Details

Autor(en) / Beteiligte

• Costford, Sheila R
• Bajpeyi, Sudip
• Pasarica, Magdalena
• Albarado, Diana C
• Thomas, Shantele C
• Xie, Hui
• Church, Timothy S
• Jubrias, Sharon A
• Conley, Kevin E
• Smith, Steven R

Titel

Skeletal muscle NAMPT is induced by exercise in humans

Ist Teil von

• American journal of physiology: endocrinology and metabolism, 2010-01, Vol.298 (1), p.E117-E126

Ort / Verlag

United States: American Physiological Society

Erscheinungsjahr

2010

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• 1 Pennington Biomedical Research Center, Baton Rouge, Louisiana; and 2 Department of Radiology, University of Washington Medical Center, Seattle, Washington Submitted 15 May 2009 ; accepted in final form 2 November 2009 In mammals, nicotinamide phosphoribosyltransferase (NAMPT) is responsible for the first and rate-limiting step in the conversion of nicotinamide to nicotinamide adenine dinucleotide (NAD + ). NAD + is an obligate cosubstrate for mammalian sirtuin-1 (SIRT1), a deacetylase that activates peroxisome proliferator-activated receptor- coactivator-1 (PGC-1 ), which in turn can activate mitochondrial biogenesis. Given that mitochondrial biogenesis is activated by exercise, we hypothesized that exercise would increase NAMPT expression, as a potential mechanism leading to increased mitochondrial content in muscle. A cross-sectional analysis of human subjects showed that athletes had about a twofold higher skeletal muscle NAMPT protein expression compared with sedentary obese, nonobese, and type 2 diabetic subjects ( P < 0.05). NAMPT protein correlated with mitochondrial content as estimated by complex III protein content ( R 2 = 0.28, P < 0.01), MRS-measured maximal ATP synthesis ( R 2 = 0.37, P = 0.002), and O 2max ( R 2 = 0.63, P < 0.0001). In an exercise intervention study, NAMPT protein increased by 127% in sedentary nonobese subjects after 3 wk of exercise training ( P < 0.01). Treatment of primary human myotubes with forskolin, a cAMP signaling pathway activator, resulted in an 2.5-fold increase in NAMPT protein expression, whereas treatment with ionomycin had no effect. Activation of AMPK via AICAR resulted in an 3.4-fold increase in NAMPT mRNA ( P < 0.05) as well as modest increases in NAMPT protein ( P < 0.05) and mitochondrial content ( P < 0.05). These results demonstrate that exercise increases skeletal muscle NAMPT expression and that NAMPT correlates with mitochondrial content. Further studies are necessary to elucidate the pathways regulating NAMPT as well as its downstream effects. nicotinamide phosphoribosyltransferase; pre-B cell colony-enhancing factor; visfatin; mitochondria; adenosine monophosphate-activated protein kinase; primary myotubes Address for reprint requests and other correspondence: S. R. Smith, Pennington Biomedical Research Center, 6400 Perkins Rd., Baton Rouge, LA 70808 (E-mail: smithsr{at}pbrc.edu ).