Triiodothyronine but Not Thyroxine Accelerates Myofibrillar Proteolysis via ATP Production in Cultured Muscle Cells(Food & Nutrition Sience)

概要

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These experiments were done to clarify that the differential effects of thyroxine (T_4) and triiodothyronine (T_3) on skeletal muscle protein turnover are caused by their roles on ATP production. Primary cultured chick muscle cells were treated with a physiological level of T_4 (60 ng/ml), T_3 (12 ng/ml), or ATP (0.5 mM) for 6 days and the protein content, ATP production, proteasome activity, and myofibrillar protein breakdown were measured. The protein content measured as an index of cell growth was not affected by T_4, T_3, or ATP. The cellular ATP level was increased by T_3 and ATP, but not by T_4. Proteasome activity and N^τ-methylhistidine (MeHis) release measured as an index of myofiblillar protein breakdown was also increased by T_3 and ATP, but not by T_4. These results indicate that T_3 but not T_4 increases ATP production followed by an increase in proteasome activity, and thus stimulates myofibrillar proteolysis.
社団法人日本農芸化学会の論文
2003-11-23