Related Experiment Video

Updated: Sep 23, 2026

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
12:26

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

Published on: May 3, 2018

hCDC4b, a regulator of cyclin E, as a direct transcriptional target of p53

Takashi Kimura1, Mitsukazu Gotoh, Yusuke Nakamura

  • 1Human Genome Center, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.

Cancer Science
|June 26, 2003
PubMed

Insights

The tumor suppressor p53 directly regulates hCDC4b gene expression, a novel finding that may explain p53

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Genetics

Background:

  • The p53 protein is a critical tumor suppressor involved in cell cycle regulation and DNA repair.
  • Glioblastoma is an aggressive brain tumor with a high mutation rate in the p53 pathway.
  • Understanding p53-target genes is crucial for developing effective cancer therapies.

Purpose of the Study:

  • To identify novel p53-target genes using a cDNA-microarray system.
  • To investigate the role of hCDC4b in p53-mediated cell cycle arrest.

Main Methods:

  • Adenovirus-mediated transfer of wild-type p53 into p53-deficient glioblastoma cells (U373MG).
  • cDNA-microarray analysis to assess gene expression changes.
  • Electrophoretic mobility-shift assay (EMSA) and chromatin immunoprecipitation (ChIP) to confirm p53 binding.
  • Reporter assays to determine transcriptional activity.
  • Genotoxic stress induction using UV irradiation and adriamycin.

Main Results:

  • Expression of hCDC4b, a subunit of the SCF ubiquitin ligase complex, was significantly upregulated by wild-type p53.
  • A functional p53-binding site (p53BS) was identified in exon 1b of the hCDC4 gene, demonstrating p53-dependent transcriptional activity.
  • Endogenous hCDC4b expression was induced in a p53-dependent manner upon genotoxic stress, unlike the alternative hCDC4a transcript.
  • p53 negatively regulates cyclin E degradation via hCDC4b induction.

Conclusions:

  • hCDC4b is a novel transcriptional target of the p53 protein.
  • p53-induced hCDC4b may contribute to cell cycle arrest at the G0-G1 phase by downregulating cyclin E.
  • This represents a new mechanism of p53-dependent cell cycle control, complementing the known p21(WAF1) pathway.

More Related Videos

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols12:02

Studying Cell Cycle-regulated Gene Expression by Two Complementary Cell Synchronization Protocols

Published on: June 6, 2017

Yeast As a Chassis for Developing Functional Assays to Study Human P5314:57

Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

Related Concept Videos

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...
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.
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.
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...