Aberrant DNA Methylation in Human iPSCs Associates with MYC-Binding Motifs in a Clone-Specific Manner Independent of Genetics

Publication date: 6 April 2017
Source:Cell Stem Cell, Volume 20, Issue 4
Author(s): Athanasia D. Panopoulos, Erin N. Smith, Angelo D. Arias, Peter J. Shepard, Yuriko Hishida, Veronica Modesto, Kenneth E. Diffenderfer, Clay Conner, William Biggs, Efren Sandoval, Agnieszka D'Antonio-Chronowska, W. Travis Berggren, Juan Carlos Izpisua Belmonte, Kelly A. Frazer
Induced pluripotent stem cells (iPSCs) show variable methylation patterns between lines, some of which reflect aberrant differences relative to embryonic stem cells (ESCs). To examine whether this aberrant methylation results from genetic variation or non-genetic mechanisms, we generated human iPSCs from monozygotic twins to investigate how genetic background, clone, and passage number contribute. We found that aberrantly methylated CpGs are enriched in regulatory regions associated with MYC protein motifs and affect gene expression. We classified differentially methylated CpGs as being associated with genetic and/or non-genetic factors (clone and passage), and we found that aberrant methylation preferentially occurs at CpGs associated with clone-specific effects. We further found that clone-specific effects play a strong role in recurrent aberrant methylation at specific CpG sites across different studies. Our results argue that a non-genetic biological mechanism underlies aberrant methylation in iPSCs and that it is likely based on a probabilistic process involving MYC that takes place during or shortly after reprogramming.

Graphical abstract

Teaser

Working as part of the NHLBI NextGen consortium, Panopoulos et al. use iPSCs derived from monozygotic twins to examine factors regulating aberrant CpG methylation. Their findings suggest that aberrant methylation is likely due to a clone-associated biological mechanism involving Myc proteins and gene expression changes.


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