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Constitutively Active Ca 2+ /Calmodulin‐Dependent Protein Kinase Kinase α (CaMKKα) Stimulates the Pentose Phosphate Pathway in Mouse Skeletal Muscle
Author(s) -
Ferey Jeremie,
Brault Jeffrey,
Witczak Carol
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.824.15
Subject(s) - pentose phosphate pathway , skeletal muscle , biochemistry , chemistry , protein kinase a , kinase , glycolysis , glucose uptake , biology , metabolism , endocrinology , insulin
In mouse skeletal muscle, expression of constitutively active Ca 2+ /calmodulin‐dependent protein kinase kinase α (CA‐CaMKKα) for 2 wks increases glucose uptake and muscle mass, suggesting that the glucose may be fueling the energetic and/or biosynthetic demands of growth. The pentose phosphate pathway (PPP) metabolizes glucose to produce NADPH for reductive biosynthesis and nucleotide precursors for DNA/RNA synthesis, and may be the key link between increased CaMKKα activity, glucose uptake, and growth. Our goal was to determine if CA‐CaMKKα expression stimulates the PPP in muscle. To assess this, plasmids containing CA‐CaMKKα or empty vector were transfected into tibialis anterior muscles using in vivo electroporation. After 2 wks, muscles were collected, and a metabolomics analysis performed to assess PPP metabolites. The results showed that CA‐CaMKKα significantly increased levels of ribulose (57%), ribose (48%), ribitol (41%), and sedoheptulose‐7‐phosphate (115%), while ribulose‐5‐phosphate/xylulose‐5‐phosphate and ribose‐5‐phosphate trended towards being increased (33% and 31%, respectively), suggesting increased PPP flux. To assess the mechanism underlying increased PPP activity, immunoblots were performed for the primary rate‐limiting enzyme, glucose‐6‐phosphate dehydrogenase (G6PD). The results showed that CA‐CaMKKα increased G6PD protein levels 137%, collectively suggesting that chronic activation of CaMKKα signaling stimulates the PPP in mouse muscle, conceivably by increasing G6PD expression. We propose that the PPP may be a key metabolic pathway linking CaMKKα, glucose and protein metabolism in skeletal muscle. NIH R00AR056298, ECU start‐up funds.