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cellular senescence

Saturday 19 July 2003

Definition : Cellular senescence is the process that limits the replicative life span of normal human cells in culture.

The senescent phenotype entails an essentially permanent arrest of cell proliferation that can be reversed under certain.

Senescent cells assume a distinctive enlarged and flattened morphology. Senescent cells accumulate in diverse tissues.

Cells continually experience stress and damage from exogenous and endogenous sources, and their responses range from complete recovery to cell death.

Proliferating cells can initiate an additional response by adopting a state of permanent cell-cycle arrest that is termed cellular senescence.

Understanding the causes and consequences of cellular senescence has provided novel insights into how cells react to stress, especially genotoxic stress, and how this cellular response can affect complex organismal processes such as the development of cancer and ageing.


They stain positive for the lysosomal senescence-associated beta-galactosidase (SA-beta-galactosidase). This histochemically detectable enzyme activity is strongly associated with senescence.

All senescent cells show changes in gene expression that appear unrelated to growth arrest.

Many, but not all, senescent cells become resistant to apoptosis, which may explain why they accumulate in vivo.


Oncogene activation in normal cells induces a permanent proliferative arrest known as cellular senescence. This phenomenon restrains the expansion of cells that bear an activated oncogene and acts as a powerful tumor-suppressive process.

Some oncogenes alter the DNA-replication process and cause DNA-damage accumulation. DNA-damage checkpoint-response activation together with the increased appearance of heterochromatin formation that leads to transcriptional silencing of proliferative genes are, presently, the two main mechanisms known that establish and maintain oncogene-induced senescence.

See also

- senescence

- replicative senescence


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