Download Telomeres are specialized nucleoprotein structures

Telomeres are specialized nucleoprotein structures capping ends of linear
chromosomes, thus preventing the termini from being recognized as
double-strand breaks. These structures are composed of repetitive
sequences of guanine-rich hexameric DNA together with specific telomerebinding proteins. In addition to protecting of the chromosomes from
damage and degradation, maintaining stable telomere complexes is
indispensable for indefinite proliferation of specific cellular types, such as
germ-line and cancer cells. The progress in our understanding of telomere
biology indicates that manipulation of telomeres and telomerase could lead
to clinically relevant applications in the diagnosis, prevention and
treatment of cancer.
Second reference and text:
Aging means a decrease in vitality due to age, subjectivity to various
diseases. This is a universal situation, which is the same for all organisms,
only at individual speeds. From the molecular point of view, it is an inability
to renew the correct structure of biomolecules for an unlimited time =
„systemic molecular disorder“ (Hayflick).
Telomere is an end section of the chromosomal DNA, consisting of many
times repeated short sequence, to which specific proteins binds. You can
imagine telomeres such as “caps”, which are placed on both ends of each
chromosome and protect them against damage (e.g. by a transfer of part of
chromosomes to another – the so-called nonreciprocal – e.g. by a transfer of
one chromosome to another – the so-called translocation).
During each cell division, telomeres are shortened a little and when they
reach a certain critical value, chromosomes are damaged and the cell
division stops or cells die. P
Telomerase prevents shortening of telomeres and thereby facilitates cell
Davison.
The ability of a cell to divide decreases with age. The reasons are DNA
structures, marked as telomeres, which protect the ends of chromosomes
and which are shortened a little during each cell division. When almost
nothing is left, the cell stops dividing and then it dies.
Division is important especially for immune system cells, which use division
to respond to the presence of an infection. The number of their possible
divisions, unlike most other body cells, is increased by the enzyme
telomerase, which prevents shortening of telomeres. However, the enzyme
telomerase in patients infected by HIV does not prevent shortening of
telomeres. In patients infected by the HIV virus, scientists have found many
dysfunctional T-lymphocytes with short telomeres, which indicates that
working of their enzyme telomerase has its limits.
Previous studies showed that shortening of telomeres can be prevented by
means of the gene therapy, when genes for telomerase are inserted into T
lymphocytes. Such modified bubbles can then war with the HIV virus for a
much longer time. The problem is that this approach cannot be used to treat
millions infected people and experts are looking for alternatives. One of
them is described by scientists from the California University in Los Angeles
in the expert magazine Journal of Immunology.
They found out that a substance isolated from the plant Astragalus
membranaceus has similar effects on T lymphocytes as gene therapy. The
plant Astragalus (), which is abundantly used in the traditional Chinese
medicine. The compound called TAT2 works as an efficient activator of
telomerase, which slows down shortening of telomeres. Moreover, it
increases the ability of cells to produce soluble factors cytokines and
chemokines, which are crucial for some patients, in order that their immune
system works again. Their very production is usually decreased in cells of
patients infected by the HIV virus. The study authors also claim that TAT2
sis a great addition, where in some cases even potential replacement of
combined antiviral therapy is considered (HAART),which could prolong the
life of people affected by the HIV virus.
Source: Telomerase-Based Pharmacologic Enhancement of Antiviral
Function of Human CD8+ T Lymphocytes, , Steven Russell Fauce,, Beth D.
Jamieson†, Allison C. Chin , Ronald T. Mitsuyasu, Stan T. Parish, Hwee L.
Ng, Christina M. Ramirez Kitchen, Otto O. Yang, Calvin B. Harley and Rita
B. Effros.