Related Experiment Video

Updated: Aug 16, 2026

A Guide to Production, Crystallization, and Structure Determination of Human IKK1/α
11:27

A Guide to Production, Crystallization, and Structure Determination of Human IKK1/α

Published on: November 2, 2018

Distinct roles of IkappaB proteins in regulating constitutive NF-kappaB activity

Vinay Tergaonkar1, Ricardo G Correa, Masahito Ikawa

  • 1Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.

Nature Cell Biology
|September 2, 2005
PubMed

Insights

The inhibitor of kappaB (IkappaB) proteins, specifically IkappaBalpha, IkappaBbeta, and IkappaBepsilon, are crucial for preventing basal NF-kappaB gene activation. Their absence leads to constitutive NF-kappaB activity and pathway unresponsiveness.

Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • Immunology

Background:

  • The inhibitor of kappaB (IkappaB) protein family regulates Nuclear Factor kappaB (NF-kappaB) activity.
  • IkappaB proteins are generally understood to sequester NF-kappaB in the cytoplasm.

Purpose of the Study:

  • To investigate the specific roles of IkappaBalpha, IkappaBbeta, and IkappaBepsilon in NF-kappaB regulation.
  • To determine if these IkappaB proteins are essential for cytoplasmic retention or for preventing basal NF-kappaB activity.

Main Methods:

  • Depletion of IkappaBalpha, IkappaBbeta, and IkappaBepsilon proteins in cellular models.
  • Analysis of p65 (a subunit of NF-kappaB) DNA binding and NF-kappaB target gene expression.
  • Assessment of NF-kappaB pathway responsiveness to activation.

Main Results:

  • Cells lacking IkappaBalpha, IkappaBbeta, and IkappaBepsilon showed constitutive NF-kappaB target gene activation despite most p65 remaining cytoplasmic.
  • These IkappaB proteins are essential for preventing basal NF-kappaB-dependent gene expression.
  • In the absence of these IkappaB proteins, other factors retain NF-kappaB in the cytoplasm, rendering the pathway unresponsive to stimulation.

Conclusions:

  • IkappaBalpha, IkappaBbeta, and IkappaBepsilon are dispensable for the cytoplasmic retention of NF-kappaB.
  • These specific IkappaB proteins are critical for suppressing NF-kappaB activity in the absence of external stimuli.
  • Loss of these IkappaB proteins leads to a permanently suppressed NF-kappaB pathway.

More Related Videos

Production, Crystallization, and Structure Determination of the IKK-binding Domain of NEMO13:02

Production, Crystallization, and Structure Determination of the IKK-binding Domain of NEMO

Published on: December 28, 2019

Methods for the Modulation and Analysis of NF-κB-dependent Adult Neurogenesis14:58

Methods for the Modulation and Analysis of NF-κB-dependent Adult Neurogenesis

Published on: February 13, 2014

Related Concept Videos

NF-κB-dependent Signaling Pathway02:26

NF-κB-dependent Signaling Pathway

The transcription factor NF-κB was discovered in 1986 in the lab of Nobel laureate Professor David Baltimore, for its interaction with the immunoglobulin light chain enhancer in B-cells. After more than three decades of study, it is now evident that NF-κB regulates the expression of over 100 genes. Most of these genes play an essential role in the innate and adaptive immune responses as well as the inflammatory responses of animals.
NF-κB-dependent Signaling Mechanism
The heterodimer of NF-κB...
Co-activators and Co-repressors02:04

Co-activators and Co-repressors

Gene transcription is regulated by the synergistic action of several proteins that form a complex at a gene regulatory site. This is observed in eukaryotes, where the regulation of gene expression is a complex process. Regulatory proteins in eukaryotes can broadly be classified into two types – regulators that bind directly to specific DNA sequences and co-regulators that associate with regulatory proteins but cannot directly bind to the DNA. These co-regulators are further divided into...
Regulation of Nuclear Protein Sorting01:45

Regulation of Nuclear Protein Sorting

Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
Regulation of the Unfolded Protein Response01:31

Regulation of the Unfolded Protein Response

Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
Cytoskeletal Linker Proteins - Plakins01:09

Cytoskeletal Linker Proteins - Plakins

Plakins are large proteins with binding domains for microtubules, microfilaments, intermediate filaments, and membrane-associated protein complexes at cell junctions. Plakin functions are evolutionarily conserved and are primarily involved in organizing the different components of the cytoskeleton by crosslinking them to each other and connecting them to the cell-matrix and cell adhesion complexes. They are also known to interact with signal transducers, serve as scaffolds for signaling...
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...