Exercise increases hexokinase II mRNA, but not activity in obesity and type 2 diabetes

Kenneth J. Cusi, Thongchai Pratipanawatr, Janice Koval, Richard Printz, Hossein Ardehali, Darryl K. Granner, Ralph A. DeFronzo, Lawrence J. Mandarino

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    Abstract

    Glucose phosphorylation, catalyzed by hexokinase, is the first committed step in glucose uptake in skeletal muscle. Hexokinase II (HKII) is the isoform that is present in muscle and is regulated by insulin and muscle contraction. Glucose phosphorylation and HKII expression are both reduced in obese and type 2 diabetic subjects. A single bout of exercise increases HKII mRNA and activity in muscle from healthy subjects. The present study was performed to determine if a moderate exercise increases HKII mRNA expression and activity in patients with type 2 diabetes. Muscle biopsies were performed before and 3 hours after a single bout of cycle ergometer exercise in obese and type 2 diabetic patients. HKII mRNA and activity and glycogen synthase activity were determined in the muscle biopsies. Exercise increased HKII mRNA in obese and diabetic subjects by 1.67 ± 0.34 and 1.87 ± 0.26-fold, respectively (P < .05 for both). Exercise did not significantly increase HKI mRNA. When HKII mRNA increases were compared with the 2.26 ± 0.36-fold increase in HKII mRNA previously reported for healthy lean subjects, no statistically significant differences were found. In contrast to the increase in HKII activity observed after exercise by lean healthy controls, exercise did not increase HKII activity in obese nondiabetic or diabetic subjects. Exercise increased glycogen synthase activity (GS0.1 and GSFV) significantly in both obese nondiabetic and type 2 diabetic patients. The present results indicate that there is a posttranscriptional defect in the response of HKII expression to exercise in obese and type 2 diabetic subjects. This defect may contribute to reduced HKII activity and glucose uptake in these patients.

    Original languageEnglish (US)
    Pages (from-to)602-606
    Number of pages5
    JournalMetabolism: Clinical and Experimental
    Volume50
    Issue number5
    DOIs
    StatePublished - May 2001

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    ASJC Scopus subject areas

    • Endocrinology, Diabetes and Metabolism
    • Endocrinology

    Cite this

    Cusi, K. J., Pratipanawatr, T., Koval, J., Printz, R., Ardehali, H., Granner, D. K., DeFronzo, R. A., & Mandarino, L. J. (2001). Exercise increases hexokinase II mRNA, but not activity in obesity and type 2 diabetes. Metabolism: Clinical and Experimental, 50(5), 602-606. https://doi.org/10.1053/meta.2001.22568