Journal of Undergraduate Research


subtelomeric silencing, aging, telomeres, chromosomes


Life Sciences


Physiology and Developmental Biology


Telomeres, located at the ends of chromosomes, are repetitive DNA sequences composed of TTAGGG repeated thousands of times. Each time a cell copies its DNA a small amount of telomeric DNA is lost due to the end replication problem. Because of this, telomeres are eventually lost. New telomeres are synthesized by telomerase. Telomerase has both a protein reverse transcriptase component (TERT) and an RNA template (TERC) that it uses to synthesize new telomeres; however, expression is tightly controlled and is not expressed in most cells in our bodies. This limits the number of times that most of our cells can divide. When telomeres get short, they trigger a DNA damage response that leads to senescence or apoptosis. Telomeres are longest when we are born and they shorten as we age. While the role of short telomeres in cellular apoptosis and senescence is well established, less is known about the gene expression changes that occur when telomeres shorten. In some pathogenic yeast, it has been shown that expression of genes located next to the telomere changes when the telomeres become short, due to epigenetic changes in the DNA1. This phenomenon has been termed subtelomeric silencing. Genes in the area close to the telomeres are suppressed by the telomeres when they are long, but when they are shortened the genes are expressed in greater frequencies. Here we will test if subtelomeric silencing occurs in human cells and examine if telomere shortening could underlie age-related changes in gene expression. This phenomenon could also play a role in certain age-associated diseases.

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