Breast Cancer Tumors Recruit Immune Cells to the Dark Side

We rely on our immune system to stave off all classes of disease—but what happens when the very system responsible for keeping us healthy turns to the dark side? In new research published today, scientists uncover new evidence that reveals how breast cancer tumors can actually recruit immune cells to spur the spread of disease.

Some forms of breast cancer tumors can actually turn the body's own immune system against itself.

Some forms of breast cancer tumors can actually turn the body’s own immune system against itself.

Breast cancer is one of the most common cancers, and if caught early, is highly treatable. In fact, the majority of deaths from breast cancer occur because the disease has been caught too late, having already spread to other parts of the body, a process called ‘metastasis.’ Recently, scientists discovered that women who have a heightened number of a particular type of immune cells, called ‘neutrophils,’ in their blood stream have a higher chance of their breast cancer metastasizing to other tissues. But they couldn’t figure out why.

Enter Karin de Visser, and her team at the Netherlands Cancer Institute, who announce today in the journal Nature the precise link between neutrophil immune cells and breast cancer metastasis.

They found that some types of breast tumors are particularly nefarious, sending out signals to the person’s immune system to speed up their production of neutrophils. And then they instruct these newly activated neutrophils to go rogue.

Rather than attack the tumor, these neutrophils turn on the immune system. They especially focus their efforts at blocking T cells—the type of immune cells whose job is normally to target and attack cancer cells. Further examination in mouse models of breast cancer revealed a particular protein, called interleukin 17 (or IL17) played a key role in this process. As Visser explained in today’s news release:

“We saw in our experiments that IL17 is crucial for the increased production of neutrophils. And not only that, it turns out that this is also the molecule that changes the behavior of the neutrophils, causing them to become T cell inhibitory.”

The solution then, was clear: block the connection, or pathway, between IL17 and neutrophils, and you can thwart the tumor’s efforts. And when Visser and her team, including first author and postdoctoral researcher Seth Coffelt, did this they saw a significant improvement. When the IL17-neutrophil pathway was blocked in the mouse models, the tumors failed to spread at the same rate.

“What’s notable is that blocking the IL17-neutrophil route prevented the development of metastases, but did not affect the primary tumor,” Visser added. “So this could be a promising strategy to prevent the tumor from spreading.”

The researchers are cautious about focusing their efforts on blocking neutrophils, however, as these cells are in and of themselves important to stave off infections. A breast cancer patient with neutrophil levels that were too low would be at risk for developing a whole host of infections from dangerous pathogens. As such, the research team argues that focusing on ways to block IL17 is the best option.

Just last month, the FDA approved an anti-IL17 based therapy to treat psoriasis. This therapy, or others like it, could be harnessed to treat aggressive breast cancers. Says Visser:

“It would be very interesting to investigate whether these already existing drugs are beneficial for breast cancer patients. It may be possible to turn these traitors of the immune system back towards the good side and prevent their ability to promote breast cancer metastasis.”

New understanding of the inner workings of our genetic tool kit should help us make smarter repairs

For young biology students the steps from genes to their function becomes a mantra: DNA makes RNA and RNA makes protein. But it is really not quite that simple. A few different types of RNA act along the path and we are now learning that the structure, or shape, of the individual RNA molecules affects their function.

Which genes succeed in producing their designated protein determines what the cell actually does—what kind of tissue it is and how well it performs the role it is assigned. Switching gene function on and off turns out to be quite complex with players among the molecules that are part of the backbone of DNA as well as the various forms of RNA. We have made great strides in the past decade in understanding the role of those DNA structural components, the so-called epigenetics, but still have major gaps in our understanding of the many roles of RNA.

DNA dogmaWith CIRM-funding, a team headed by Howard Chang at Stanford has gotten around a major hurdle in unlocking this complex issue. Like DNA, RNA is made up of various repeats of four molecules called bases. Prior to Chang’s work researchers could only track the structure of RNA associated with two of those bases. His team modified a commonly used bio-chemical tool called SHAPE to reveal the workings of all four RNA bases in living cells.

The team verified something that is increasingly being shown, static cells frozen in time a lab dish do not necessarily reflect what goes on in living cells. In this study those differences manifest in the structure of the RNA that determines what molecules are next to each other, which impacts their activity. After more than 2 billion measurements of more than 13,000 RNAs in the lab and in living cells, the team quantified those differences and showed how this molecular “folding” changes the function of the various RNAs.

They published the work, for which they used mouse embryonic stem cells, on-line today in Nature. In the closing paragraph of the journal article they speculate on the impact of the new ability to better understand the roles of RNA:

“In the future, viewing the RNA structurome when cells are exposed to different stimuli or genetic perturbations should revolutionize our understanding of gene regulation in biology and medicine.”

Since so many of the research projects that seek to reverse the course of disease try to change the genetic functioning of cells, this new understanding should be able to reduce the number of blind alleys scientist have to go down to get a desired result. It should allow the design of studies based on more logic and less chance, speeding the development of therapies.

Pathway discovered that could yield therapies to prevent hearts turning to “bone”

In the Rolling Stones’ lyrics having a “Heart of Stone” protected you from heartbreak. But over a million Americans are developing hearts of bone and it could kill them.

CIRM-funded researchers at the Gladstone Institutes think they have uncovered the path to this destructive hardening of the heart and that could lead to therapies to stop the damage. In particular, they looked at heart valves and why in some people the cells in those valves start acting like bone and produce calcium that causes them to get rigid and loose their proper function.

Valve cells come from a family of cells called endothelial cells that includes the lining of blood vessels, which are also prone to inappropriate production of calcium and hardening. So, the findings could have much broader implication for heart disease and therapy.

A mutation in the Notch1 gene makes cells react inappropriately to the sheer stress caused by blood flow. Team found BMP, SFB and MMP genes control this.

A mutation in the Notch1 gene makes cells react inappropriately to the sheer stress caused by blood flow. Team found BMP, SFB and MMP genes control this.

Led by senior author Deepak Srivastava, the team used stem cell technology to create endothelial cells from patients with genetic calcific aortic valve disease (CAVD) and from normal individuals. They then pushed those cells to mature into valve cells in the lab and monitored which genes were turned on or off during the process, comparing the disease carrying and normal cells.

They built on a previous discovery of Srivastava, who found that a defect in the gene NOTCH1 can cause valve birth defects and CAVD. Searching hundreds of genes and gene switches they came upon three genes that appear to be master regulators of the path that leads cells to overproduce calcium. In a press release from the Gladstone, he said:

“Identifying these master regulators is a big step in treating CAVD, not just in people with the NOTCH1 mutation, but also in other patients who experience calcification in their valves and arteries. Now that we know how calcification happens and what the key nodes are, we know what genes to look for that might be mutated in other related forms of cardiovascular disease.”

The release noted that the research team is now screening for drugs that can act on this gene network. Srivastava’s main focus has been on congenital pediatric heart disease. He discusses that research in three brief videos that include the story of one very special young patient.

Pioneer’s 25-year struggle to treat blindness

Being a pioneer is never easy. You are charting unknown territory, tackling problems that have defeated others before you. You have to overcome so many obstacles that at times the challenge can seem insurmountable. But for those who succeed in reaching their goal, the rewards can be extraordinary.

Graziella Pellegrini, Center for Regenerative Medicine, University of Modena, Italy

Graziella Pellegrini, Center for Regenerative Medicine, University of Modena, Italy

Last month Italian researcher Graziella Pellegrini saw 25 years of work pay off when a treatment she developed to cure a form of blindness was given approval for sale by the European Commission.

This is quite an achievement as this means her treatment, called Holoclar, is among the first commercial stem therapies in the world (the first was Prochymal, which has been approved in Canada and New Zealand for the treatment of pediatric GVHD. This drug was developed by Osiris, which was led by our current President & CEO, Dr. Randy Mills.)

Holoclar uses stem cells to help stimulate the regrowth of a cornea. It can only be used for certain rare conditions, but that in no way diminishes its importance for patients or significance for the regenerative medicine field as a whole.

Nature recently sat down with Dr. Pellegrini to talk about her work, her struggle, and the many obstacles she had to overcome to get market approval for her work.

The interview makes for fascinating reading, and is a timely reminder why this kind of groundbreaking research never goes quite as quickly, or smoothly, as one would hope.

CIRM currently has a number of projects focused treating different causes of blindness on limbal cells (the kind Dr. Pellegrini worked on) and other forms of blindness; including a project to treat macular degeneration that has been approved for a clinical trial, and a therapy for retinitis pigmentosa that we hope will be approved for a clinical trial later this year.

One-Time, Lasting Treatment for Sickle Cell Disease May be on Horizon, According to New CIRM-Funded Study

For the nearly 1,000 babies born each year in the United States with sickle cell disease, a painful and arduous road awaits them. The only cure is to find a bone marrow donor—an exceedingly rare proposition. Instead, the standard treatment for this inherited blood disorder is regular blood transfusions, with repeated hospitalizations to deal with complications of the disease. And even then, life expectancy is less than 40 years old.

In Sickle Cell Disease, the misshapen red blood cells cause painful blood clots and a host of other complications.

In Sickle Cell Disease, the misshapen red blood cells cause painful blood clots and a host of other complications.

But now, scientists at UCLA are offering up a potentially superior alternative: a new method of gene therapy that can correct the genetic mutation that causes sickle cell disease—and thus help the body on its way to generate normal, healthy blood cells for the rest of the patient’s life. The study, funded in part by CIRM and reported in the journal Blood, offers a great alternative to developing a functional cure for sickle cell disease. The UCLA team is about to begin a clinical trial with another gene therapy method, so they—and their patients—will now have two shots on goal in their effort to cure the disease.

Though sickle cell disease causes dangerous changes to a patient’s entire blood supply, it is caused by one single genetic mutation in the beta-globin gene—altering the shape of the red blood cells from round and soft to pointed and hard, thus resembling a ‘sickle’ shape for which the disease is named. But the UCLA team, led by Donald Kohn, has now developed two methods that can correct the harmful mutation. As he explained in a UCLA news release about the newest technique:

“[These results] suggest the future direction for treating genetic diseases will be by correcting the specific mutation in a patient’s genetic code. Since sickle cell disease was the first human genetic disease where we understood the fundamental gene defect, and since everyone with sickle cell has the exact same mutation in the beta-globin gene, it is a great target for this gene correction method.”

The latest gene correction technique used by the team uses special enzymes, called zinc-finger nucleases, to literally cut out and remove the harmful mutation, replacing it with a corrected version. Here, Kohn and his team collected bone marrow stem cells from individuals with sickle cell disease. These bone marrow stem cells would normally give rise to sickle-shaped red blood cells. But in this study, the team zapped them with the zinc-finger nucleases in order to correct the mutation.

Then, the researchers implanted these corrected cells into laboratory mice. Much to their amazement, the implanted cells began to replicate—into normal, healthy red blood cells.

Kohn and his team worked with Sangamo BioSciences, Inc. to design the zinc-finger nucleases that specifically targeted and cut the sickle-cell mutation. The next steps will involve improving the efficiency and safest of this method in pre-clinical animal models, before moving into clinical trials.

“This is a promising first step in showing that gene correction has the potential to help patients with sickle cell disease,” said UCLA graduate student Megan Hoban, the study’s first author. “The study data provide the foundational evidence that the method is viable.”

This isn’t the first disease for which Kohn’s team has made significant strides in gene therapy to cure blood disorders. Just last year, the team announced a promising clinical trial to cure Severe Combined Immunodeficiency Syndrome, also known as SCID or “Bubble Baby Disease,” by correcting the genetic mutation that causes it.

While this current study still requires more research before moving into clinical trials, Kohn and his team announced last month that their other gene therapy method, also funded by CIRM, has been approved to start clinical trials. Kohn argues that it’s vital to explore all promising treatment options for this devastating condition:

“Finding varied ways to conduct stem cell gene therapies is important because not every treatment will work for every patient. Both methods could end up being viable approaches to providing one-time, lasting treatments for sickle cell disease and could also be applied to the treatment of a large number of other genetic diseases.”

Find Out More:
Read first-hand about Sickle Cell Disease in our Stories of Hope series.
Watch Donald Kohn speak to CIRM’s governing Board about his research.

Stay on Target: Scientists Create Chemical ‘Homing Devices’ that Guide Stem Cells to Final Destination

When injecting stem cells into a patient, how do the cells know where to go? How do they know to travel to a specific damage site, without getting distracted along the way?

Scientists are now discovering that, in some cases they do but in many cases, they don’t. So engineers have found a way to give stem cells a little help.

As reported in today’s Cell Reports, engineers at Brigham and Women’s Hospital (BWH) in Boston, along with scientists at the pharmaceutical company Sanofi, have identified a suite of chemical compounds that can help the stem cells find their way.

Researchers identified a small molecule that can be used to program stem cells (blue and green) to home in on sites of damage. [Credit: Oren Levy, Brigham and Women's Hospital]

Researchers identified a small molecule that can be used to program stem cells (blue and green) to home in on sites of damage. [Credit: Oren Levy, Brigham and Women’s Hospital]

“There are all kinds of techniques and tools that can be used to manipulate cells outside the body and get them into almost anything we want, but once we transplant cells we lose complete control over them,” said Jeff Karp, the paper’s co-senior author, in a news release, highlighting just how difficult it is to make sure the stem cells reach their destination.

So, Karp and his team—in collaboration with Sanofi—began to screen thousands of chemical compounds, known as small molecules, that they could physically attach to the stem cells prior to injection and that could guide the cells to the appropriate site of damage. Not unlike a molecular ‘GPS.’

Starting with more than 9,000 compounds, the Sanofi team narrowed down the candidates to just six. They then used a microfluidic device—a microscope slide with tiny glass channels designed to mimic human blood vessels. Stem cells pretreated with the compound Ro-31-8425 (one of the most promising of the six) stuck to the sides. An indication, says the team, Ro-31-8425 might help stem cells home in on their target.

But how would these pre-treated cells fare in animal models? To find out, Karp enlisted the help of Charles Lin, an expert in optical imaging at Massachusetts General Hospital. First, the team injected the pre-treated cells into mouse models each containing an inflamed ear. Then, using Lin’s optical imaging techniques, they tracked the cells’ journey. Much to their excitement, the cells went immediately to the site of inflammation—and then they began to repair the damage.

According to Oren Levy, the study’s co-first author, these results are especially encouraging because they point to how doctors may someday soon deliver much-needed stem cell therapies to patients:

“There’s a great need to develop strategies that improve the clinical impact of cell-based therapies. If you can create an engineering strategy that is safe, cost effective and simple to apply, that’s exactly what we need to achieve the promise of cell-based therapy.”

Stem cell stories that caught our eye; progress toward artificial brain, teeth may help the blind and obesity

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

More progress toward artificial brain. A team at the RIKEN Institute in Japan has used stem cells in a 3-D culture to create brain tissue more complex than prior efforts and from an area of the brain not produced before, the cerebellum—that lobe at the lower back of the brain that controls motor function and attention. As far back as 2008, a RIKEN team had created simple tissue that mimicked the cortex, the large surface area that controls memory and language.

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The Inquisitr web portal wrote a feature on a wide variety of efforts to create an artificial brain teeing off of this week’s publication of the cerebellum work in Cell Reports. The piece is fairly comprehensive covering computerized efforts to give robots intelligence and Europe’s Human Brain Project that is trying to map all the activity of the brain as a starting point for recapitulating it in the lab.

The experts interviewed included Robert Caplan of Tufts University in Massachusetts who is using 3-D scaffolding to build functional brain tissues that can process electrical signals. He is not planning any Frankenstein moments; he hopes to create models to improve understanding of brain diseases.

“Ideally we would like to have a laboratory brain system that recapitulates the most devastating diseases. We want to be able to take our existing toolkit of drugs and understand how they work instead of using trial and error.”

Teeth eyed as source of help for the blind. Today the European Union announced the first approval of a stem cell therapy for blindness. And already yesterday a team at the University of Pittsburg announced they had developed a new method to use stem cells to restore vision that could expand the number of patients who could benefit from stem cell therapy.

Many people have lost part or all their vision due to damage to the cornea on the surface of their eye. Even when they can gain vision back through a corneal transplant, their immune system often rejects the new tissue. So the ideal would be making new corneal tissue from the patient’s own cells. The Italian company that garnered the EU approval does this in patients by harvesting some of their own cornea-specific stem cells, called limbal stem cells. But this is only an option if only one eye is impacted by the damage.

The Pittsburgh team thinks it may have found an unlikely alternative source of limbal cells: the dental pulp taken from teeth that have be extracted. It is not as far fetched at it sounds on the surface. Teeth and the cornea both develop in the same section of the embryo, the cranial neural crest. So, they have a common lineage.

The researchers first treated the pulp cells with a solution that makes them turn into the type of cells found in the cornea. Then they created a fiber scaffold shaped like a cornea and seeded the cells on it. Many steps remain before people give up a tooth to regain their sight, but this first milestone points the way and was described in a press release from the journal Stem Cells Translational Medicine, which was picked up by the web site ClinicaSpace.

CIRM funds a project that also proposes to use the patient’s own limbal stem cells but using methods more likely to gain approval of the Food and Drug Administration than those used by the Italian company.

Stem cells and the fight against obesity. Of the two types of stem cells found in your bone marrow, one can form bone and cartilage and, all too often, fat. Preventing these stem cells from maturing into fat may be a tool in the fight against obesity according to a team at Queen Mary University of London.

The conversion of stem cells to fat seems to involve the cilia, or hair-like projections found on cells. When the cilia lengthen the stem cells progress toward becoming fat. But if the researchers genetically prevented that lengthening, they stopped the conversion to fat cells. The findings opens several different ways to think about understanding and curbing obesity says Melis Dalbay one of the authors of the study in a university press release picked up by ScienceNewsline.

“This is the first time that it has been shown that subtle changes in primary cilia structure can influence the differentiation of stem cells into fat. Since primary cilia length can be influenced by various factors including pharmaceuticals, inflammation and even mechanical forces, this study provides new insight into the regulation of fat cell formation and obesity.”

Roadmap to our epigenome reveals the genetic switches that make one adult cell type different from others

A decade ago scientists made a huge news splash when they announced the completion of the human genome project declaring it the first road map of our genes. But it did not take long to realize that the early road map was like some of the early days of GPS systems: it lacked knowledge of many on-ramps, off-ramps and one-way streets.

Today, the scientific world announced a massive fix to its genetic GPS. While all of our cells carry the same genes, their function varies wildly based one which genes are turned off, which are turned on, and even which are turned on in a hyper active way. Complex chemical and structural changes in the chromosomes that house our genes—collectively called the epigenome—determine that activity.

This video from Nature explaining the epigenome with music metaphors is linked in the last paragraph.

This video from Nature explains the epigenome with music metaphors.


A massive project, mostly funded by the National Institutes of Health through a consortium of research teams around the country, published a series of papers today in Nature. The Roadmap Epigenomic Consortium did extensive analysis of 111 epigenomes from different types of cells: normal heart tissue and immune cells, for example, as well as cells from patients with diseases such as neurons from patients with Alzheimer’s. The Scientist this morning quoted one member of the Consortium, MIT’s Manolis Kellis:

“The human epigenome is this collection of . . . chemical modifications on the DNA itself and on the packaging that holds DNA together. All our cells have a copy of the same book, but they’re all reading different chapters, bookmarking different pages, and highlighting different paragraphs and words.”

CIRM funding contributed to two of the papers authored by a team at the University of California, San Diego. One of the papers looked at how the genetic structure of stem cells changes as they mature and differentiate into specific types of adult tissue. The other looked at how structural differences determine which of the chromosomes we inherit—the one from mom or the one from dad—has a stronger influence on specific traits. The senior author on the studies, Bing Ren, noted in a university press release that these differences will be important as we think about individualizing therapies:

“Both of these studies provide important considerations for clinicians and researchers who are developing personalized medicines based on a patient’s genomic information”

The consortium’s publications today resulted from a massive data analysis. A press release from the Broad Institute in Cambridge, Massachusetts, describes the effort that required grouping two million predicted areas of change in the chromosomes into 200 sets or modules and then looking for how those modules impacted different cell types.

But if you are still having trouble understanding the concept of the epigenome, I highly recommend taking the five minutes it takes to watch this video produced by Nature. It equates the process to a symphony and what occurs when you change notes and intensity in the score.

Combination Cancer Therapy Gives Cells a Knockout Punch

For some forms of cancer, there really is no way to truly eradicate it. Even the most advanced chemotherapy treatments leave behind some straggler cells that can fuel a relapse.

By hitting breast cancer cells with a targeted therapeutic immediately after chemotherapy, researchers were able to target cancer cells during a transitional stage when they were most vulnerable. [Credit: Aaron Goldman]

By hitting breast cancer cells with a targeted therapeutic immediately after chemotherapy, researchers were able to target cancer cells during a transitional stage when they were most vulnerable.
[Credit: Aaron Goldman]

But now, scientists have devised a unique strategy, something they are calling a ‘one-two punch’ that can more effectively wipe out dangerous tumors, and lower the risk of them ever returning for a round two.

Reporting in the latest issue of the journal Nature Communications, bioengineers at Brigham and Women’s Hospital (BWH) in Boston describe how treating breast cancer cells with a targeted drug immediately after chemotherapy was effective at killing the cancer cells and preventing a recurrence. According to lead scientist Shiladitya Sengupta, these findings were wholly unexpected:

“We were studying the fundamentals of how [drug] resistance develops and looking to understand what drives [cancer] relapse. What we found is a new paradigm for thinking about chemotherapy.”

In recent years, many scientists have suggested cancer stem cells are one of the biggest hurdles to curing cancer. Cancer stem cells are proposed to be a subpopulation of cancer cells that are resistant to chemotherapy. As a result, they can propagate the cancer after treatment, leading to a relapse.

In this work, Sengupta and his colleagues treated breast cancer cells with chemotherapy. And here is where things started getting interesting.

After chemotherapy, the breast cancer cells began to morph into cells that bore a close resemblance to cancer stem cells. For a brief period of time after treatment, these cells were neither fully cancer cells, nor fully stem cells. They were in transition.

The team then realized that because these cells were in transition, they may be more vulnerable to attack. Testing this hypothesis in mouse models of breast cancer, the team first zapped the tumors with chemotherapy. And, once the cells began to morph, they then blasted them with a different type of drug. The tumors never grew back, and the mice survived.

Interestingly, the team did not have similar success when they altered the timing of when they administered the therapy. Treating the mice with both types of drugs simultaneously didn’t have the same effect. Neither did increasing the time between treatments. In order to successfully treat the tumor they had a very slim window of opportunity.

“By treating with chemotherapy, we’re driving cells through a transition state and creating vulnerabilities,” said Aaron Goldman, the study’s first author. “This opens up the door: we can then try out different combinations and regimens to find the most effective way to kill the cells and inhibit tumor growth.”

In order to test these combinations, the researchers developed an ‘explant,’ a mini-tumor derived from a patient’s biopsy that can be grown in an environment that closely mimics its natural surroundings. The ultimate goal, says Goldman, is to map the precise order and timing of this treatment regimen in order to move toward clinical trials:

“Our goal is to build a regimen that will be [effective] for clinical trials. Once we’ve understood specific timing, sequence of drug delivery and dosage better, it will be easier to translate these findings clinically.”

All Things Being (Un)Equal: Scientists Discover Gene that Breaks Traditional Laws of Inheritance

One of the most fundamental laws of biology is about to be turned on its head, according to new research from scientists at the University of North Carolina (UNC) School of Medicine.

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As reported in the journal PLOS Genetics, UNC researchers identified a gene that does not obey traditional laws that determine how genes get passed down from parents to offspring. In experiments on laboratory mice, they found a gene called R2d2 causes female mice to pass on more genetic information than the males did—an observation that appears to contradict principles of genetic inheritance set forth more than a century ago.

As you may (or may not) remember from freshmen biology class, the laws of inheritance were laid down by the 19th century monk Gregor Mendel. Through meticulous observations of his garden’s pea plants, he found that each parent contributes their genetic information equally to their offspring.

But 150 years of scientific discovery later, scientists have discovered that this isn’t always the case.

Instead, in some cases one of the parents will contribute a greater percentage of genetic information than the other, a process called meiotic drive. Scientists had seen evidence of this process occurring in mammals for quite some time, but hadn’t narrowed down the driver of the process to a particular gene. According to UNC researchers, R2d2 is that gene. Senior author Fernando Pardo-Manuel de Villena explains:

“R2d2 is a good example of a poorly understood phenomenon known as female meiotic drive—when an egg is produced and a ‘selfish gene’ is segregated to the egg more than half the time.”

Pardo-Manuel de Villena notes that one example of this process occurs during trisomies—when three chromosomes (two from one parent and one from the other) are passed down to the embryo. The most common trisomy, trisomy 21, is more commonly known as Down Syndrome.

With these findings, Pardo-Manuel de Villena and the team are hoping to gain important insights into the underlying cause of trisomies, as well as the underlying causes for miscarriage—which are often not known.

“Understanding how meiotic drive works may shed light on the … abnormalities underlying these disorders,” said Pardo-Manuel de Villena.

This research was performed in large part by first author John Didion, who first discovered R2d2 when breeding two different types of mice for genetic analysis. Using whole-genome sequencing of thousands of laboratory mice, Didion and his colleagues saw that genes were passed down equally from each mouse’s parents. But a small section, smack dab in the middle of chromosome 2, was different.

Further analysis revealed that this section of chromosome 2 had a disproportionately larger number of genes from the mouse’s mother, compared to its father—showing a clear example of female meiotic drive. And at the heart of it all, Didion discovered, was the R2d2 gene.

The UNC team are already busy diving deeper into the relationship between R2d2 and meiotic drive with a focus on understanding, and one day perhaps correcting, genetic abnormalities in the developing embryo.