Transcriptional activation of the suppressor of cytokine signaling-3 (SOCS-3) gene via STAT3 is increased in F9 REX1 (ZFP-42) knockout teratocarcinoma stem cells relative to wild-type cells.
Rex1 (Zfp42), first identified as a gene that is transcriptionally repressed by retinoic acid (RA), encodes a zinc finger transcription factor expressed at high levels in F9 teratocarcinoma stem cells, embryonic stem cells, and other stem cells. Loss of both alleles of Rex1 by homologous recombination alters the RA-induced differentiation of F9 cells, a model of pluripotent embryonic stem cells. We identified Suppressor of Cytokine Signaling-3 (SOCS-3) as a gene that exhibits greatly increased transcriptional activation in RA, cAMP, and theophylline (RACT)-treated F9 Rex1(-/-) cells (approximately 25-fold) as compared to wild-type (WT) cells ( approximately 2.5-fold). By promoter deletion, mutation, and transient transfection analyses, we have shown that this transcriptional increase is mediated by the STAT3 DNA-binding elements located between -99 to -60 in the SOCS-3 promoter. Overexpression of STAT3 dominant-negative mutants greatly diminishes this SOCS-3 transcriptional increase in F9 Rex1(-/-) cells. This increase in SOCS-3 transcription is associated with a four- to fivefold higher level of tyrosine-phosphorylated STAT3 in the RACT-treated F9 Rex1(-/-) cells as compared to WT. Dominant-negative Src tyrosine kinase, Jak2, and protein kinase A partially reduce the transcriptional activation of the SOCS 3 gene in RACT-treated F9 Rex1 null cells. In contrast, parathyroid hormone peptide enhances the effect of RA in F9 Rex1(-/-) cells, but not in F9 WT. Thus, Rex1, which is highly expressed in stem cells, inhibits signaling via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, thereby modulating the differentiation of F9 cells.
Xu
Juliana
J
Pharmacology Department, Weill Cornell Medical College, 1300 York Avenue, Room E-409, New York, NY 10021, USA.
Sylvester
Renia
R
Tighe
Ann P
AP
Chen
Siming
S
Gudas
Lorraine J
LJ
D000818:Animals; D001665:Binding Sites; D003994:Bucladesine / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D054278:Embryonal Carcinoma Stem Cells; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D053614:Janus Kinase 2 / Q000378:metabolism; D008623:Mercaptoethanol / Q000494:pharmacology; D051379:Mice; D046228:Microarray Analysis; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics* / Q000378:metabolism; D018243:Teratocarcinoma / Q000201:enzymology / Q000235:genetics*; D013806:Theophylline / Q000494:pharmacology; D014157:Transcription Factors / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology
D010281:Parathyroid Hormone; D010455:Peptides; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; C513672:Zfp42 protein, mouse; D050796:STAT3 Transcription Factor; C491411:Socs3 protein, mouse; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D014157:Transcription Factors; D014212:Tretinoin; D008623:Mercaptoethanol; D003994:Bucladesine; D013806:Theophylline; D053614:Janus Kinase 2; D016392:Proto-Oncogene Proteins pp60(c-src); D017868:Cyclic AMP-Dependent Protein Kinases