“Exclusome is a cytoplasmic organelle that contains circular plasmid or telomeric DNA inside. Here is the complete story of Exclusome DNA and how it differs from genome DNA.”
For years, we’ve been taught that the eukaryotic cell is organized with a nucleus that contains the cell’s DNA, neatly packaged into chromosomes. However, recent groundbreaking research from ETH Zurich in Germany has uncovered a surprising twist to this story.
However, the story of organelle-bounded DNA, such as chloroplast and mitochondrial DNA, just unfolded a few decades ago!
A team of scientists has identified a new compartment inside mammalian cells that also contains DNA! They’ve named it Exclusome. This discovery challenges our long-standing understanding of how cells organize and handle their genetic material.
Want to know more about Exclusome? Check out this article.
Related article: Unraveling the Mystery of DNA: Definition, Structure, Function and Types.
Disclaimer: The content presented herein has been compiled from reputable, peer-reviewed sources and is presented in an easy to understand manner for better comprehension. A complete list of sources is provided after the article for reference.
Key Topics:
What Is the Exclusome?
The Exclusome is a newly discovered compartment in the cytoplasm (the fluid inside the cell) where small, ring-shaped DNA molecules called plasmids are found.
Unlike the chromosomes we are familiar with, plasmids are not housed in the nucleus but are instead located in the cell’s plasma. This is an unusual finding, as DNA in eukaryotic cells has always been thought to be confined to the nucleus.
Plasmids in the Exclusome come in two forms:
1. External Plasmids – These are DNA molecules that originate from outside the cell, perhaps from bacteria or other external sources.
2. Teloremic Rings – These are special plasmids that are created from the telomeres, which are the protective caps at the ends of chromosomes. In certain cells, particularly in cancerous cells, these telomeres can break off, form rings, and end up in the cytoplasm.
How Does the Exclusome Work?
One of the most fascinating aspects of this discovery is how the cell manages DNA. It turns out that the nucleus is not a simple container of DNA. In fact, it has the ability to selectively eject certain DNA molecules that are no longer needed and send them to the Exclusome in the cytoplasm.
This suggests that the cell has a way of distinguishing between DNA that is essential and DNA that is not, allowing it to maintain genetic integrity by disposing of unnecessary or potentially harmful DNA.
This process of DNA selection could be a way for cells to regulate what stays inside the nucleus, ensuring that only important, functional DNA is kept there.
Related article: Full form of 10 Different Types of DNA.
The Evolutionary Significance of the Exclusome
The discovery of the Exclusome also sheds light on the evolutionary origins of eukaryotic cells. Scientists believe that eukaryotic cells evolved from a fusion between bacteria and archaea (a type of microorganism).
During this process, cells may have developed the ability to manage extrachromosomal DNA (DNA outside the nucleus), which is likely reflected in the creation of the Exclusome.
The researcher also believes that Exclusome consists of gaps that can be seen on nuclear envelopes in the early stage of transformation. These gaps are sealed up or occupied by proteins over time.
The Role of the Exclusome in the Cell
Beyond just storing extrachromosomal DNA, the Exclusome may play an active role in the cell’s response to external threats. It is believed that the DNA in the Exclusome contains “DNA sensors,” which can detect foreign genetic material, such as viruses or bacteria. In response, the cell can initiate the production of cytokines – signaling molecules that alert the immune system to potential infections.
This makes the Exclusome a kind of “signaling hub,” helping the cell communicate with other parts of the body regarding potential threats. Interestingly, if this signaling becomes overactive, it can lead to autoimmune disorders, where the immune system mistakenly attacks the body’s own cells.
Additionally, the Exclusome may serve as a memory bank for DNA encounters. It might store information about past infections or genetic changes, helping the cell “remember” how to respond if the same foreign DNA enters again in the future.
How does it differ from Genomic DNA?
The first thing is, that genomic DNA is well-studied and well-researched. We, now, know so many things regarding our genome but a little regarding the Exclusome.
Our genome contains genes that are inherited, while Exclusome DNA can not be inherited.
On a larger landscape, our genome’s role is to produce proteins and regulate gene expression, conversely, Exclusome’s function is still not well-recognized. Scientists believe that it’s a kind of ‘cell communication device’ and works for the defense system.
Genomic DNA is located on chromosomes. In contrast, the Exclusome contains external or internal circular DNA.
Related article: What is genome?- Definition, Structure and Function.
Wrapping up:
The discovery of the Exclusome reveals a new way cells manage DNA outside the nucleus, adding complexity to cellular function. This breakthrough could impact cancer research, immunity, and our understanding of evolution.
The Exclusome plays an active role in communication, protection, and genetic integrity. However, scientists still do not know more about the mechanism and function of Exclusome. We hope in the near future the mystery will be solved.
Resources:
Schenkel L, Wang X, Le N, Burger M, Kroschewski R. A dedicated cytoplasmic container collects extrachromosomal DNA away from the mammalian nucleus. Mol Biol Cell. 2023 Oct 1;34(11):ar105. doi: 10.1091/mbc.E23-04-0118. Epub 2023 Aug 9. PMID: 37556227; PMCID: PMC10559310.
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