Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How a genetic locus protects adult blood-forming stem cells

26.11.2015

A particular location in DNA, called the Dlk1-Gtl2 locus, plays a critical role in protecting hematopoietic, or blood-forming, stem cells--a discovery revealing a critical role of metabolic control in adult stem cells, and providing insight for potentially diagnosing and treating cancer, according to researchers from the Stowers Institute for Medical Research.

In their study, published online Nov. 25 in Cell Stem Cell, Stowers Investigator Linheng Li, Ph.D., and first author Pengxu Qian, Ph.D., along with other collaborators, reveal how the mammalian imprinted Gtl2, located on mouse chromosome 12qF1, protects adult hematopoietic stem cells by restricting metabolic activity in the cells' mitochondria.


These are MicroRNA clusters expressed from imprinted Gtl2 locus maintain adult hematopoietic stem cells through suppression of mitochondrial biogenesis and metabolic activity.

Credit: Linheng Li Lab

The research focused on imprinted genes--genes "stamped" according to whether they are inherited from the mother or father. With imprinted genes, one working copy, or allele, is inherited instead of two. Either the copy from the mother or father is inactivated or "silenced." Typically, the paternally inherited allele's expression promotes growth, while the maternally inherited allele's expression suppresses it.

The researchers found that when the Gtl2 locus is expressed from the maternally inherited allele, it produces non-coding RNAs to curb metabolic activity. Mechanistically, Gtl2's "megacluster" of microRNA, the largest cluster of microRNA in the mammalian genome, suppresses the mTOR signaling pathway and downstream mitochondrial biogenesis and metabolism, thus blocking mitochondrial-associated byproducts called reactive oxygen species (ROS) that can damage adult stem cells.

"Reactive oxygen species are like the potentially harmful byproducts that come from industrial manufacturing," says Li. "ROS are unavoidable derivatives of the mitochondrial metabolic process and need to be managed by the cell," he explains.

Hematopoietic stems cells renew themselves and differentiate into other cells, including white blood cells, red blood cells, and platelets, constantly renewing the body's blood supply in a process called hematopoiesis. Because of their extraordinary transformative qualities, the transplantation or transfusion of isolated human hematopoietic stem cells has been used in the treatment of anemia, immune deficiencies, and other diseases, including cancer.

While hematopoietic stem cells have gained attention in research, it remains largely unknown how cell metabolic states are controlled. The new findings shed light on the delicate metabolic control required to balance hematopoietic stem cell maintenance and action and the associated healthy hematopoiesis.

An upset in that balance can cause cells to grow abnormally and lead to disease. Abnormalities in the Gtl2 locus on human chromosome 14q32.2 are associated with uniparental disomy in which an individual receives two copies of a chromosome from one parent and no copy from the other parent. Uniparental disomy may cause delayed development, mental retardation, or other medical problems. Differences in gene expression at the Gtl2 locus have also been linked to fetal alcohol exposure disorder.

But when working properly, the Gtl2 locus acts as a great protector of cells.

"Most of the non-coding RNAs at the Gtl2 locus have been documented to function as tumor suppressors to maintain normal cell function," Qian says.

Li's team zeroed in on Gtl2 by studying hematopoietic stem cells in mice with support from Stowers core centers including cytometry, bioinformatics, histology and electron microscopy, molecular biology, and tissue culture. Other collaborators included researchers from the University of Kansas; the University of Kansas Medical Center; Tianjin Medical University, China; Christian Medical College, Vellore, India; Tokyo University of Agriculture, Japan; and University of Cambridge, United Kingdom.

Over the three-year study, investigators used transcriptome profiling to analyze 17 hematopoietic cell types and found that non-coding RNAs expressed from the Gtl2 locus are predominantly located in a subset of the cell types, including adult "long-term" hematopoietic stem cells which have long-term self-renewal capacity. In subsequent experiments, deleting the locus from the maternally inherited allele in hematopoietic stem cells increased mitochondrial biogenesis and subsequent metabolic activity as well as increased ROS levels, with the latter inducing cell death.

The finding opens the possibility for Gtl2 to be used as a biomarker because it could help label dormant (or reserve) stem cells in normal or potentially cancerous stem cell populations, Li says. The addition of a fluorescent tag to the Gtl2 locus could allow researchers to mark other adult stem cells in the gut, hair follicle, muscle, and neural systems.

Other Stowers authors include Xi C. He, M.D., Ariel Paulson, Zhenrui Li, Fang Tao, John M. Perry, Ph.D., Fengli Guo, Ph.D., Meng Zhao, Ph.D., Jeffrey S. Haug, Tari Parmely, and Hua Li, Ph.D.

The research was funded in part by the Stowers Institute for Medical Research, the American Society of Hematology, the National Natural Science Foundation of China and the Natural Science Foundation of Tianjin.

Lay Summary

Hematopoietic stems cells are essential to the healthy functioning of the human body. These cells renew themselves and differentiate into other cells, including white blood cells, red blood cells, and platelets, and constantly renew the body's blood supply. The creation of new blood cells in the body, a process called hematopoiesis, requires a delicate metabolic balance that is not well understood. Stowers Investigator Linheng Li, Ph.D., and colleagues found that the genetic locus Dlk1-Gtl2 plays a critical role in protecting hematopoietic cells by restricting metabolic activity in the cells' mitochondria. This discovery suggests that Gtl2 may be useful clinically as a biomarker to determine if cells are normal or potentially cancerous. The locus' tumor suppression qualities also may lead to future treatments targeting cancer.

###

About the Stowers Institute for Medical Research

The Stowers Institute for Medical Research is a non-profit, basic biomedical research organization dedicated to basic research - the critical first step in the quest for new medical diagnostics, therapies and treatments. Jim Stowers, founder of American Century Investments, and his wife, Virginia, opened the Institute in 2000. Since then, the Institute has spent over one billion dollars in pursuit of its mission.

Currently, the Stowers Institute is home to 500 researchers and support personnel, over 20 independent research programs, and more than a dozen technology development and core facilities.

Media Contact

Kim Bland
ksb@stowers.org
816-926-4015

 @ScienceStowers

http://www.stowers.org/ 

Kim Bland | EurekAlert!

More articles from Life Sciences:

nachricht Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

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...

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

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>