Constitutive protein content of procaspases in murine tissue

Caspases are proteases most notably involved in apoptosis and inflammation. Although mRNA content is better described, the constitutive protein content of procaspases between tissue types is not well documented. Since mRNA and protein content do not necessarily correlate, we aimed to discern protein content differences between various tissues. Protein content of procaspase-1, -8, -9, and -12 was assessed in gastrocnemius, heart, liver, and kidney. Since highly expressed in skeletal muscle, content of procaspase-12 was also analyzed in muscles with different fiber type compositions to discern any fiber type differences. Furthermore, Western analysis for procaspase-12 revealed prominent bands of ??40 kDa and ??30 kDa under basal conditions, in addition to the 50 kDa band corresponding to the full-length procaspase. Therefore, the content of these caspase-12 related species in the tissue and muscle types is also described. Results show protein content of procaspase-1,-8, -9, and -12 and caspase-12 related species differs between tissue types and do not necessarily correlate with mRNA content reported in the published literature. Procaspase-12 content in skeletal muscle may be fiber-type dependent with higher expression in more oxidative fibers. Furthermore, the 40 kDa species of caspase-12 was the dominant form of the protein in most tissues analyzed.