Role of Jumping Genes During Stress
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Role of Jumping Genes During Stress: New Research Study Findings

In human DNA, only one percent of the DNA codes for proteins while the rest, approximately half of the remaining genome is made of sequences that used to be called “junk” and these sequences can jump from one location to another copying themselves into RNA or DNA. At Massachusetts General Hospital (MGH), an important role of one of these jumping genes during stress was revealed in the previous research by a research team. The same group discovered a surprising new property of this jumping RNA in this new research published in the Proceedings of the National Academy of Sciences.

In the genome, the sequences that jump from place to place are generally known as transposable elements and we still have not fully understood their role in health and disease. However, for a long time, these elements have been suspected to be more than just parasitic elements without good function.

An investigator in the Department of Molecular Biology at MGH, Jeannie Lee, MD, Ph.D., and her colleagues in their original study found that one of these transposable elements, short interspersed nuclear element (SINE), present very abundant, known as B2 in mice and

ALU in humans makes an RNA that is cut when together with a protein called EZH2. They were, however, not aware of how the RNA was cut at that time. Scientists have now cracked the code and found that B2 and ALU cut themselves.

It was considered until four decades ago that enzymes were made only by proteins and that only enzymes can cut the building blocks of RNA and DNA, the nucleic acids. Yet, in 1982, it was shown that RNA can function as enzymes as well, these RNAs are known as ribozymes This discovery won the Nobel Prize in Chemistry in 1989. Currently, there are 15 classes of ribosomes been described, but most of these are primarily observed in viruses and bacteria. There are very few of them known in mammals such as humans, with their functions remaining mostly unclear.

The Lee group’s discovery puts a new twist to the ribozyme story because of the abundant presence of B2 and ALU in our cells. Lee said, “Hundreds of thousands of B2 and ALU copies are present in our DNA and during stress, they are expressed massively.  The amount of ribosome activity is mind-boggling!” It was found that when B2 and ALU were subjected to heat or other forms of stress, they become activated and if not, they are normally silent. Also, by interacting with the EZH2 protein, their RNA-cutting activity is enhanced

It was noted that those cells are continually challenged by stress, and a swift response could mean the difference between life and death. She said, ” It seems highly adaptive when self-cutting RNAs are hinged with the induction of stress-related genes. There would be no requirement for the new synthesis of gene products and instead, the main event would be the protein factor, EZH2 recruitment, that stands ready to be mobilized and exists already.”

There might be important clinical implications of the findings for helping the body to respond to stress, like during the development of autoimmune diseases, or infections or cancer.