Recent evidence points to a strong relationship between increased mitochondrial biogenesis and increased survival in eukaryotes. Branched-chain amino acids (BCAAs) have been shown to extend chronological life span in yeast. However, the role of these amino acids in mitochondrial biogenesis and longevity in mammals is unknown. Here, we show that a BCAA-enriched mixture (BCAAem) increased the average life span of mice. BCAAem supplementation increased mitochondrial biogenesis and sirtuin 1 expression in primary cardiac and skeletal myocytes and in cardiac and skeletal muscle, but not in adipose tissue and liver of middle-aged mice, and this was accompanied by enhanced physical endurance. Moreover, the reactive oxygen species (ROS) defense system genes were upregulated, and ROS production was reduced by BCAAem supplementation. All of the BCAAem-mediated effects were strongly attenuated in endothelial nitric oxide synthase null mutant mice. These data reveal an important antiaging role of BCAAs mediated by mitochondrial biogenesis in mammals.

OBJECTIVECannabinoid type 1 (CB1) receptor is involved in whole-body and cellular energy metabolism. We asked whether CB1 receptor stimulation was able to decrease mitochondrial biogenesis in different metabolically active tissues of obese high-fat diet (HFD)-fed mice.RESEARCH DESIGN AND METHODSThe effects of selective CB1 agonist arachidonyl-2-chloroethanolamide (ACEA) and endocannabinoids anandamide and 2-arachidonoylglycerol on endothelial nitric oxide synthase (eNOS) expression were examined, as were mitochondrial DNA amount and mitochondrial biogenesis parameters in cultured mouse and human white adipocytes. These parameters were also investigated in white adipose tissue (WAT), muscle, and liver of mice chronically treated with ACEA. Moreover, p38 mitogen-activated protein kinase (MAPK) phosphorylation was investigated in WAT and isolated mature adipocytes from eNOS−/− and wild-type mice. eNOS, p38 MAPK, adenosine monophosphate–activated protein kinase (AMPK), and mitochondrial biogenesis were investigated in WAT, muscle, and liver of HFD mice chronically treated with ACEA.RESULTSACEA decreased mitochondrial biogenesis and eNOS expression, activated p38 MAPK, and reduced AMPK phosphorylation in white adipocytes. The ACEA effects on mitochondria were antagonized by nitric oxide donors and by p38 MAPK silencing. White adipocytes from eNOS−/− mice displayed higher p38 MAPK phosphorylation than wild-type animals under basal conditions, and ACEA was ineffective in cells lacking eNOS. Moreover, mitochondrial biogenesis was downregulated, while p38 MAPK phosphorylation was increased and AMPK phosphorylation was decreased in WAT, muscle, and liver of ACEA-treated mice on a HFD.CONCLUSIONSCB1 receptor stimulation decreases mitochondrial biogenesis in white adipocytes, through eNOS downregulation and p38 MAPK activation, and impairs mitochondrial function in metabolically active tissues of dietary obese mice.

This study was designed to test the hypothesis that improved mitochondrial biogenesis could help reducing ischemic cerebral injury. We found that levels of proliferator-activated receptor c coactivator 1a and nuclear respiratory factor-1, mitochondrial DNA content and other markers of mitochondrial biogenesis and function were reduced in primary mouse cortical neurons under oxygen-glucose deprivation (OGD). The glycogen synthase kinase-3 (GSK-3) inhibitor SB216763 activated an efficient mitochondrial biogenesis program in control cortical neurons and counteracted the OGD-mediated mitochondrial biogenesis impairment. This was accompanied by the activation of an antioxidant response that reduced mitochondrial reactive oxygen species generation and ischemic neuronal damage. The in vitro effects of SB216763 were mimicked by two other structurally unrelated GSK-3 inhibitors. The protective effects of SB216763 on OGD-mediated neuronal damage were abolished in the presence of diverse mitochondrial inhibitors. Finally, when systemically administered in vivo, SB216763 reduced the infarct size and recovered the loss of mitochondrial DNA in mice subjected to permanent middle cerebral artery occlusion. We conclude that GSK-3 inhibition by SB216763 might pave the way of novel promising therapies aimed at stimulating the renewal of functional mitochondria and reducing reactive oxygen species-mediated damage in ischemic stroke. Keywords: cerebral ischemia, glycogen synthase kinase-3, mitochondrial biogenesis, PGC-1a, reactive oxygen species. Ischemic damage to mitochondria is a key determinant to neuronal injury also because of the increase in the rate of mitochondrial-driven reactive oxygen species (ROS) generation (Galluzzi et al. 2009). Consistent research evidence suggests that the biogenesis of a higher pool of functional mitochondria may lead to reduced ROS production (Guarente 2008). We hypothesized that stimulation of mitochondrial biogenesis could compensate for the deleterious effects of ischemia on neuronal bioenergetics and contribute to reduce brain oxidative damage.Based on pivotal studies in experimental myocardial infaction (Tong et al. 2002) and extensive further evidence reviewed by Juhaszova and colleagues (Juhaszova et al. 2009), the enzyme glycogen synthase kinase-3 (GSK-3) and particularly the GSK-3b isoform is becoming an attractive target for the therapy of cerebral ischemia (Koh et al. 2008;Cowper-Smith et al. 2008). Recent data point to an intriguing relationship between GSK-3b and mitochondrial biology. Activation of the enzyme targets proliferator-activated receptor c coactivator 1a (PGC-1a, a transcriptional coactivator that coordinately regulates the entire mitochondrial biogenesis program) for proteasomal degradation (Anderson and Prolla 2009). Accordingly, GSK-3b inhibition has been linked to PGC-1a stabilization and increased PGC-1a levels in primary neurons (Olson et al. 2008). Further, GSK-3b inactivation has been found to augment cell content of nuclear respiratory factor-1 (NRF-1) ,...