Nuclear membrane repairs the 'dark matter' of DNA

DNA
A depiction of the double helical structure of DNA. Its four coding units (A, T, C, G) are color-coded in pink, orange, purple and yellow. Credit: NHGRI

Scientists have found a new function of the nuclear membrane, the envelope that encases and protects DNA in the nucleus of a cell - it fixes potentially fatal breaks in DNA strands.

Previously, the nuclear membrane was thought to be mostly just a protective bubble around the nuclear material, with pores acting as channels to transport molecules in and out. But in a study published on October 26 in Nature Cell Biology, a research team led by Irene Chiolo documents how broken strands of a portion of DNA known as heterochromatin are dragged to the nuclear membrane for repair.

DNA exists inside of a cell's nucleus in two forms: euchromatin and heterochromatin. Euchromatin gets all of the attention because it encodes most of the genome, while heterochromatin, which is mostly composed of repeated DNA sequences, has long been ignored as "junk DNA."

"Scientists are now starting to pay a lot of attention to this mysterious component of the genome," said Chiolo, assistant professor at the USC Dornsife College of Letters, Arts and Sciences. "Heterochromatin is not only essential for chromosome maintenance during cell division; it also poses specific threats to genome stability. Heterochromatin is potentially one of the most powerful driving forces for cancer formation, but it is the 'dark matter' of the genome. We are just beginning to unravel how repair works here."

The reason why we don't experience thousands of cancers every day in our body is because we have incredibly efficient molecular mechanisms that repair the frequent damages occurring in our DNA. But those that work in heterochromatin are quite extraordinary.

"Repeated sequences tend to recombine with each other during DNA repair," said Taehyun Ryu, USC graduate student and first author on this study. "This would lead to chromosome aberrations as frequently observed in . What prevents these outcomes in normal cells was unclear."

"We knew that nuclear membrane dysfunctions are common in cancer cells," Chiolo said. "Our studies now suggest how these dysfunctions can affect heterochromatin repair and have a causative role in cancer progression."

Working with the fruit fly Drosophila melanogaster, the team observed that breaks in are repaired after damaged sequences move away from the rest of the chromosome to the inner wall of the nuclear membrane. There, a trio of proteins mends the break in a safe environment, where it cannot accidentally get tangled up with incorrect chromosomes.

This study may help reveal how and why organisms become more predisposed to as they age - the progressively deteriorates as an organism ages, removing this bulwark against genome instability.

Next, Chiolo, Ryu and their colleagues will explore how the movement of broken sequences is accomplished and regulated, and what happens in cells and organisms when this membrane-based repair mechanism fails. Their ultimate goal is to understand how this mechanism functions in human and identify new strategies to prevent their catastrophic failure and .


Explore further

Active deformation dynamics of cell nuclei contribute to the formation of intra-nuclear chromosome architectures

More information: Taehyun Ryu et al. Heterochromatic breaks move to the nuclear periphery to continue recombinational repair, Nature Cell Biology (2015). DOI: 10.1038/ncb3258
Journal information: Nature Cell Biology

Citation: Nuclear membrane repairs the 'dark matter' of DNA (2015, October 29) retrieved 17 September 2019 from https://phys.org/news/2015-10-nuclear-membrane-dark-dna.html
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JVK
Oct 31, 2015
Excerpt: "This study may help reveal how and why organisms become more predisposed to cancer as they age - the nuclear membrane progressively deteriorates as an organism ages, removing this bulwark against genome instability."

Wasn't that problem addressed in the context of the links from base pairs and microRNAs to RNA-mediated amino acid substitutions and cell adhesion proteins that appear to protect supercoilded DNA and prevent virus-driven genomic entropy?

Oct 31, 2015
Euchromatin gets all of the attention because it encodes most of the genome, while heterochromatin, which is mostly composed of repeated DNA sequences, has long been ignored as "junk DNA."

From this statement we can understand that only heterochromatin get random damages but no euchromatin. But this claim is not consistent with reality. The reparing DNA mechanisms work everywhere on DNA. Do not have a preferenses which part of DNA to try to repair and which not.

Oct 31, 2015
viko_mx has shown his true colours and STILL refuses to gain ANY education in Physics !

All this time he has proselyted by naive subtle attempts to push an anti-science agenda !

He now believes Relativity is a lie to conspire against his god and makes that claim in public, showing himself to be complete untrustworthy and betrays immense anti-science agenda, see details here:-
http://www.phys.o...ies.html

Why is his god so very silent & why does his god act exactly like an ugly punishing Devil over all ?

viko_mx can only be inferred to be a Devil worshiper and should therefore be banned !

viko_mx I have asked you MANY times to explain WHY your god is a VERY bad communicator ?

viko_mx, show HOW your god communicates ?

I give you ONE more chance, explain WHY your god acts exactly as a Devil & is not trustworthy ?

AND explain WHY Physics & relativity should NOT work with GPS, spacetravel etc ?

JVK
Oct 31, 2015
The reparing DNA mechanisms work everywhere on DNA. Do not have a preferenses which part of DNA to try to repair and which not.


Thanks viko-mx. That's the problem addressed in this parody. Repair starts with energy and base pairs. https://www.youtu...youtu.be

The parody conveys that complexity of the problem that arose as 2 generations were taught to believe in a static structure of the DNA double helix.

Biologically uninformed science idiots like "Mike_Massen" will claim that religious beliefs prevent understanding of the obvious links from physics and chemistry to molecular biology.

To people like him, the links from atoms to ecosystems in all living genera that protect DNA from virus-driven genomic entropy, are the products of "evolution" (his religion).

See also: http://medicalxpr...les.html

Oct 31, 2015
That's the problem addressed in this parody
@jk
a parody is not scientific evidence, and neither is youtube or facebook
an actual scientist or reputable experimental biologist/microbiologist would know that
religious beliefs prevent understanding of the obvious links from physics and chemistry to molecular biology
a faith is not detrimental to science... only when you accept the dogma/religion instead of following the evidence and allow it to dictate the situation or reality instead of following the evidence

This is why you fail so regularly, jk (and viko/ren/verkle) - you let creationist dogma rule your brain instead of actual science
this is why you call the Theory of Evolution a religion: because you don't comprehend science or the power of evidence over religious or delusional beliefs
http://www.ploson...tion=PDF


JVK
Oct 31, 2015
a parody is not scientific evidence


The parody is based on accumulated experimental evidence of biologically-based cause and effect that links this 1992 publication and this 2015 publication.

1992 DNA twist as a transcriptional sensor for environmental changes
http://www.ncbi.n.../1508037

2015 Structural diversity of supercoiled DNA
http://dx.doi.org...omms9440 o


Oct 31, 2015
It is interesting to look the posts of science deniers, although I really should call them those who fear science. They fear their favorite interpretation of the world will be trashed. So, they do things like trying to sow confusion, question the use of resources, or just behave like typical Internet trolls.

Now, it is true that persons like Copernicus, Galileo, and Darwin did alter a lot of fundamental religious thought, but those effects happened over a long time. Those in the trenches of their own belief were mostly untouched and were safely dead long before they had to worry as a practical matter about bending their thinking. So, if you are worried that science is going to get you and yours, I say relax. Generally science and religion can live happily in separate worlds. Many scientists are religious, but do not let their scientific beliefs affect their religious beliefs and vice versa. That is not new. Check how the ancient Greeks dealt with mythos and logos.

JVK
Nov 01, 2015
They have prevented advances in medicine that might well have cured or at least effectively treated all pathology.

Supercoiled DNA links nutrient-dependent microRNAs and adhesion proteins to the stability of organized genomes in all genera. Why are scientists just now revealing what has been known for decades?

https://youtu.be/yGYTLOGZ40U

Does anyone have any idea what they are not being told?

Nov 01, 2015
They have prevented advances in medicine that might well have cured or at least effectively treated all pathology.
@jk
trying to make everyone fear scientific advancement and turn to your religion?
where is your empirical evidence that any medical research or scientific/biological research prevented advances in medicine?

please provide evidence equivalent to a reputable peer reviewed journal and it's validating secondary studies proving this point... otherwise, quit sowing discontent because of your religious beliefs

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