-bound IGF-I at 22 degrees C, and increased 4.5-fold at 37 degrees C, indicating that endothelial metabolism is required for the transport. However, neither monensin and cytochalasin B, both of which block endocytosis, nor aIR-3 did inhibit transport of (125)I-IGF-I into the ECM. In order to characterize IGF-I binding to the subendothelial ECM, HUVEC were removed nonenzymatically by treatment with Triton X-100 and ammonia. Specific, saturable binding of (125)I-IGF-I to the isolated ECM was observed, which was protease-sensitive. Antibodies directed against vitronectin inhibited IGF-I binding to the matrix by 35%, while antibodies directed against other ECM proteins had no significant influence on IGF-I binding. Using radioimmunoassays the IGF binding protein-2 was detected in the ECM, while IGFBP-1 and IGFBP-3 were below the detection limits. I...Continue Reading

Citations

Mar 21, 2006·Annals of Biomedical Engineering·Julie M D Paye, Kimberly Forsten-Williams
Jul 30, 2016·Biomedicine & Pharmacotherapy = Biomédecine & Pharmacothérapie·Mona K Tawfik, Magda I Mohamed
Oct 20, 2010·Nature Reviews. Endocrinology·Peter E ClaytonAndrew G Renehan
Aug 26, 2006·Endocrine Reviews·Amir Abbas SamaniPnina Brodt

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