title: Abcc9 is required for the transition to oxidative metabolism in the newborn heart.
abstract: The newborn heart adapts to postnatal life by shifting from a fetal glycolytic metabolism to a mitochondrial oxidative metabolism. Abcc9, an ATP-binding cassette family member, increases expression concomitant with this metabolic shift. Abcc9 encodes a membrane-associated receptor that partners with a potassium channel to become the major potassium-sensitive ATP channel in the heart. Abcc9 also encodes a smaller protein enriched in the mitochondria. We now deleted exon 5 of Abcc9 to ablate expression of both plasma membrane and mitochondria-associated Abcc9-encoded proteins, and found that the myocardium failed to acquire normal mature metabolism, resulting in neonatal cardiomyopathy. Unlike wild-type neonatal cardiomyocytes, mitochondria from Ex5 cardiomyocytes were unresponsive to the KATP agonist diazoxide, consistent with loss of KATP activity. When exposed to hydrogen peroxide to induce cell stress, Ex5 neonatal cardiomyocytes displayed a rapid collapse of mitochondria membrane potential, distinct from wild-type cardiomyocytes. Ex5 cardiomyocytes had reduced fatty acid oxidation, reduced oxygen consumption and reserve. Morphologically, Ex5 cardiac mitochondria exhibited an immature pattern with reduced cross-sectional area and intermitochondrial contacts. In the absence of Abcc9, the newborn heart fails to transition normally from fetal to mature myocardial metabolism.-Fahrenbach, J. P., Stoller, D., Kim, G., Aggarwal, N., Yerokun, B., Earley, J. U., Hadhazy, M., Shi, N.-Q., Makielski, J. C., McNally, E. M. Abcc9 is required for the transition to oxidative metabolism in the newborn heart.
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and.
authors.forename: John P
authors.initials: JP
authors.lastname: Fahrenbach
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and.
authors.forename: Douglas
authors.initials: D
authors.lastname: Stoller
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and.
authors.forename: Gene
authors.initials: G
authors.lastname: Kim
authors.affiliation: Department of Medicine, Division of Cardiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Nitin
authors.initials: N
authors.lastname: Aggarwal
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and.
authors.forename: Babatunde
authors.initials: B
authors.lastname: Yerokun
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and.
authors.forename: Judy U
authors.initials: JU
authors.lastname: Earley
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and.
authors.forename: Michele
authors.initials: M
authors.lastname: Hadhazy
authors.affiliation: Department of Medicine, Division of Cardiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Nian-Qing
authors.initials: NQ
authors.lastname: Shi
authors.affiliation: Department of Medicine, Division of Cardiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Makielski
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, and Department of Human Genetics, The University of Chicago, Chicago, Illinois, USA; and emcnally@uchicago.edu.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: McNally
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D009202:Cardiomyopathies / Q000151:congenital; D002462:Cell Membrane / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006321:Heart / Q000502:physiology*; D054086:KATP Channels / Q000378:metabolism; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D064233:Sulfonylurea Receptors / Q000378:metabolism*
chemical_list: C577511:Abcc9 protein, mouse; D005227:Fatty Acids; D054086:KATP Channels; D064233:Sulfonylurea Receptors
keywords: cardiomyopathy; mitochondria; neonatal heart failure; sulfonylurea receptor