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  • Kun-Hyung Roh

They're Both The Same Age and Have Identical DNA. What Happened?

Source: Dr. David Sinclair and colleagues of Harvard Medical School


The only difference between the two mice is in their epigenomes. All about the epigenome is about turning the DNA, or the gene, on and off. The epigenome has the chemical compounds and the proteins that can control these genes. 


Until recently researchers have thought that viruses, diseases, and aging were caused by changes within the DNA, or mutations. But it turns out that the epigenetic process also plays a major role in this. 


Epigenetics allows our body to organize the DNA. The epigenome packages the DNA like wires around beads. The wire is the DNA, and beads are proteins called histones.


When genes are turned off, this package tightens up, and when turned on, the package loosens. This tightening and loosening of the package depends on the pattern the chemicals are added onto the histone proteins.


This pattern of chemicals stores information on how to read the DNA. It’s like a CD disc with little grooves on it. The CD disc itself is the DNA, but the epigenome tells the body to only read the grooves and access information selectively.


The way how this chemical information looks changes dynamically over the course of life, unlike DNA. Epigenomes can be influenced by lifestyle factors like smoking, exercising, and drinking.


Harvard Professor David Sinclair came up with the idea that maybe this epigenome has a major role in aging. He created genetically identical mice, and then on one mouse he mouse he turned on enzymes that can break up its DNA at a much higher rate. After each mouse he turned on enzymes that can break up its DNA at a much higher rate. After each breakage, the tightness of the DNA package does not return to its original tightness and actually causes a loss in the information that is read. It's basically like leaving scratches on a new CD. 


This confuses the body, making genes that are supposed to be on, turned off, and the genes that are supposed to be off actually turned on. And this is primarily different from the nature of mutations, which changes the breakage, the tightness of the DNA package does not return to its original tightness and actually causes a loss in the information that is read. It's basically like leaving scratches on a new CD. 


This confuses the body, making genes that are supposed to be on, turned off, and the genes that are supposed to be off actually turned on. And this is primarily different from the nature of mutations, which changes the turned on enzymes that can break up its DNA at a much higher rate. After each breakage, the tightness of the DNA package does not return to its original tightness and actually causes a loss in the information that is read. It's basically like leaving scratches on a new CD. 


This confuses the body, making genes that are supposed to be on, turned off, and the genes that are supposed to be off actually turned on. And this is primarily different from the nature of mutations, which changes the structure and function of the proteins. 


In this experiment, to ensure that this wasn't actually impairing the functionality of normal proteins, the Cuts were only made in the region that are not coding for the proteins or genes and it basically only precisely cut in the locations where the chains were missing. As an additional step, they read the DNA sequence again in the end to ensure that the changes of this was not caused by mutation


The results were astonishing–the genetically identical mice that started off at the same age, when they were measured again at the same age, one of the mice showed much more signs of aging. 

 

What was even more interesting is that he used something called the yamanaka factors to essentially Wipe Out the these scratches on the disc 


Especially in the retinal cells or the eye cells and he safely reversed age-related damage that cased blindness and basically restored the vision and this actually made the cover to Nature journal. Another piece evidence that supports this type of a theory is that Professor Steve Horvath wondered, “can we actually look at the patterns of these chemical tags and predict the chronological age?”. And these are these now became known as what we call the methylation clocks and it turns out it's quite accurate in terms of predicting the age of different organs, tissues, and is being used to measure the epigenetic age. 


By quantifying the biological age, experiments are ongoing to see the effects of different compounds that may be effective in even reversing aging. People thought that aging is the effect of mutations and that this causes the genetic information lost forever.

But as research went on, we have now proved that as long as the DNA stays intact, we just need to teach the body again on how to read them correctly.

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