Category: Cells

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Meet Nels Elde and His Team’s Amazing, Expandable Viruses

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Nels Elde, Ph.D.
Credit: Kristan Jacobsen
Nels Elde, Ph.D.
Fields: Evolutionary genetics, virology, microbiology, cell biology
Works at: University of Utah, Salt Lake City
When not in the lab, he’s: Gardening, supervising pets, procuring firewood
Hobbies: Canoeing, skiing, participating in facial hair competitions

“I really look at my job as an adventure,” says Nels Elde. “The ability to follow your nose through different fields is what motivates me.”

Elde has used that approach to weave evolutionary genetics, bacteriology, virology, genomics and cell biology into his work. While a graduate student at the University of Chicago and postdoctoral researcher at the Fred Hutchinson Cancer Research Center in Seattle, he became interested in how interactions between pathogens (like viruses and bacteria) and their hosts (like humans) drive the evolution of both parties. He now works in Salt Lake City, where, as an avid outdoorsman, he draws inspiration from the wild landscape.

Outside the lab, Elde keeps diverse interests and colorful company. His best friend wrote a song about his choice of career as a cell biologist. (You can hear this song at the end of the 5-minute video Exit icon in which Elde explains his work.) Continue reading “Meet Nels Elde and His Team’s Amazing, Expandable Viruses”

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Cellular ‘Cruise Control’ Systems Let Cells Sense and Adapt to Changing Demands

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Cells are the ultimate smart material. They can sense the demands being placed on them during critical life processes and then respond by strengthening, remodeling or self-repairing, for instance. To do this, cells use “mechanosensory” systems similar to the cruise control that lets a car’s engine adjust its power output when going up or down hills.

Researchers are uncovering new details on cells’ molecular cruise control systems. By learning more about the inner workings of these systems, scientists hope ultimately to devise ways to tinker with them for therapeutic purposes.

Cell Fusion

To examine how cells fine-tune their architecture and force output during the merging or fusion of cells, Elizabeth Chen and Douglas Robinson of Johns Hopkins University teamed up with Daniel Fletcher of the University of California, Berkeley. Cell fusion is critical to many developmental and physiological processes, including fertilization, placenta formation, immune response, and skeletal muscle development and regeneration.

Illustration of cell fusion

Fingerlike protrusions of one cell (pink) invade another cell prior to cell fusion. Credit: Shuo Li. Used with permission from Developmental Cell.

Using the fruit fly Drosophila melanogaster as a model system, Chen’s research group Exit icon previously found that when two muscle cells merge during muscle development, fingerlike protrusions of one cell invade the territory of the other cell to promote fusion. In the new study, led by Chen, the researchers showed that cell fusion depends on the ability of the “receiving” cell to put up resistance against the invading cell Exit icon.

In fusing fruit fly cells, the scientists saw that in areas where the invading cells drilled in, the receiving cells quickly stiffened their cell skeletons, effectively pushing back. This mechanosensory response allows the outer membranes of the two cells to be pushed together and later fuse, Chen explains.

The team then explored the mechanisms underlying the stiffening response. They found that a protein called myosin II, which is part of the cell skeleton, senses the pushing force from the invading cell. Myosin II swarms to the fusion site and binds with fibers just beneath the cell membrane to put up the necessary resistance. Continue reading “Cellular ‘Cruise Control’ Systems Let Cells Sense and Adapt to Changing Demands”

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Surprising Role for Protein Involved in Cell Death

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C. elegans
Many of the key players in regulating apoptosis were discovered in C. elegans. This tiny roundworm has more than 19,000 genes, and a vast number of them are very similar to genes in other organisms, including people. Credit: Ewa M. Davison.

Our cells come equipped with a self-destruct mechanism that’s activated during apoptosis, a carefully controlled process by which the body rids itself of unneeded or potentially harmful cells. Scientists have long known that a protein called PSR-1 helps clean up the cellular remains. Now they’ve found that PSR-1 also can repair broken nerve fibers.

Ding Xue of the University of Colorado, Boulder, and others made the finding in the tiny roundworm C. elegans, which scientists have used to study apoptosis and identify many of the genes that regulate the process. While apoptotic cells sent “eat me” signals to PSR-1, injured nerve cells sent “save me” signals to the protein. These SOS signals helped reconnect the broken nerve fibers, called axons, that would otherwise degenerate after an injury.

Continue reading “Surprising Role for Protein Involved in Cell Death”
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5 Reasons Biologists Love Math

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Biologists use math in a variety of ways, from designing experiments to mapping complex biological systems. Credit: Stock image.

On Saturday (at 9:26:53 to be exact), math lovers and others around the world will celebrate Pi—that really long number that represents the ratio of the circumference of a circle to its diameter. I asked our scientific experts why math is important to biomedical research. Here are a few reasons.

  1. Math allows biologists to describe how molecules move in and out of cells, how bacteria shuttle through blood vessels, how drugs get broken down in the body and many other physiological processes.
  2. Studying the geometry, topology and other physical characteristics of DNA, proteins and cellular structures has shed light on their functions and on approaches for enhancing or disrupting those functions.
  3. Math helps scientists design their experiments, including clinical trials, so they result in meaningful data, a.k.a statistical significance.
  4. Scientists use math to piece together all the different parts of a cell, an organ or an entire organism to better understand how the parts interact and how perturbations in these complex systems may contribute to disease.
  5. Sometimes it’s impossible or too difficult to answer a research question through traditional lab experiments, so biologists rely on math to develop models that represent the system they’re studying, whether it’s a metastasizing cancer cell or an emerging infectious disease. These approaches allow scientists to indicate the likelihood of certain outcomes as well as refine the research questions.

Want more? Here’s a video with 10 reasons biologists should know some math.

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Unprecedented Views of HIV

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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.”

Continue reading “Unprecedented Views of HIV”
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Untangling a Trending Topic

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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. Continue reading “Untangling a Trending Topic”

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Illuminating Biology

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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 “Illuminating Biology”

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Field Focus: Bringing Biology Into Sharper View with New Microscopy Techniques

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Composite image of mitochondria in a cell
In this composite image of mitochondria in a cell, the left panel shows a conventional optical microscopy image, the middle panel shows a three-dimensional (3-D) STORM image with color indicating depth, and the right panel shows a cross-section of the 3-D STORM image. Credit: Xiaowei Zhuang laboratory, Howard Hughes Medical Institute, Harvard University. View larger image.

Much as a photographer brings distant objects into focus with a telephoto lens, scientists can now see previously indistinct cellular components as small as a few billionths of a meter (nanometers). By overcoming some of the limitations of conventional optical microscopy, a set of techniques known as super-resolution fluorescence microscopy has changed once-blurry images of the nanoworld into well-resolved portraits of cellular architecture, with details never seen before in biology. Reflecting its importance, super-resolution microscopy was recognized with the 2014 Nobel Prize in chemistry.

Using the new techniques, scientists can observe processes in living cells across space and time and study the movements, interactions and roles of individual molecules. For instance, they can identify and track the proteins that allow a virus to invade a cell or those that enable tumor cells to migrate to distant parts of the body in metastatic cancer. The ability to analyze individual molecules, rather than collections of molecules, allows scientists to answer longstanding questions about cellular mechanisms and behavior, such as how cells move along a surface or how certain proteins interact with DNA to regulate gene activity. Continue reading “Field Focus: Bringing Biology Into Sharper View with New Microscopy Techniques”

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Correcting a Cellular Routing Error Could Treat Rare Kidney Disease

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AGT protein and peroxisomes in untreated and treated cells.
The altered AGT protein (red) and peroxisomes (green) appear in different places in untreated cells (top), but they appear together (shown in yellow) in cells treated with DECA (bottom). Credit: Carla Koehler/Reproduced with permission from Proceedings of the National Academy of Sciences USA. View larger image.

Our cells have organized systems to route newly created proteins to the places where they’re needed to do their jobs. For some people born with a rare and potentially fatal genetic kidney disorder called PH1, a genetically altered form of a particular protein mistakenly ends up in mitochondria instead of in another organelle, the peroxisome. This cellular routing error of the AGT protein results in the harmful buildup of oxalate, which leads to kidney failure and other problems at an early age.

In new work led by UCLA biochemist Carla Koehler Exit icon, researchers used a robotic screening system to identify a compound that interferes with the delivery of proteins to mitochondria. Koehler’s team Exit icon showed that adding a small amount of the compound, known as DECA, to cells grown in the laboratory prevented the altered form of the AGT protein from going to the mitochondria and sent it to the peroxisome. The compound also reduced oxalate levels in a cell model of PH1.

The team’s findings suggest that DECA, which is already approved by the Food and Drug Administration for treating certain bacterial infections, could be a promising candidate for treating children affected by PH1. And, Koehler notes, the screening strategy that she and her team used to identify DECA as a potential therapy may help researchers identify other new therapies for the disorder.

This work was funded in part by NIH under grant R01GM061721.

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Molecules Known to Damage Cells May Also Have Healing Power

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Free radicals in an ying-yang symbol
Biology in balance: Molecules called free radicals—like the peroxide molecules illustrated here—have a reputation for being dangerous. Now, they’ve revealed healing powers. In worms, at least. Credit: Stock image

When our health is concerned, some molecules are widely labeled “good,” while others are considered “bad.” Often, the truth is more complicated.

Consider free radical molecules. These highly reactive, oxygen-containing molecules are well known for damaging DNA, proteins and other molecules in our bodies. They are suspected of contributing to premature aging and cancer. But now, new research shows they might also have healing powers.

Using the oft-studied laboratory roundworm known as C. elegans, a research group led by Andrew Chisholm at the University of California, San Diego, made a surprising discovery. Free radicals, specifically those made in cell structures called mitochondria, appear necessary for skin wounds to heal. In fact, higher (but not dangerously high) levels of the molecules can actually speed wound closure.

If further research shows the same holds true in humans, the work could point to new ways to treat hard-to-heal wounds, like diabetic foot ulcers.

This work was funded in part by NIH under grants R01GM054657 and P40OD010440.