Forum on Cellular Senescence.......
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Cellular Senescence Forum Forums
A blog for those interested in the physiological and pathological impact of senescent cells.
Why induce Cellular Senescence Rather than Apoptosis?
When
cells become senescent in vitro they often become resistant to apoptotic stimuli in comparison to proliferating cells.
It can be speculated that if immune cells are necessary for eliminating senescent
cells, the pro-survival phenotype of senescent cells may function to favor such
elimination. In conjunction with regulating immune ligands and the secretory
phenotype, persistent activation of the DDR, particularly double strand breaks
(DSBs), may also promote a pro-survival response to facilitate DNA repair. However, if senescent cells are not removed by the immune system, this
pro-survival phenotype inadvertently promotes their persistence in tissues. Alternatively,
the pro- survival phenotype of senescent cells may be an adaptive response
mediated by stresses within the microenvironment to facilitate protection from
further stress.
The
question still arises as to why senescent cells may favor removal by the immune
system rather than undergoing programmed cell death. One plausible explanation
could be related to the potential function of senescent cells during cellular
repair following tissue
damage. During wound healing, senescent cells
most likely play a positive role by (1) secreting chemo-attractants that
recruit and activate immune cells to the site of injury, (2) secrete
growth factors to stimulate cellular proliferation required for cellular
replacement and protein synthesis and (3) the secretion of proteases to debride
damaged tissue. In addition, senescent
cells may help to preserve
tissue integrity during wound
healing, that may otherwise be lost if cells underwent apoptosis, until such
time that non- resident cells from other sources, such as stem cells are
present to repopulate the tissue with functional cells. In an orchestrated
response, senescent cells would be subsequently eliminated by the immune system
when no longer required.
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