Related Experiment Video

Updated: Aug 23, 2025

Repressing Gene Transcription by Redirecting Cellular Machinery with Chemical Epigenetic Modifiers
10:28

Repressing Gene Transcription by Redirecting Cellular Machinery with Chemical Epigenetic Modifiers

Published on: September 20, 2018

6.5K

The Binding of CSL Proteins to Either Co-Activators or Co-Repressors Protects from Proteasomal Degradation Induced by

Johannes Fechner1, Manuela Ketelhut1, Dieter Maier1

  • 1Department of General Genetics 190g, University of Hohenheim, Garbenstr. 30, 70599 Stuttgart, Germany.

International Journal of Molecular Sciences
|October 27, 2022
PubMed

Insights

Notch signaling relies on CSL proteins for gene regulation. This study reveals that Suppressor of Hairless (Su(H)) protein stability is controlled by proteasomal degradation, a mechanism conserved across species for regulating Notch signaling.

Area of Science:

  • Molecular Biology
  • Developmental Biology
  • Cell Signaling

Background:

  • Notch signaling is crucial for specifying cellular identities, with cells highly sensitive to its activity levels.
  • CSL proteins are central to Notch signal transduction, mediating gene activation or silencing through cofactors.
  • CSL proteins exhibit high sequence and structural similarity across species.

Purpose of the Study:

  • To investigate the regulation of CSL protein stability, specifically the fly homologue Suppressor of Hairless (Su(H)).
  • To determine if CSL protein turnover is a conserved mechanism for regulating Notch signaling output.

Main Methods:

  • Utilized transgenic fly lines and HeLa RBPJ knockout (KO) cells.
  • Investigated the role of co-repressor hairless and co-activator Notch in stabilizing Su(H).
  • Examined the impact of MAPK-dependent phosphorylation on Su(H) stability and tested RBPJ degradation upon mutating protein contact sites.

Main Results:

  • Su(H) is stabilized in transcription complexes and undergoes proteasomal degradation with a half-life of approximately two hours when not bound to co-factors.
  • MAPK-dependent phosphorylation controls Su(H) stability, similar to RBPJ in human cells.
  • Murine and human RBPJ proteins showed resistance to degradation, but mutations sensitized RBPJ to proteolysis.

Conclusions:

  • CSL protein stability is regulated by proteasomal degradation, a conserved mechanism across species.
  • The turnover of CSL proteins is a key regulatory point for Notch signaling output at the transcriptional level.
Keywords:
CSLMAPKNotch signalling dynamicsactivator complexdegronproteasomal degradationprotein stabilityrepressor complexsuppressor of hairless

More Related Videos

Oligopeptide Competition Assay for Phosphorylation Site Determination09:16

Oligopeptide Competition Assay for Phosphorylation Site Determination

Published on: May 18, 2017

8.5K
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

18.8K

Related Concept Videos

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...
5.9K
Covalently Linked Protein Regulators02:04

Covalently Linked Protein Regulators

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein....
6.9K
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...
7.4K
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
5.2K
Microtubule Associated Proteins (MAPs)01:42

Microtubule Associated Proteins (MAPs)

Microtubule function and architecture are regulated by an array of specialized proteins called microtubule-associated proteins or MAPs. These proteins are widespread across different organisms and have conserved protein motifs, like the multi-TOG domain for tubulin binding found in the CLASP family of MAPs. Some MAPs are lineage-specific based on their conserved domains. Their functions depend upon the cytoskeletal architecture and cell type they are located within. In-plant cells, a specific...
4.5K
Anaphase Promoting Complex00:50

Anaphase Promoting Complex

The stepwise destruction of specific proteins is necessary for the progression and completion of the cell cycle. Such proteins are ubiquitinated by ubiquitin ligases and then subsequently destroyed by the proteasome. The SCF (Skp1/Cullin/F-box) and the anaphase-promoting complex (APC) are two important ubiquitin ligases involved in cell cycle progression. While SCF is active throughout the cell cycle, APC gets activated during metaphase to anaphase transition. Cdc20 or Cdh1 binds to APC and...
2.9K