Related Experiment Video
Updated: May 28, 2026
SA-β-Galactosidase-Based Screening Assay for the Identification of Senotherapeutic Drugs
Published on: June 28, 2019
Cellular senescence and tumor suppressor gene p16
Hani Rayess1, Marilene B Wang, Eri S Srivatsan
1Department of Surgery, VA Greater Los Angeles Healthcare system, West Los Angeles, CA, USA.
Abstract:
Cellular senescence is an irreversible arrest of cell growth. Biochemical and morphological changes occur during cellular senescence, including the formation of a unique cellular morphology such as flattened cytoplasm. Function of mitochondria, endoplasmic reticulum and lysosomes are affected resulting in the inhibition of lysosomal and proteosomal pathways. Cellular senescence can be triggered by a number of factors including, aging, DNA damage, oncogene activation and oxidative stress. While the molecular mechanism of senescence involves p16 and p53 tumor suppressor genes and telomere shortening, this review is focused on the mechanism of p16 control. The p16-mediated senescence acts through the retinoblastoma (Rb) pathway inhibiting the action of the cyclin dependant kinases leading to G1 cell cycle arrest. Rb is maintained in a hypophosphorylated state resulting in the inhibition of transcription factor E2F1. Regulation of p16 expression is complex and involves epigenetic control and multiple transcription factors. PRC1 (Pombe repressor complex (1) and PRC2 (Pombe repressor complex (2) proteins and histone deacetylases play an important role in the promoter hypermethylation for suppressing p16 expression. While transcription factors YY1 and Id1 suppress p16 expression, transcription factors CTCF, Sp1 and Ets family members activate p16 transcription. Senescence occurs with the inactivation of suppressor elements leading to the enhanced expression of p16.
Insights
Cellular senescence, a permanent cell cycle arrest, is regulated by the p16 gene. This review details how p16 controls senescence through the retinoblastoma pathway, impacting cell growth and gene expression.
Area of Science:
- Cellular and Molecular Biology
- Epigenetics and Gene Regulation
Background:
- Cellular senescence is a state of irreversible cell growth arrest characterized by distinct morphological and functional changes.
- It can be triggered by various stressors, including aging, DNA damage, and oncogene activation.
- Key molecular players include p16 and p53 tumor suppressor genes and telomere shortening.
Purpose of the Study:
- This review focuses on the intricate mechanisms regulating p16 expression and its role in initiating cellular senescence.
- It aims to elucidate the p16-mediated control of the retinoblastoma (Rb) pathway and subsequent cell cycle arrest.
Main Methods:
- The review synthesizes existing literature on the molecular regulation of p16.
- It examines the roles of epigenetic modifiers like PRC1, PRC2, and histone deacetylases in p16 promoter methylation.
- It discusses the opposing actions of various transcription factors (e.g., YY1, Id1, CTCF, Sp1, Ets) on p16 transcription.
Main Results:
- The p16-mediated senescence pathway involves the Rb pathway, leading to G1 cell cycle arrest via inhibition of E2F1.
- Epigenetic mechanisms, including promoter hypermethylation mediated by PRC1, PRC2, and histone deacetylases, play a crucial role in suppressing p16 expression.
- A complex interplay of transcription factors either activates (CTCF, Sp1, Ets) or suppresses (YY1, Id1) p16 transcription.
Conclusions:
- Cellular senescence is a complex process involving the p16 tumor suppressor.
- Regulation of p16 expression is tightly controlled by a balance of epigenetic modifications and transcription factor activity.
- Inactivation of suppressor elements leads to enhanced p16 expression, driving senescence.
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...
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...
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
02:15Replicative Cell Senescence