Related Experiment Video

Updated: Aug 29, 2026

Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene
08:18

Focus Formation: A Cell-based Assay to Determine the Oncogenic Potential of a Gene

Published on: December 31, 2014

MdmX represses E2F1 transactivation

Mark Wunderlich1, Mithua Ghosh, Karen Weghorst

  • 1Wright State University, Department of Biochemistry & Molecular Biology, Dayton, Ohio 45435, USA.

Cell Cycle (Georgetown, Tex.)
|January 24, 2004
PubMed

Insights

MdmX protein inhibits E2F1 transactivation independently of p53 and Mdm2. This novel function, mediated by MdmX

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Oncology

Background:

  • Mdm2 and MdmX are known regulators of the p53 tumor suppressor protein, particularly during early development.
  • Both Mdm2 and MdmX have been implicated in oncogenic activities, and studies suggest they possess p53-independent functions.

Purpose of the Study:

  • To investigate the effect of Mdm2 overexpression on E2F1 transactivation.
  • To uncover novel functions of MdmX, specifically its role in regulating E2F1 transactivation.

Main Methods:

  • Utilized knockout mouse studies to understand Mdm2 and MdmX roles.
  • Employed a series of MdmX deletion mutants to identify the repressive domain.
  • Analyzed E2F1 transactivation in cells overexpressing Mdm2 and MdmX.

Main Results:

  • Discovered a novel MdmX function: inhibition of E2F1 transactivation, independent of p53 and Mdm2.
  • Identified amino acids 128-444 of MdmX as the repressive domain.
  • Observed a slight reduction in DP1 and increased cytoplasmic localization of E2F1 in MdmX-overexpressing cells, without direct in vivo association.

Conclusions:

  • Elevated MdmX expression can repress E2F1-regulated genes, such as p14ARF.
  • This suggests MdmX acts as a regulatory mechanism within the Rb-p53 signaling pathway, independent of its canonical p53 interactions.

More Related Videos

Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis09:58

Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis

Published on: June 27, 2020

Identification of MyoD Interactome Using Tandem Affinity Purification Coupled to Mass Spectrometry14:47

Identification of MyoD Interactome Using Tandem Affinity Purification Coupled to Mass Spectrometry

Published on: May 17, 2016

Related Concept Videos

Master Transcription Regulators02:23

Master Transcription Regulators

Master transcription regulators are regulatory proteins that are predominantly responsible for regulating the expression of multiple genes. Often these genes work in concert to drive a  complex process. Activation of a master transcription regulator can lead to a cascade of transcriptional activation necessary for that outcome. These regulators can directly bind to the regulatory sequences of the various genes involved, or they can indirectly regulate transcription by binding to regulatory...
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...
Eukaryotic Transcription Inhibitors01:52

Eukaryotic Transcription Inhibitors

Certain biochemical processes, such as embryonic development and cell growth regulation, depend on the repression of specific genes. DNA binding proteins known as eukaryotic transcription inhibitors regulate the repression of gene expression in eukaryotes. The presence of these inhibitors at the required location and time in the cell is triggered by the presence of hormones and additional signals from other cells.
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Mitogens and the Cell Cycle02:38

Mitogens and the Cell Cycle

Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...
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...
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.