How a Cell's Mitotic Motors Direct Key Life Processes

Feb 02, 2009

University of Massachusetts Amherst biologists have discovered a secret of how cells organize chromosomes to prepare for dividing. Their unexpected finding is reported in this week’s issue of the journal, Current Biology.

The experiments sought to reveal how the cell’s tiny, two-part chemical engine known as dynein, just 40 nanometers in diameter, takes charge of mitosis and keeps the delicate strands of chromosomes in order and in position. Until now, cell biologists had assumed it was the dynein’s cargo domain that regulated this process. UMass Amherst cell biologist Wei-lih Lee and colleagues showed that it is the motor domain instead.

Dynein, like a delivery truck, carries cargo, Lee explains, but this protein truck is specialized because it interacts chemically and physically with the road. In the cell, this means dynein travels along segments of polymeric microtubule “roads” that grow and shrink as needed by adding or dropping sections. From experiments in budding yeast, Lee, with a talented postdoctoral fellow, Steven Markus, and biology junior fellow Jesse Punch, found that “dynein has a preference for locating at the ends of these microtubule tracks.”

Lee says a lot of credit for a cleverly designed and executed set of experiments goes to Markus, who cut the dynein engines into motor and cargo halves and challenged the yeast cells to divide with access to only one part of the protein at a time. Markus also designed brighter-than-usual fluorescent probes to attach to the two dynein parts, red for the engine, green for the cargo domain. The strategies worked. The UMass Amherst research team now has one of the most elegant and practical probes for studying dynein function. Lee says, “I’m already getting requests from other researchers who want to use our new probes.”

In this system, they observed that like a moving walkway at the airport, “dynein is a smart truck because it parks at the end of the microtubule, and ‘rides’ along as the track grows,” Lee explains. “Our findings show that the dynein’s motor domain, the engine’s core, is responsible for this end-binding property, which is surprising given that the same domain is used for walking along the track.”

Applying their new understanding to cell division, the researchers say, “our findings further suggest that the dynein engine is turned off when it is parked on the microtubule end, but then turned on upon reaching the proper attachment site in the daughter cell’s wall,” says Lee. “This mechanism allows the yeast cell to control dynein activation with high accuracy” and avoids potential problems of transporting an “activated” protein through the cell.

Results of this new knowledge in basic science are also relevant for human nerve cell function. “It has already been shown that nerve cells use the same mechanism as yeast does to move the cell body,” says Lee. Dynein malfunction can lead to mistakes in nerve cell migration which causes poor brain development disease such as lissencephaly.

Provided by University of Massachusetts Amherst

Explore further: Study identifies first-ever human population adaptation to toxic chemical, arsenic

add to favorites email to friend print save as pdf

Related Stories

Evolving robot brains

6 hours ago

Researchers are using the principles of Darwinian evolution to develop robot brains that can navigate mazes, identify and catch falling objects, and work as a group to determine in which order they should ...

Facebook fends off telecom firms' complaints

6 hours ago

Facebook founder Mark Zuckerberg fended off complaints on Monday that the hugely popular social network was getting a free ride out of telecom operators who host its service on smartphones.

Scientists find clues to cancer drug failure

6 hours ago

Cancer patients fear the possibility that one day their cells might start rendering many different chemotherapy regimens ineffective. This phenomenon, called multidrug resistance, leads to tumors that defy ...

Glass coating improves battery performance

6 hours ago

Lithium-sulfur batteries have been a hot topic in battery research because of their ability to produce up to 10 times more energy than conventional batteries, which means they hold great promise for applications ...

Recommended for you

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.