The human body has more than a trillion cells, most of them connected, cell to neighboring cells.
How, exactly, do those bonds work? What happens when a pulling force is applied to those bonds? How long before they break? Does a better understanding of all those bonds and their responses to force have implications for fighting disease?
Sanjeevi Sivasankar, an Iowa State assistant professor of physics and astronomy and an associate of the U.S. Department of Energy's Ames Laboratory, is leading a research team that's answering those questions as it studies the biomechanics and biophysics of the proteins that bond cells together.
The researchers discovered three types of bonds when they subjected common adhesion proteins (called cadherins) to a pulling force: ideal, catch and slip bonds. The three bonds react differently to that force: ideal bonds aren't affected, catch bonds last longer and slip bonds don't last as long.
The findings have just been published by the online Early Edition of the Proceedings of the National Academy of Sciences.
Sivasankar said ideal bonds – the ones that aren't affected by the pulling force – had not been seen in any previous experiments. The researchers discovered them as they observed catch bonds transitioning to slip bonds.
"Ideal bonds are like a nanoscale shock absorber," Sivasankar said. "They dampen all the force."
And the others?
"Catch bonds are like a nanoscale seatbelt," he said. "They become stronger when pulled. Slip bonds are more conventional; they weaken and break when tugged."
In addition to Sivasankar, the researchers publishing the discovery are Sabyasachi Rakshit, an Iowa State post-doctoral research associate in physics and astronomy and an Ames Laboratory associate; Kristine Manibog and Omer Shafraz, Iowa State doctoral students in physics and astronomy and Ames Laboratory student associates; and Yunxiang Zhang, a post-doctoral research associate for the University of California, Berkeley's California Institute for Quantitative Biosciences.
The project was supported by a $308,000 grant from the American Heart Association, a $150,000 Basil O'Connor Award from the March of Dimes Foundation and Sivasankar's Iowa State startup funds.
The researchers made their discovery by taking single-molecule force measurements with an atomic force microscope. They coated the microscope tip and surface with cadherins, lowered the tip to the surface so bonds could form, pulled the tip back, held it and measured how long the bonds lasted under a range of constant pulling force.
The researchers propose that cell binding "is a dynamic process; cadherins tailor their adhesion in response to changes in the mechanical properties of their surrounding environment," according to the paper.
When you cut your finger, for example, cells filling the wound might use catch bonds that resist the pulls and forces placed on the wound. As the forces go away with healing, the cells may transition to ideal bonds and then to slip bonds.
Sivasankar said problems with cell adhesion can lead to diseases, including cancers and cardiovascular problems.
And so Sivasankar said the research team is pursuing other studies of cell-to-cell bonds: "This is the beginning of a lot to be discovered about the role of these types of interactions in healthy physiology as well as diseases like cancer."
Iowa State University: http://www.iastate.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
In a new book, San Francisco-based photographer Susan Middleton captures the curious gestures and expressions of marine invertebrates
Lab at the University of Texas at San Antonio gets Pentagon funding to see if brain waves can direct drone movement
After a severe brain injury, some people remain in a vegetative or minimally conscious state, unable to speak or move intentionally, and apparently unaware of the world around them. But in recent years, neuroscientists have found signs that some of these patients may still be conscious, at least to a degree. Now researchers have used a branch of mathematics called graph theory to search for neural signatures of consciousness.
Few parasitoids are more bizarre or disturbing than the wasps of the genus Glyptapanteles, whose females inject their eggs into living caterpillars. Once inside, the larvae mature, feeding on the caterpillar’s body fluids before gnawing through its skin en masse and emerging into the light of day. And despite the trauma, not only does the caterpillar survive---initially at least---but the larvae proceed to mind-control it, turning their host into a bodyguard that protects them as they spin their cocoons and finish maturing. Then, finally, the caterpillar starves to death, but only after the tiny wasps emerge from their cocoons and fly away.
From their new book A History of Life in 100 Fossils, Paul Taylor and Aaron O'Dea share the story of 10 incredible fossils
We love origin stories. When we see successful groups of animals and plants, we wonder where they came …
First research of its kind shows that tasers could impair a person's memory and thought process
Sometimes the most fascinating animals are the ones that are no longer with us. The oddly named sthenurine is no exception.
Australian banded stilts use mysterious cues to know when to head toward ephemeral lakes in the country’s otherwise dry interior
The intriguing story of how whale evolution was unpicked is told in The Walking Whales, revealing what it's like to be a globe-trotting palaeontologist