Publikationsdatum:
2015-09-26
Beschreibung:
Oncostatin-M (OSM) is a patho-physiologically important pleiotropic, multifunctional cytokine. OSM mRNA sequence analysis revealed that its 3'UTR contains three highly conserved GC-rich cis -elements (GCREs) whose role in mRNA stability is unidentified. In the present study, the functional role of the proximal GC-rich region of osm 3'-UTR (GCRE-1) in post-transcriptional regulation of osm expression in U937 cells was assessed by transfecting construct containing GCRE-1 at 3' end of a fairly stable reporter gene followed by analysis of the expression of the reporter. GCRE-1 showed mRNA destabilizing activity however, upon PMA treatment the reporter message containing GCRE-1 was stabilized. This stabilization is owing to a time dependent progressive binding of trans -factors (atleast five proteins) to GCRE-1 post PMA treatment. Nucleolin was identified as one of the proteins in the RNP complex of GCRE-1 with PMA treated U937 cytosolic extracts by oligo-dT affinity chromatography of poly-adenylated GCRE-1. Immuno-blot revealed time dependent enhancement of nucleolin in the cytoplasm which in turn directly binds GCRE-1. RNA co-immunoprecipitation confirmed the GCRE-1-nucleolin interaction in-vivo . To elucidate the functional role of nucleolin in stabilization of osm mRNA, nucleolin was overexpressed in U937 cells and found to stabilize the intrinsic osm mRNA, where co-transfection with the reporter containing GCRE-1 confirms the role of GCRE-1 in stabilization of the reporter mRNA. Thus in conclusion, the results asserted that PMA treatment in U937 cells leads to cytoplasmic translocation of nucleolin that directly binds GCRE-1, one of the major GC-rich instability elements, thereby stabilizing the osm mRNA. This article is protected by copyright. All rights reserved
Digitale ISSN:
0091-7419
Thema:
Biologie
,
Chemie und Pharmazie
,
Medizin
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