Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Punctuating messages encoded in human genome with transposable elements

04.08.2015

Since the classical studies of Jacob and Monod in the early 1960s, it has been evident that genome sequences contain not only blueprints for genes and the proteins that they encode, but also the instructions for a coordinated regulatory program that governs when, where and to what extent these genes and proteins are expressed.

The execution of this regulatory code is what allows for the creation of very different cell- and tissue-types from the same set of genetic instructions found in the nucleus of every cell. A recent study published in PNAS (July 27, 2015) shows that critical aspects of this regulatory program are encoded by genomic sequence elements that were previously thought to be mere "junk DNA" with no important functions.


A recent study published in Proceedings of the National Academy of Sciences and conducted by a team of researchers at the Georgia Institute of Technology and Aelan Cell Technologies has identified regulatory elements that allow for the creation of a diverse range of different cell types from different genetic information.

Credit: Aelan Cell Technologies

The vast majority of the human genome (~98% of the total genetic information) is not dedicated to encoding proteins, and this non-coding sequence was initially designated as "junk DNA" to underscore its lack of apparent function. Much of the so-called junk DNA in our genomes has accumulated over evolutionary time due to the activity of retrotransposable elements (RTEs), which are capable of moving (transposing) from one location to another in the genome and make copies of themselves when they do so. These elements have been considered as genomic parasites that exist by virtue of their ability to replicate themselves to high numbers within genomes without providing any beneficial function for the hosts in which they reside.

However, recent studies on RTEs have shown that they can in fact encode important functions, and much of their functional activity turns out to be related to how genomes are regulated. RTEs have been linked to stem cell function, tissue differentiation, cancer progression and ultimately to aging and age-related pathologies.

The study by Wang et al. recently published in PNAS (July 27, 2015) provides a new perspective on the role that RTE-derived sequences play in the precise execution of the human genome's regulatory program. This study found that one particular class of RTEs - Mammalian-wide Interspersed Repeats (MIRs) - can serve as genetic landmarks that help to target specific regulatory mechanisms to a large number of genomic sites and thereby lead to the coordinated regulation of the genes located nearby these sites.

This discovery was spearheaded by a team of computational biologists, led by Dr. King Jordan, Associate Professor and Director of the Bioinformatics Graduate Program at the Georgia Institute of Technology, who performed a "big data" analysis of massive datasets generated by hundreds of scientists from dozens of laboratories around the world working as part of the "Encyclopedia of DNA Elements" or ENCODE project. Their comprehensive and integrated data analysis, conducted by primarily by Dr. Jianrong Wang from Dr. Jordan's team, allowed them to pinpoint the location of thousands of individual MIR elements in the human genome that appear to function as so-called "boundary elements" in T lymphocyte cells of the immune system.

Boundary elements are epigenetic regulatory sequences that separate transcriptionally active regions of the human genome from transcriptionally silent regions in a cell-type specific manner. In so doing, these critical regulatory elements help to provide distinct identities to different cell types, although they all contain identical sets of information. The regulatory programs that underlie these cell- and tissue-specific functions and identities are based largely on genome packaging.

Genes that should not be expressed in a given cell or tissue are located in tightly packaged regions of the genome and inaccessible to the transcription factors that would otherwise turn them on. These boundary elements help to establish the geography of genome packaging by delineating the margins between silent regions in which genes are not expressed and active regions in which they are. In this critical role, boundary elements help to control the timing and extent of gene expression across the entire genome. As a result, defects in the organization of the genome by boundary elements are highly relevant for physiological and pathological processes.

"Our colleagues at the Georgia Institute of Technology were able to build upon our early discovery that another class of retrotransposon, the SINEB2 element, can provide boundary function at the mouse growth hormone locus," said Dr. Victoria Lunyak, CEO of Aelan Cell Technologies whose research team collaborated with Jordan lab on this project.

"We randomly picked a hand full of the MIR sequences predicted to serve as boundary elements by the Jordan lab and experimentally validated their activity in mouse cell lines and, with help of our Spanish collaborators, in Zebra fish upon embryonic development," Dr. Lunyak said. "This testing revealed that MIR sequences can serve as punctuation marks within our genome that enable cells to correctly read and comprehend the message transmitted by the genomic sequences."

"One thing that is particularly striking is the fact that these punctuation marks, as Victoria calls them, play a role that is deeply evolutionary conserved," said Dr. Jordan. "The same exact MIR sequences were able to function as boundaries in human CD4+ lymphocytes, in mouse cell models and in Zebrafish."

"This is an important discovery because the understanding of how RTEs punctuate messages encoded in the human genome can help researchers to develop treatments for a wide variety of human diseases, including aging," added Dr. Lunyak

Aging is characterized by a number of global changes in genome organization and function, and aging-associated defects in how our genome is packaged can have severe pathological consequences. In particular, age-related defects in genomic packaging can greatly increase the susceptibility of the genome to damage. Based on the discoveries published in their PNAS paper, the Jordan lab at Georgia Tech and the Lunyak team at Aelan Cell Technologies and their partner Nuclea Biotechnologies are now working towards the development of novel diagnostic and therapeutic strategies that target the critical roles of epigenetic regulators, such as human retrotransposons, in coordinating cell-type specific regulatory programs.

The study was published in the journal Proceedings of the National Academy of Sciences, USA.

Media Contact

Greg D'Agostino
greg@libertysquaregroup.com
617-695-0369

http://www.aelanct.com 

Greg D'Agostino | EurekAlert!

Further reports about: DNA data analysis epigenetic genomes genomic human genome junk DNA role sequence sequences transposable elements

More articles from Health and Medicine:

nachricht Speed data for the brain’s navigation system
06.12.2016 | Deutsches Zentrum für Neurodegenerative Erkrankungen e.V. (DZNE)

nachricht Study suggests possible new target for treating and preventing Alzheimer's
02.12.2016 | Oregon Health & Science University

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Predicting unpredictability: Information theory offers new way to read ice cores

07.12.2016 | Earth Sciences

Sea ice hit record lows in November

07.12.2016 | Earth Sciences

New material could lead to erasable and rewriteable optical chips

07.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>