title: C/EBPα bypasses cell cycle-dependency during immune cell transdifferentiation.
abstract: 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 G(0), 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 G(0)/G(1) and G(2)/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.
authors: Gene Regulation, Stem Cells and Cancer Program, Center for Genomic Regulation and Pompeu Fabra University, Barcelona, Spain.
authors: Alessandro
authors: A
authors: Di Tullio
authors: Thomas
authors: T
authors: Graf
mesh_terms: D000818:Animals; D018941:Antigens, CD19 / Q000378:metabolism; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D002455:Cell Division; D002460:Cell Line; D054338:Cell Transdifferentiation; D004247:DNA / Q000378:metabolism; D016193:G1 Phase; D016195:G2 Phase; D057026:Induced Pluripotent Stem Cells / Q000166:cytology; D051379:Mice; D054448:Precursor Cells, B-Lymphoid / Q000166:cytology / Q000276:immunology; D016192:Resting Phase, Cell Cycle; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D018941:Antigens, CD19; D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D016159:Tumor Suppressor Protein p53; D004247:DNA