Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pluripotent and Differentiated Human Cells Reside in Decidedly Different Epigenomic Landscapes

10.05.2010
Human embryonic stem cells (hESCs) possess remarkable properties of self-renewal and pluripotency, the ability to become almost any kind of cell within the body. And yet they share the same genome or set of genes with lineage-committed cells, cells fated to be or do one thing.

Scientists have long suspected that the distinct properties of different cells were attributable to their particular epigenomes – the collection of attendant molecules, compounds and chemicals that direct and influence the behaviors and functions of genes. The question has been: how much do the epigenomes of hESCs and lineage-committed cells differ? The answer was not clear.

In a paper published in the May 7 issue of Cell—Stem Cell, Bing Ren, PhD, a professor of cellular and molecular medicine at the University of California, San Diego and a member of the Ludwig Institute for Cancer Research, reports with colleagues that the epigenomic landscapes of hESCs and lineage-committed cells are, in fact, drastically different.

“You can think of it this way,” said Ren. “Neurons and skin cells share the identical set of genetic material – DNA – yet their structure and function are very different. The difference can be attributed to differences in their epigenome. This is analogous to computer hardware and software. You can load the same computer with distinct operating systems, such as Linux or Windows, or with different programs and the computer will run very different types of operations.

“Similarly, the unique epigenome in each cell directs the cell to interpret its genetic information differently in response to common environmental factors. Understanding the differences of epigenomic landscapes in different cell types, especially between pluripotent and lineage-committed cells, is essential for us to study human development and mechanisms of human diseases.”

To compare these epigenomic landscapes, Ren and colleagues looked at chromatin-modification profiles and DNA methylomes in hESCs and primary fibroblasts, the latter a type of cell commonly found in animal connective tissues. Chromatin is a complex combination of DNA and proteins that makes up chromosomes. The basic component of the chromatin is a complex of proteins called histones. Histone proteins can be chemically modified depending upon the contexts of the underlying gene sequences and can influence gene activities locally.

The scientists found that nearly one-third of the genome differs in chromatin structure. Most of the changes arise from dramatic redistributions of repressive chromatin modifications that involve the addition of methyl-groups to particular lysine residues on the histone protein.

“A fundamental question is how the identical genome sequence gives rise to a diversity of cell types with different gene expression profiles and cellular functions,” said David Hawkins of the Ludwig Institute and co-first author of the study. “We’ve found evidence that lineage-committed cells are characterized by significantly expanded domains of repressive chromatin that selectively affect genes involved in pluripotency and development. In other words, these epigenetic mechanisms play a critical role in deciding a cell’s fate and function, and in maintaining it.”

The findings are likely to push forward the emerging science of epigenetics, which seeks to identify the processes that impact gene regulation and help determine human development and disease. Ren is director of The San Diego Epigenome Center at the Ludwig Institute. San Diego is one of four centers in the United States participating in the National Institutes of Health’s Roadmap Epigenomics Program, a five-year, $190 million effort.

Co-authoring the paper with Ren are R. David Hawkins, Gary C. Hon, Leonard K. Lee and QueMinh Ngo, E. Edsall, Samantha Kuan, Ying Luu, Sarit Klugman, Zhen Ye, Celso Espinoza and Saurabh Agarwahl, all of the Ludwig Institute for Cancer Research in La Jolla, CA; Li Shen and Wei Wang, department of chemistry and biochemistry at the University of California, San Diego; Ryan Lister, Mattia Pelizzola and Joseph R. Ecker at the Genomic Analysis Laboratory, The Salk Institute for Biological Studies in La Jolla, CA; and Jessica Antosiewicz-Bourget, Victor Ruotti, Ron Stewart and James A. Thomson at the Morgridge Institute for Research in Madison, WI.

Scott LaFee | Newswise Science News
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Show me your leaves - Health check for urban trees
12.12.2017 | Gesellschaft für Ökologie e.V.

nachricht Liver Cancer: Lipid Synthesis Promotes Tumor Formation
12.12.2017 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>