C/EBPα bypasses cell cycle-dependency during immune cell transdifferentiation
Volume 11, Issue 14
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July 15, 2012
Pages 2739 - 2746http://dx.doi.org/10.4161/cc.21119
: C/EBPa, cell cycle, cell fate, lineage reprogramming, transdifferentiation
Authors: Alessandro Di Tullio and Thomas Graf View affiliations
Our earlier work has shown that pre-B cells can be converted into macrophage-like cells by overexpression of the transcription factor C/EBPα or C/EBPβ with high efficiency. Using inducible pre-B cell lines, we have now investigated the role of cell division during C/EBP-induced reprogramming. The majority of cells reprogrammed by C/EBPα incorporated BrdU before arresting at G0, and all C/EBPβ-induced cells incorporated the compound. This contrasts with reports from other systems where transdifferentiating cells essentially do not divide. Although inhibition of DNA synthesis led to an impairment of C/EBPα-induced transdifferentiation, sorted G0/G1 and G2/M fractions showed no significant differences in their reprogramming kinetics. In addition, knocking-down p53 did not accelerate the transdifferentiation frequency, as it has been described for reprogramming of induced pluripotent (iPS) cells. Time-lapse experiments showed that, after C/EBPα induction, approximately 90% of cells divide once or twice, while 8% do not divide at all before acquiring a macrophage phenotype, supporting our BrdU incorporation results. Importantly, the non-dividing cell subset expressed the highest levels of C/EBPα and was the fastest in differentiating, suggesting that high levels of C/EBPα accelerate both the switching process and the cells’ growth arrest. Our data show that traversing the cell cycle is not strictly required for pre-B cell to macrophage conversion and provides new evidence for the notion that the mechanisms of transcription factor induced transdifferentiation and iPS cell reprogramming differ.
Received: May 8, 2012; Accepted: June 13, 2012
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