Quiescence loosens epigenetic constraints in bovine somatic cells and improves their reprogramming into totipotency

Prasanna K. Kallingappa, Pavla M. Turner, Michael P. Eichenlaub, Andria L. Green, Fleur C. Oback, Alice M. Chibnall, David N. Wells, Björn Oback

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12 Citations (Scopus)

Abstract

Reprogramming by nuclear transfer (NT) cloning forces cells to lose their lineage-specific epigenetic marks and reacquire totipotency. This process often produces molecular anomalies that compromise clone development. We hypothesized that quiescence alters the epigenetic status of somatic NT donor cells and elevates their reprogrammability. To test this idea, we compared chromatin composition and cloning efficiency of serum-starved quiescent (G0) fibroblasts versus nonstarved mitotically selected (G1) controls. We show that G0 chromatin contains reduced levels of Polycomb group proteins EED, SUZ12, PHC1, and RING2, as well as histone variant H2A.Z. Using quantitative confocal immunofluorescence microscopy and fluorometric enzyme-linked immunosorbent assay, we further show that G0 induced DNA and histone hypomethylation, specifically at H3K4me3, H3K9me2/3 and H3K27me3, but not H3K9me1. Collectively, these changes resulted in a more relaxed G0 chromatin state. Following NT, G0 donors developed into blastocysts that retained H3K9me3 hypomethylation, both in the inner cell mass and trophectoderm. G0 blastocysts from different cell types and cell lines developed significantly better into adult offspring. In conclusion, serum starvation induced epigenetic changes, specifically hypotrimethylation, that provide a mechanistic correlate for increased somatic cell reprogrammability.

Original languageEnglish
Article number16
Number of pages10
JournalBiology of Reproduction
Volume95
Issue number1
DOIs
Publication statusPublished - 1 Jul 2016

Keywords

  • Cell cycle
  • Epigenetics
  • Histone modifications
  • Nuclear transfer
  • Reprogramming

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