Phosphorylation of SIMPL modulates RelA-associated NF-kappaB-dependent transcription.
Epidemiological data have implicated perturbations in the regulation of NF-kappaB activity to diseases that affect a large number of Americans today. Specifically, chronic activation of genes involved in the inflammatory response is associated with the progression of and complications in diabetes, arthritis, atherosclerosis, and cancer. Insight into the mechanisms governing the regulation of NF-kappaB transcriptional activity will provide the molecular link between NF-kappaB and these pathological states. SIMPL (signaling molecule that associates with mouse Pelle-like kinase) is a component of a signaling pathway through which tumor necrosis factor-alpha (TNF-alpha) induces NF-kappaB-controlled gene transcription. SIMPL interacts with the nuclear pool of the NF-kappaB subunit, p65, in a TNF-alpha-dependent manner to enhance p65-dependent gene transcription. How SIMPL activity is regulated is unknown. Under basal as well as TNF-alpha-stimulated conditions, SIMPL phosphopeptides were identified. SIMPL mutants lacking sites that are phosphorylated under basal conditions diminished p65 transactivation activity but had no effect on SIMPL nuclear localization. SIMPL mutants lacking sites of TNF-alpha-enhanced phosphorylation impaired nuclear localization and prevented TNF-alpha-induced p65 transactivation activity. Together, these studies reveal that phosphorylation of the SIMPL protein plays a critical role in SIMPL regulation by affecting both SIMPL subcellular localization and the p65 coactivator function of SIMPL.
Luo
Yong
Y
Dept. of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202-5122, USA.
Kwon
Hyung-Joo
HJ
Montano
Sherwin
S
Georgiadis
Millie
M
Goebl
Mark G
MG
Harrington
Maureen A
MA
D002352:Carrier Proteins; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008025:Ligases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D051996:Transcription Factor RelA / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; C493527:SIMPL protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases