Decrease in the insulin receptor protein level by anti-insulin receptor antibodies: roles of tyrosine kinase activity and receptor internalization
| Autor: | Shigeo Uotani, Hironori Yamasaki, Hirofumi Takino, Naruhiro Fujita, Kenichi Yamakawa, Takahiro Abe, Yoshihiko Yamaguchi, Masako Ozaki, Eiji Kawasaki, Hironaga Kuwahara, K Eguchi, Yasunori Sera, Mikako Degawa-Yamauchi |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
medicine.medical_specialty
Insulin Receptor Substrate Proteins Endocrinology Diabetes and Metabolism medicine.medical_treatment CHO Cells Biology Antibodies Endocrinology Insulin resistance Cricetinae Internal medicine Insulin receptor substrate Internal Medicine medicine Animals Humans Insulin Insulin-Like Growth Factor I Phosphorylation Insulin-like growth factor 1 receptor Binding Sites General Medicine Middle Aged Protein-Tyrosine Kinases Phosphoproteins medicine.disease Receptor Insulin IRS2 Insulin receptor internalization Insulin receptor Immunoglobulin G Mutation biology.protein Female |
| Zdroj: | Acta Diabetologica. 39:221-227 |
| ISSN: | 1432-5233 0940-5429 |
| DOI: | 10.1007/s005920200038 |
| Popis: | To investigate the mechanism of severe impairment of insulin action in type B insulin resistance, we extracted IgG from the serum of a patient with type B insulin resistance (B-IgG) and analyzed the inhibiting effect of B-IgG not only on insulin signaling but also on IGF-I signaling in Chinese hamster ovary (CHO) cells expressing human insulin receptor or human IGF-I receptor. Preincubation with 1 mg/ml B-IgG prevented insulin-induced phosphorylation of insulin receptor and insulin receptor substrate-1 (IRS-1) but did not alter the IGF-I-induced phosphorylation of the IGF-I receptor and IRS-1. (125)I-insulin binding was inhibited by 93% after preincubation with B-IgG at 37 degrees C and was recovered up to 50% of the control value by acid washing. However, when cells were preincubated with B-IgG at 4 degrees C, the insulin binding completely recovered the control value by acid washing. (125)I-IGF-I binding was not altered by B-IgG preincubation. Immunoblot study revealed that the protein level of the insulin receptor was strongly decreased by preincubation with 1 mg/ml B-IgG at 37 degrees C, but never at 4 degrees C. The IRS-1 protein level did not change by B-IgG preincubation. In order to know the role of the insulin receptor internalization in the inhibiting effect of B-IgG, we employed CHO cells expressing mutant insulin receptors which do not undergo internalization (CHO-K1018R). B-IgG incubation of CHO-K1018R at 37 degrees C failed to decrease the protein level of the insulin receptor. The present data indicate that IgG from the diabetic patient with type B insulin resistance decreased insulin receptor protein level, probably due to the enhanced degradation rate of the insulin receptor, in which insulin receptor tyrosine kinase activity and internalization are required for this process. This effect of B-IgG was specific for the insulin receptor with no effect on either IGF-I receptor or IRS-1, as reflected by the IGF-I effectiveness on glycemic control in this patient. |
| Databáze: | OpenAIRE |
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