Tpt1 activates transcription of oct4 and nanog in transplanted somatic nuclei.
Nuclear transfer to eggs or oocytes provides a potential route for cell-replacement therapies because oocytes directly reprogram transplanted mammalian somatic-cell nuclei such that they have an embryo-like pattern of gene expression. This includes a large increase in the mRNA level of the stem-cell marker gene oct4. We have developed a novel procedure to identify new proteins that greatly increase the level of oct4 mRNA upon nuclear transfer. We have isolated Xenopus oocyte proteins that bind to the regulatory region of the mouse oct4 gene and identified these by mass spectrometry. The proteins include the retinoic-acid-receptor gamma, a known repressor of oct4 transcription, and Tpt1, a cancer-associated factor. The depletion of transcripts of retinoic-acid receptor gamma from oocytes increases oct4 and nanog transcription as expected, and depletion of tpt1 transcripts in oocytes reduces oct4 and nanog transcription in injected HeLa nuclei. An elevation of tpt1 transcripts in oocytes results in an earlier activation of oct4 transcription. Therefore, we identify a novel role for tpt1 in activating pluripotency genes upon nuclear transfer. Our results help to elucidate the mechanism by which somatic-cell nuclei are reprogrammed to have an embryo-like pattern of gene expression.
Koziol
Magdalena J
MJ
Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK.
Garrett
Nigel
N
Gurdon
J B
JB
D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D004268:DNA-Binding Proteins; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000502:physiology*; D006367:HeLa Cells; D018398:Homeodomain Proteins; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D000071317:Nanog Homeobox Protein; D053652:Nuclear Transfer Techniques; D050814:Octamer Transcription Factor-3 / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D000090324:Tumor Protein, Translationally-Controlled 1; D014982:Xenopus laevis; D000097768:Retinoic Acid Receptor gamma
D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D000090324:Tumor Protein, Translationally-Controlled 1; D000097768:Retinoic Acid Receptor gamma; C475540:Nanog protein, mouse; C000715647:TPT1 protein, human; C000715648:Tpt1 protein, mouse