title: Nicotinamide overcomes pluripotency deficits and reprogramming barriers.
abstract: Crosstalk between intracellular signaling pathways has been extensively studied to understand the pluripotency of human pluripotent stem cells (hPSCs), including human embryonic stem cells and human induced pluripotent stem cells (hiPSCs); however, the contribution of NAD(+) -dependent pathways remains largely unknown. Here, we show that NAD(+) depletion by FK866 (a potent inhibitor of NAD(+) biosynthesis) was fatal in hPSCs, particularly when deriving pluripotent cells from somatic cells and maintaining pluripotency. NAD and its precursors (nicotinamide [NAM] and nicotinic acid) fully replenished the NAD(+) depletion by FK866 in hPSCs. However, only NAM effectively enhanced the reprogramming efficiency and kinetics of hiPSC generation and was also significantly advantageous for the maintenance of undifferentiated hPSCs. Our molecular and functional studies reveal that NAM lowers the barriers to reprogramming by accelerating cell proliferation and protecting cells from apoptosis and senescence by alleviating oxidative stress, reactive oxygen species accumulation, and subsequent mitochondrial membrane potential collapse. We provide evidence that the positive effects of NAM (occurring at concentrations well above the physiological range) on pluripotency control are molecularly associated with the repression of p53, p21, and p16. Our findings establish that adequate intracellular NAD(+) content is crucial for pluripotency; the distinct effects of NAM on pluripotency may be dependent not only on its metabolic advantage as a NAD(+) precursor but also on the ability of NAM to enhance resistance to cellular stress.
authors.affiliation: Regenerative Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.
authors.forename: Myung Jin
authors.initials: MJ
authors.lastname: Son
authors.forename: Mi-Young
authors.initials: MY
authors.lastname: Son
authors.forename: Binna
authors.initials: B
authors.lastname: Seol
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Chae Hwa
authors.initials: CH
authors.lastname: Yoo
authors.forename: Myung-Kwan
authors.initials: MK
authors.lastname: Han
authors.forename: Yee Sook
authors.initials: YS
authors.lastname: Cho
mesh_terms: D017209:Apoptosis / Q000235:genetics; D002460:Cell Line; D049109:Cell Proliferation; D065150:Cellular Reprogramming / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism; D007700:Kinetics; D053078:Membrane Potential, Mitochondrial / Q000235:genetics; D009243:NAD / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D009525:Niacin / Q000235:genetics / Q000378:metabolism; D009536:Niacinamide / Q000235:genetics* / Q000378:metabolism*; D018384:Oxidative Stress / Q000235:genetics; D039904:Pluripotent Stem Cells / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C493956:CDKN1A protein, human; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D009243:NAD; D009536:Niacinamide; D009525:Niacin