Supplement 121

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Supplement 12-1

• What is the Relationship Between Replicative Cell
  Senescence Functional Tissue Senescence.
• Addition to Biology of Aging 3e by Robert Arking

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Relationship between stress telomeres? von
Ziglincki psychological stress alters telomere
length Relationship between telomere
length/replicative senescence, cell function
tissue senescence? heart skin other tissues
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(No Transcript)
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Psychological Stress Induces Oxidative Stress
Shortens Telomeres
Perceived Stress Makes You Age!
This, when combined with data from glucocorticoid
studies, provides the mechanistic basis for the
findings of the MIDUS twin study
Epel et al., PNAS 101 17312, 2005
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Senescence of the Heart is Related to Changes in
Cell Demographics Brought About By Changes in
Stem Cell Activity
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Lakatta, Circulation 107490, 2003
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Cardiac Myocyte Stem Cells Are Found In the Mouse
Heart
Torella et al., Circulation Res. 94514, 2004
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Cardiac Stem Cells and Aging mtOxDam in Cardiac
Myocytes with Normal (WT) and Elevated (TG)
Levels of IGF-1
Rep Hyp Die
Rep Hyp Die
Torella et al., Circulation
Res. 94514, 2004
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Torella et al., Circulation Res. 94514, 2004
Cell Senescence Markers Increase in WT but not in
TG myocytes
Telomere lengths decrease significantly more in
WT than in TG myocytes
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Note difference in growth kinetics the
functional effects of these different growth
strategies.
Deaths gtgtBirths Function Lost
Deaths Births Function Kept
TG mice with elevated IGF-1 Have Larger Numbers
of Functional Cardiac Stem Cells, Their
Demographic Balance Keeps Their Heart Functional
Longer Than in WT
Torella et al., Circulation Res. 94514, 2004
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Summary of the Data
Is there a contradiction between these effects of
elevated IGF 1 effects on the heart the effects
of decreased IGF 1 on longevity?
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Note that localized high levels of IGF-1 also
maintain regenerative capacity in skeletal muscle
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ROS Limits the Lifespan of Hematopoetic Cells in
vivo
HSC treated in vitro with a GSH depleter (BSO)
have dose-dependent increases in ROS levels
This treatment has no effect on HSCs ability to
form colonies in vitro within 1 week after
treatment
This treatment has an obvious effect on the HSCs
ability to form colonies in vivo 16 wks after
being injected into a mouse.
Ito et al., Nature Medicine 12445, 2006
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One way to interpret the data of the prior slide
is to make the reasonable assumption that the
depletion of GSH brought about by BSO
pre-treatment causes oxidative damage to the
telomeres. The damaged telomeres adversely
affect the replicative potential of the HSC
population. The damaged cells cannot effectively
replicate in an otherwise permissive environment.
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Skin Senescence
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The Role of Senescent Cells in Skin Aging
Young --------------??----?Old
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What Is The Relationship Between Cell Aging
Tissue Aging?
Improbable Possible
Probable
Fossel, Cells, Aging Human Disease, Oxford 2005
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Dimri et al., PNAS 929363, 1995
Early Passage Late Passage
pH 4, non-specific
pH 6.0, SA-ß-Gal
SA-ß-Gal stained cells in culture do not engage
in scheduled DNA synthesis.
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Young Young Sun
Old, staining Old, staining
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SA-ß-Gal Staining in Human Skin of Different Ages
Dimri et al, 1995
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Severino et al., ECR 257162
Lack of Strong Correlation Between Age Number
of Stained Cells in Human Tissue Sections
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SA-ß-Gal Staining is Induced by Oxidative Stress
As Well As By Age (?)
Young Adult, 26 y
Old Adult, 80 y
WI38 cells Ox Stress
? ?
? ?
Fetal
Severino et al., 2000
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SA-ß-Gal Staining is Induced by Culture
Conditions
Early Passage Cells
Late Passage Cells
Conclusion SA-ß-Gal Staining is a non-specific
marker of senescent cells. It is a useful but not
definitive marker.
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Telomere Structure
Blasco, Nat. Rev. Gen. 6611, 2005
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Histone Modification Telomeres Yields Epigenetic
Regulation of Cell Cycle
These complexes of altered histones and bound
telomere binding proteins yield distinctive
chromatin structures which can be detected by
antibody staining. This allows one to determine
the telomeric status of treated and control
cells.
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Cell Senescence In Aging Primate Skin As Assayed
By Telomere Dysfunction
Herbig et al., Science 3111257, 2006
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Reconstruction of Skin From a Suspension of Skin
Cells From a 15-Day Embryonic Mouse
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ltlt Normal Human Skin
ltltHuman Skin Equiv. (grown in vitro from only
keratinocytes fibroblasts )
Not an exact imitation!
Carasco et al., Anat. Rec. 264261, 2001
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Reconstituted Human Skin Expresses Appropriate
Cell Differentiation Antigens
From Carasco et al, Anat. Rec. 2642612001
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The Cells in the HSE Appear to Go Through The
Cell Cycle In A Normal Manner
DNA Content
Carasco et al., Anat. Rec. 264261, 2001
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• Modified HSE protocol. Took dermal fibroblasts
  from culture with or without pTERT, and assayed
  their contribution to the phenotype of
  reconstituted skin.
• Dissociated keratinocytes were mixed with aged
  and treated fibroblasts in culture chambers on
  nude mice.
• Questions being asked
• Does telomerase treatment affect fibroblast
  function?
• 2. Does skin structure and function correlate
  with functional state of fibroblasts?

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Resistance to Mechanical Blistering of Skin With
Different Fibroblasts
PD20
PD60
ltLaminin 5
ltCollagen VII
PD85
PD 110 hTERT
Funk et al, ECR 258270, 2000
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FINE STRUCTURE IS RELATED TO FIBROBLAST CELL
STATE?
Note that skin reconstituted with young passage
fibroblasts (upper fig.) and fibroblasts
expressing a telomerase transgene (lower fig.)
both show hemidesmosomes linked into intermediate
filaments within the epidermis are positioned
directly across from regions containing collagen
filaments (arrows). Also note there was no EM
photo of skin reconstituted with old passage
fibroblasts, although the implication of the
article is that the properties of young skin are
associated with fibroblast cells expressing
telomerase and certain patterns of gene
expression. From Funk et al ECR 258271, 2000
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Late Cells
Sen/young gtgt hTERT/young
Early Cells
Young/sen hTERT/sen
Funk et al, ECR 258270, 2000