The human immune system is in a perpetual state of self-experimentation. It expertly mutates and shuffles the DNA of its own cells to evolve new defenses against the vast array of microbes that try to invade our bodies. But when the genetic experiment goes awry, the result can be a deadly cancer.
Now, Rockefeller University scientists have discovered that the same enzyme that enables the immune system’s defensive creativity is also responsible for a particular genetic malfunction -- a translocation of one piece of DNA to the wrong chromosome -- that causes Burkitt’s lymphoma. The findings, to be published in the December 12 edition of Cell, suggest the enzyme, called activation-induced deaminase (AID), is probably involved in a broader range of cancers as well.
“We strongly suspect that many or all of the translocations of human lymphomas in mature B cells are the product of this enzyme,” says Michel C. Nussenzweig, Sherman Fairchild Professor and head of the Laboratory of Molecular Immunology. “And there’s more and more data to show that it may be involved in other cancers as well. It’s been identified in stomach cancers, for instance.”
A very specific translocation causes Burkitt’s lymphoma, a cancer that plagues children in equatorial Africa. It involves a DNA break in an immune system antibody gene and the much more rare break in a cancer-promoting gene called c-myc. Previous work had shown that AID was responsible for breaking antibody genes but not c-myc. In fact, scientists thought a host of other factors might be involved in the c-myc break, but AID had been all but ruled out.
Despite the prior studies, Davide Robbiani, a research associate in Nussenzweig’s lab and a Leukemia and Lymphoma Society Fellow, believed AID was the culprit. To prove it, he and his colleagues started by deleting the promoter region of the c-myc oncogene, rendering the gene inactive, in a mutant line of mice. By looking for -- and not finding -- the specific translocation in these mice, he showed that c-myc had to be active in order for its DNA break to take place.
He then inserted a DNA tag into the mouse genome that allowed him to induce a break at the c-myc gene, which occurs only very rarely if left to its own devices. He found that his artificially created breaks were comparable in most every way to the breaks caused by AID, but when he looked for the translocation in mice that didn’t produce this enzyme, they were nowhere to be found.
“This is a definitive study,” says Nussenzweig, who is also a Howard Hughes Medical Institute investigator. “We now know AID is causing damage in other parts of the genome, not just in antibody genes.”
Because AID normally enables the genetic experimentation that’s critical to an effective immune response, shutting it down even to fight cancer is perilous. “As a general rule, you wouldn’t want to give an AID inhibitor to everyone because immune systems would not be working so well,” Nussenzweig says. Still, a pharmaceutical AID inhibitor, if developed, might prove useful in treating certain tumors that are expressions of this powerful gene mutator.
The next step is to figure out exactly how AID works and identify other genetic sites where AID is active. “We are now developing the tools to do exactly that,” Robbiani says.
Brett Norman | Newswise Science News
Repairing damaged hearts with self-healing heart cells
22.08.2017 | National University Health System
Biochemical 'fingerprints' reveal diabetes progression
22.08.2017 | Umea University
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
22.08.2017 | Health and Medicine
22.08.2017 | Materials Sciences
22.08.2017 | Life Sciences