Telomeric Theory-Back Ground
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Tue Aug 25 23:46:37 EST 1998
II. BACK GROUND OF THE TELOMERIC THEORY OF AGING
A) Origin Of The Theory
In 1961 L. Hayflick and P.S. Moorhead published a paper showing that
replicating cells have a finite life span and that cells in culture and
presumably the body would only reproduce up to a specified limit and then
stop reproducing altogether.
In 1972 J.D. Watson showed that the telomeres at the of the chromosomes
shortened with each cellular reproduction.
Putting these two findings together a Russian scientist A,M. Olovnikov
proposed in 1973 that "each DNA replication depletes telomere material to a
point that signals the cell to stop dividing." This was the origin of the
telomeric theory of aging.
B) Early Research & Finding Telomerase
Research in 1985 by E.H. Blackburn and C.W. Greider found an enzyme that
maintained telomeric length in yeast that allowed the yeast to continue
replicating without depleting the telomeres. In 1987 this same team named
this enzyme telomerase.
G.B. Morin in 1989 showed that telomerase was active in the immortal cell
line HeLa and suggested that this was the cause of the cell lines
Subsequent research by C. Harley and others showed that the enzyme telomerase
was active in almost all cancerous tissue. In 1992 Dr. Harley formed the
Geron Corporation primarily to find a means of inactivating telomerase in
these cancers with the expectation that the uncontrolled growth of the tumors
would be halted in the absence of telomerase. Geron Corp would also be
looking into both senescent gene expression and telomere length modulation.
The implications of attempts to effect a change in telomeric length would
soon become apparent.
C) Relating Telomeres To Aging
On March 15th, 1996, in the European Molecular Biology Organization Journal
Dr. J. Shay and Dr. W. Wright published research showing that the enzyme
telomerase could maintain telomeric length in normal human tissues and extend
their life span beyond their expected Hayflick limit. This confirmed the
research in cancerous and HeLa cells that maintaining telomeric length could
extend the life span of cells but for the first time it was with human cells
that continued to function and reproduce in a normal manner.
These finding were confirmed by research published in Science, in January
1998. Geron Corps. Dr. Harley in collaboration with Dr. Shay and Dr. Wright,
among others, showed that normal human cells could be maintained in a
"phenotypically youthful state".
(Next: State of the research into the telomeric theory of aging.)
Thomas Mahoney, Pres.
Lifeline Laboratories, Inc.
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