| Telomeres have been compared with the plastic tips on shoelaces because they prevent chromosome ends from fraying and sticking to each other, which would scramble an organism's genetic information to cause cancer, other diseases or death. Could finding ways of controlling telomeres in our cells lead to a cure for aging? Many researchers think so. |
Telomeres have been compared with the plastic tips on shoelaces because they prevent chromosome ends from fraying and sticking to each other, which would scramble an organism's genetic information to cause cancer, other diseases or death.
Yet, each time a cell divides, the telomeres get shorter. When they get too short, the cell no longer can divide and becomes inactive or senescent or dies. This process is associated with aging, cancer and a higher risk of death.
Like the rest of a chromosome and its genes, telomeres are sequences of DNA - chains of chemical code. Like other DNA, they are made of four nucleic acid bases: G for guanine, A for adenine, T for thymine and C for cytosine.
Telomeres are made of repeating sequences of TTAGGG on one strand of DNA bound to AATCCC on the other strand. Thus, one section of telomere is a "repeat" made of six "base pairs."
In human blood cells, the length of telomeres ranges from 8,000 base pairs at birth to 3,000 base pairs as people age and as low as 1,500 in elderly people. (An entire chromosome has about 150 million base pairs.) Each time a cell divides, an average person loses 30 to 200 base pairs from the ends of that cell's telomeres.
Cells normally can divide only about 50 to 70 times, with telomeres getting progressively shorter until the cells become senescent, die or sustain genetic damage that can cause cancer.
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| Image Source: Nature |
Without telomeres, the main part of the chromosome - the part containing genes essential for life - would get shorter each time a cell divides. So telomeres allow cells to divide without losing genes. Cell division is needed so we can grow new skin, blood, bone and other cells when needed.
Without telomeres, chromosome ends could fuse together and degrade the cell's genetic blueprint, making the cell malfunction, become cancerous or die. Because broken DNA is dangerous, a cell has the ability to sense and repair chromosome damage. Without telomeres, the ends of chromosomes would look like broken DNA, and the cell would try to fix something that wasn't broken. That also would make them stop dividing and eventually die.—
In 1998, a team at Geron Corporation added the gene for telomerase to normal human cells by use of a plasmid, and using these cells, created a line of telomerase-positive cells. They found that cells from this line were able to divide indefinitely, without entering replicative senescence as an unmodified cell culture would. This demonstrated that normal human cell lines could be made immortal.
More recently, Spanish researchers published a study on a line of mice whose cells had been engineered to produce ten times more telomerase than wild mice. Telomerase overexpression allowed these mice to live an average of 38% longer than normal. Further, the mice stayed healthier and athletic longer. In the control group, approximately half of all mice had lost the ability to walk a tightrope by the time they were 116-160 weeks old; the telomerase-positive sample showed no loss in this ability at all.
The following video is excerpted from Dr. Bill Andrew's presentation at the Manhattan Beach Project Longevity Conference. Dr. Andrews leads the scientific research and development function of Sierra Sciences. Under Dr. Andrews' direction, Sierra Sciences has discovered and filed patent applications on many previously unknown, key elements of the regulation of telomerase. Dr. Andrews' team at Sierra Sciences is now pursuing direct molecular approaches to temporarily activate telomerase expression, and is performing high-throughput screening and drug discovery efforts.
While Director of Molecular Biology at Geron Corporation, Dr. Andrews was one of the principal discoverers of the telomerase genes. He also authored the book, Telomere Basics
on the subject. Andrews and his company are searching for drugs that will induce telomerase in all our cells. But will that plan work? Will it cure aging? That's the trillion-dollar question, and scientists have been trying to answer it for more than a decade. So far according to Sirera Sciences, all the signs point to yes: telomerase is a possible cure for aging.
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