Related Experiment Videos
A constitutive active MEK --> ERK pathway negatively regulates NF-kappa B-dependent gene expression by modulating
1University of Iowa College of Medicine and the Iowa City Veterans Administration Medical Center, Iowa City, Iowa 52242, USA. aaron-carter@uiowa.edu
Abstract:
Endotoxin-induced cytokine gene expression is regulated, in part, by NF-kappaB. We have shown that both the ERK and p38 mitogen-activated protein (MAP) kinases are necessary for cytokine gene transcription and that the p38 MAP kinase is required for NF-kappaB-driven transcription, so we hypothesized that the MEK --> ERK pathway regulated NF-kappaB-driven transcription as well. We found that a constitutive active MEK --> ERK pathway inhibited NF-kappaB-driven transcription. In addition, both PD 98059 and a dominant negative ERK2 augmented NF-kappaB-driven transcription; however, neither PD 98059 nor MEK1 altered NF-kappaB activation at any level. The constitutive active MEK --> ERK pathway inhibited the phosphorylation of TBP, which is necessary for both interaction with RelA and binding to the TATA box. Due to the fact that we have shown that the p38 MAP kinase modulates TBP activation, we evaluated the effect of the constitutive active MEK --> ERK pathway on p38 MAP kinase activity. We found that the MEK --> ERK pathway negatively regulates NF-kappaB-driven transcription, in part, by inhibiting p38 MAP kinase activity. Thus, the ERK and p38 MAP kinases have differential effects on NF-kappaB-driven transcription.
Insights
The ERK pathway negatively regulates NF-kappaB-driven transcription by inhibiting p38 MAP kinase activity. ERK and p38 MAP kinases show differential regulation of NF-kappaB transcription.
Area of Science:
- Molecular Biology
- Cell Signaling
- Immunology
Background:
- Cytokine gene expression is critical in inflammatory responses.
- Nuclear Factor-kappaB (NF-kappaB) is a key regulator of cytokine genes.
- Mitogen-activated protein (MAP) kinases, including ERK and p38, are involved in cellular signaling pathways.
Purpose of the Study:
- To investigate the role of the MEK --> ERK pathway in regulating NF-kappaB-driven transcription.
- To determine if the MEK --> ERK pathway affects NF-kappaB activation or transcription.
- To elucidate the interplay between ERK, p38 MAP kinases, and NF-kappaB.
Main Methods:
- Utilized constitutive active MEK and dominant-negative ERK2 to modulate the MEK --> ERK pathway.
- Assessed NF-kappaB-driven transcription using reporter assays.
- Examined the phosphorylation of TATA-binding protein (TBP) and p38 MAP kinase activity.
Main Results:
- A constitutively active MEK --> ERK pathway inhibited NF-kappaB-driven transcription.
- Inhibitors of the ERK pathway (PD 98059) and dominant-negative ERK2 augmented NF-kappaB-driven transcription.
- The MEK --> ERK pathway negatively regulates NF-kappaB transcription by inhibiting p38 MAP kinase activity and TBP phosphorylation.
Conclusions:
- The ERK and p38 MAP kinases exert differential control over NF-kappaB-driven transcription.
- The MEK --> ERK pathway negatively modulates NF-kappaB transcription, partly through suppressing p38 MAP kinase activity.
- These findings reveal distinct roles for ERK and p38 in regulating inflammatory gene expression via NF-kappaB.