Telomere is a biomarker for longevity in Japan - part 1

Abstract

A telomere is a region of repetitive DNA sequence at the end of a chromosome, which potects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. The telomere regions deter the degradation of genes near the ends of chromosomes by allowing for the shortening of chromosome ends, which necessarily occurs during chromosome replication. The telomere length at Conception is: 15,000 kb, at Birth: 10,000 kb, during the Life cycle we lose approximately 50 base pairs per year, which may be accelerated by stress factors; at Death it remains only: 5,000 base pairs. Lenhard Hayflick is the researcher responsible for proving in 1961 that somatic cells are not immortal. He showed that somatic cells have a finite limit to the number of replications they can undergo. The number of replications varies among somatic cells, presumably because of the varying activity of telomerase. Specifically, highly replicative cells, such as lymphocytes and epidermal cells, have higher telomerase activity than bone, brain, and heart cells. In normal humans, cells with higher telomerase activity are more replicative and can undergo more divisions and extend cellular lifespan. Cells from less replicative tissues (bone, brain, heart) have lower telomerase activity (or none) because they do not replicate as often. This allows for the possibility of replicative synchronicity: Your immune system should not fail before your heart stops! Replicative senescence refers to the inability of a cell to further duplicate itself. When a cell can no longer divide, it either becomes senescent or goes into apoptosis and dies. When too many cells in an organ system cease to perform their proper function, that organ system shuts down leading to the death of the whole organism. Replicative senescence happens when telomeres get too short. So you can see how telomere length limits human lifespan. In 1990 Calvin Harley solved the mystery of the Hayflick Limit by showing that telomere shortening caused cells to stop dividing and senesce. The cell life can be extended beyond the Hayflick Limit if the telomeres are made active and lengthened by adding enzyme telomerase to normal cells so that they could keep dividing, technology discovered by Bill Andrews and his team working then at the Geron Corp under Calvin Harley. People who live a healthy lifestyle and doing what their doctor tells them have been shown to have longer telomeres than people who lead unhealthy lives. Does this mean that healthy living activates telomerase and lengthens telomeres? Although Telomere Length (TL) is known to play a critical role in cellular senescence, the relationship of TL to aging and longevity in humans is not well understood. Findings suggest that TL may not be a strong biomarker of survival in older individuals, but it may be an informative biomarker of healthy aging. In order to clarify whether telomere is a biomarker for longevity in Japan, we investigated the telomere length of individuals living in one of the longevity village in Nagano prefecture. Interestingly, the telomere length of the people in this village is significantly longer than the people living in other parts of Japan. This result strongly suggests that the telomere is a useful biomarker for longevity and healthy lifespan in Japan, which is possibly determined by the lifestyle in the village. We are now focusing on which environmental factors are contributing to the telomere length with respect to diet, exercises, and attitude towards life.