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The truth about DNA damage: How much genetic damage occurs in your body every day?
An invisible battle is taking place in our bodies every day - DNA damage and repair. Whether due to natural aging or external environmental insults, DNA damage occurs with surprising frequency. According to research, each human cell experiences approximately 10,000 DNA damage events per day. In other organisms, such as mice and rats, the number is as high as 100,000. These damages are not limited to single chemical structural changes, but also include chain breaks, missing nucleotides, and even chemically altered base groups, such as 8-hydroxy-2'-deoxyguanosine (8-OHdG).
DNA damage is an abnormal chemical structure, while mutations are changes in the gene sequence.
These DNA damages not only affect the normal functions of cells, but may also trigger deeper pathological changes, such as the development of cancer. Repair mechanisms exist, but they are not always effective, and a lot of damage can accumulate in cells, especially in cells that no longer divide, such as brain or muscle cells. This accumulated damage over time leads to aging phenomena. As we age, the amount of DNA damage gradually increases, and this phenomenon is increasingly being used to explain the DNA damage theory of aging.
During the cell cycle, there are multiple checkpoints that ensure that cells are in a healthy state before entering mitosis.
Cells have multiple checkpoints to detect DNA damage. The G1, G2, and spindle assembly checkpoints are key and specifically monitor DNA integrity during these critical periods. Especially during the S phase, cells are most vulnerable to DNA damage. This suggests that the occurrence of DNA damage is not only random, but also closely related to the life cycle of cells. Based on these facts, we can gain a deeper understanding of the diversity of DNA damage and its consequences.
Oxidative damage to cells occurs daily through metabolism and hydrolysis.
Naturally occurring DNA damage mainly involves the breaking of chemical bonds during hydrolysis and oxidants released by cellular metabolism. Whenever cells undergo oxidation, damage is inevitable. Specifically, oxidative damage can alter the structure of DNA, resulting in more than 30 different changes. Therefore, in such a dangerous environment, how cells respond to these challenges has become a focus of scientific research.
DNA repair pathways include several important mechanisms, such as gene excision repair and homologous recombination repair.
When DNA is damaged, cells can choose to repair it or trigger a cell death program. If the damage cannot be repaired, the cell will choose to self-destruct, a process called apoptosis. Apoptosis prevents harmful mutations and carcinogenesis. Studies have shown that approximately 17 DNA repair proteins work together to respond to DNA damage, and the repair functions and apoptosis signals of these proteins alternate to provide protection when cells are damaged.
Inflammation is an important factor leading to oxidative DNA damage.
Inflammatory conditions such as chronic hepatitis or gastritis can lead to an increase in reactive oxygen species and enhance intracellular oxidative stress, which increases the risk of DNA damage. Although this type of damage can be alleviated by repair mechanisms, when the damage exceeds the repair capacity, regenerative mechanisms will be activated, ultimately promoting the development of cancer.
When faced with tens of thousands of DNA damages every day, we can't help but ask, how will this invisible battle affect our health?
