EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Regulation of insulin and insulin like growth factor responsiveness by insulin like growth factors in rat hepatoma cells


Endocrinology 118(6): 2555-2560
Regulation of insulin and insulin like growth factor responsiveness by insulin like growth factors in rat hepatoma cells
We have previously reported that insulin induces a complete and reversible desensitization to the induction of tyrosine aminotransferase by insulin and insulin-like growth factors (IGFs) in HTC rat hepatoma cells. This loss of responsiveness cannot be accounted for by down-regulation of cell surface receptors, but occurs at a postbinding step in hormone action. Here we present evidence that IGF-I and IGF-II also induce desensitization to the actions of both IGFs and insulin and that this effect is mediated by IGF receptors. First, the concentration dependence for this effect is similar to that for the IGF-I and IGF-II induction of tyrosine aminotransferase, which has been shown to be mediated by IGF receptors. Second, antibody to the insulin receptor, which blocks insulin, but not IGF-II, binding to HTC cells, causes a rightward shift in the concentration dependence for insulin induction of desensitization, but does not significantly change the concentration dependence for IGF-II. These results indicate that IGF-II-induced desensitization of IGF-II is not mediated by the insulin receptor, but presumably by an IGF receptor. Although the IGFs do cause a moderate decrease in the binding of IGFs and insulin (to .apprx. 50-75% of the control value), this cannot account for the virtually complete desensitization to their actions. We conclude that IGFs, like insulin, induce a nearly complete loss of responsiveness to insulin and IGFs, that this effect is mediated via IGF receptors, and that desensitization occurs to a step distal to hormone binding which may be common to the actions of insulin and the IGFs.


Accession: 006288754



Related references

Regulation of insulin and insulin-like growth factor (IGF) responsiveness by IGFs in rat hepatoma cells. Endocrinology 118(6): 2555-2560, 1986

Regulation of insulin and insulin growth factor responsiveness in hepatoma cells. Clinical Research 30(2): 524A, 1982

Comparative studies on the regulation of insulin-like growth factor-binding protein-1 and sex hormone-binding globulin production by insulin and insulin-like growth factors in human hepatoma cells. Journal of Steroid Biochemistry & Molecular Biology 86(2): 197-200, August, 2003

Comparative studies on the regulation of insulin-like growth factor-binding protein-1 (IGFBP-1) and sex hormone-binding globulin (SHBG) production by insulin and insulin-like growth factors in human hepatoma cells. Journal of Steroid Biochemistry and Molecular Biology 86(2): 197-200, 2003

Increases in free, unbound insulin-like growth factor I enhance insulin responsiveness in human hepatoma G2 cells in culture. Journal of Biological Chemistry 277(16): 13620-7, 2002

Insulin-like growth factors, insulin, and epidermal growth factor cause rapid cytoskeletal reorganization in KB cells. Clarification of the roles of type I insulin-like growth factor receptors and insulin receptors. Journal of Biological Chemistry 261(34): 16141-7, 1986

Insulin like growth factors insulin and epidermal growth factor cause rapid cytoskeletal reorganization in kb cells clarification of the roles of type i insulin like growth factor receptors and insulin receptors. Journal of Biological Chemistry 261(34): 16141-16147, 1986

Differential effect of insulin insulin like growth factor i and other growth factors on insulin like growth factor i gene expression in cultured vascular smooth muscle cells. Diabetologia 32(7): 468A, 1989

Insulin regulation of insulin-like growth factor action in rat hepatoma cells. Journal of Biological Chemistry 259(4): 2396-2402, 1984

Insulin-like growth factor II (IGF-II) inhibits insulin-like growth factor binding protein I (IGFBP-1) production in luteinized human granulosa cells with a potency similar to insulin-like growth factor I (IGF-I) and higher than insulin. Journal of Clinical Endocrinology and Metabolism 81(9): 3412-3414, 1996