PT  - JOURNAL ARTICLE
AU  - Hiroki Yokoo
AU  - Tomokazu Saitoh
AU  - Seiji Shiraishi
AU  - Toshihiko Yanagita
AU  - Takashi Sugano
AU  - Shin-Ichi Minami
AU  - Hideyuki Kobayashi
AU  - Akihiko Wada
TI  - Distinct Effects of Ketone Bodies on Down-Regulation of Cell Surface Insulin Receptor and Insulin Receptor Substrate-1 Phosphorylation in Adrenal Chromaffin Cells
AID  - 10.1124/jpet.102.044115
DP  - 2003 Mar 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 994--1002
VI  - 304
IP  - 3
4099  - http://jpet.aspetjournals.org/content/304/3/994.short
4100  - http://jpet.aspetjournals.org/content/304/3/994.full
SO  - J Pharmacol Exp Ther2003 Mar 01; 304
AB  - Treatment (≧24 h) of cultured bovine adrenal chromaffin cells with ketoacidosis-related concentrations (≧3 mM) of acetoacetate (but not β-hydroxybutyrate, acetone, and acidic medium) caused a time- and concentration-dependent reduction of cell surface125I-insulin binding by ∼38%, with no change in theKd value. The reduction of125I-insulin binding returned to control nontreated level at 24 h after the washout of acetoacetate-treated cells. Acetoacetate did not increase the internalization rate of cell surface insulin receptor (IR), as measured in the presence of brefeldin A, an inhibitor of cell surface vesicular exit from thetrans-Golgi network. Acetoacetate (10 mM for 24 h) lowered cellular levels of the immunoreactive IR precursor molecule (∼190 kDa) and IR by 22 and 28%, respectively. Acetoacetate decreased IR mRNA levels by ∼23% as early as 6 h, producing their maximum plateau reduction at 12 and 24 h. The half-life of IR mRNA was shortened by acetoacetate from 13.6 to 9.5 h. Immunoprecipitation followed by immunoblot analysis revealed that insulin-induced (100 nM for 10 min) tyrosine-phosphorylation of insulin receptor substrate-1 (IRS-1) was attenuated by 56% in acetoacetate-treated cells, with no change in IRS-1 level. These results suggest that chronic treatment with acetoacetate selectively down-regulated the density of cell surface functional IR via lowering IR mRNA levels and IR synthesis, thereby retarding insulin-induced activation of IRS-1. The American Society for Pharmacology and Experimental Therapeutics