UC Irvine biologists have discovered that fats within cells store a class of proteins with potent antibacterial activity, revealing a previously unknown type of immune system response that targets and kills bacterial infections.
Steven Gross, UCI professor of developmental & cell biology, and colleagues identified this novel intercellular role of histone proteins in fruit flies, and it could herald a new approach to fighting bacterial growth within cells. The study appears today in eLife, a new peer-reviewed, open-access journal supported by the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust.
"We found that these histone proteins have pan-antibacterial abilities and can have a wide-ranging effect," Gross said. "If we can discover how to manipulate the system to increase histone levels, we may one day have a new way to treat patients with bad bacterial infections."
Histones exist in large numbers in most animal cells; their primary job is to help DNA strands fold into compact and robust structures inside the nucleus. Gross said there is some evidence that histones secreted from cells protect against bacteria living outside cells. However, many bacteria enter cells, where they can avoid the immune system and continue replicating.
In principle, Gross said, histones could protect cells against such bacteria from the inside, but for many years this was thought unlikely because most histones are bound to DNA strands in the cell nucleus, whereas bacteria multiply in the cellular fluid outside the nucleus, called cytosol. Additionally, free histones can be extremely damaging to cells, so most species have developed mechanisms to detect and degrade free histones in the cytosol.
In their study, Gross and colleagues demonstrate that histones bound to lipid (fat) droplets can protect cells against bacteria without causing any of the harm normally associated with the presence of free histones. In experiments with lipid droplets purified from Drosophila fruit fly embryos, they show that lipid-bound histones can be released to kill bacteria.
The researchers injected similar numbers of bacteria into Drosophila embryos that contained lipid-bound histones and into embryos genetically modified to not contain them. They discovered that the histone-deficient flies were 14 times more likely to die of bacterial infections. Similar results were found in experiments on adult flies. Additional evidence suggested that histones might also protect mice against bacteria.
"Because numerous studies have now identified histones on lipid droplets in many different cells – from humans as well as mice and flies – it seems likely that this system may be quite general," Gross said.
University of California - Irvine: http://www.uci.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.
Claims that Ai Hin was faking pregnancy to get better treatment have been debunked by leading panda expert
The recent release of Susan Greenfields new book and the film Lucy, both of which are dependent on tired misconceptions or dubious theories about the brain, suggest one worrying conclusion: we are running out of myths about the brain. So here are some new ones, to keep things mysterious
These are the siphonophores, some 180 known species of gelatinous strings that can grow to 100 feet long, making them some of the longest critters on the planet. But instead of growing as a single body like virtually every other animal, siphonophores clone themselves thousands of times over into half a dozen different types of specialized cloned bodies, all strung together to work as a team---a very deadly team at that.
Researchers who study memory have had a thrilling couple of years. Some have erased memories in people with electroshock therapy, for example. Others have figured out, in mice, how to create false memories and even turn bad memories into good ones.
Hunting bats don't just listen out for male frogs' mating calls: they can also use echolocation to detect when the frogs inflate their throat sacs
A crèche of 30 dinosaur infants looked over by an older animal shows that even terrible lizards needed a night away from the kids
Families have identifiable collections of microbes that travel with them. It can take just 24 hours for the microbes to take over a new house
When rabbits were domesticated, around 100 regions of their genome changed to make them less fearful, but the variations are not fixed
Scientists never understood what became of the Paleo-Eskimos who once peopled the north. Now they know—and there's new reason to miss them
NOAA whittles down initial list of 66 species to be covered by Endangered Species Act