Transcript Слайд 1 - Newdiamed

ФЕНОМЕН "СТАЦИОНАРНОГО
СТАРЕНИЯ" КЛЕТОЧНЫХ КУЛЬТУР:
ТРИДЦАТЬ ЛЕТ СПУСТЯ
А.Н.Хохлов
Сектор эволюционной цитогеронтологии,
биологический факультет МГУ имени
М.В.Ломоносова, Москва, Россия
[email protected]
Cell Senescence
In culture experiments а la
Hayflick, researchers
estimate the replicative
capacity of cells by counting
the number of times a culture
can be split before the cells
stop dividing. Trypsin is added
to free the cells from the
extracellular matrix, and
cultures are grown until cells
carpet the floor of the flasks.
This protocol spawned the
legendary Hayflick limit (from
Hopkin, 2001).
• Hayflick’s phenomenon (IOW - “cell senescence”;
unfortunately, last years this term, in my opinion, has rather often
been used incorrectly by those who relate it to so called DNA
damage response) – limited normal cell proliferation in vitro and in
vivo (Population Doubling Level limit)
• From the first to the last passage of “senescing” cells they
change in the same way as cells of aging multicellular organism
• We cannot explain why we age just with the help of the
Hayflick’s phenomenon (say, the most important organs – brain
and heart – contain a lot of postmitotic cells like neurons or
cardiomyocytes)
• The Hayflick’s phenomenon is defined by a set of various
correlations only
However, now we know how the Hayflick’s
phenomenon is realized (thanks to Alexei
Olovnikov!)
Хохлов А.Н., Чиркова Е.Ю., Ушаков В.Л.
Использование стационарных культур
для изучения механизмов клеточного
старения
В сб.: Первый съезд Белорус. общества
геронтологов и гериатров. Тез. докл.
Минск, 1983, 188-189
THEORY OF AGING
Cell proliferation restriction is the main
cause of accumulation in cells of DNA
damage inducing, in turn, other damage
and, as a result, cell death
PROPOSED MODEL
Stationary cell cultures (it is assumed
that under in vitro cell proliferation
restriction cells accumulate the damage
similar to those in cells aging in vivo)
PRIMARY CAUSE OF AGING
DNA damage
Influence on this stage
by geroprotector or
geropromoter modulates
the rate of aging only
temporarily
Influence on this stage
allows to find out whether
the factor investigated is
geroprotector or geropromoter
ALL OTHER AGE-DEPENDENT
CHANGES, AGE DISEASES
INCREASE OF ORGANISM’S
DEATH PROBABILITY
Cell aging is the
accumulation in a cell
population of various types
of damage identical to the
damage arising in senescing
multicellular organism
Cell density (relative units)
Schematic representation of cultured cell
“stationary phase aging” phenomenon
Time after subcultivation (days)
Survival curve of Chinese hamster stationary cell culture (solid line –
experimental points; dotted line – approximation by the Gompertz equation;
straight line – mortality rate changes with time)
?
Telomeres and Telomerase
«Age» changes shown to really
occur in stationary cell cultures
• Accumulation of DNA breaks and DNA-protein crosslinks
• Accumulation of 8-oxo-2’-deoxyguanosine in DNA
• Inhibition of poly-ADP-ribosylation of chromatin proteins
• DNA demethylation
• Changes of spontaneous sister chromatid exchange
level
• Plasma membrane changes
• Nuclear structure modulations
• Decrease of the rate of mitogen-stimulated cell cycling
and of cell colony-forming ability
«Stationary phase aging» experiments
have been already carried out on:
• Normal and transformed human and
animal cells
• Plant cells
• Bacteria
• Mycoplasmas
• Yeasts
Bacteria
Yeasts
2012
Thanks for your attention and patience,
sincerely yours,
AN Khokhlov
If you want to make God laugh –
describe to Him your theory of
aging
Naturally, anybody from the
audience has the right to object to
me. And I can certainly agree with
him.
But then we'll both be wrong - .