Browsing by keyword "*Nuclear Reprogramming"

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    • Midbody accumulation through evasion of autophagy contributes to cellular reprogramming and tumorigenicity
      Kuo, Tse-Chun; Chen, Chun-Ting; Baron, Desiree; Onder, Tamer T.; Loewer, Sabine; Almeida, Sandra; Weismann, Cara M.; Xu, Ping; Houghton, JeanMarie; Gao, Fen-Biao; et al. (2011-09-11)
      The midbody is a singular organelle formed between daughter cells during cytokinesis and required for their final separation. Midbodies persist in cells long after division as midbody derivatives (MB(d)s), but their fate is unclear. Here we show that MB(d)s are inherited asymmetrically by the daughter cell with the older centrosome. They selectively accumulate in stem cells, induced pluripotent stem cells and potential cancer 'stem cells' in vivo and in vitro. MB(d) loss accompanies stem-cell differentiation, and involves autophagic degradation mediated by binding of the autophagic receptor NBR1 to the midbody protein CEP55. Differentiating cells and normal dividing cells do not accumulate MB(d)s and possess high autophagic activity. Stem cells and cancer cells accumulate MB(d)s by evading autophagosome encapsulation and exhibit low autophagic activity. MB(d) enrichment enhances reprogramming to induced pluripotent stem cells and increases the in vitro tumorigenicity of cancer cells. These results indicate unexpected roles for MB(d)s in stem cells and cancer 'stem cells'.

    • Pluripotency: toward a gold standard for human ES and iPS cells
      Smith, Kelly P.; Luong, Mai X.; Stein, Gary S. (2009-07-28)
      With the advent of technologies for the derivation of embryonic stem cells and reprogrammed stem cells, use of the term "pluripotent" has become widespread. Despite its increased scientific and political importance, there are ambiguities with this designation and a common standard for experimental approaches that precisely define this state in human cells remains elusive. Recent studies have revealed that reprogramming may occur via many pathways which do not always lead to pluripotency. In addition, the pluripotent state itself appears to be highly dynamic, leading to significant variability in the results of molecular studies. Establishment of a stringent set of criteria for defining pluripotency will be vital for biological studies and potential clinical applications in this rapidly evolving field. In this review, we explore the various definitions of pluripotency, examine the current status of pluripotency testing in the field and provide an analysis of how these assays have been used to establish pluripotency in the scientific literature.