Matarne 2015 Abstract MiPschool Greenville 2015

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Chronic activation of AMP-activated protein kinase increases oxidative capacity and monocarboxylate transporter expression in skeletal muscle of pigs.

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Matarneh SK, England EM, Oliver EM, Helm ET, Shi H, Scheffler TL, Gerrard DE (2015)

Event: MiPschool Greenville 2015

Porcine AMPKγ3R200Q mutation is a single base substitution mutation in the PRKAG3 gene, encoding the γ3 regulatory subunit of AMPK, resulting in constitutive AMPK activation [1]. Lower lactate levels have been previously reported in glycolytic muscle of AMPKγ3R200Q pigs when compared to wild-type pigs [2]. We hypothesized that greater capacity for lactate elimination and(or) greater oxidative capacity in muscle of these pigs may help explain this phenomenon. To test our hypothesis, we measured monocarboxylate transporter (MCT) 1, 2, and 4 mRNA expression and protein abundance in the longissimus muscle (glycolytic, white) and masseter (oxidative, red) from wild-type (control) and AMPKγ3R200Q pigs. We also compared mitochondrial respiration and protein and mRNA abundance for key oxidative enzymes in longissimus muscle. MCT1 and MCT2 mRNA expression was greater (P<0.05) in the masseter than the longissimus muscle. MCT1 protein was not detected in skeletal muscle but MCT2 was greater in the masseter than the longissimus muscle. Furthermore, MCT2 protein abundance was greater (P<0.05) in the longissimus muscle of AMPKγ3R200Q pigs compared to the longissimus muscle of wild-type pigs. MCT2 was also detected in muscle mitochondria and may explain the differences between oxidative and glycolytic muscles. MCT4 mRNA expression was greater (P< 0.05) in the longissimus muscle than the masseter. Further, MCT4 protein expression in the longissimus muscle from AMPKγ3R200Q pigs was greater (P<0.05) than the longissimus muscle from wild-type animals. AMPKγ3R200Q increases muscle oxidative capacity, evidenced by enhanced (P<0.05) citrate synthase and β-HAD activity and ADP-stimulated respiration (state 3), as well as augmented mitochondrial content. In totality, our data indicate that chronic AMPK activation simultaneously increases oxidative capacity and MCT2 and MCT4 expression in porcine skeletal muscle, which contributes to the lower resting lactate levels in the AMPKγ3R200Q pigs.


Labels: MiParea: Respiration 


Organism: Pig  Tissue;cell: Skeletal muscle 


Coupling state: OXPHOS 


Event: Poster 


Affiliations

1-Dept Animal Poultry Sc, Virginia Polytechnic Inst State Univ, Blacksburg, VA; 2-Dept Animal Sc, Univ Florida, Gainesville, FL, USA. - matatrneh@vt.edu

References and acknowledgements

  1. Milan D, Jeon JT, Looft C, Amarger V, Robic A, Thelander M, Rogel-Gaillard C, Paul S, Iannuccelli N, Rask L, Ronne H, Lundstroem K, Reinsch N, Gellin J, Kalm E, Le Roy P, Chardon P, Andersson L (2000) A mutation in PRKAG3 associated with excess glycogen content in pig skeletal muscle. Sc 288:1248-51.
  2. Matarneh SK, England EM, Scheffler TL, Oliver EM, Gerrard DE (2015) Net lactate accumulation and low buffering capacity explain low ultimate pH in the longissimus lumborum of AMPKγ3R200Q mutant pigs. Meat Sc (Submitted).