Andersen 2014 Abstract IOC 2014-04 Schroecken

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Andersen M, Vienberg SG, Novod JB, Brandauer J, Holst B, Treebak JT (2014) Nicotinamide phosphoribosyltransferase knockdown impairs mitochondrial function in mouse myoblasts. Mitochondr Physiol Network 19.02.

Link: www.metabol.ku.dk/

Andersen M, Vienberg SG, Novod JB, Brandauer J, Holst B, Treebak JT (2014)

Event: MiPNet19.02 IOC88

Proper mitochondrial biogenesis and function play a key role for energy metabolism in skeletal muscle as mitochondrial dysfunction is associated with development of metabolic disorders. Sirtuins, a family of energy sensing enzymes, deacetylates and thus activate transcription factors involved in mitochondrial biogenesis. Nicotinamide adenine dinucleotide (NAD) is a required substrate for sirtuin activation which results in the conversion of NAD to nicotinamide. Nicotinamide phosphoribosyltransferase (Nampt) is the rate-limiting enzyme for recycling nicotinamide to NAD. However, evidence for the role of Nampt in maintaining NAD levels, sirtuin activity and mitochondrial function is lacking. In order to determine the importance of Nampt in maintaining mitochondrial function we generated a stable Nampt knockdown (KD) mouse myoblast (C2C12) cell line using a shRNA lentiviral approach. Nampt mRNA expression, protein abundance and activity were reduced by ≈80% leading to a ≈70% decrease in NAD levels in the KD cells. Using a Seahorse X-96 Extracellular Flux Analyzer we found mitochondrial respiratory capacity was significantly (p <0.01) decreased by ≈60% in the Nampt KD cells compared to cells expressing non-sense shRNA (control). Moreover, palmitate-induced fatty acid oxidation was significantly (p <0.01) decreased by ≈25% in Nampt KD cells compared to control cells. These findings were not due to altered expression of proteins involved in the electron transport chain or fatty acid oxidation. These data suggest that Nampt is required for optimal oxidation of fatty acids and Nampt may play an important role for maintaining NAD levels and mitochondrial function in skeletal muscle cells.

Keywords: Mitochondrial respiration, metabolism, skeletal muscle, nicotinamide phosphoribosyltransferase


Labels: MiParea: Respiration  Pathology: Diabetes, Obesity 

Organism: Mouse  Tissue;cell: Skeletal muscle, Other cell lines  Preparation: Intact cells  Enzyme: Complex I, Complex II;succinate dehydrogenase, Complex III, Complex IV;cytochrome c oxidase, Uncoupling protein 




Affiliations

1) Marianne A. Andersen & 1) Sara G. Vienberg & 1) Julie B. Novod & 1,2) Josef Brandauer & 3) Birgitte Holst & 1) Jonas T. Treebak.

  1. Section of Integrative Physiology, The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen.
  2. Health Sciences Department, Gettysburg College, Gettysburg PA, USA.
  3. Section of Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen.