Different expression of calpain in skeletal muscle of Japanese quail (Coturnix coturnix japonica) lines selected for body weight

Abstract

Calpain activity was determined by western blot analysis of steady-state concentrations of m-calpain (calpain requiring millimolar Ca2+ for activation) and also by northern blot analysis of steady-state concentrations of mRNA encoding m-calpain in three lines of quail: a random-bred control line (RR) and two lines selected for body weight, one for increased body weight (LL) and another for decreased body weight (SS). The m-calpain activities in skeletal muscle were higher in the SS line and lower in the LL line. From western blot analysis, enzyme levels of calpain were almost the same for all three lines. At the level of gene expression, the mRNA concentration encoding m-calpain was higher in the LL and lower in the SS line. These results suggest that the regulation of calpain activity in skeletal muscle is a three-step process, regulation at the transcription level, regulation at the enzyme level, and regulation of the activation of calpain.