Related Experiment Video
Updated: May 6, 2026
Utilizing Murine Inducible Telomerase Alleles in the Studies of Tissue Degeneration/Regeneration and Cancer
Published on: April 13, 2015
Tumor induction and tissue atrophy in mice lacking E2F-1
L Yamasaki1, T Jacks, R Bronson
1Massachusetts General Hospital Cancer Center, Charlestown 02129, USA.
Abstract:
The retinoblastoma tumor suppressor protein (pRB) is a transcriptional repressor that regulates gene expression by physically associating with transcription factors such as E2F family members. Although pRB and its upstream regulators are commonly mutated in human cancer, the physiological role of the pRB-E2F pathway is unknown. To address the function of E2F-1 and pRB/E2F-1 complexes in vivo, we have produced mice homozygous for a nonfunctional E2F-1 allele. Mice lacking E2F-1 are viable and fertile, yet experience testicular atrophy and exocrine gland dysplasia. Surprisingly, mice lacking E2F-1 develop a broad and unusual spectrum of tumors. Although overexpression of E2F-1 in tissue culture cells can stimulate cell proliferation and be oncogenic, loss of E2F-1 in mice results in tumorigenesis, demonstrating that E2F-1 also functions as a tumor suppressor.
Insights
Loss of E2F-1, a protein regulating gene expression, surprisingly leads to tumor development in mice. This indicates E2F-1 acts as a crucial tumor suppressor, contrary to previous in vitro findings.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- The retinoblastoma tumor suppressor protein (pRB) represses transcription by binding to E2F factors.
- Mutations in pRB and its regulators are frequent in human cancers.
- The in vivo function of the pRB-E2F pathway remains largely uncharacterized.
Purpose of the Study:
- To investigate the in vivo function of E2F-1 and pRB/E2F-1 complexes.
- To determine the physiological role of E2F-1 in mammalian development and tumorigenesis.
Main Methods:
- Generation of mice homozygous for a nonfunctional E2F-1 allele.
- Phenotypic analysis of E2F-1 deficient mice, including reproductive and developmental assessments.
- Tumor spectrum analysis in E2F-1 knockout mice.
Main Results:
- E2F-1 deficient mice are viable and fertile but exhibit testicular atrophy and exocrine gland dysplasia.
- Mice lacking E2F-1 develop a wide and unexpected range of tumors.
- In vitro studies suggested E2F-1 is oncogenic, but in vivo data contradicts this.
Conclusions:
- E2F-1 plays a critical role in preventing tumor formation in vivo.
- Loss of E2F-1 function acts as a tumor suppressor, leading to tumorigenesis.
- The physiological role of E2F-1 is complex, with distinct functions in vitro and in vivo.
Related Concept Videos
02:23Abnormal Proliferation
01:12Loss of Tumor Suppressor Gene Functions
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...