A budding role for a cellular dynamo

Feb 18, 2009

Actin, a globular protein found in all eukaryotic cells, is a workhorse that varies remarkably little from baker's yeast to the human body. Part of the cytoskeleton, actin assembles into networks of filaments that give the cell structural plasticity while driving many essential functions, from cell motility and division, to vesicle and organelle transport within the cell. In a groundbreaking new study in the current issue of Developmental Cell, Brandeis researchers raise the curtain on how this actin maintains just the right filament length to keep the cell healthy and happily dividing.

Using baker's yeast as the model organism, Brandeis researchers Melissa Chesarone, Christopher Gould, and James Moseley, all in the lab of biologist Bruce Goode, set out to discover how the length of actin fibers is controlled. By answering this question, the scientists sought to advance understanding of asymmetrical cell division, a process that not only allows yeast to divide, but also ensures the proper renewal of human stem cells and plays a crucial role in early stages of embryonic development.

In yeast cells, as in all other cells, actin fibers serve as internal "railways" or tracks that give the cell directionality and provide the wherewithal for transporting various molecular and membrane-bound cargoes from one end of the cell to the other. Molecular machines called formins produce many of the actin fibers, but in the absence of a displacement factor to put a brake on the process, formins will essentially stop at nothing, producing excessively long actin filaments at ridiculously fast rates, and wreaking cellular havoc, says Goode. In humans, genetic defects in formins are associated with conditions such as infertility and deafness.

"We wanted to know how you turn the formins off. What disrupts the interaction of the formin with the actin filament, thus terminating actin assembly and regulating its length?" Goode explained.

The researchers discovered that a protein called Bud14 is a potent inhibitor, directly binding to the formin and displacing it, thereby producing actin filaments of normal length, a prerequisite for proper actin cable architecture and cargo transport.

"In all animal, plant, and human cells, life depends on rapidly producing actin filaments of defined lengths, and we now have an important clue as to how this is regulated," said Goode. "We're now homing in on the precise mechanism by which Bud14 works and extending this analysis to mammalian cells. Once again, yeast has provided the ideal system in which to pioneer a basic problem that applies to most other species."

Source: Brandeis University

Explore further: Researchers discover new mechanism of DNA repair

Related Stories

Wine-making shortcut gives bubbly a fruitier aroma

Jun 17, 2015

The best sparkling wines take months to ferment to perfection. In recent years, many winemakers have turned to commercial yeast products to give this process a boost. How they ultimately affect bubbly has ...

New map uncovers the traffic of life in a cell

Jun 08, 2015

Toronto scientists have recorded, in unprecedented detail, the locations of all proteins in a cell. This new protein map allows scientists to look much more closely into what happens in a cell when disease ...

Recommended for you

Researchers discover new mechanism of DNA repair

Jul 03, 2015

The DNA molecule is chemically unstable giving rise to DNA lesions of different nature. That is why DNA damage detection, signaling and repair, collectively known as the DNA damage response, are needed.

The math of shark skin

Jul 03, 2015

"Sharks are almost perfectly evolved animals. We can learn a lot from studying them," says Emory mathematician Alessandro Veneziani.

Cuban, US scientists bond over big sharks

Jul 03, 2015

Somewhere in the North Atlantic right now, a longfin mako shark—a cousin of the storied great white—is cruising around, oblivious to the yellow satellite tag on its dorsal fin.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.