Researchers explain the intricate interactions that shape DNA organization



Imagine if understanding how DNA folds could unlock new breakthroughs in medicine — researchers have now developed a multilayer model that explains the intricate folding and packaging of chromatin, accounting for the complex physical, chemical, and structural constraints of chromosomes.

DNA is packed into chromatin by wrapping around proteins called histones, forming small units called nucleosomes — like “beads on a string,” with the DNA as the string. These nucleosomes coil into thicker fibers, which then twist and fold into tightly packed chromosomes.


In each human cell, the DNA stretches about two meters long, yet through this intricate compaction process, it fits neatly inside a nucleus that is much smaller than a strand of human hair. This efficient system allows the long strands of DNA to fit neatly inside the cell’s nucleus while keeping it organized and accessible for important tasks like gene expression and cell division.

Over the years, researchers have developed many models to explain the folding mechanism of DNA, but none have been able to truly capture it. A better understanding of DNA packaging would help researchers understand how heredity is practically modulated and realized into discernible features.

“I tried to demonstrate that the detailed analysis of the difficulties for the high compaction of the enormously long genomic DNA molecules can help to construct a physically consistent structural model of chromosomes,” wrote Joan-Ramon Dabon, a researcher at Universitat Autònoma de Barcelona, in Spain, in an email.


Where current models come up short

Existing models depict chromatin with long chromatin and empty spaces lacking the repeating nucleosome unit, which are at odds with the “sardine can” arrangement required to fit large amounts of DNA. “There are models that do not consider the self-associative properties of nucleosomes and cannot explain the elongated cylindrical shape of chromosomes,” said Daban. Previous models often overlooked important constraints based on experimental findings and computer simulations.

To create a realistic model of chromatin folding, researchers need to take into account the contours of chromatin and how its shape changes as it folds, bends, and twists. Chromatin models need to also evaluate how long DNA strands are protected from entangling and breakage, while allowing for easy unspooling to facilitate gene expression.

Through imaging microscopy studies carried out in Daban’s lab, the researchers found that chromatin forms flat, stacked layers where each layer is as thick as a single sheet of nucleosomes. The thickness of each layer led scientists to suggest that in chromosomes, the chromatin folds in a regular pattern with many layers of nucleosomes neatly stacked along the length of the chromosome.

This multilayer chromatin folding pattern also does away with significant tangling, as would be otherwise expected in any lengthy cable or fiber.

“The organization of DNA in chromosomes can be explained from repetitive interactions between nucleosomes,” said Daban. “A multilayer organization of chromatin provides a structural framework that can support the epigenetic mechanisms of gene regulation and is compatible with DNA replication and repair, and chromosome duplication.”


Multilayering provides deeper insights

Epigenetic mechanisms are akin to switches that control which genes are turned on or off, and are controlled by our environment, diet, and experiences. Even without changing the DNA itself, the signals can be passed down to future generations. The high-level organization is central to how epigenetic mechanisms control gene regulation, and better models of DNA packaging will help researchers understand these mechanisms.

Most models, except for the multilayer chromatin model proposed by Daban, struggle to explain certain chromosome features, such as the light and dark bands observed when chromosomes are stained and viewed under a microscope, or the structural changes seen in genetic studies when chromosome segments break and swap places.

For example, competing models, like the fibrillar model, do not adequately account for the orientation of DNA folding or the thickness and width of individual layers, which appear as distinct bands in microscopy.#DNAOrganization #GeneRegulation #ChromatinStructure #DNAInteractions
#Epigenetics


International Young Scientist Awards
Website link: youngscientistawards.com
Nomination Link: https://youngscientistawards.com/award-nomination/?ecategory=Awards&rcategory=Awardee
Contact Us: support@youngscientistawards.com _________________________________________________________________________________________________________

Social Media:

Twitter : https://twitter.com/youngsc06963908
Linkedin- : https://www.linkedin.com/in/shravya-r...
Pinterest : https://in.pinterest.com/youngscienti...
Blog : https://youngscientistaward.blogspot....
Tumblr : https://www.tumblr.com/blog/shravya9



Comments

Post a Comment

Popular posts from this blog

14 recent scientific breakthroughs

Image
1. Cell therapy for melanoma The U.S. Food and Drug Administration (FDA) approved the first cellular therapy for aggressive forms of melanoma. The treatment, called Amtagvi, is "designed to fight off advanced forms of melanoma by extracting and replicating T cells derived from a patient's tumor," said NPR. These cells are also called tumor-infiltrating lymphocytes (TIL). T cells are integral in the immune system but can become "dysfunctional inside tumors." "The approval of Amtagvi represents the culmination of scientific and clinical research efforts leading to a novel T cell immunotherapy for patients with limited treatment options," Dr. Peter Marks, the director of the FDA's Center for Biologics Evaluation and Research, said in a statement. The treatment won't work for everyone, but research by the National Institutes of Health showed a "56% response rate among patients with melanoma, and 24% of patients had a complete disappearance of
Read more

8th Edition of International Young Scientist Awards

Image
  8th Edition of International Young Scientist Awards The Magic of Rainbows: Unveiling Nature's Miracles The term "rainbow" refers to a meteorological phenomenon that appears as a circular arc of multicolored light in the sky. It occurs when sunlight is refracted, or bent, by water droplets in the air, such as raindrops or mist. Rainbows typically form when there are rain showers or storms with sunlight breaking through the clouds. he colors of a rainbow are usually seen in a specific order, from top to bottom: red, orange, yellow, green, blue, indigo, and violet. This order of colors can be remembered using the acronym "ROYGBIV." Each color corresponds to a different wavelength of light, and the bending of light causes the separation and dispersion of these colors, creating the distinct rainbow pattern. Rainbows are usually seen as semicircles, with the center of the circle below the horizon. However, when observed from high altitudes, such as from an airplane
Read more

1st Edition of International Young Scientist Awards

Image
Scientists Discover Massive "Ocean" Near Earth's Core The study confirmed something that it was only a theory, namely that ocean water accompanies subducting slabs and thus enters the transition zone. Scientists have discovered a reservoir of water three times the volume of all the oceans beneath the Earth's surface, according to an international study . The water has been found between the transition zone of the Earth's upper and lower mantle. The research team analyzed a rate diamond formed 660 meters below the Earth's surface using techniques including Raman spectroscopy and FTIR spectrometry, ANI reported. The study confirmed something that for a long time it was just a theory, namely that ocean water accompanies subducting slabs and thus enters the transition zone. This means that our planet's water cycle includes the Earth's interior. "These mineral transformations greatly hinder the movements of rock in the mantle," explains Prof. Fran
Read more