Clearance of p16 Ink4a -positive senescent cells delays ageing-associated disorders Darren J. Baker1,2,3, TobiasWijshake1,4, Tamar Tchkonia3, Nathan K.

Clearance of p16Ink4a-positive senescent cells delays ageing-associated disorders

Darren J. Baker1,2,3, TobiasWijshake1,4, Tamar Tchkonia3, Nathan K. LeBrasseur3,5, Bennett G. Childs1, Bart van de Sluis4,James L. Kirkland3 & Jan M. van Deursen1,2,3

1 0 N O V E M B E R 2 0 1 1 | VO L 4 7 9 | N AT U R E | 2 3 3

Presented by: Chang chu

Jan.13, 2013

Cellular senescence

mouse embryonic fibroblast 

? whether senescent cells are causally implicated in age relatedDysfunction? whether their removal is beneficial

1 http://en.wikipedia.org/wiki/P16_(gene)

P161: Cyclin-dependent kinase inhibitor 2A

multiple tumor suppressor 1 (MTS-1)

Transgenic strategy:

An earlier mouse model ： FAT-ATTAC2 (fat apoptosis through targeted activation of caspase ）

2 Pajvani, U. B. et al. Fat apoptosis through targeted activation of caspase 8: a new mouse model of inducible and reversible lipoatrophy. Nature Med. 11, 797–803(2005).

Fabp4 promotor

Pronuclear injection of the INK-ATTAC construct into FVB oocytesNine transgenic INK-ATTAC founder lines

• adipose tissue, skeletal muscle and eye

• shortened lifespan age-related phenotypes

BubR1H/H mice

• BubR1 encodes a key member of the mitotic checkpoint

inguinal adipose tissue (IAT)

1. Transgenic INK-ATTAC and endogenous p16Ink4a are under the same transcriptional control mechanism

Rosiglitazone

2. INK-ATTAC is expressed in senescent cells in BubR1 hypomorphic tissue.

SA-b-Gal stained IAT

Expression of senescence markers in tissues

INK-ATTAC is selectively expressed in p16Ink4a-positive senescent cells

3. INK-ATTAC can eliminate senescent cells

• Bone marrow cells of WT;INK-ATTAC transgenic lines 3 and 5

• Cultured with rosiglitazone for 5 days

• Treated with AP20187 for 48h

FKBP–Casp8 activation efficiently eliminates p16Ink4a-positive senescent cells in vitro.

4. Clearance of p16Ink4a-expressing cells from BubR1H/H mice prevents or delays the onset of age-related phenotypes

9-month-old mice

BubR1H/H;INK-ATTAC-3 and -5 mice at 3 weeks of age : AP20187 every third day Untreated

Sarcopenia, cataracts and loss of adipose tissue

Continuous removal of p16Ink4a-expressing cells from BubR1H/H;INK-ATTAC mice selectively delays age-related phenotypes

5. The delayed onset of age-related pathologies coincided with a reduction in the number of senescent cells in these tissues.

Senescent cells were cleared from tissues and that this delays acquisition of age-related dysfunction in BubR1 hypomorphic mice.

BubR1H/H at 5 months: age-related phenotypes are apparentAP20187 treatmentMeasured p16Ink4a-dependent age-related phenotypes at 10 months

6.Investigating the effect of senescent cell clearance later in life

Senescence markers were substantially reduced

Late-life clearance of p16Ink4a positive senescent cells attenuates progression of age-related decline rather than a reversal of ageing in BubR1 hypomorphic mice.

• A novel transgenic mouse model

• Both life-long and late-life clearance of the p16Ink4a expressing senescent cells selectively delayed age-related pathologies in tissues that accumulate these cells.

• Therapeutic interventions to clear senescent cells or block their effects may represent an avenue for treating or delaying age-related diseases and improving healthy human lifespan.