Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Technique Reveals a Role for Histones in Cell Division

26.09.2014

Proteins known as histones give structure to DNA, which coils around them like string on spools. But as is so often the case in biology, it turns out there is more to these structures than meets the eye. Scientists already know histones play a part in controlling the expression of genes, and more recently they have accumulated evidence that certain aspects of cell division depend on these proteins. But this last suspicion has proven difficult to test.

Now a new technique developed at Rockefeller University in Hironori Funabiki’s Laboratory of Chromosome and Cell Biology allows researchers to examine histones’ role in crucial cell division processes that revolve around DNA, such as the segregation of chromosomes and the construction of the cell’s nucleus.


Hooray for histones: Researchers found that beads covered with histones and DNA (top) attracted a protein called lamin B3 (green) that supports the membrane around a new cell’s nucleus. Beads with only DNA (bottom) did not attract lamins.

“Manipulating the genes that code for histones — the typical approach for this sort of research — usually causes massive changes within the cell. But because histones themselves regulate gene expression, the reasons for these changes are nearly impossible to interpret,” Funabiki says. “We have addressed this problem by developing a new way to study histones that sidesteps this problem, and we have used it to explore these proteins’ role in organizing large-scale, DNA-based structures within the cell.”

Histones without DNA are like an instruction manual without words, so these experiments, led by research associate Christian Zierhut, focused on the two together, which form structures known as nucleosomes. Their work revealed nucleosomes must be present in order for the mitotic spindle, the cellular machine responsible for dividing up chromosomes during cell division, to form. Additionally, nucleosomes proved necessary for some key aspects in the formation of the nuclear envelope that cordons off the cell’s control center.

To experiment with histones, Zierhut and his colleagues turned to frog eggs, a model system ideally suited to studies of cell division. Scientists have long known it is possible to purify the fluid, or cytosol, from inside the eggs, and then, by adding DNA, induce almost every event in a cell’s life cycle. Because these events play out outside the cell, they are much more accessible. What’s more, the eggs are transcriptionally silent, meaning no genes are expressed. As a result, the researchers did not need to deal with confusing downstream effects. However, these eggs carry large stockpiles of histones, making histone manipulation a daunting task.

“Just as manipulating histone genes is not a realistic approach, neither is getting rid of them altogether, because histones, like DNA, are essential for viability. This has been a major hurdle for histone research, and one we managed to overcome,” Zierhut says. “We found a way to generate an egg extract free from essential histones, an accomplishment once thought not to be possible.”

By thus interfering with nucleosome formation in the extract, the researchers could test what happened when they added naked DNA or nucleosomes with altered histones.

In experiments described in the July issue of Nature Structural Molecular Biology, they added DNA alone to the frog-egg extract, and saw that the mitotic spindles that drive cell division did not form. But when they added nucleosomes, the spindles formed. Using similar experiments, the researchers examined histones’ role in other aspects of this process — with mixed results.

They found membrane proteins, important for the formation of the nucleus in the daughter cells, were attracted to the naked DNA. However, histones proved necessary for the formation of a support structure called the lamina. The experiments also showed an important role for them in the formation of nuclear pore complexes, which act as selective gates into and out of the nucleus. In this case, histones appear to help initiate the process by recruiting two other molecules, RCC1 and ELYS.

“The requirement for the presence of histones may help the cell control where the mitotic spindle and the nuclear envelope form,” Funabiki says. “This is particularly important for large cells that need to make sure they are forming these structures in the right spot, on or around their own histone-containing chromosomes. Without this requirement, the cells may risk establishing a nuclear envelope around viral DNA, for example, or forming nuclear pores on other intracellular membrane structures not connected to DNA. This way the cell ensures only the right set of genetic instructions can be preserved, accessed and propagated over generations.”

Contact Information

Zach Veilluex
212-327-8982
newswire@rockefeller.edu

Zach Veilluex | newswise

More articles from Life Sciences:

nachricht The birth of a new protein
20.10.2017 | University of Arizona

nachricht Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>