Related Experiment Video

Updated: Aug 8, 2026

Analysis of Cell Cycle Position in Mammalian Cells
12:19

Analysis of Cell Cycle Position in Mammalian Cells

Published on: January 21, 2012

Early growth response 1 protein, an upstream gatekeeper of the p53 tumor suppressor, controls replicative senescence

Anja Krones-Herzig1, Eileen Adamson, Dan Mercola

  • 1Sidney Kimmel Cancer Center, San Diego, CA 92121, USA.

Proceedings of the National Academy of Sciences of the United States of America
|March 12, 2003
PubMed

Insights

Early growth response 1 (EGR1) acts as a crucial gatekeeper for the p53 tumor suppressor pathway, regulating cell senescence. Its absence allows cells to bypass senescence and achieve immortal growth, highlighting EGR1

Area of Science:

  • Cellular senescence
  • Tumor suppressor pathways
  • Molecular biology

Background:

  • Cell proliferation is typically limited by replicative senescence and crisis, processes dependent on the p53 protein.
  • The upstream regulators controlling p53's function, particularly in senescence, remain largely undefined.
  • Understanding these regulatory mechanisms is critical for comprehending tumor suppression and cellular aging.

Purpose of the Study:

  • To investigate the role of the early growth response 1 (EGR1) transcription factor in regulating cellular senescence and the p53 pathway.
  • To determine if EGR1 functions as a suppressor of cellular immortalization.
  • To elucidate the relationship between EGR1, p53, and the onset of replicative senescence.

Main Methods:

  • Generation and characterization of EGR1-null mouse embryo fibroblasts (MEFs).
  • Analysis of p53 expression, p53 target genes (e.g., p21Cip1/Waf1), and cell cycle arrest.
  • Assessment of senescence bypass, immortal growth, and tumorigenicity in EGR1-deficient cells.
  • Complementation assays using retroviral expression of EGR1 in EGR1-null and wild-type (WT) MEFs.

Main Results:

  • EGR1-null MEFs exhibited a complete bypass of senescence and demonstrated immortal growth potential.
  • EGR1 deficiency led to significantly decreased expression of p53 and p21(Cip1/Waf1) proteins.
  • While wild-type MEFs entering crisis developed mutated p53 and became tumorigenic, EGR1-null MEFs maintained wild-type p53 sequence with reduced expression and remained untransformed.
  • Restoration of EGR1 expression in EGR1-null cells re-established p53 expression and induced senescence.

Conclusions:

  • Early growth response 1 (EGR1) is a critical regulator of cellular senescence.
  • EGR1 acts as an upstream gatekeeper for the p53 tumor suppressor pathway, controlling its expression and function.
  • Loss of EGR1 function contributes to cellular immortalization by impairing the p53-dependent senescence response.

More Related Videos

Techniques to Induce and Quantify Cellular Senescence06:51

Techniques to Induce and Quantify Cellular Senescence

Published on: May 1, 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

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.
DNA Damage can Stall the Cell Cycle02:36

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
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...
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
Interactions Between Signaling Pathways01:19

Interactions Between Signaling Pathways

Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
DNA Damage Can Stall the Cell Cycle02:36

DNA Damage Can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...