Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dividing Cells Find Their Middle by Following Protein Contour Map

02.07.2008
Scientists at Rockefeller University have shown that a protein-chemistry-based contour map, which helps individual proteins locate the center of their cell without direction from a "master organizer," is key to ensuring accurate division during mitosis.

Self-organization keeps schools of fish, flocks of birds and colonies of termites in sync. It's also, according to new research, the way cells regulate the final stage of cell division. Scientists at Rockefeller University have shown that a protein-chemistry-based contour map, which helps individual proteins locate the center of their cell without direction from a "master organizer," is key to ensuring accurate division during mitosis. The finding is reported in the June 19 issue of Nature.

In self-organizing systems, each individual, whether bird, fish, termite or protein, constantly receives and evaluates visual and chemical signals in order to maintain position or determine action, and properties and patterns of the larger whole system emerge from a multiplicity of simple local interactions. Scientists have hypothesized that similar systems exist in cells to carry out numerous functions. The Rockefeller team, led by Professor Tarun Kapoor, head of the Laboratory of Chemistry and Cell Biology, focused on a self-organizing system in mitosis.

As a cell divides, chromosomes in the nucleus duplicate, separate and move to the outer edge of the cell while the cell membrane pinches inward in the middle to form a structure called the cleavage furrow. In order to do this, the cell must know where its middle is.

... more about:
»Division »Kapoor »Kinase »mitosis »phosphorylation

Kapoor, working with colleagues in his laboratory and at the University of Virginia School of Medicine, tracked the activity of a key regulator of mitosis, a protein called Aurora B. Aurora is a kinase, an enzyme that attaches phosphate chemical groups to proteins in a process called phosphorylation. Other enzymes, called phosphatases, reverse this process by removing phosphates.

To follow Aurora activity, the researchers, in collaboration with Alison North of Rockefeller's Bio-Imaging Resource Center, adapted a powerful microscopy technique called FRET imaging, which measures how close two fluorescent molecules are to each other. Chemical modification of proteins cannot easily be visualized with microscopes, so Kapoor and his colleagues engineered a biosensor to measure the balance between phosphorylation by Aurora and dephosphorylation by phosphatases.

The biosensor was anchored to different sites in the cell -- the equivalent of positioning a microphone at different locations in a room -- then analyzed how the information changes over time. The findings: proteins in the middle of the cell had a higher probability of being phosphorylated by Aurora kinase than those located near the edges.

"Aurora kinase essentially generates a protein chemistry-based contour map, which tells individual molecular players where the middle is," says Kapoor. "And the middle is where there would be the highest probability of being modified by Aurora kinase. It's roughly equivalent, Kapoor says, to a self-organizing school of fish, in which fish in the middle feel something different from the fish on the edges.

"What's really exciting is the discovery of a phosphorylation gradient by tracking in living cells the chemical modifications of proteins," says Kapoor. "We can't actually see aurora kinase activity itself, but we can look at the balance of the phosphorylation of a reporter substrate that depends on this kinase."

"This remarkable study shows how an enzyme, aurora B, governs a key step in cell division: positioning of the cleavage furrow," said Richard Rodewald, who oversees cell division grants at the National Institute of General Medical Sciences, which partially supported the research. "This study also underscores the value of the new generation of fluorescent probes for visualizing in exquisite detail the inner workings of living cells."

Joseph Bonner | newswise
Further information:
http://www.rockefeller.edu

Further reports about: Division Kapoor Kinase mitosis phosphorylation

More articles from Life Sciences:

nachricht RUDN chemist tested a new nanocatalyst for obtaining hydrogen
18.10.2018 | RUDN University

nachricht Dandelion seeds reveal newly discovered form of natural flight
18.10.2018 | University of Edinburgh

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Goodbye, silicon? On the way to new electronic materials with metal-organic networks

Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz (Germany) together with scientists from Dresden, Leipzig, Sofia (Bulgaria) and Madrid (Spain) have now developed and characterized a novel, metal-organic material which displays electrical properties mimicking those of highly crystalline silicon. The material which can easily be fabricated at room temperature could serve as a replacement for expensive conventional inorganic materials used in optoelectronics.

Silicon, a so called semiconductor, is currently widely employed for the development of components such as solar cells, LEDs or computer chips. High purity...

Im Focus: Storage & Transport of highly volatile Gases made safer & cheaper by the use of “Kinetic Trapping"

Augsburg chemists present a new technology for compressing, storing and transporting highly volatile gases in porous frameworks/New prospects for gas-powered vehicles

Storage of highly volatile gases has always been a major technological challenge, not least for use in the automotive sector, for, for example, methane or...

Im Focus: Disrupting crystalline order to restore superfluidity

When we put water in a freezer, water molecules crystallize and form ice. This change from one phase of matter to another is called a phase transition. While this transition, and countless others that occur in nature, typically takes place at the same fixed conditions, such as the freezing point, one can ask how it can be influenced in a controlled way.

We are all familiar with such control of the freezing transition, as it is an essential ingredient in the art of making a sorbet or a slushy. To make a cold...

Im Focus: Micro energy harvesters for the Internet of Things

Fraunhofer IWS Dresden scientists print electronic layers with polymer ink

Thin organic layers provide machines and equipment with new functions. They enable, for example, tiny energy recuperators. In future, these will be installed...

Im Focus: Dynamik einzelner Proteine

Neue Messmethode erlaubt es Forschenden, die Bewegung von Molekülen lange und genau zu verfolgen

Das Zusammenspiel aus Struktur und Dynamik bestimmt die Funktion von Proteinen, den molekularen Werkzeugen der Zelle. Durch Fortschritte in der...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Conference to pave the way for new therapies

17.10.2018 | Event News

Berlin5GWeek: Private industrial networks and temporary 5G connectivity islands

16.10.2018 | Event News

5th International Conference on Cellular Materials (CellMAT), Scientific Programme online

02.10.2018 | Event News

 
Latest News

RUDN chemist tested a new nanocatalyst for obtaining hydrogen

18.10.2018 | Life Sciences

Massive organism is crashing on our watch

18.10.2018 | Earth Sciences

Electrical enhancement: Engineers speed up electrons in semiconductors

18.10.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>