Related Experiment Video

Updated: Jul 16, 2026

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
10:54

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Published on: September 17, 2012

Uncovering residues that regulate cyclin D1 proteasomal degradation

Q Feng1, D Sekula, R Müller

  • 1Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH 03755, USA.

Oncogene
|February 22, 2007
PubMed

Insights

Specific mutations in cyclin D1 (cell cycle regulator) block its proteasomal degradation, revealing key residues involved in ubiquitination and stabilizing the protein. This offers insights into cancer chemoprevention.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • Cyclin D1 is crucial for cell cycle progression and its abnormal expression is linked to cancer.
  • Proteasomal degradation of cyclin D1 is a recognized mechanism for cancer chemoprevention.

Purpose of the Study:

  • To identify specific amino acid residues in cyclin D1 responsible for its ubiquitination and proteasomal degradation.
  • To elucidate the mechanism by which all-trans-retinoic acid (RA) induces cyclin D1 degradation.

Main Methods:

  • Site-directed mutagenesis was used to engineer mutations in eighteen lysine residues of cyclin D1.
  • Mutated cyclin D1 was transfected into BEAS-2B human bronchial epithelial cells.
  • Cellular stability of mutated cyclin D1 was assessed following treatment with all-trans-retinoic acid (RA) or cycloheximide.

Main Results:

  • Specific lysine mutations, particularly those near the cyclin box domain, stabilized cyclin D1 and inhibited RA-mediated degradation.
  • Complete mutation of all lysine residues abolished cyclin D1 polyubiquitination.
  • N-terminal modifications stabilized cyclin D1, whereas C-terminal modifications did not.
  • Ubiquitination-resistant cyclin D1 mutants showed preferential nuclear localization, suggesting a role for subcellular localization in degradation regulation.

Conclusions:

  • Specific lysine residues in cyclin D1 are critical for its ubiquitination and subsequent proteasomal degradation.
  • These findings provide a mechanistic understanding of cyclin D1 regulation and its role in cancer chemoprevention.

More Related Videos

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

Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk113:15

Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1

Published on: February 25, 2016

Related Concept Videos

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...
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Inhibition of CDK Activity02:34

Inhibition of CDK Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Regulated Protein Degradation02:58

Regulated Protein Degradation

It is vital to regulate the activity of enzymatic as well as non-enzymatic proteins inside the cell. This can be achieved either through creating a balance between their rate of synthesis and degradation or regulating the intrinsic activity of the protein. Both these regulation mechanisms play an essential role in the normal functioning of cells.
Protein degradation plays two important roles in the cells. It helps to protect cells from misfolded or damaged proteins before they lead to a...
Positive Regulator Molecules02:39

Positive Regulator Molecules

Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
Positive Regulator Molecules01:45

Positive Regulator Molecules

To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated.