Author: Gianpiero Pescarmona
Date: 13/03/2007


NAD description and metabolism

Energy and signal transduction by NAD:Signalling pathways and subcellular compartmentation of NAD biosynthesis

The local NADH/NAD ratio can drive metabolic pathways

  • inositol synthesis is inhibited by NADH and affects
    • IP3 related pathways
    • membrane bound Proteins (with GPI anchor)
  • regulate proteins acetylation and deacetylation (Sirtuins).
  • regulate triglyceride synthesis

  • regulate T4 deiodination to T3

Glucose restriction blocks skeletal muscle cell differentiation 2008

  • Abstract
    Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway (PPP) and plays an essential role in the oxidative stress response by producing NADPH, the main intracellular reductant. G6PD deficiency is the most common human enzyme defect, affecting more than 400 million people worldwide. Here, we show that G6PD is negatively regulated by acetylation on lysine 403 (K403), an evolutionarily conserved residue. The K403 acetylated G6PD is incapable of forming active dimers and displays a complete loss of activity. Knockdown of G6PD sensitizes cells to oxidative stress, and re-expression of wild-type G6PD, but not the K403 acetylation mimetic mutant, rescues cells from oxidative injury. Moreover, we show that cells sense extracellular oxidative stimuli to decrease G6PD acetylation in a SIRT2-dependent manner. The SIRT2-mediated deacetylation and activation of G6PD stimulates PPP to supply cytosolic NADPH to counteract oxidative damage and protect mouse erythrocytes. We also identified KAT9/ELP3 as a potential acetyltransferase of G6PD. Our study uncovers a previously unknown mechanism by which acetylation negatively regulates G6PD activity to maintain cellular NADPH homeostasis during oxidative stress.

Working hypothesis

High NADH/NAD means excess Acetyl-CoA--> G6PD acetylation --> G6PD inactivation --> less NADPH -->less Fatty acids synthesis

Sirtuin SRT2 revert G6PD inactivation

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