Their findings, published in the June issue of Plos Biology, counter the prevailing belief that HIV and other retroviruses can only leave and enter cells by virus-specific mechanisms.
“It appears that cells make HIV and other retroviruses by a naturally occurring export mechanism,” says Stephen Gould, Ph.D., Professor of Biological Chemistry at Johns Hopkins. Cells normally export certain membrane-bound molecules to the outside world by means of small sacs known as exosomes. By studying human T-cells under a microscope, Gould, Yi Fang, Ning Wu, and other members of his team discovered what’s needed to qualify proteins for exosomal travel.
“Surprisingly, all that’s needed for a protein to get out of the cell in exosomes are the ability to clump together and attach to the cell’s membrane,” Gould says.
In one experiment, Gould and his team added chemicals to normal human cells that force nearby proteins together into a clump, and this was enough to get them sent out of the cell in exosomes. If they added a tether to force naturally-clumping proteins inside the cell to the membrane, the proteins met a similar exosomal deportation fate.
The major HIV protein ‘Gag’ has both of these properties that cells sense in selecting exosomal cargoes. When the researchers removed the tethers or clumping signals from Gag it could no longer get out of the cell. However, if they were replaced with synthetic membrane anchors and clumping domains Gag regained its ability to get out of cells in exosomes.
Gould speculates that cells may have initially developed exosomes as a quality control mechanism to get rid of clumped proteins, which are generally broken and useless. However, just as retroviruses exploit other cell processes for their own ends, it now appears they rely on exosomes to get out of infected cells and infect fresh cells. As such, drugs that interfere with exosome formation might be one way to inhibit HIV infections.
“Viruses like HIV use pathways we barely recognize, much less understand,” Gould says. “Our paper highlights the importance of studying their basic biochemistry and cell biology, which can yield a better understanding of normal human biology as well as identify new avenues in the fight against human disease.”
Nick Zagorski | EurekAlert!
Not of Divided Mind
19.01.2017 | Hertie-Institut für klinische Hirnforschung (HIH)
CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
19.01.2017 | Earth Sciences
19.01.2017 | Life Sciences
19.01.2017 | Physics and Astronomy