Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Illuminating the dark zone

30.04.2015

UCSB scientists make new discoveries about a specific protein and its effects on the final step of cell division

The human body is a cross between a factory and a construction zone -- at least on the cellular level. Certain proteins act as project managers, which direct a wide variety of processes and determine the fate of the cell as a whole.


In addition to its location in the cell nucleus, WDR5-EGFP was also found in central dark zone of the midbody.

Credit: UCSB

One group of proteins called the WD-repeat (WDR) family helps a cell choose which of the thousands of possible gene products it should manufacture. These WDR proteins fold into a three-dimensional structure resembling a doughnut -- an unusual shape that allows WDR proteins to act as stable platforms on which large protein complexes can assemble or disassemble.

A new study conducted by scientists at UC Santa Barbara reveals a novel function for WDR5, a protein known for its critical role in gene expression whereby information encoded in genes is converted into products like RNA (ribonucleic acid) and protein. In cells, WDR5 is a subunit of a five-protein complex. Mutations in members of this complex can result in childhood leukemia and other disorders affecting numerous organ systems in the body. The UCSB team worked with WDR5 in cultured human cell lines. The results of the study appear in the Journal of Biological Chemistry.

"We found that when two cells divide, WDR5 is localized to a very interesting cellular structure called the midbody," said lead author Jeff Bailey, a graduate student in UCSB's Department of Molecular, Cellular and Developmental Biology (MCDB). "In the past, although associated with cell division, the midbody was considered 'junk,' but that has changed in the last decade. Now the midbody is believed to be important during stem cell differentiation."

When a stem cell divides to produce a differentiated type of cell like a skin cell or a neuron, stem cells retain the midbody while differentiated cells do not. "This suggests that the midbody has important functions," Bailey explained. "Also, when the midbody isn't cut correctly, the cells can re-fuse, creating one cell with two nuclei. This is thought to be part of what happens when a tumor forms."

Conducted in the laboratory of MCDB associate professor Zach Ma, this new work involved the fusion of WDR5 to a green fluorescent protein molecule called EGFP. Although dense material within the midbody thwarts conventional methods of protein detection, the fluorescence of EGFP tethered to WDR5 revealed its location during cell division, or cytokinesis.

The researchers were surprised to find WDR5 in a part of the midbody called the dark zone. "It was very unexpected," Bailey said. "The presence of WDR5 outside the cell nucleus gave us a clue about its function, which we tested," Ma added.

The scientists found that not only did the protein localize in the midbody, it also contributed to abscission, the separation of two daughter cells at the completion of cytokinesis. In addition, WDR5 promotes the disassembly of midbody microtubules, the major structural components of the midbody that must be cleared before abscission can occur.

When the investigators artificially reduced the amount of WDR5 in cells, cytokinesis was substantially delayed and more cells failed to divide properly. "When histology is performed on a tumor, pathologists look for cells that have two nuclei," Bailey explained. "This can indicate that cells within the tumor are failing to properly finish cytokinesis."

Because a single protein can perform several distinct functions according to its location within a cell, it can be challenging to study one function without disrupting the others. Guided by previous structural studies, however, the UCSB team identified surfaces of the WDR5 "doughnut" that may be specific to its role in cell division.

"We have shed some light on the role of WDR5 in cytokinesis," Ma said, "which may in turn help us better understand the diverse array of physiological as well as pathological events related to malfunction of these proteins in the process of cell division."

Media Contact

Julie Cohen
julie.cohen@ucsb.edu
805-893-7220

 @ucsantabarbara

http://www.ucsb.edu 

Julie Cohen | EurekAlert!

More articles from Life Sciences:

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

nachricht Researchers discover specific tumor environment that triggers cells to metastasize
22.11.2017 | University of California - San Diego

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

UCLA engineers use deep learning to reconstruct holograms and improve optical microscopy

22.11.2017 | Medical Engineering

Watching atoms move in hybrid perovskite crystals reveals clues to improving solar cells

22.11.2017 | Materials Sciences

New study points the way to therapy for rare cancer that targets the young

22.11.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>