-transparent.png){kind=logo}
Insulin and the insulin-like growth factors (IGFs) are chemically related polypeptides that interact with distinct receptors and elicit the same biological responses. We have sought a readily propagated cell line from a potential target tissue in which to probe the multiple and complex interrelationships among receptor and effector pathways for these polypeptides. We now report that the mouse muscle cell line BC3H-1 represents such a model system. BC3H-1 cells differentiate spontaneously at high density to form cells with muscle-specific properties, but do not fuse. Standaert et al. reported that differentiated BC3H-1 myocytes possess insulin receptors that mediate glucose and amino acid uptake and are down-regulated by prolonged incubation with insulin. The present report demonstrates that BC3H-1 myocytes also possess functional and regulated IGF receptors. Two subtypes of IGF receptors, types I and II, differing in structure and peptide specificity, were demonstrated by competitive binding and affinity cross-linking experiments. Low concentrations of IGFs stimulated glucose incorporation and alpha-aminoisobutyric acid uptake by BC3H-1 myocytes, suggesting that these effects were mediated primarily by IGF receptors rather than insulin receptors. Preincubation with IGFs (or high concentrations of insulin) selectively down-regulated type I IGF receptors without affecting type II IGF receptors. Since [125I]IGF-I binds to both type I and type II receptors in BC3H-1 cells, and since type I receptors have a higher affinity for IGF-I, the selective down-regulation of type I IGF receptors results in an apparent decrease in affinity for IGF-I. This difference in the regulation of type I and type II receptors in BC3H-1 myocytes is consistent with observations in other systems in which only one IGF receptor was present or examined. In their ability to be down-regulated by IGFs and insulin, type I IGF receptors are more similar to the structurally homologous insulin receptors than to the structurally dissimilar type II IGF receptors. These findings indicate that the BC3H-1 cell line provides an excellent model system in which to study the structure-function relationships of the receptor and effector pathways for insulin and the IGFs.
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
March 1977,
The Journal of biological chemistry,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
November 1977,
Biochemistry,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
July 1979,
The Journal of biological chemistry,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
May 1998,
Annals of the New York Academy of Sciences,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
March 1995,
Growth regulation,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
June 1996,
Endocrinology,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
October 1995,
Metabolism: clinical and experimental,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
November 1994,
The Journal of investigative dermatology,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
June 1996,
Growth regulation,
M A de Vroede, and
J A Romanus, and
M L Standaert, and
R J Pollet, and
S P Nissley, and
M M Rechler
December 1993,
Experimental cell research,
