Nicotinamide adenine dinucleotide (NAD) exists in two forms in the cell: NAD+ (oxidized) and NADH (reduced). This molecule plays a pivotal role in metabolic processes, serving as a key electron carrier in the redox reactions that drive cellular metabolism. The balance between these two forms, commonly expressed as the NAD+/NADH ratio, is crucial for maintaining cellular function and the intracellular redox state. This article explores the significance of this ratio, how it impacts cellular processes, and the consequences of NAD+/NADH ratio dysregulation.
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NAD: A Renaissance Molecule and its Role in Cell Health
NAD is a pyridine nucleotide. It provides the oxidation and reduction power for generation of ATP by mitochondria. For many years it was believed that the primary function of NAD/NADH in cells was to harness and transfer energy from glucose, fatty and amino acids through pathways like glycolysis, beta-oxidation and the citric acid cycle.
However NAD also is recognized as an important cell signaling molecule and substrate. The many regulatory pathways now known to use NAD+ in signaling include multiple aspects of cellular homeostasis, energy metabolism, lifespan regulation, apoptosis, DNA repair and telomere maintenance.
This resurrection of NAD importance is due in no small part to the discovery of NAD-using enzymes, especially the sirtuins.
Continue reading “NAD: A Renaissance Molecule and its Role in Cell Health”Finding Chinks in the Armor: Cancer’s Need for Metabolites
Cancer has been studied for decades by scientists trying to find a vulnerability to exploit and testing compounds to develop as potential drugs. As the “Emperor of All Maladies”, cancer has proven itself to be a wily beast with many varieties of genetic mutations for eluding cellular control, tireless in its ability to divide and spread. In the end, a cancer cell is still a cell and subject to its environment even though cancer does not play by the same rules as the normal cells that exist around it. To be able to grow, a cell needs access to metabolites, molecules needed for building the materials and machinery needed by the cell to function and divide. These requirements also offer potential pathways to target for halting cancer growth and spread.
All cells use glucose to generate ATP, but normal and cancer cells differ in how glucose is converted to ATP. Most cells use glucose in oxidative phosphorylation, but cancer cells use aerobic glycolysis, converting glucose to lactate without oxygen. This Warburg effect (glucose converted to lactate) is a hallmark of cancer cells as they take up glucose at a much higher rate than normal cells. Blocking glucose uptake is one way to target cancer cells. While 2-deoxyglucose (2DG) has been shown to slow glucose uptake in vitro, the compound proved toxic in clinical trials and lower dosages do not seem to be an effective treatment against cancer. While not an ideal drug target, glucose uptake has been helpful in monitoring cancer response to therapies via fluorodeoxyglucose positron emission tomography (FDG-PET).
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