Telomeres are the ends of chromosomes, which package genetic information to pass from parents to children. As the cell divides, these endcaps help keep the genetic information stable and prevent the chromosomes from fusing together. But as cells divide, the telomeres shorten and, eventually, trigger DNA damage that in conjunction with other factors can lead to progression of aging and an increased chance of cancer emerging. Now, a study from researchers at the UT Southwestern Medical Center identifies a new method for determining the length of telomeres, the endcaps of chromosomes, which can influence cancer progression and aging. The opensource study is published in the journal BioTechniques.
Previous studies show that telomeres help determine whether a cell reproduces accurately. As the cell divides, these endcaps degrade, causing the cell to age, and it is believed this degradation may lead to some aspects of aging in humans. Finding the best and most sensitive methods for measuring telomeres is an important initial step that could eventually enable scientists to encourage healthy cell growth or, in the case of cancer, limit or halt the cell growth. The standard method to measure telomere length relies on Southern blot analysis with radioactively or non-radioactively labeled probes containing several telomeric DNA repeats. However, this approach requires relatively large amounts of genomic DNA, making it difficult to measure telomere length when a limited amount of sample is available. A popular nonradioactive alternative called DIG (digoxigenin) probes requires relatively large amounts of genomic DNA and is less sensitive. The current study generates DIG-based probes to detect both C- and G-rich telomeric DNA strands, which significantly enhance the sensitivity of telomere length measurements.
The current study develops a nonradioactive method which uses multiple DIG molecules to increases both the sensitivity and stability of telomere detection. The lab, after applying 3′ fill-in reactions, applied T4 DNA polymerase for DNA blunting in order to remove the additional nucleotide at the 3′ end from the template DNA generated by 3′ fill-in reactions. Results show that this reaction greatly improved the specificity of DIG-labeled telomere probes.
The team surmise that they hope to use knowledge of telomeres to slow or stop cells from aging, or to potentially help stop the uncontrolled growth of cancer cells that maintain their telomeres. For the future, the researchers state that they are interested in understanding this cellular aging process to create an ‘immortal cell,’ which could continue to create new cells without degrading and that could have important implications for diseases related to aging, which, in reverse, could accelerate the mortality of cancer cells.