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Electromagnetic Fields Mediate Efficient Cell Reprogramming into a Pluripotent State
Baek, Soonbong,Quan, Xiaoyuan,Kim, Soochan,Lengner, Christopher,Park, Jung-Keug,Kim, Jongpil American Chemical Society 2014 ACS NANO Vol.8 No.10
<P>Life on Earth is constantly exposed to natural electromagnetic fields (EMFs), and it is generally accepted that EMFs may exert a variety of effects on biological systems. Particularly, extremely low-frequency electromagnetic fields (EL-EMFs) affect biological processes such as cell development and differentiation; however, the fundamental mechanisms by which EMFs influence these processes remain unclear. Here we show that EMF exposure induces epigenetic changes that promote efficient somatic cell reprogramming to pluripotency. These epigenetic changes resulted from EMF-induced activation of the histone lysine methyltransferase Mll2. Remarkably, an EMF-free system that eliminates Earth’s naturally occurring magnetic field abrogates these epigenetic changes, resulting in a failure to undergo reprogramming. Therefore, our results reveal that EMF directly regulates dynamic epigenetic changes through Mll2, providing an efficient tool for epigenetic reprogramming including the acquisition of pluripotency.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-10/nn502923s/production/images/medium/nn-2014-02923s_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn502923s'>ACS Electronic Supporting Info</A></P>
Lim, Seung‐,Oe,Park, Young Min,Kim, Hyeon Seop,Quan, Xiaoyuan,Yoo, Jeong Eun,Park, Young Nyun,Choi, Gi Hong,Jung, Guhung Wiley Subscription Services, Inc., A Wiley Company 2011 Hepatology Vol.53 No.4
<P><B>Abstract</B></P><P>The tumor suppressor p53 is a key prognostic factor in hepatocellular carcinoma (HCC), yet only 35% of grade III tumors exhibit mutation of p53. Several other pathways have been implicated in HCC and, among these, the role of the Notch1/Snail pathway remains unclear. Therefore, we investigated the expression of p53, Notch1, and Snail proteins in HCC with regard to both clinical grade and p53 mutational status. Immunoblotting for p53 revealed that, whereas in many tumors increased p53 was a result of p53 mutation, wildtype p53 (p53WT) expression was also frequently elevated in HCCs. Coordinated evaluation of p53, Notch1, and Snail expression suggests that grade III HCC can be subdivided based on the expression of these three proteins. We found that Notch1 expression in HCC tissues and cell lines is differentially affected by p53WT and mutant p53 (p53Mut). Notch1 expression was correlated with p53 expression in cells expressing p53WT, but was not elevated in p53Mut‐expressing cells. Virally mediated expression or silencing of p53WT or p53Mut confirmed that p53WT overexpression causes Notch1 up‐regulation in HCC. Surprisingly, the consequence of Notch1 overexpression for the proliferative and invasive capacity of HCC cells depends on both the p53 mutational status and activation of the Snail pathway. <I>Conclusion:</I> In the presence of p53WT, Snail/Notch1 activation increased the invasiveness of HCC cells. In contrast, in the absence of p53WT, Notch1 decreased the invasiveness of HCC. Taken together, these findings shed new light on the complex role of the Notch1/Snail axis in HCC and provide a framework for further classifying HCC based on the expression and mutational status of p53 and the expression of Notch1 and Snail. (H<SMALL>EPATOLOGY</SMALL> 2011;53:1352‐1362)</P>