Cellular responses elicited by insulin mimickers in cells lacking detectable plasma membrane insulin receptors
✍ Scribed by Cecilia Hofmann; Marco Crettaz; Pamela Bruns; Patricia Hessel; Gina Hadawi
- Publisher
- John Wiley and Sons
- Year
- 1985
- Tongue
- English
- Weight
- 747 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Madin-Darby canine kidney (MDCK) cells were previously shown to have few or no pla.ma membrane insulin binding sites [Hofmann et al: J Biol Chem 258: 11774, 19831. Accordingly, neither insulin-stimulated incorporation of [ ''C]glucose into glycogen, nor insulin-induced uptake of radiolabeled a-aminoisobutyrate ( L3H]A1B) could be demonstrated. To probe for rece tors, MDCK cultures were surfacelabeled with Na1251 or were labeled with [ 3 Slmethionine. When solubilized cells were immunoprecipitated with sera containing antibodies to the insulin receptor, and immunoprecipitates were analyzed on SDS-gel electrophoresis, no evidence for insulin receptor components was found. Also, when intact MDCK cells were incubated first with serum containing antibodies to the insulin receptor and then with 1251-protein A, no radiolabeling of insulin receptors occurred. Various agents reported to have insulin-like activity were tested on MDCK cells. The insulinomimetic lectins concanavalin A and wheat germ agglutinin as well as hydrogen peroxide enhanced incorporation of [ 14C]glucose into glycogen and induced stimulated [3H]AIB uptake, whereas trypsin, vanadate, and serum containing antibodies to the insulin receptor were without effects. Altogether, these results showed that MDCK cells had few or no insulin receptors and were correspondingly insulin-insensitive. However, since insulin-associated responses could be elicited by some insulin mimickers, the post-receptor limb of response in MDCK cells was apparently intact.