Submitted on February 28, 2008
Revised on June 3, 2008
Accepted on June 4, 2008
Influence of AMP-activated protein kinase and calcineurin on metabolic networks in skeletal muscle
Yun Chau Long1 and Juleen R. Zierath2*
1 1Howard Hughes Medical Institute, Children's Hospital Boston, Harvard Medical School
2 Karolinska Institute
* To whom correspondence should be addressed. E-mail: Juleen.Zierath{at}ki.se.
Skeletal muscle fibers differ considerably in their metabolic and physiological properties. Skeletal muscle displays a high degree of metabolic flexibility, which allows the myofibers to adapt to various physiological demands by shifting energy substrate utilization. Transcriptional events play a pivotal role in the metabolic adaptations of skeletal muscle. The expression of genes essential for skeletal muscle glucose and lipid metabolism is tightly coordinated in support of a shift in substrate utilization. AMP-activated protein kinase (AMPK) and calcineurin (a calcium-regulated serine/threonine protein phosphatase) regulate metabolic gene expression programs in skeletal muscle in response to alterations in changes in the energy status and levels of neuronal input, respectively. AMPK and calcineurin activate transcriptional regulators such as PGC1
(peroxisome proliferator-activated receptor gamma coactivator 1) and MEF (myocyte enhancer factor), and increase skeletal muscle oxidative capacity and mitochondrial gene expression. Activation of either the AMPK or calcineurin pathway can also enhance the glycogen storage capacity and insulin-sensitivity in skeletal muscle. Characterization of pathways governing skeletal muscle metabolism offers insight into physiological and pharmacological strategies to prevent or ameliorate peripheral insulin resistance associated with metabolic disorders such as type 2 diabetes.
