title: Activation of AMPKα2 Is Not Required for Mitochondrial FAT/CD36 Accumulation during Exercise.
abstract: Exercise has been shown to induce the translocation of fatty acid translocase (FAT/CD36), a fatty acid transport protein, to both plasma and mitochondrial membranes. While previous studies have examined signals involved in the induction of FAT/CD36 translocation to sarcolemmal membranes, to date the signaling events responsible for FAT/CD36 accumulation on mitochondrial membranes have not been investigated. In the current study muscle contraction rapidly increased FAT/CD36 on plasma membranes (7.5 minutes), while in contrast, FAT/CD36 only increased on mitochondrial membranes after 22.5 minutes of muscle contraction, a response that was exercise-intensity dependent. Considering that previous research has shown that AMP activated protein kinase (AMPK) α2 is not required for FAT/CD36 translocation to the plasma membrane, we investigated whether AMPK α2 signaling is necessary for mitochondrial FAT/CD36 accumulation. Administration of 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) induced AMPK phosphorylation, and resulted in FAT/CD36 accumulation on SS mitochondria, suggesting AMPK signaling may mediate this response. However, SS mitochondrial FAT/CD36 increased following acute treadmill running in both wild-type (WT) and AMPKα 2 kinase dead (KD) mice. These data suggest that AMPK signaling is not required for SS mitochondrial FAT/CD36 accumulation. The current data also implicates alternative signaling pathways that are exercise-intensity dependent, as IMF mitochondrial FAT/CD36 content only occurred at a higher power output. Taken altogether the current data suggests that activation of AMPK signaling is sufficient but not required for exercise-induced accumulation in mitochondrial FAT/CD36.
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Monaco
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Whitfield
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: Swati S
authors.initials: SS
authors.lastname: Jain
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Spriet
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: Arend
authors.initials: A
authors.lastname: Bonen
authors.affiliation: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: Graham P
authors.initials: GP
authors.lastname: Holloway
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D012508:Sarcolemma / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
chemical_list: D018955:CD36 Antigens; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases