Search Results - (Author, Cooperation:S. Trippel)

2014-07-19

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

0736-0266

Somatomedin ; Receptors ; Growth plate ; Chondrocytes ; Affinity labeling ; Life and Medical Sciences

Wiley InterScience Backfile Collection 1832-2000

Medicine

The chondrocytes of the epiphyseal growth plate are the presumed target cells for hormones regulating skeletal growth. The somatomedins, a family of low molecular weight peptides, are thought to play a stimulatory role in this regulation. The cellular actions of the somatomedins are themselves determined by binding to specific receptors on target cells. Previous studies have characterized a specific receptor for somatomedin-C (Sm-C) or insulin-like growth factor I (IGF-I) on bovine growth plate chondrocytes (GPCs). We now report the characterization of a second type of somatomedin receptor on these cells that is more specific for another class of somatomedin represented by multiplication-stimulating activity (MSA) or rat insulin-like growth factor II (rIGF-II). Binding of [125I]MSA/rIGF-II to isolated GPCs was time dependent and saturable. Unlabeled Mr 7.100 MSA/rIGF-II and Sm-C/IGF-I were approximately equipotent in competing with [125I] MSA/rIGF-II for binding. while Mr 8,600 MSA/rIGF-II was an order of magnitude less potent. Low levels of competition by insulin appeared in some studies at concentrations of 10-7 M and higher. suggesting displacement of [125I]MSA/rIGF-II binding. to the Sm-C/IGF-I receptor. In affinity-labeling studies. [125I]Sm-C/IGF-I labeled a complex of Mr 〉300.000 (unreduced) and of Mr 140.000 (reduced). consistent with a type I somatomedin receptor composed of disulfide-linked subunits. [125I]MSA/rIGF-II labeled a Mr 240.000 moiety (unreduced) and Mr 260.000 (reduced). consistent with a type II somatomedin receptor. Both affinity-labeling and kinetic data revealed cross-binding of MSA/rIGF-II and insulin with the type I receptor and of Sm-C/IGF-I with the type II receptor. In contrast. the type II receptor did not recognize insulin. These data suggest a complex pattern of graded specificity of these receptors for their ligands. These data are consistent with the hypothesis that IGF-II as well as Sm-C/IGF-I participate in the stimulation of skeletal growth.

6 Ill.

Electronic Resource

0736-0266

Sarcoma ; Growth factor ; Flow cytometry ; Tumour ploidy ; Life and Medical Sciences

Wiley InterScience Backfile Collection 1832-2000

Medicine

Cell lines derived from human sarcomas have been previously shown to produce a protein growth factor which, similar to platelet-derived growth factor (PDGF), can induce competence for mitosis in fibroblasts. Whether this factor production is an important feature of sarcomas in vivo or simply an artefact caused by long-term culture conditions is unclear, however. We demonstrated growth factor activity in conditioned medium from six of 11 primary sarcoma cultures, utilizing flow cytometric analysis of DNA to monitor the presence of sarcoma cells in cultures. Cells isolated from control tissues failed to show a similar mitotic effect.

2 Ill.

Electronic Resource