Decreased Expression of Alpha-B-crystallin in C2C12 Cells that Express Human DMPK/160CTG Repeats

Abstract

The effect of oxidative stress on myogenic cells with expanded CTG repeats in the myotonic dystrophy protein kinase (DMPK) gene was investigated using DMPK cDNA-transformants in order to investigate the disease process underlying myotonic dystrophy. It was reported that DM model cell was highly sensitive against oxidative stress. In this study, we investigated the viability to hydrogen peroxide or menadione of DM model C2C12 cells, which were stably transfected with DMPK cDNA containing 160 CTG repeats in 3’untranslated region. We found that cells containing 160 CTG repeats were more sensitive to oxidants than the cells containing 5 CTG repeats. We confirmed that the mutant cells died with low concentrations of the oxidant, compared with that of control. Next, total RNA was isolated from these cell cultures and Northern blot analysis was performed. Decrease in the expression of alpha-B-crystallin was observed in C2C12 with longer CTG repeats. These results suggest that expanded CTG repeats in DMPK increase the susceptibility of cells to oxidative stress by suppressing chaperon genes expression