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Autoimmune Disease, Genetics, Immunology, Science, Stanford News, Technology

Women and men’s immune system genes operate differently, Stanford study shows

Women and men's immune system genes operate differently, Stanford study shows

A new technology for studying the human body’s vast system for toggling genes on and off reveals that genes connected with the immune system switch on and off more frequently than other genes, and those same genes operate differently in women and men. What’s more, the differences in gene activity are mostly not genetic.

A couple of years ago, geneticists Howard Chang, MD, PhD; Will Greenleaf, PhD, and others at Stanford invented a way to map the epigenome – essentially the real time on/off status of each of the 22,000 genes in our cells, along with the switches that control whether each gene is on or off.

Imagine a fancy office vending machine that can dispense 22,000 different drinks and other food items. Some selections are forever pumping out product; other choices are semi permanently unavailable. Still others dispense espresso, a double espresso or hot tea depending on which buttons you push. The activity of the 22,000 genes that make up our genomes are regulated in much the same way.

That’s a lot to keep track of. But Chang and Greenleaf’s technology, called ATAC-seq, makes it almost easy to map all that gene activity in living people as they go about their lives. Their latest study, published in Cell Systems, showed that the genes that switch on and off differently from person to person are more likely to be associated with autoimmune diseases, and also that men and women use different switches for many immune system genes. That sex-based difference in activity might explain the much higher incidence of autoimmune diseases in women — diseases like multiple sclerosis, lupus and rheumatoid arthritis.

The team took ordinary blood samples from 12 healthy volunteers and extracted immune cells called T cells. T cells are easy to isolate from a standard blood test and an important component of the immune system. With T cells in hand, the team looked at how certain genes are switched on and off, and how that pattern varied from individual to individual. Chang’s team also looked at how much change occurred from one blood draw to the next in each volunteer.

Chang told me, “We were interested in exploring the landscape of gene regulation directly from live people and look at differences. We asked, ‘How different or similar are people?’ This is different from asking if they have the same genes.”

Even in identical twins, he said, one twin could have an autoimmune disease and the other could be perfectly well. And, indeed, the team reported that over a third of the variation in gene activity was not connected to a genetic difference, suggesting a strong role for the environment. “I would say the majority of the difference is likely from a nongenetic source,” he said.

Previously: Caught in the act! Fast, cheap, high-resolution, easy way to tell which genes a cell is using
Photo by Baraka Office Support Services

Imaging, Microbiology, Research, Science, Stanford News, Technology

3-D structure of key signaling protein and receptor revealed

3-D structure of key signaling protein and receptor revealed

Using ultra-bright X-rays at SLAC National Accelerator Laboratory, a team of international researchers has captured the 3-D structure of a key signaling protein and its receptor for the first time.

The discovery provides new insight into the functioning of a common cell receptor called a G protein-coupled receptor or GPCR. Researchers estimate this protein, and its relatives, are the targets of about 40 percent of pharmaceuticals. From a SLAC release:

“This work has tremendous therapeutic implications,” said Jeffrey Benovic, PhD, a biochemist who was not involved with the study. “The study is a critical first step and provides key insight into the structural interactions in these protein complexes.”

Specifically, the researchers were able to illuminate the structure of the GPCR bonded with a signaling protein called arrestin. Arrestins and G proteins both dock with the GPCRs, however, researchers had previously only examined a bonded G protein. G proteins are generally the “on” switch, while arrestins usually signal the GPCR to turn off:

Many of the available drugs that activate or deactivate GPCRs block both G proteins and arrestins from docking.

“The new paradigm in drug discovery is that you want to find this selective pathway – how to activate either the arrestin pathway or the G-protein pathway but not both — for a better effect,” said Eric Xu, PhD, a scientist at the Van Andel Research Institute in Michigan who led the experiment. The study notes that a wide range of drugs would likely be more effective and have fewer side effects with this selective activation.

Previously: Why Stanford Nobel Prize winner Brian Kobilka is a “tour de force of science”, Funding basic science leads to clinical discoveries, eventually and Video of Brian Kobilka’s Nobel lecture
Video by SLAC National Accelerator Laboratory

Ethics, In the News, Medicine and Society, Science, Science Policy, Sports, Stanford News

Stanford expert celebrates decision stopping testosterone testing in women’s sports

Stanford expert celebrates decision stopping testosterone testing in women's sports

Female track and field athletes no longer need to have their natural testosterone levels below a certain threshold to compete in international events, the so-called “Supreme Court of sports”, the Court of Arbitration for Sport, ruled Monday.

Katrina Karkazis, PhD, a Stanford senior research scholar who was closely involved with the case, got the news on Friday, while she was in a San Francisco dog park. “What a day!” she said. “I was madly refreshing my email — I thought we were going to lose… I just started screaming and crying.”

Karkazis, who is an expert on ethics in sports and also gender, said she spent a year of her life working on the case.

She served as an advisor to 19-year-old sprinter Dutee Chand, who challenged the regulation that female athletes must have certain testosterone levels or undergo medical interventions to lower their testosterone to be allowed to compete against women in events governed by the International Association of Athletics Federations (IAAF), the international regulatory body of track and field.

The ruling suspends the IAAF’s testing regimen for two years, but Karkazis expects the decision will lead to permanent changes in women’s sports, including a reevalution by the International Olympic Committee.

“I’m thrilled,” Karkazis said. She said she was also surprised. “I didn’t think it was our time. I thought there were still too many entrenched ideas about testosterone being a ‘male hormone’ and it not belonging in women.”

Karkazis gained international attention after penning an op-ed in The New York Times in 2012 when the IAAF and the International Olympic Committee crafted a new policy banning women with naturally high levels of testosterone from competing.

“You can’t test for sex,” Karkazis said. “It’s impossible. There’s no one trait you can look at to classify people. There are many traits and there are always exceptions.”

She said that now women who have lived and competed their entire lives as women will be eligible to compete, a default policy she believes is sufficient to ensure a level playing field.

Previously: “Drastic, unnecessary and irreversible medical interventions” imposed upon some female athletes, Arguing against sex testing in athletes and Is the International Olympic Committee’s policy governing sex verification fair?
Photo by William Warby

Cancer, Genetics, Research, Science, Stanford News

Using CRISPR to investigate pancreatic cancer

Using CRISPR to investigate pancreatic cancer

dna-154743_1280Writing about pancreatic cancer always gives me a pang. My grandmother died from the disease over 30 years ago, but I still remember the anguish of her diagnosis and the years of chemotherapy and surgery she endured before her death. This disease is much more personal to me than many I cover.

Unfortunately, survival rates haven’t really budged since I was in high school, in part because the disease is often not diagnosed until it’s well established. As geneticist  Monte Winslow, PhD, described to me in an email:

Pancreatic cancer is very common and almost uniformly fatal. Human pancreatic cancers usually have many mutations in many different genes but we know very little about how most of them drive pancreatic cancer initiation, development, and progression. Recreating these cancer-causing mutations in cells of the mouse pancreas can generate tumors that look and behave very similarly to human pancreas cancer.

Unfortunately, traditional methods used to generate mouse models of human cancer are very time-consuming and costly.

Winslow, along with postdoctoral scholar Shin-Heng Chiou, PhD, and graduate student Ian Winters, turned to the latest darling of the biochemistry world — the gene-editing system known as CRISPR — to devise a way to quickly and efficiently turn off genes implicated in the development of pancreatic cancer in laboratory mice. Their work will be featured on the cover of Genes and Development on Monday. As Winslow described:

Our goal was use CRISPR/Cas9 genome editing to make altering a gene of interest in pancreas cancer simple and fast. Shin-Heng and Ian worked together to develop novel tools and bring them together to generate this new system that we hope will dramatically accelerate our understanding of pancreas cancer. The increased basic understanding of how this cancer works may ultimately lead to better therapies for patients.

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Big data, Cancer, Genetics, Immunology, Research, Science, Stanford News

Linking cancer gene expression with survival rates, Stanford researchers bring “big data” into the clinic

Linking cancer gene expression with survival rates, Stanford researchers bring "big data" into the clinic

Magic 8 ball“What’s my prognosis?” is a question that’s likely on the mind, and lips, of nearly every person newly diagnosed with any form of cancer. But, with a few exceptions, there’s still not a good way for clinicians to answer. Every tumor is highly individual, and it’s difficult to identify anything more than general trends with regard to the type and stage of the tumor.

Now, hematologist and oncologist Ash Alizadeh, MD, PhD; radiologist Sylvia Plevritis, PhD; postdoctoral scholar Aaron Newman, PhD; and senior research scientist Andrew Gentles, PhD, have created a database that links the gene-expression patterns of individual cancers of 39 types with the survival data of the more than 18,000 patients from whom they were isolated. The researchers hope that the resource, which they’ve termed PRECOG, for “prediction of cancer outcomes from genomic profiles” will provide a better understanding of why some cancer patients do well, and some do poorly. Their research was published today in Nature Medicine.

As I describe in our release:

Researchers have tried for years to identify specific patterns of gene expression in cancerous tumors that differ from those in normal tissue. By doing so, it may be possible to learn what has gone wrong in the cancer cells, and give ideas as to how best to block the cells’ destructive growth. But the extreme variability among individual patients and tumors has made the process difficult, even when focused on particular cancer types.

Instead, the researchers pulled back and sought patterns that might become clear only when many types of cancers, and thousands of patients were lumped together for study:

Gentles and Alizadeh first collected publicly available data on gene expression patterns of many types of cancers. They then painstakingly matched the gene expression profiles with clinical information about the patients, including their age, disease status and how long they survived after diagnosis. Together with Newman, they combined the studies into a final database.

“We wanted to be able to connect gene expression data with patient outcome for thousands of people at once,” said Alizadeh. “Then we could ask what we could learn more broadly.”

The researchers found that they were able to identify key molecular pathways that could stratify survival across many cancer types:

In particular, [they] found that high expression of a gene called FOXM1, which is involved in cell growth, was associated with a poor prognosis across multiple cancers, while the expression of the KLRB1 gene, which modulates the body’s immune response to cancer, seemed to confer a protective effect.

Alizadeh and Plevritis are both members of the Stanford Cancer Institute.

Previously: What is big data?Identifying relapse in lymphoma patients with circulating tumor DNA,  Smoking gun or hit-and-run? How oncogenes make good cells go bad and Big data = big finds: Clinical trial for deadly lung cancer launched by Stanford study
Photo by CRASH:candy

Neuroscience, Research, Science, Stanford News

Nobelist neuroscientist Tom Südhof still spiraling in on the secrets of the synapse

Nobelist neuroscientist Tom Südhof still spiraling in on the secrets of the synapse

spiral staircase“History,” said Winston Churchill (or was it Arnold Toynbee or Edna St. Vincent Millay?), “is just one damn thing after another.” In many respects, so is good science.

And that’s just how it should be, Stanford neuroscientist and molecular physiologist Tom Südhof, MD, told me a few years ago when I interviewed him for a story I wrote in connection with the Lasker Award, a prestigious prize he’d won shortly before receiving the 2013 Nobel Prize in physiology or medicine:

Asked to recall any defining “eureka!” moments that had catapulted his hunches forward to the status of certainty, Südhof noted that in his experience, science advances step by step, not in jumps. “I believe strongly that most work is incremental,” he said. The systematic solution of highly complex problems requires a long view and plenty of patience.

Climbing a long ladder to the Nobel one small step at a time, Südhof continually raised the power of his conceptual microscope over the decades as he probed the intricate workings of synapses: the all-important junctions in the nervous system where information, in the form of chemical messengers called neurotransmitters, gets passed from one nerve cell to another.

From an explanation of Südhof’s synaptic studies:

The firing patterns of our synapses underwrite our consciousness, emotions and behavior. The simple act of taking a step forward, experiencing a fleeting twinge of regret, recalling an incident from the morning commute or tasting a doughnut requires millions of simultaneous and precise synaptic firing events throughout the brain and peripheral nervous system.

A philosopher might say that synapses collectively constitute the physiological substrate for the soul. A futurist might write (as I once did):

With nanobots monitoring every critical neural connection’s involvement in a thought or emotion or experience, you’ll be able to back up your brain – or even try on someone else’s – by plugging into a virtual-reality jack. The brain bots feed your synapses the appropriate electrical signals and you’re off and running, without necessarily moving.

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Dermatology, Evolution, Pediatrics, Research, Science, Stanford News, Surgery

To boldly go into a scar-free future: Stanford researchers tackle wound healing

To boldly go into a scar-free future: Stanford researchers tackle wound healing

scarshipAs I’ve written about here before, Stanford scientists Michael Longaker, MD, and Irving Weissman, MD, are eager to find a way to minimize the scarring that arises after surgery or skin trauma. I profiled the work again in the latest issue of Stanford Medicine magazine, which focuses on all aspects of skin health.

My story, called “Scarship Enterprise,” discusses how scarring may have evolved to fulfill early humans’ need for speed in a cutthroat world:

“We are the only species that heals with a pathological scar, called a keloid, which can overgrow the site of the original wound,” says Longaker. “Humans are a tight-skinned species, and scarring is a late evolutionary event that probably arose in response to a need, as hunter-gatherers, to heal quickly to avoid infection or detection by predators. We’ve evolved for speedy repair.”

Check out the piece if you’re interested in reading more about this or learning how scarring happens, or why, prior to the third trimester, fetuses heal flawlessly after surgery. (Surprisingly, at least to me, many animals also heal without scarring!)

Previously: This summer’s Stanford Medicine magazine shows some skinWill scars become a thing of the past? Stanford scientists identify cellular culprit, New medicine? A look at advances in wound healing and Stanford-developed device shown to reduce the size of existing scars in clinical trial
Illustration by Matt Bandsuch

Applied Biotechnology, Big data, Cancer, Genetics, Research, Science, Stanford News

Peeking into the genome of a deadly cancer pinpoints possible new treatment

Peeking into the genome of a deadly cancer pinpoints possible new treatment

small cell lung cancerSmall cell lung cancer is one of the most deadly kinds of cancers. Typically this aggressive disease is diagnosed fairly late in its course, and the survival rates are so dismal that doctors are reluctant to even subject the patient to surgery to remove the tumor for study. As a result, little is known about the molecular causes of this type of cancer, and no new treatments have been approved by the Food and Drug Administration since 1995.

Now a massive collaboration among researchers around the world, including the University of Cologne in Germany and Stanford, has resulted in the collection of more than 100 human small cell lung cancer tumors. Researchers sequenced the genomes of the tumors and identified some key steps in their development. They also found a potential new weak link for treatment.

The findings were published today in Nature, and Stanford cancer researcher Julien Sage, PhD, one of three co-senior authors of the paper, provided some details in an email:

With this larger number of specimens analyzed, a more detailed picture of the mutations that contribute to the development of small cell lung cancer now emerges. These studies confirmed what was suspected before, that loss of function of the two tumor suppressor genes, Rb and p53, is required for tumor initiation. Importantly, these analyses also identified new therapeutic targets.

The researchers also saw that, in about 25 percent of cases, the Notch protein receptor was also mutated. This protein sits on the surface of a cell; when Notch binds, it initiates a cascade of signaling events within the cell to control its development and growth. As Sage explained:

The mutations in the Notch recepetor were indicative of loss of function, suggesting that Notch normally suppresses small cell lung cancer development. Indeed, when graduate student Jing Lim in my lab activated Notch in mice genetically engineered to develop small cell lung cancer, we found a potent suppression of tumor development. These data identify the Notch signaling pathway as a novel therapeutic target in a cancer type for which new therapies are critically needed.

This is not Sage’s first foray into fighting small cell lung cancer. In 2013, he collaborated with other researchers at Stanford, including oncologist Joel Neal, MD, PhD, to identify a class of antidepressants as a possible therapy for the disease.

Previously: Gene-sequencing rare tumors – and what it means for cancer research and treatment, Listening in on the Ras pathway identifies new target for cancer therapy and Big data = big finds: Clinical trial for deadly lung cancer launched by Stanford study
Image by Yale Rosen

Genetics, In the News, Research, Science, Stanford News, Stem Cells, Technology

CRISPR marches forward: Stanford scientists optimize use in human blood cells

CRISPR marches forward: Stanford scientists optimize use in human blood cells

The CRISPR news just keeps coming. As we’ve described here before, CRISPR is a breakthrough way of editing the genome of many organisms, including humans — a kind of biological cut-and-paste function that is already transforming scientific and clinical research. However, there are still some significant scientific hurdles that exist when attempting to use the technique in cells directly isolated from human patients (these are called primary cells) rather than human cell lines grown for long periods of time in the laboratory setting.

Now pediatric stem cell biologist Matthew Porteus, MD, PhD, and postdoctoral scholars Ayal Hendel, PhD, and Rasmus Bak, PhD, have collaborated with researchers at Santa Clara-based Agilent Research Laboratories to show that chemically modifying the guide RNAs tasked with directing the site of genome snipping significantly enhances the efficiency of editing in human primary blood cells — an advance that brings therapies for human patients closer. The research was published yesterday in Nature Biotechnology.

As Porteus, who hopes to one day use the technique to help children with genetic blood diseases like sickle cell anemia, explained to me in an email:

We have now achieved the highest rates of editing in primary human blood cells. These frequencies are now high enough to compete with the other genome editing platforms for therapeutic editing in these cell types.

Porteus and Hendel previously developed a way to identify how frequently the CRISPR system does (or does not) modify the DNA where scientists tell it. Hendel characterizes the new research as something that will allow industrial-scale manufacturing of pharmaceutical-grade CRISPR reagents. As he told me:

Our research shows that scientists can now modify the CRISPR technology to improve its activity and specificity, as well as to open new doors for its use it for imaging, biochemistry, epigenetic, and gene activation or repression studies.

Rasmus agrees, saying, “Our findings will not only benefit researchers working with primary cells, but it will also accelerate the translation of CRISPR gene editing into new therapies for patients.”

Onward!

(Those of you wanting a thorough primer on CRISPR —how it works and what could be done with it — should check out Carl Zimmer’s comprehensive article in Quanta magazine. If you prefer to learn by listening (perhaps, as I sometimes do, while on the treadmill), I found this podcast from Radiolab light, but interesting.)

Previously: Policing the editor: Stanford scientists devise way to monitor CRISPR effectiveness and “It’s not just science fiction anymore”: Childx speakers talk stem cell and gene therapy

 

Bioengineering, Cancer, Imaging, Microbiology, Research, Science, Stanford News

Stanford team develops technique to magnetically levitate single cells

Stanford team develops technique to magnetically levitate single cells

Remember the levitating frog? That feat — the levitation of a live frog using a powerful magnet — was awarded the 2000 Ig Nobel Prize. Fascinating to watch, the demonstration also cemented a longstanding belief that levitating anything smaller than 20 microns was flat-out impossible. Much less something alive.

Not so, a team of Stanford-based researchers showed in a paper published today in the Proceedings of the National Academy of Sciences (PNAS). Using a 2-inch-long device made of two magnets affixed with plastic, the team showed it’s possible to levitate individual cells.

The video above demonstrates the technique in a population of breast cancer cells. Originally, the cells hover, suspended between the two magnets. But when exposed to an acid, they start to die and fall as their density increases.

“It has very broad implications in multiple diseases including cancer, especially for point-of-care applications where it can bring the central lab diagnostics to the comfort of patients’ homes or physicians’ office,” Utkan Demirci, PhD, a co-senior author and associate professor of radiology, told me.

The technique makes it possible to distinguish healthy cells from cancerous cells, monitor the real-time response of bacteria or yeast to drugs and distinguish other differences between cells that were thought to be homogenous, said Naside Gozde Durmus, PhD, a postdoctoral research fellow and first author of the paper.

Critically, the technique does not require treating the cells with antibodies or other markers, Durmus said. That ensures the cells are not altered by any treatments and makes the technique easy to use in a variety of settings, including potentially in physicians’ offices or in resource-poor settings.

The device works by balancing the gravitational mass of a cell against its inherent magnetic signature, which is negligible when compared with the cell’s density, Durmus said.

Interestingly, however, the cells — or bacteria treated with an antibiotic — do not die at the same rate, providing hints at their individual adaptations to environmental stressors, said co-senior author Lars Steinmetz, PhD, a professor of genetics.

To enhance the precision of the technique, the researchers can tweak the concentration of the solution that holds the cells, Durmus said. A highly concentrated solution allows for the differentiation of cells of similar densities, while a less concentrated solution can be used to examine a population of heterogeneous cells.

The team plans to investigate the applications of the device next, including its use in resource-poor settings where the cells can be observed using only a lens attached to an iPhone, Durmus said.

Previously: Harnessing magnetic levitation to analyze what we eat, Researchers develop device to sort blood cells with magnetic nanoparticles and Stanford-developed smart phone blood-testing device wins international award
Video courtesy of Naside Gozde Durmus

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