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.
Pigs ‘edited’ with a warthog gene to resist African swine fever could help spawn GM animal farms in the UK
Mouse House to make naturalist biopic, six years after box-office failure of Creation, starring Paul Bettany
International team spends 10 years making inroads into treatment of bacterium which kills up to half of those it infects
You may not know it, but you probably have some Neanderthal in you. For people around the world, except sub-Saharan Africans, about 1 to 3 percent of their DNA comes from Neanderthals, our close cousins who disappeared roughly 39,000 years ago.
Research at Yale plotted what happened in the brains of two scientists as they held a conversation
From medicines to jet fuel, we have so many reasons to celebrate the microbes we live with every day
Genome sequencing indicates Kennewick Man is Native American, reopening the bitter battle over whether he should be reburied or studied
In the article on the discovery of dinosaurs (They’re back, Review, 6 June) you state: “In Sussex, a local doctor uncovered fragmentary remains of what appeared to be two more species of colossal extinct land reptiles.” You grossly underplay the contribution of Lewes-born Gideon Mantell, geologist and palaeontologist, author and diarist, friend to princes and international scholars as well as local doctor. Mantell not only discovered (aided by his wife) the first remains of the iguanodon in 1824 but named it – as it resembled the tooth of an iguana. This was the first known land dinosaur, Mary Anning having identified the first sea-living dinosaur.Mantell went on to put together more pieces of the jigsaw with extra fossil discoveries. In contrast to Richard Owen, whose models form the basis for the Crystal Palace dinosaurs, Mantell stated correctly that iguanodon would have walked on their back legs, using their forearms to fight or gather food. He did, however, attribute the thumb spike to a nose horn though later corrected this assumption. The Natural History Museum has a display on Gideon and his wife Mary’s contribution as well as the large “Mantell-piece” of Iguanodon fossils that he had on show in his museum in Brighton. He sold it, along with many more priceless items, to the British Museum in 1838. Gideon Mantell’s reputation deserves better than your throwaway remark. Debby MatthewsLewes, East Sussex Continue reading...
Unique triangular hairs help keep Saharan silver ants cool at 70°C by manipulating the physics of light
Most animals wouldn't confront a fearsome predator like a lion. But through sophisticated group work, hyenas launch successful raids