Oncostatin-M (OSM) is a pleotropic cytokine belonging to the interleukin-6 family. Differential expression of OSM in response to varying stimuli and exhibiting repertoire of functions in different cells renders it challenging to study the mechanism of its expression. Prostaglandin E2 (PGE2) transcriptionally increased osm levels. In silico studies of ∼1 kb upstream of osm promoter region yielded the presence of CRE (cyclic AMP response element)-like sites at the distal end (CREosm). Deletion and point mutation of CREosm clearly indicated that this region imparted an important role in PGE2-mediated transcription. Nuclear protein(s) from PGE2-treated U937 cells, bound to this region, was identified as CRE-binding protein (CREB). CREB was phosphorylated on treatment and was found to be directly associated with CREosm. The presence of cofactors p300 and CREB-binding protein in the complex was confirmed. A marked decrease in CREB phosphorylation, binding and transcriptional inhibition on treatment with PKA (protein kinase A) inhibitor, H89 (N-[2-[[3-(4-bromophenyl)-2-propenyl]amino]ethyl]-5-soquinolinesulfonamide), revealed the role of phosphorylated CREB in osm transcription. Additionally, other nuclear protein(s) were specifically associated with the proximal GC region (GCosm) post PGE2 treatment, later confirmed to be specificity protein 1 (Sp1). Interestingly, Sp1 bound to the proximal osm promoter was found to be associated with phospho-CREB–p300 complex bound to the distal osm promoter. Knockdown of Sp1 abrogated the expression and functionality of OSM. Thus, the present study conclusively proves that these transcription factors, bound at the distal and proximal promoter elements are found to associate with each other in a DNA-dependent manner and both are responsible for the PGE2-mediated transcriptional up-regulation of Oncostatin-M.
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January 2018
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In this issue of the Biochemical Journal, Dukic et al. report that ezrin-anchored PKA phosphorylates serine 369 and 373 on connexin 43 to enhance gap junction assembly, communication, and cell fusion. The cover image, taken from Figure 6 in the article, shows HEK293 cells transfected with mammalian expression vectors encoding siRNA-resistant Cx43 without ability to bind to ezrin and with a phosphomimicking S to D substitution in residue 369.
Research Article|
January 31 2018
Mechanism of prostaglandin E2-induced transcriptional up-regulation of Oncostatin-M by CREB and Sp1
Srimoyee Mukherjee;
Srimoyee Mukherjee
1Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009, India
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Sumita Sengupta Bandyopadhyay
1Department of Biophysics, Molecular Biology and Bioinformatics, University of Calcutta, 92 A.P.C. Road, Kolkata 700009, India
Correspondence: Sumita Sengupta Bandyopadhyay (ssbmbg@caluniv.ac.in, bandyopas@gmail.com)
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Publisher: Portland Press Ltd
Received:
July 06 2017
Revision Received:
December 19 2017
Accepted:
December 20 2017
Accepted Manuscript online:
December 22 2017
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2018
Biochem J (2018) 475 (2): 477–494.
Article history
Received:
July 06 2017
Revision Received:
December 19 2017
Accepted:
December 20 2017
Accepted Manuscript online:
December 22 2017
Citation
Srimoyee Mukherjee, Sumita Sengupta Bandyopadhyay; Mechanism of prostaglandin E2-induced transcriptional up-regulation of Oncostatin-M by CREB and Sp1. Biochem J 31 January 2018; 475 (2): 477–494. doi: https://doi.org/10.1042/BCJ20170545
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