Protein Expression in Skeletal Muscle is Influenced by Changes in Dietary Zinc

Abstract

The purpose of this experiment was to determine the effects of different amounts of dietary zinc (Zn) on protein expression in rat skeletal muscle. The overall goal of this research is to identify those proteins essential for maintaining normal muscle function that are affected by dietary Zn. Male Sprague-Dawley rats (125 to 149 g) were fed a stock diet for 14 d, then separated into three groups and fed test diets containing 5, 30, or 200 ppm Zn for 42 d. All rats consumed the test diets and deionized water ad libitum. Body weight was measured daily and 24 h food intakes were determined weekly. The rats were sacrificed on day 43, and the soleus muscle dissected from each leg and snap frozen in liquid nitrogen for storage at −70 °C. The muscles were prepared for two-dimensional gel electrophoresis using a sample preparation kit that fractionated the muscle into soluble and insoluble fractions. One mg soluble protein was loaded on to 17 cm immobilized pH gradient strips for isoelectric focusing. The strips were then applied to the SDS-PAGE second dimension 10–20 % gradient gel. Following fixing, the separated proteins were visualized with colloidal Coomassie blue stain. Hundreds of proteins were observed. Compared to the 30 ppm Zn group, approximately 100 proteins were affected by the Zn-deficient diet and 70 proteins were affected by the excess-Zn diet. Analyzing these proteins using mass spectrometry will identify them, and aid in determining their role in muscle function under conditions of Zn deficiency and excess.