Premium
The role of phosphatase 2A on the post‐transcriptional regulation of TNF alpha secretion in alveolar macrophages
Author(s) -
Sun Lei,
Stoecklin Georg,
Vanway Susan M,
HinkovskaGalcheva Vania,
Shanley Thomas P
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1081
Subject(s) - protein phosphatase 2 , messenger rna , untranslated region , microbiology and biotechnology , p38 mitogen activated protein kinases , tristetraprolin , tumor necrosis factor alpha , chemistry , phosphatase , secretion , au rich element , kinase , transcriptional regulation , luciferase , protein kinase a , biology , gene expression , transfection , phosphorylation , biochemistry , endocrinology , gene
TNF alpha expression is regulated by transcriptional as well as post‐transcriptional mechanisms. Post‐transcriptional regulation includes the control of mRNA stability through an AU‐rich element (ARE) in the 3′ untranslated region (UTR). Here we show that inhibition of phosphatase activity by the pharmacological inhibitor, Okadaic acid (OA), or by PP2A siRNA could strongly augment LPS‐stimulated TNF alpha secretion in a mouse alveolar macrophage cell line, MHS cell. In OA pre‐treated cells, the half‐life of TNF alpha mRNA was prolonged and the luciferase activity of a reporter gene containing the 3′‐UTR of TNF alpha mRNA was increased. The enhancing effects were significantly suppressed by the addition of p38 specific inhibitor, SB203580, but not by JNK, MEK1/2, NF‐κB inhibitors. Furthermore, p38‐MAPK and MK2 kinase activity were increased by OA treatment. RNA gel shift experiment showed an increased binding of the fourth complex (LPS inducible complex) in OA pre‐treated cell lysates to a radio‐labeled RNA probe containing the TNF alpha ARE. The LPS inducible complex can be supershifted by the antibodies to Tristetraprolin (TTP) and scaffold protein 14‐3‐3, and addition of recombinant PP2A completely depleted these bands. These data suggest the PP2A regulates the TNF alpha mRNA stability by p38‐MAPK/MK2/TTP‐14‐3‐3 signaling pathway. *This work was supported by the National Institute of Health Grant 7R01GM066839‐03 (to T.P. Shanley).