Related Experiment Video

Updated: Aug 12, 2026

Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

Differential regulation of E2F and Sp1-mediated transcription by G1 cyclins

Z Shao1, P D Robbins

  • 1Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, PA 15261.

Oncogene
|January 19, 1995
PubMed

Insights

Cyclins regulate gene transcription by interacting with transcription factors like E2F and Sp1. Different cyclins, particularly D-type cyclins, exhibit distinct effects, with some stimulating and others repressing transcription.

Area of Science:

  • Molecular Biology
  • Cell Cycle Regulation
  • Gene Transcription

Background:

  • Cyclins are key regulators of the cell cycle.
  • The retinoblastoma tumor suppressor gene product (Rb) controls transcription via E2F and Sp1.
  • Understanding cyclin interactions with transcription factors is crucial for cell cycle research.

Purpose of the Study:

  • To investigate the impact of cyclin overexpression on E2F and Sp1-mediated transcription.
  • To determine if cyclins differentially regulate specific transcription factors.
  • To explore the functional distinctions among G1 cyclins, including D-type cyclins.

Main Methods:

  • Cotransfection assays in 3T3 cells were used to assess promoter activity.
  • Overexpression of various cyclins (C, D1, D2, D3, E, A) was performed.
  • The activity of the E2F-dependent adenovirus E2 promoter and Sp1-mediated transcription was measured.

Main Results:

  • G1 cyclins (C, D1, D2, D3, E) and cyclin A stimulated E2 promoter activity, with cyclin D3 showing the strongest effect.
  • Cyclin C stimulated both E2F and Sp1-mediated transcription, indicating a general transcriptional activation role.
  • Cyclin D1 specifically repressed Sp1-mediated transcription via an Rb-independent pathway.

Conclusions:

  • Cyclins possess both positive and negative regulatory roles in transcription mediated by specific factors.
  • Distinct functional differences exist among cyclins, especially within the D-type cyclin family.
  • These findings highlight the complex regulatory network of cell cycle progression and gene expression.

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

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

Related Concept Videos

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.
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.
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...
The Cell Cycle Control System01:28

The Cell Cycle Control System

The cell cycle regulation directs how a cell proceeds from one phase to the next and begins mitosis. The cell cycle control system includes intracellular regulatory molecules and external triggers. They provide "stop" or "advance" signals and operate at specific cell cycle stages termed checkpoints to ensure that a particular process is completed before the cell advances to the next phase.
Cyclins and cyclin-dependent kinases (Cdks) are the primary cell cycle regulators and function at the cell...