Cell lines

Transfected COS-7 cells expressing mutant or wild-type insulin receptors

Preparation method

Soluble in DMSO. General tips for obtaining a higher concentration: Please warm the tube at 37℃ for 10 minutes and/or shake it in the ultrasonic bath for a while. Stock solution can be stored below -20℃ for several months.

Reaction Conditions

50 μM; 2 hrs

Applications

In the Leu1193 and Asp1179 mutant cell lines, MG-115 increased the intensities of the bands of the insulin proreceptors and the mature β-subunits to 3- and 4.2-fold, respectively. However, in the wild-type cell lines, there was no change in the intensities of these bands. The results suggested that both Leu1193 and Asp1179 mutant insulin proreceptors were degraded by the proteasome in the cytosol.

MG-115 (Z-Leu-Leu-Nva-H) is a potent, reversible peptide aldehyde inhibitor of proteasome chymotrypsin-like and caspase-like activities. It induces p53 dependent apoptosis. Blockade of proteasomal degradation by MG115 can activate autophagy.

Treatment with proteasome inhibitors Z-Leu-Leu-Nva-H (MG-115) or Z-Leu-Leu-Leu-H (MG-132) prevented the accelerated degradation of these mutant receptors, resulting in increased amounts of the mutant receptors in the COS-7 cells [1].

A potent, reversible proteasome inhibitor with Ki of 21 nM for 20S proteasome and 35 nM for 26S proteasome. The inhibition of proteasome was through specific inhibition of chymotrypsin-like activity of the proteasome. Also shown to induce apoptosis in Rat-1 and PC12 cells via a p3-independent pathway.

References:
1. Involvement of heat shock protein 90 in the degradation of mutant insulin receptors by the proteasome. Imamura, T., Haruta, T., Takata, Y., Usui, I., Iwata, M., Ishihara, H., Ishiki, M., Ishibashi, O., Ueno, E., Sasaoka, T., Kobayashi, M.J. Biol. Chem. (1998)