'Fusion' protein found by Johns Hopkins researchers

April 10, 2007

Working with fruit flies, scientists at Johns Hopkins have discovered a protein required for two neighboring cells to fuse and become one "super cell."

Most cells enjoy their singular existence, but the strength and flexibility of muscles relies on hundreds or even thousands of super cells that make large-scale motion smooth and coordinated, such as flexion of a bicep.

The newly discovered protein, dubbed Solitary, coordinates the movement of tiny molecular delivery trucks to a cell's surface. Cells that lack Solitary stay, well, solitary. "They refuse to fuse," says Hopkins assistant professor of molecular biology and genetics Elizabeth Chen, Ph.D., whose report on the work is online this week in Developmental Cell.

Chen and her team studied fruit fly embryo muscles to find the molecular signals that tell two neighboring cells to join as one, plucking out for further study those embryos containing cells that refused to fuse.

They then compared the genetic sequences from healthy embryos with sequences from defective embryos to locate differences and identify the genes responsible for unfused muscle cells. In the process, they identified Solitary.

Chen's team next made a tool to see the Solitary protein, enabling them to track its localization under a fluorescent microscope. At each future fusion point between cells that they examined in the fly muscles, they saw concentrations of glowing clumps of Solitary protein.

"As we uncover more of the players in cell fusion, we get closer to manipulating fusion for our benefit," Chen adds. Muscular dystrophy, for example, might be treated by injecting into patients healthy muscle cells that are designed to fuse efficiently with the diseased muscles, saving the diseased cells from deteriorating.

They also discovered that Solitary protein is attached to the cell's skeleton. "It was so bizarre to see Solitary - something meant to regulate the cell's internal structure - to be involved in the external events of cell fusion," says Chen.

But in addition to structural support, the cell's "skeleton" provides an internal railway of sorts, along which other proteins and molecules can move. Indeed, the researchers saw that while normal cells were able to shuttle tiny storage compartments within the cell - presumably holding important molecular tools needed for cell fusion - to the fusion site, these storage compartments were scattered haphazardly, seemingly lost in the cellular wilderness, in cells lacking Solitary.

When two neighboring cells fuse, they need to break down the barrier between them, explains Chen. It turns out that the Solitary protein marks where that break is happening and subsequently tells the cell where to build its skeleton railway. "In this role, Solitary acts not like the delivery truck, but more like a construction site foreman," says Chen. "It's told where the cell barrier needs to be broken, then directs the building of a delivery road so that the molecular supplies can be brought to the fusion site."
-end-
The research was funded by the National Institutes of Health, the American Heart Association, the Edward Mallinckrodt Jr. Foundation, March of Dimes, Packard Foundation and Searle Scholars Program.

Authors on the paper are Sangjoon Kim, Khurts Shilagardi, Shiliang Zhang, Sabrina Hong, Kristen Sens, Jinyan Bo, Guillermo Gonzalez and Elizabeth Chen, all of Johns Hopkins.

On the Web:

http://www.developmentalcell.com/
http://www.mbg.jhmi.edu/

Johns Hopkins Medicine

Related Fruit Flies Articles from Brightsurf:

Sestrin makes fruit flies live longer
Researchers identify positive effector behind reduced food intake.

Circular RNA makes fruit flies live longer
The molecule influences the insulin signalling pathway and thus prolongs life

Fruit flies respond to rapid changes in the visual environment
Researchers have discovered a mechanism employed by the fruit fly Drosophila melanogaster that broadens our understanding of visual perception.

How fruit flies flock together in orderly clusters
Opposing desires to congregate and maintain some personal space drive fruit flies to form orderly clusters, according to a study published today in eLife.

Fruit flies help in the development of personalized medicine
It is common knowledge that there is a connection between our genes and the risk of developing certain diseases.

Fruit flies' microbiomes shape their evolution
In just five generations, an altered microbiome can lead to genome-wide evolution in fruit flies, according to new research led researchers at the University of Pennsylvania.

Why fruit flies eat practically anything
Kyoto University researchers uncover why some organisms can eat anything -- 'generalists -- and others have strict diets -- 'specialists'.

Why so fly: MU scientists discover some fruit flies learn better than others
Fruit flies could one day provide new avenues to discover additional genes that contribute to a person's ability to learn and remember.

Fruit flies find their way by setting navigational goals
Navigating fruit flies do not have the luxury of GPS, but they do have a kind of neural compass.

Tolerance to stress is a 'trade-off' as fruit flies age
With the help of the common fruit fly (D. melanogaster), which ages quickly because it only lives about 60 days, FAU neuroscientists provide insights into healthy aging by investigating the effects of a foraging gene on age and stress tolerance.

Read More: Fruit Flies News and Fruit Flies Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.