Unprecedented Views of HIV

Visualizations can give scientists unprecedented views of complex biological processes. Here’s a look at two new ones that shed light on how HIV enters host cells.

Animation of HIV’s Entry Into Host Cells

Screen shot of the video
This video animation of HIV’s entry into a human immune cell is the first one released in Janet Iwasa’s current project to visualize the virus’ life cycle. As they’re completed, the animations will be posted at http://scienceofhiv.org Exit icon.

We previously introduced you to Janet Iwasa, a molecular animator who’s visualized complex biological processes such as cells ingesting materials and proteins being transported across a cell membrane. She has now released several animations from her current project of visualizing HIV’s life cycle Exit icon. The one featured here shows the virus’ entry into a human immune cell.

“Janet’s animations add great value by helping us consider how complex interactions between viruses and their host cells actually occur in time and space,” says Wes Sundquist, who directs the Center for the Structural Biology of Cellular Host Elements in Egress, Trafficking, and Assembly of HIV Exit icon at the University of Utah. “By showing us how different steps in viral replication must be linked together, the animations suggest hypotheses that hadn’t yet occurred to us.”

To help other researchers explore complex biological processes, Iwasa and her colleagues recently launched Molecular Flipbook Exit icon, an open-source software toolkit for making molecular animations.

Model of HIV’s Surface Proteins

Model of HIV
This model of HIV was generated by a new software program called cellPACK. Credit: Graham Johnson and Ludovic Autin, The Scripps Research Institute.

Graham Johnson Exit icon, a medical illustrator for more than 15 years, created this model of an HIV particle using an open-source software program called cellPACK Exit icon that he developed as a graduate student at The Scripps Research Institute (TSRI).

The cellPACK visualizations reconcile experimental results about the distribution of “spike” proteins on the surface of the immature HIV viral particle. These proteins help the virus enter host cells. The cellPACK models reveal that the arrangement of the proteins is not random, as had been previously suggested. This conclusion, according to the research paper, shows the power of the software to simulate and interpret results from other studies. Plus, the improved understanding of the spike proteins will further elucidate the HIV life cycle and ways to disrupt it.

Getting a closer look at HIV is just one application of the software. In a news release about the software Exit icon, Art Olson, director of the HIV Interaction and Viral Evolution Center Exit icon at TSRI and Johnson’s graduate school advisor, says, “We hope to ultimately increase scientists’ ability to target any disease.”

Zinc’s Role in Healthy Fertilization

Screen shot of the video
Fluorescent sensors at the cell surface show zinc-rich packages being released from the egg during fertilization. Credit: Northwestern Visualization. View video Exit icon

Whether aiding in early growth and development, ensuring a healthy nervous system or guarding the body from illness, zinc plays an important role in the human body.

Husband-and-wife team, Thomas O’Halloran Exit icon and Teresa Woodruff Exit icon, plus other researchers at Northwestern University, evaluated the role that zinc plays in healthy fertilization Exit icon. The study revealed how mouse eggs gather and release billions of zinc atoms at once in events called zinc sparks. These fluxes in zinc concentration are essential in regulating the biochemical processes that facilitate the egg-to-embryo transition.

The scientists developed a series of techniques to determine the amount and location of zinc atoms during an egg cell’s maturation and fertilization as well as in the following two hours. Special imaging methods allowed the researchers to also visualize the movement of zinc sparks in three dimensions. Continue reading

Remotely and Noninvasively Controlling Genes and Cells in Living Animals

Remote control car key.
Researchers are developing a system to remotely control genes or cells in living animals with radio wave technology similar to that used to operate remote control car keys. Credit: Stock image.

One of the items on biomedical researchers’ “to-do” list is devising noninvasive ways to control the activity of specific genes or cells in order to study what those genes or cells do and, ultimately, to treat a range of human diseases and disorders.

A team of scientists recently reported progress on a new, noninvasive system that could remotely and rapidly control biological targets in living animals Exit icon. The system can be activated remotely using either low-frequency radio waves or a magnetic field. Similar radio wave technology operates automatic garage-door openers and remote control car keys and is used in medicine to control electronic pacemakers noninvasively. Magnetic fields are used to activate sensors in burglar alarm systems and to turn your laptop to hibernate mode when the cover is closed.

One of the two components of the new system is a natural iron storage particle called ferritin. This particle is tethered to a temperature-sensitive channel protein that controls the flow of calcium into a cell. Together, the two molecules work as a nano-machine that can be used to trigger gene activity, or expression, in cells. When the ferritin particle is exposed to radio waves or a magnetic field, it opens the channel, activating a gene engineered to respond to calcium.

The researchers found that radio waves and magnets may have different ways of causing the calcium channel to open. Low-frequency radio waves cause mild heating of the ferritin’s iron core, tripping a switch that opens the channel, while the tug of a magnetic field most likely causes the ferritin particles to move slightly and nudge the channel open. Calcium then flows into the cell and turns on the calcium-responsive gene.

As proof of principle, the team, led by Jeffrey Friedman Exit icon at Rockefeller University and Jonathan Dordick Exit icon at Rensselaer Polytechnic Institute, showed that they could use their system to turn on insulin production and thereby lower blood sugar in diabetic mice. The researchers used genetic techniques to introduce the ferritin-tethered channels into mice along with a calcium-responsive version of the insulin gene.

In a news release, Friedman says that the system could potentially be used to control the production of a missing protein in conditions like hemophilia or to control neural activity in the brain. Indeed, another member of the research team, Sarah Stanley of Rockefeller University, is leading a follow-up study to adapt the system to switch neurons on and off so she can study their roles within the brain.

While other techniques exist for remotely controlling gene expression or cell activity in living animals, those methods have limitations. Systems that use light as an on/off signal require permanent implants or are only effective close to the skin, and those that rely on drugs can be slow to switch on and off.

In a commentary on the new study, Ingo Leibiger and Per-Olof Berggren of Sweden’s Karolinska Institute write: “A genetically encoded switch to control biological systems in the living organism by either low-frequency radio waves or by a magnetic field is an exciting noninvasive approach with many potential applications.”

This research was funded in part by NIH under grants R01GM095654 and T32GM067545.

Meet Maureen L. Mulvihill

Maureen L. Mulvihill, Ph.D.
Credit: Actuated Medical, Inc.
Maureen L. Mulvihill, Ph.D.
Fields: Materials science, logistics
Works at: Actuated Medical, Inc., a small company that develops medical devices
Second job (volunteer): Bellefonte YMCA Swim Team Parent Boost Club Treasurer
Best skill: Listening to people
Last thing she does every night: Reads to her 7- and 10-year-old children until “one of us falls asleep”

If you’re a fan of the reality TV show Shark Tank, you tune in to watch aspiring entrepreneurs present their ideas and try to get one of the investors to help develop and market the products. Afterward, you might start to think about what you could invent.

Maureen L. Mulvihill has never watched the show, but she lives it every day. She is co-founder, president and CEO of Actuated Medical, Inc. (AMI), a Pennsylvania-based company that develops specialized medical devices. The devices include a system for unclogging feeding tubes, motors that assist MRI-related procedures and needles that gently draw blood.

AMI’s products rely on the same motion-control technologies that allow a quartz watch to keep time, a microphone to project sound and even a telescope to focus on a distant object in a sky. In general, the devices are portable, affordable and unobtrusive, making them appealing to doctors and patients.

Mulvihill, who’s trained in an area of engineering called materials science, says, “I’m really focused on how to translate technologies into ways that help people.” Continue reading

Untangling a Trending Topic

Jean Chin
NIGMS’ Jean Chin answers questions about a new device for untangling proteins. Credit: National Institute of General Medical Sciences.

It’s not every day that we log into Facebook and Twitter to see conversations about denaturing proteins and the possibility of reducing biotechnology costs, but that changed last week when a story about “unboiling” eggs became a trending topic.

Since NIGMS partially funded the research advance Exit icon that led to the media scramble, we asked our scientific expert Jean Chin to tell us more about it.

What’s the advance?

Gregory Weiss of the University of California, Irvine, and his collaborators have designed a device that basically unties proteins that have been tangled together.

Screen shot from the video
In this video, UC Irvine’s Gregory Weiss describes the research and its implications.

Why’s this important?

Many human proteins or their cousins from other mammals can be made in bacterial cells. These cells can quickly produce the large quantity of a protein that researchers need to study its structure, function, dynamics and potential clinical value. But there’s a catch: The proteins can end up in clumps stored inside structures called inclusion bodies. The current methods to release and refold the proteins take days and are expensive.
This new device can do it quickly—in just minutes—and cheaply, saving researchers, pharmaceutical companies and others interested in making useful proteins time and money.

What’s the egg connection?

One of the proteins used to test the device is lysozyme, which makes up about 4 percent of the protein content of egg white. The researchers boiled egg white lysozyme and used the device to refold the protein back into its normal form.

Unboiling an egg was a great hook to get people’s attention, but the real goal of the work is to unfold and refold proteins for biomedical research and biotechnology applications.

This work was funded in part by NIH under grant R01GM100700.

A Bright New Method for Rapidly Screening Cancer Drugs

Illustration of red, green and blue fluorescent proteins.
Chemists have devised a new approach to screening cancer drugs that uses gold nanoparticles with red, green and blue outputs provided by fluorescent proteins. Credit: University of Massachusetts Amherst.

Scientists may screen billions of chemical compounds before uncovering the few that effectively treat a disease. But identifying compounds that work is just the first step toward developing a new therapy. Scientists then have to determine exactly how those compounds function.

Different cancer therapies attack cancer cells in distinct ways. For example, some drugs kill cancer cells by causing their outer membranes to rapidly rupture in a process known as necrosis. Others cause more subtle changes to cell membranes, which result in a type of programmed cell death known as apoptosis.

If researchers could distinguish the membrane alterations of chemically treated cancer cells, they could quickly determine how that chemical compound brings about the cells’ death. A new sensor developed by a research team led by Vincent Rotello Exit icon of the University of Massachusetts Amherst can make these distinctions in minutes. Continue reading

New Streamlined Technique for Processing Biological Samples

Illustration of Slug flow microextraction.
Researchers have discovered a faster, easier and more affordable technique for processing biological samples. Credit: Weldon School of Biomedical Engineering, Purdue University.

It’s not unusual for the standard dose of a drug to work well for one person but be less effective for another. One reason for such differences is that individuals can break down drugs at different rates, leading to different concentrations of drugs and of their breakdown products (metabolites) in the bloodstream. A promising new process Exit icon called slug-flow microextraction could make it faster, easier and more affordable to regularly monitor drug metabolites so that medication dosages could be tailored to each patient’s needs, an approach known as personalized medicine. This technique could also allow researchers to better monitor people’s responses to new drug treatments during clinical trials. Continue reading

Delivering Gene-Editing Proteins to Living Cells

Illustration of a DNA strand being cut by a pair of scissors.
Researchers are testing new ways to get gene editing proteins into living cells to potentially modify human genes associated with disease. Credit: Stock image.

Over the last two decades, exciting tools have emerged that allow researchers to cut and paste specific sequences of DNA within living cells, a process called gene editing. These tools, including one adapted from a bacterial defense system called CRISPR, have energized the research community with the possibility of using them to modify human genes associated with disease.

A major barrier to testing medical applications of gene editing has been getting the proteins that do the cutting into the cells of living animals. The main methods used in the laboratory take a roundabout route: Researchers push the DNA templates for making the proteins into cells, and then the cells’ own protein factories produce the editing proteins.

Researchers led by David Liu Exit icon from Harvard University are trying to cut out the middleman, so to speak, by ferrying the editing proteins, not the DNA instructions, directly into cells. In a proof-of-concept study, their system successfully delivered three different types of editing proteins into cells in the inner ears of live mice. Continue reading

Illuminating Biology

This time of year, lights brighten our homes and add sparkle to our holidays. Year-round, scientists funded by the National Institutes of Health use light to illuminate important biological processes, from the inner workings of cells to the complex activity of the brain. Here’s a look at just a few of the ways new light-based tools have deepened our understanding of living systems and set the stage for future medical advances.

RSV infected cell
A new fluorescent probe shows viral RNA (red) in an RSV-infected cell. Credit: Eric Alonas and Philip Santangelo, Georgia Institute of Technology and Emory University.

Visualizing Viral Activity

What looks like a colorful pattern produced as light enters a kaleidoscope is an image of a cell infected with respiratory syncytial virus (RSV) lit up by a new fluorescent probe called MTRIPS (multiply labeled tetravalent RNA imaging probes).

Although relatively harmless in most children, RSV can lead to bronchitis and pneumonia in others. Philip Santangelo of the Georgia Institute of Technology and Emory University, along with colleagues nationwide, used MTRIPS to gain a closer look at the life cycle of this virus.

Once introduced into RSV-infected cells, MTRIPS latched onto the genetic material of individual viral particles (in the image, red), making them glow. This enabled the researchers to follow the entry, assembly and replication of RSV inside the living cells. Continue reading

E. Coli Bacteria as Medical Sensors and Hard Drives?

E.Coli
Modified E. coli bacteria can serve as sensors and data storage devices for environmental and medical monitoring. Credit: Centers for Disease Control and Prevention. View larger image

E. coli bacteria help us digest our food, produce vitamin K and have served as a model organism in research for decades. Now, they might one day be harnessed as environmental or medical sensors and long-term data storage devices Exit icon.

MIT researchers Timothy Lu Exit icon and Fahim Farzadfard modified the DNA of E. coli cells so that the cells could be deployed to detect a signal (for example, a small molecule, a drug or the presence of light) in their surroundings. To create the modified E. coli, the scientists inserted into the bacteria a custom-designed genetic tool.

When exposed to the specified signal, the tool triggers a series of biochemical processes that work together to introduce a single mutation at a specific site in the E. coli’s DNA. This genetic change serves to record exposure to the signal, and it’s passed on to subsequent generations of bacteria, providing a continued record of exposure to the signal. In essence, the modified bacteria act like a hard drive, storing biochemical memory for long periods of time. The memory can be retrieved by sequencing the bacteria or through a number of other laboratory techniques. Continue reading