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Early role for IL-6 signalling during generation of induced pluripotent stem cells revealed by heterokaryon RNA-Seq

Nature Cell Biology volume 15, pages 12441252 (2013) | Download Citation


Molecular insights into somatic cell reprogramming to induced pluripotent stem cells (iPS) would aid regenerative medicine, but are difficult to elucidate in iPS because of their heterogeneity, as relatively few cells undergo reprogramming (0.1–1%; refs 1, 2). To identify early acting regulators, we capitalized on non-dividing heterokaryons (mouse embryonic stem cells fused to human fibroblasts), in which reprogramming towards pluripotency is efficient and rapid3, enabling the identification of transient regulators required at the onset. We used bi-species transcriptome-wide RNA-seq to quantify transcriptional changes in the human somatic nucleus during reprogramming towards pluripotency in heterokaryons. During heterokaryon reprogramming, the cytokine interleukin 6 (IL6), which is not detectable at significant levels in embryonic stem cells, was induced 50-fold. A 4-day culture with IL6 at the onset of iPS reprogramming replaced stably transduced oncogenic c-Myc such that transduction of only Oct4, Klf4 and Sox2 was required. IL6 also activated another Jak/Stat target, the serine/threonine kinase gene Pim1, which accounted for the IL6-mediated twofold increase in iPS frequency. In contrast, LIF, another induced GP130 ligand, failed to increase iPS frequency or activate c-Myc or Pim1, thereby revealing a differential role for the two Jak/Stat inducers in iPS generation. These findings demonstrate the power of heterokaryon bi-species global RNA-seq to identify early acting regulators of reprogramming, for example, extrinsic replacements for stably transduced transcription factors such as the potent oncogene c-Myc.

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We thank M. Wernig and S. Marro for providing expert guidance with iPS protocols and for the STEMCAA 4F lentiviral construct and R. Tran-Bussat for isolating MEFs. We thank S. L. Oliver, S. Corbel and D. Burns for their insightful comments on the manuscript, the ENCODE Project, in particular Barbara Wold who was very helpful in the initiation of this work, and the Stanford FACS Facility, PAN Facility, and Stem Cell Institute Genome Facility. This work was supported by NSF and Bio-X Graduate Research Fellowships to J.J.B., by NIH grant R01 HG005717 and HG006018 to W.H.W., and by CIRM grant RB1-01292, NIH U01 HL100397, NIH R01 AG009521 and the Baxter Foundation to H.M.B.

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Author notes

    • Hui Jiang

    Present address: Department of Biostatistics, University of Michigan, Ann Arbor, Michigan 48109, USA


  1. Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California 94305, USA

    • Jennifer J. Brady
    • , Silpa Suthram
    •  & Helen M. Blau
  2. Institute for Computational and Mathematical Engineering, Stanford University, Stanford, California 94305, USA

    • Mavis Li
    •  & Hui Jiang
  3. Department of Statistics, Stanford University, Stanford, California 94305, USA

    • Mavis Li
    • , Hui Jiang
    •  & Wing H. Wong


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J.J.B. and H.M.B. designed the experiments, interpreted the results and wrote the manuscript. J.J.B. performed all of the experiments, H.J. designed SeqMap and M.L. generated the RPKM values under the direction of W.H.W. S.S. performed the NOISeq analysis.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Helen M. Blau.

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