[[White blood cell|Leukocytes]] are important components in our [[Immune system|immune systems]] that include [[Neutrophil|neutrophils]]. Neutrophils, are the most abundant type of granulocytes and are responsible for leading the majority of the immune system response against invaders. Granulocyte-colony stimulating factor (G-CSF) is a [[glycoprotein]] that stimulates proliferation of neutrophil [[Progenitor cell|progenitor cells]] and leads to the maturation of neutrophils. [[Monocyte|Monocytes]] and [[Macrophage|macrophages]] are the cells that secrete G-CSF, but it is found that [[Endothelium|endothelial cells]], [[Fibroblast|fibroblasts]], and [[Bone marrow|bone marrow stromal cells]] also secrete the glycoprotein. Expression of G-CSF glycoprotein is complex and has both transcription and post transcription regulation. Two specific types of [[Regulatory sequence|regulatory elements]] are present in the [[Three prime untranslated region|3' untranslated region]] (3'UTR) of G-CSF [[Messenger RNA|mRNA]]. These elements are referred to as adenylate uridylate-rich elements (AUREs) and stem-loop destabilizing element (SLDE). They have been shown to be destabilizing elements of the G-CSF mRNA. On the other hand, the stability of the mRNA is regulated by [[P38 mitogen-activated protein kinases|p38 mitogen-activated protein kinase]] (MAPK) and this phosphorylating enzyme has been shown to be linked to the AUREs in the 3'UTR. However, much is not known about the role p38 MAPK plays in the regulation of the stability of G-CSF mRNA.
ASB203580 studyspecifically publishedinhibits the [[Catalysis|catalytic activity]] of p38 MAPK by Shwu-Fencompetitively Changbinding to the active site where [[ATP synthase|ATP]] is supposed to etbind and is widely used in other studies to display the role of p38 MAPK in other biological systems.al<ref>{{Cite journal|last=Chang|first=Shwu-Fen|last2=Li|first2=Huai-Ci|last3=Huang|first3=Yu-Pei|last4=Tasi|first4=Wen-Ju|last5=Chou|first5=Yuan-Yi|last6=Lu|first6=Shao-Chun|date=2016-12|title=SB203580 increases G-CSF production via a stem-loop destabilizing element in the 3’ untranslated region in macrophages independently of its effect on p38 MAPK activity|url=http://www.jbiomedsci.com/content/23/1/3|journal=Journal of Biomedical Science|language=en|volume=23|issue=1|pages=3|doi=10.1186/s12929-016-0221-z|issn=1423-0127|pmc=PMC4715298|pmid=26772539}}</ref> investigated the effect of [[SB 203580|SB203580]], which is a specific inhibitor of p38 MAPK, on the lipopolysaccharide-induced G-CSF expression in macrophages at the [[Post-transcriptional regulation|post-transcription]] level. SB203580 specifically inhibits the [[Catalysis|catalytic activity]] of p38 MAPK by competitively binding to the active site where [[ATP synthase|ATP]] is supposed to bind and is widely used in other studies to display the role of p38 MAPK in other biological systems. Surprisingly, the results of the study showed that SB203580 amplified the lipopolysaccharide-induced increase in the G-CSF mRNA levels in mouse [[Bone marrow-derived macrophage|bone marrow-derived macrophages]] and in THP-1 human macrophages. By displaying that the decay of G-CSF mRNA, in the presence of [[Dactinomycin|actinomycin D]], was slower in SB203580-treated cells, it was shown SB203580 increased the stability of G-CSF mRNA. Finally, by using experiments showing the effect of the 3’UTR of G-CSF on G-CSF stability, the SLDE was shown to beis essential for the SB203580-induced increase in the stability of mRNA.{{short description|RNA element}}
