title: PU.1 is dispensable to block erythroid differentiation in Friend erythroleukemia cells.
abstract: Friend murine erythroleukemia cell lines derive from erythroblasts transformed with the Friend complex where the spleen-focus forming virus integrated in the vicinity of the Sfpi-1 locus. Erythroleukemia cells do not differentiate and grow indefinitely in the absence of erythropoietin. Activation of the transcription factor PU.1, encoded by the Sfpi-1 gene, is thought to be responsible for the transformed phenotype. These cells can overcome the blockage and reinitiate their differentiation program when exposed to some chemical inducers such as hexamethylene bisacetamide. In this study, we established cell cultures that were capable to proliferate unconstrained in the presence of the inducer. Resistant cell lines restart erythroid differentiation, though, if forced to exit the cell cycle or by overexpressing the transcription factor GATA-1. Unexpectedly, expression of PU.1 was suppressed in the resistant clones albeit the spleen-focus forming virus was still integrated in the proximity of the Sfpi-1 locus. Exposure to 5-Aza-2'-deoxycytidine activates PU.1 expression suggesting that the PU.1 coding gene is highly methylated in the resistant cells. Altogether these results suggest that PU.1 is dispensable to block erythroid differentiation.
authors.affiliation: Department of Cell and Developmental Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040-Madrid, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Fernández-Nestosa
authors.forename: Pablo
authors.initials: P
authors.lastname: Hernández
authors.forename: Jorge B
authors.initials: JB
authors.lastname: Schvartzman
authors.forename: Dora B
authors.initials: DB
authors.lastname: Krimer
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000818:Animals; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002454:Cell Differentiation; D000077209:Decitabine; D004351:Drug Resistance; D041905:Erythroid Cells / Q000473:pathology; D005622:Friend murine leukemia virus; D050982:GATA1 Transcription Factor / Q000378:metabolism; D016259:Genes, myc; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology*; D007942:Leukemia, Experimental / Q000378:metabolism / Q000473:pathology; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D000081:Acetamides; D001374:Azacitidine; D000077209:Decitabine; D050982:GATA1 Transcription Factor; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C494689:Gata1 protein, mouse; C014026:hexamethylene bisacetamide