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Evidence that transcriptional activation by p53 plays a direct role in the induction of cellular senescence

Evidence that transcriptional activation by p53 plays a direct role in the induction of cellular senescence
Evidence that transcriptional activation by p53 plays a direct role in the induction of cellular senescence
Wild-type p53 is necessary for the growth arrest of human diploid fibroblasts (HDF) (and many other cell types) at the end of their proliferative lifespan. Although p53 may actively mediate senescence, possibly in response to telomere erosion, it is however equally possible that it is merely a permissive factor required for response to some other inducer. To address this question, we have generated stable transfectants of early passage HDF, represented here by clone LacZ21, in which expression of a beta-galactosidase reporter construct reflects p53 transactivation activity. During continuous passage, the proportion of beta-gal positive LacZ21 cells remained below 2% for 25 population doublings (pd), first became significantly increased after 29 pd, and thereafter increased rapidly, reaching a maximum of 88% in fully-senescent cells (32 pd), which exceeded the response observed following an optimum dose (20 J/m2) of u.v. radiation. Correspondingly, the proportion of cells incorporating bromodeoxyuridine (BrdU) (initially 45-50%) began to fall at 29 pd and thereafter dropped rapidly to below 1% by pd 32. There was therefore a near-perfect reciprocal relationship between reporter construct expression and DNA synthesis as cells approached senescence. Furthermore, a dominant-negative p53 mutant (introduced by retroviral transduction) rescued LacZ21 cells from senescence and generated colonies with extended lifespan in which beta-gal expression was totally abolished. These data, although not excluding the need for other p53 functions, strongly suggest that p53-mediated transactivation of growth regulatory genes is a direct trigger, rather than a permissive factor, for cellular senescence.
0950-9232
2097-2104
Bond, J
fec0a192-9490-46f3-a601-755ba4e3fd85
Haughton, M
3279283d-5399-4922-ba7c-17b7c1d45934
Blaydes, J
e957f999-fd91-4f77-ad62-5b4ef069b15b
Gire, V
8c808840-a67a-4281-abda-771c72eefba9
Wynford-Thomas, D
b95cdf4a-87cc-4390-a893-eee9cc7fff5d
Wyllie, F
7b60e765-96bd-4d23-ba8f-72156420c0c6
Bond, J
fec0a192-9490-46f3-a601-755ba4e3fd85
Haughton, M
3279283d-5399-4922-ba7c-17b7c1d45934
Blaydes, J
e957f999-fd91-4f77-ad62-5b4ef069b15b
Gire, V
8c808840-a67a-4281-abda-771c72eefba9
Wynford-Thomas, D
b95cdf4a-87cc-4390-a893-eee9cc7fff5d
Wyllie, F
7b60e765-96bd-4d23-ba8f-72156420c0c6

Bond, J, Haughton, M, Blaydes, J, Gire, V, Wynford-Thomas, D and Wyllie, F (1996) Evidence that transcriptional activation by p53 plays a direct role in the induction of cellular senescence. Oncogene, 13 (10), 2097-2104.

Record type: Article

Abstract

Wild-type p53 is necessary for the growth arrest of human diploid fibroblasts (HDF) (and many other cell types) at the end of their proliferative lifespan. Although p53 may actively mediate senescence, possibly in response to telomere erosion, it is however equally possible that it is merely a permissive factor required for response to some other inducer. To address this question, we have generated stable transfectants of early passage HDF, represented here by clone LacZ21, in which expression of a beta-galactosidase reporter construct reflects p53 transactivation activity. During continuous passage, the proportion of beta-gal positive LacZ21 cells remained below 2% for 25 population doublings (pd), first became significantly increased after 29 pd, and thereafter increased rapidly, reaching a maximum of 88% in fully-senescent cells (32 pd), which exceeded the response observed following an optimum dose (20 J/m2) of u.v. radiation. Correspondingly, the proportion of cells incorporating bromodeoxyuridine (BrdU) (initially 45-50%) began to fall at 29 pd and thereafter dropped rapidly to below 1% by pd 32. There was therefore a near-perfect reciprocal relationship between reporter construct expression and DNA synthesis as cells approached senescence. Furthermore, a dominant-negative p53 mutant (introduced by retroviral transduction) rescued LacZ21 cells from senescence and generated colonies with extended lifespan in which beta-gal expression was totally abolished. These data, although not excluding the need for other p53 functions, strongly suggest that p53-mediated transactivation of growth regulatory genes is a direct trigger, rather than a permissive factor, for cellular senescence.

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Published date: 21 November 1996

Identifiers

Local EPrints ID: 150583
URI: http://eprints.soton.ac.uk/id/eprint/150583
ISSN: 0950-9232
PURE UUID: adff7a35-8623-4b1d-b002-dbdde76d9a69
ORCID for J Blaydes: ORCID iD orcid.org/0000-0001-8525-0209

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Date deposited: 20 Jul 2010 14:18
Last modified: 23 Jul 2022 01:47

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Contributors

Author: J Bond
Author: M Haughton
Author: J Blaydes ORCID iD
Author: V Gire
Author: D Wynford-Thomas
Author: F Wyllie

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