Related Experiment Video

Updated: Aug 11, 2026

Assays for the Degradation of Misfolded Proteins in Cells
10:56

Assays for the Degradation of Misfolded Proteins in Cells

Published on: August 28, 2016

Regulation of MDMX nuclear import and degradation by Chk2 and 14-3-3

Cynthia LeBron1, Lihong Chen, Daniele M Gilkes

  • 1Molecular Oncology Program, H Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA.

The EMBO Journal
|March 3, 2006
PubMed

Insights

DNA damage triggers MDMX protein binding to 14-3-3. This interaction, regulated by Chk2 phosphorylation, promotes MDMX degradation and enhances the tumor suppressor p53

Area of Science:

  • Molecular biology
  • Cellular signaling
  • Cancer research

Background:

  • MDMX (MDM2 homolog) regulates p53, a crucial tumor suppressor.
  • p53 activity is vital for embryonic development and DNA damage response.
  • MDMX is degraded by MDM2 following DNA damage.

Purpose of the Study:

  • To investigate the role of MDMX interaction with 14-3-3 in the p53 DNA damage response.
  • To elucidate the molecular mechanisms regulating MDMX stability and localization.

Main Methods:

  • Co-purification assays to identify binding partners of MDMX.
  • Phosphorylation site-directed mutagenesis (S367) to assess functional impact.
  • Western blotting and immunofluorescence to track protein localization and degradation.

Main Results:

  • DNA damage induces MDMX binding to 14-3-3 proteins.
  • Chk2-mediated phosphorylation of MDMX at S367 is essential for 14-3-3 binding, nuclear import, and MDM2-dependent degradation.
  • Mutating S367 blocks MDMX ubiquitination, degradation, and nuclear translocation.
  • 14-3-3 expression enhances the degradation of phosphorylated MDMX.
  • Chk2 and 14-3-3 cooperate to promote MDMX ubiquitination and overcome p53 inhibition.

Conclusions:

  • The MDMX-14-3-3 interaction is a key regulatory step in the p53 response to DNA damage.
  • This interaction controls MDMX localization and stability, impacting p53 pathway activation.
  • Targeting the MDMX-14-3-3 axis may offer therapeutic strategies for cancer treatment.

More Related Videos

Visualization of DNA Repair Proteins Interaction by Immunofluorescence07:55

Visualization of DNA Repair Proteins Interaction by Immunofluorescence

Published on: June 26, 2020

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

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...
Nuclear Export of mRNA02:31

Nuclear Export of mRNA

Before mRNAs are exported to the cytoplasm, it is crucial to check each mRNA for structural and functional integrity. Eukaryotic cells use several different mechanisms, collectively known as mRNA surveillance, to look for irregularities in mRNAs. Irregular or aberrant mRNA are rapidly degraded by various enzymes. If a defective mRNA escapes the surveillance, it would be translated into a protein which would either be non-functional or not function properly. One of the primary irregularities in...
Export of Misfolded Proteins out of the ER01:32

Export of Misfolded Proteins out of the ER

After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...
Nonsense-mediated mRNA Decay02:27

Nonsense-mediated mRNA Decay

The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
M-Cdk Drives Transition Into Mitosis02:15

M-Cdk Drives Transition Into Mitosis

Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...