1. Telomerase in Psychiatry
In 1961 Dr. Leonard Hayflick published a now classic paper on cellular aging. According to this article
normal human cells have a limited capacity for dividing before they die out.
Some types of cells, such as those that produce red and white blood cells, can divide millions of times.
Others, such as neurons, do not reproduce at all.If a cell's Hayflick limit is 50, for example, it will divide
50 times and then become senescent, than die. When enough of our cells die, we die.
Telomeres
A telomere is a repeating sequence of DNA at the end of a chromosome, a sort of cap. Telomeres
resemble the aglets on the ends of shoelaces. They keep the ends of the chromosomes from sticking
together, and from sticking onto other chromosomes. Telomeres are believed to be “cellular clocks” that
set the rate at which the cells age and eventually die.
Each time a cell divides, its telomeres shorten. When the telomeres become short enough, cell division
stops and the cell soon dies. This resembles sharpening a pencil. Each time the pencil is renewed by
sharpening, a little bit of it is removed, until after repeated sharpenings, there is no longer enough of
the pencil remaining to perform its function.
Telomerase
A telomerase is an enzyme (ribonucleoprotein polymerase) that was discovered in 1998. Its function is
maintenance and building of new telomeres by addition of the nucleotide repeat TTAGGG.
The enzyme consists of a protein component (TERT) with reverse transcriptase activity, and an RNA
component, encoded by this gene, that serves as a template for the telomere repeat.

2. http://www.youtube.com/watch?v=MjfIWzufq_I&noredirect=1
Telomerase is present in neuroblastsand early postmitotic embryonic neurons but is absent from adult
neurons because they do not reproduce. However,recently it was discovered that the telomerase
protein TERT is very prevalent in neurons and mitochondria from brain tissue. This suggests that
mitochondrial TERT may protect neurons from oxidative stress known to contribute to age-related
dysfunction and neurodegenerative disease.
Telomerase is believed to have a stress-protective function upon the mitochondrion.
http://www.crter.org/NRR-E/2009/6k/405-412.pdf
There seems to be a mutual exclusion of TERT and tau proteins in cortical and hippocampal neurons
from patients with Alzheimers’ disease (AD).
http://brain.oxfordjournals.org/content/134/7/2044.full
Application in Psychiatry
The role of telomerase in cancer is well documented, but recently, telomere dysfunction in peripheral
leukocytes has been described in psychiatric conditions:
1. Telomere length is reduced in peripheral blood lymphocytes from individuals with schizophrenia
probably due to decreased telomerase activity.
Further studies are needed since this is avalid candidate for a biological marker in this condition (Kao et
al., 2008; Porton et al., 2008).
2. Accelerated telomere shortening and decreased telomerase activity has been reported in chronically
stressed individuals (Epel et al., 2004), mood disorders (Simon et al., 2006).
http://www.jneurosci.org/content/31/34/12258.full.pdf
3. Mice deficient in mTERT exhibited significantly altered anxiety-like behaviors (Lee et al., 2010).
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017837
4. Exposure to violence in childhood short telomeres
http://www.moffittcaspi.com/WhatsNew/Shalev_2012_MPepub.pdf
ADONIS SFERA, MD