Their "molecular dynamics" model is the latest example of computational biology, in which scientists use computers to analyze biological phenomena for insights that may not be available via experiment. As you'd expect from a model that accounts for the activities of half a million atoms at once, the integrin model takes a lot of computing horsepower to pull off. Some of its simulations require 48 hours of run time on 600 parallel processors at the U.S. Department of Energy's (DOE) National Energy Research Scientific Computing Center (NERSC), which is located at Berkeley Lab.
The model is already shedding light on what makes integrin tick, such as how they "know" to respond to more force with greater numbers. When activated by an external force, integrins cluster together on a cell's surface and join other proteins to form structures called focal adhesions. These adhesions recruit more integrins when they're subjected to higher forces. As the model indicates, this ability to pull in more integrins on demand may be due to the fact that a subunit of integrin is connected to actin filaments, which form a cell's skeleton.
"We found that if actin filaments sustain more forces, they automatically bring more integrins together, forming a larger cluster," says Mehrbod.
The model may also help answer a longstanding question: Do integrins interact with each other immediately after they're activated? Or do they not interact with each other at all, even as they cluster together?
To find out, the scientists ran simulations that explored whether it's physically possible for integrins to interact when they're embedded in the plasma membrane. They found that interactions are likely to occur only between one compartment of integrin called the β-subun
|Contact: Dan Krotz|
DOE/Lawrence Berkeley National Laboratory