Regulation of the human leukemia inhibitory factor gene by ETS transcription factors.
OBJECTIVE
Leukemia inhibitory factor (LIF) is a pleiotropic cytokine mainly produced by activated T lymphocytes. We previously demonstrated that human Jurkat T lymphoma cells represent a valid model of LIF gene expression. This study was designed to identify regions critical for LIF promoter activation in Jurkat cells.


METHODS
Luciferase constructs under the control of different portions of the human LIF promoter were transfected into Jurkat cells, and promoter activity was determined by luminometry. Similar experiments were performed with constructs bearing mutations in the putative ETS binding regions in the LIF promoter. RT-PCR, Western blot and gelshift experiments were performed to study expression and DNA binding of ETS factors in lymphoid cells.


RESULTS
With the exception of the shortest construct not including the putative ETS binding sites, all wildtype LIF promoter constructs were strongly inducible by phorbol ester/ionomycin. In contrast, the mutant constructs were significantly less inducible. Cotransfection of the wild-type constructs with ETS expression vectors resulted in significant enhancement of promoter activity. ets-1 and ets-2 mRNA and protein were shown to be expressed in Jurkat cells. Gelshift experiments revealed that proteins present in nuclear extracts from Jurkat cells specifically bind to both artificial ETS consensus sites and ETS binding sites present in the LIF promoter.


CONCLUSIONS
We conclude that binding of ETS transcription factors to the ETS binding sites in the human LIF promoter is critical for its inducibility in response to T cell activators. ETS transcription factors thus play an important functional role within the endocrine-immune network.
Bamberger
Ana-Maria
AM
Institute of Pathology, University Hospital Eppendorf, Hamburg, Germany. bamberger@uke.uni-hamburg.de
Jenatschke
Susanne
S
Schulte
Heinrich M
HM
Ellebrecht
Iring
I
Beil
Frank Ulrich
FU
Bamberger
Christoph M
CM
D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D005822:Genetic Vectors; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D019169:Jurkat Cells; D053605:Leukemia Inhibitory Factor; D008213:Lymphocyte Activation / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D010703:Phorbol Esters / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D050784:Proto-Oncogene Protein c-ets-1; D050787:Proto-Oncogene Protein c-ets-2; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics*; D014162:Transfection
D004268:DNA-Binding Proteins; C107465:ERF protein, human; C494041:ETS1 protein, human; C494069:ETS2 protein, human; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D010703:Phorbol Esters; D050784:Proto-Oncogene Protein c-ets-1; D050787:Proto-Oncogene Protein c-ets-2; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D004247:DNA