Regulation of the Human Leukemia Inhibitory Factor Gene by <i>ets</i> Transcription Factors

Abstract

Objectives: 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.

Exercise-Induced Myokines With Therapeutic Potential for Muscle Wasting

“…These results contrast with other reports of a pro-cachectic role of (tumor-derived) LIF in cancer-associated muscle wasting (Seto et al, 2015), so further studies are needed to dissect the signaling pathway activated by LIF in muscle fibers and verify whether endogenous expression of LIF is altered in muscles atrophying because of various conditions. The upregulated expression of LIF by exercise is confirmed by other studies (Broholm et al, 2008) and further proven by the existence in the human LIF promoter of two nuclear factor of activated T cells (NFAT) binding sites (Bamberger et al, 2004), a transcription factor well-known to be activated by muscle contractions through the Ca 2+ calmodulin-calcineurin axis (Schiaffino and Serrano, 2002).…”

Pleiotropy and Specificity: Insights from the Interleukin 6 Family of Cytokines

“…Putative NF-kB binding sites can also be found in LIF and OSM promoters, but not CT-1 or CNTF promoters (Bamberger et al, 2004;Chen et al, 2014;Erdmann et al, 1998;Keasey et al, 2013). The p28 (a subunit of IL-27) promoter also contains NF-kB binding sites, and LPS-induced p28 expression is partially dependent on NF-kB p65 and IRF-1 in macrophages (Liu et al, 2007).…”

LIF in the regulation of T-cell fate and as a potential therapeutic

“…21,22 In the human Jurkat T lymphoma cell line, LIF gene expression is regulated by ets (E-twenty six) transcription factors. 23 Alternative splicing results in three forms of LIF The organisation of the LIF gene is complex. By alternative splicing of three alternative first exons to common second and third exons, LIF-D, LIF-M and LIF-T transcripts can occur, each being independently regulated.…”