Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nuclear hormone receptors, microRNAs form developmental switch

06.04.2009
A particular nuclear hormone receptor called DAF-12 and molecules called microRNAs in the let-7 family form a molecular switch that encourages cells in the larvae of a model worm to shift to a more developed state, said a consortium led by researchers from Baylor College of Medicine (www.bcm.edu) in a report that appears online today in the journal Science (www.sciencemag.org).

As organisms go through the stages of life, hormones coordinate the changes. Nuclear receptors respond to hormones to coordinate stage transitions, but how they do so is not well understood.

GOING FROM STAGE 2 TO STAGE 3

"We knew that nuclear hormone receptors were involved in stage 2 to stage 3 transitions in Caenorhabditis elegans," said Dr. Adam Antebi (http://www.bcm.edu/mcb/?PMID=8411), associate professor in the Huffington Center on Aging at BCM and the report's senior author. "Another class of molecules called microRNAs is also involved in that transition. We hypothesized that maybe if they are involved in the same process, one turns on the other."

That turns out to be the case in C. elegans and may be true in more advanced organisms as well, he said.

A MODEL WORM ENABLES STUDIES

Scientists use the tiny worm called Caenorhabditis elegans to study such processes because it has a simple anatomy and life cycle. C. elegans develops from embryo through four larval stages into adulthood.

Each "stage" has specific programs of cell division, migration, differentiation and death that are crucial to the organism's final development. Particular master regulators in the worm determine each stage transition and are responsible for organizing developmental time.

"Expression of the let-7 family of microRNAs is dependent on the nuclear receptor and its hormone," Antebi said. "We can show in the worm and in cell culture that DAF-12 and its steroid hormone are directly activating these microRNAs."

HOW TRANSITIONS OCCUR

But how does this cause stage transitions? The tiny molecules called microRNAs work as switches to turn off other genes. In this case, the nuclear hormone receptor DAF-12 and its ligand turn on the microRNAs, which then turn off the earlier developmental "programming" of the cell (stage 2), allowing the later programming (stage 3) to take over.

Specifically, the microRNAs dial-back the activity of a protein called "hunchback," which specifies that the cells are in stage 2. That enables stage 3 to start and development to continue.

PROVIDES CANCER INSIGHTS

"We think this could also give insight into cancers," Antebi said, "particularly those that are hormone-dependent, such as breast or prostate cancer. When worm skin cells go from stage 2 to stage 3 they reduce their cell proliferation. When they fail this transition, skin cells overproliferate (grow uncontrollably)."

It is known that both nuclear receptors and microRNAs play a role in human cancers. These studies could help bridge understanding of the effects of the two.

LINKING DEVELOPMENT AND ENVIRONMENT

Antebi also thinks that this system links development to the environment. DAF-12 plays a role in a long-lived quiescent stage called the dauer diapause, which the worms enter in times of starvation and overcrowding.

"In good times, the DAF-12 steroid ligand is made, the microRNAs are turned on, and the worm goes through all stages of development to adult," said Antebi. (A ligand is a molecule that binds to the receptor to form a biologically active complex.)

"In bad times, the ligand is not made and the nuclear receptor (DAF-12) causes the animals to go into the long lived dauer stage, shutting down the microRNAs and the developmental clock," he said.

In this way, environmental signals actually affect the worm's rate of development, and perhaps even its aging, said Antebi.

Dipali Pathak | EurekAlert!
Further information:
http://www.bcm.edu
http://www.sciencemag.org/

More articles from Life Sciences:

nachricht Embryonic development: How do limbs develop from cells?
18.05.2018 | Humboldt-Universität zu Berlin

nachricht Reading histone modifications, an oncoprotein is modified in return
18.05.2018 | American Society for Biochemistry and Molecular Biology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>