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Involvement of KSRP in the post-transcriptional regulation of human iNOS expression–complex interplay of KSRP with TTP and HuR

Katrin Linker, Andrea Pautz, Marcel Fechir, Thomas Hubrich, Jobst Greeve, Hartmut Kleinert
We purified the KH-type splicing regulatory protein (KSRP) as a protein interacting with the 3 0 -untranslated region (3 0 -UTR) of the human inducible nitric oxide (iNOS) mRNA. Immunodepletion of KSRP enhanced iNOS 3 0 -UTR RNA stability in in vitrodegradation assays. In DLD-1 cells overexpressing KSRP cytokine-induced iNOS expression was markedly reduced. In accordance, downregulation of KSRP expression increases iNOS expression by stabilizing iNOS mRNA. Co-immunoprecipitations showed
more » ... ion of KSRP with the exosome and tristetraprolin (TTP). To analyze the role of KSRP binding to the 3 0 -UTR we studied iNOS expression in DLD-1 cells overexpressing a non-binding mutant of KSRP. In these cells, iNOS expression was increased. Mapping of the binding site revealed KSRP interacting with the most 3 0 -located AU-rich element (ARE) of the human iNOS mRNA. This sequence is also the target for HuR, an iNOS mRNA stabilizing protein. We were able to demonstrate that KSRP and HuR compete for this binding site, and that intracellular binding to the iNOS mRNA was reduced for KSRP and enhanced for HuR after cytokine treatment. Finally, a complex interplay of KSRP with TTP and HuR seems to be essential for iNOS mRNA stabilization after cytokine stimulation.
doi:10.7892/boris.115135 fatcat:7aiguidlivdqzef4br7pppfrvu

Pathomechanisms in hepatocellular carcinoma : characterisation of leukocyte recruitment, the role of the mRNA-binding protein tristetraprolin and nuclear paraspeckles [article]

Kevan Hosseini, Universität Des Saarlandes, Universität Des Saarlandes
Hartmut Kleinert (Fechir et al., 2005) and the sequence was verified by sequencing.  ...  Marcel H. Schulz (Department of Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarbrücken, Germany).  ... 
doi:10.22028/d291-27154 fatcat:xydzqtdy5rfrbhla5pxhltszdm