Research

Small steps to treat neuromuscular disorder

Researchers find evidence of a genetic modifier that can improve symptoms of Spinal Muscular Atrophy

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Chris Lorson examines axons through a microscope. Lorson’s lab recently published results that showed evidence that the protein plastin 3 affects the severity of SMA. | Photo by Eleanor Hasenbeck, Bond LSC

Eleanor Hasenbeck | Bond Life Sciences Center

Two new potential treatments might improve the lives of patients living with Spinal Muscular Atrophy.

Researchers in the Lorson lab at Bond Life Sciences Center recently produced a new drug that increases the lifespans of mice with SMA, and they found evidence that an increased level of the protein plastin 3 lengthened life span and improved the animal’s nerve function.

Two genes impact Spinal Muscular Atrophy, SMN1 and SMN2. In a healthy body, SMN1 creates a protein called SMN that helps maintain motor neurons controlling muscle movement. If someone is born without SMN1, their body relies on SMN2 to produce this protein, but a small change in the SMN2 gene causes it to make much less of the protein than needed. This leads to SMA, a disorder where an individual loses motor and nervous function, often starting in childhood, over a number of years.

Although rare, sometimes siblings develop SMA, providing an unusual insight into SMA development. Discordant siblings — or siblings that both have SMA but have different severities of the disorder— suggest that other factors could contribute to SMA.

Researchers are investigating why this happens. One theory is that a “genetic modifier,” another gene or protein elsewhere in the DNA, impacts the severity of SMA. The protein plastin 3 could be this modifier.

Plastin 3 doesn’t improve the severe SMA mice, but extended the lives of mice with more mild cases of the disorder. The Lorson lab created its own SMA drug, an antisense oligonucleotide that allows SMN2 to produce a functional protein. The drug is capable of extending survival of SMA mice from approximately 13 days up to 150 days from a single treatment. The typical lifespan of a lab mouse is 1.3 to 3 years.

Kevin Kaifer, a graduate student in the Lorson lab, gave the SMA mice a low dose injection of the drug, increasing their lifespan to about 30 days. Then, they modified a gene in the mice to increase the level of plastin 3. Mice that received the drug and the plastin 3 therapy lived about 40% longer than mice that received only the drug.

Lorson said the results provide proof of concept that plastin 3 does not make more SMN, but actually decreased disease severity. The SMA mice showed improved neuromuscular junctions, the sites where nerve cells fire electrical impulses to the muscles in the body.

“That’s really where plastin 3 is designed to function, at the neuromuscular junction,” Lorson said. “So that brings the idea of plastin 3 full circle; it does not increase SMN, but it does improve the function of the nerve which is where plastin 3 is supposed to function normally.”

This discovery shows promise for a future treatment to some with the disease.

“SMA is a very broad clinical spectrum disease, so there are patients who have an incredibly severe form, and patients that don’t develop disease until adulthood,” said Chris Lorson, a Bond LSC scientist. “Perhaps one therapy is not going to address that very broad clinical spectrum, and you’re going to need to address different parts of the disease with different therapeutics.”

Despite it’s relative rarity as a disease, new treatments for SMA are hitting the market. In December, the Food and Drug Administration approved Spinraza, an antisense oligonucleotide similar to the drug the Lorson lab. But the infrequency of SMA means treatment comes at a cost: $750,000 for the first year of Spinraza and $375,000 for subsequent years. Spinraza is an FDA-designated orphan drug, meaning it’s a treatment for a disease that affects less than 200,000 people in the U.S. To incentivize research into rare diseases, The Orphan Drug Act allows pharmaceutical companies longer exclusive patent rights. Drugs that treat rare diseases that impact children, including Spinraza, can be allowed priority review, basically putting these drugs on a faster track from lab to market. Though the act has led to more research in certain diseases, it has sparked controversy as patients with no other treatment options are burdened with the resulting drugs’ high cost.

Still, it’s the first FDA approved treatment available to the 9,000 Americans living with SMA.

“I think collectively this is a very exciting time in the SMA field, whether we’re talking about SMN targeting compounds or drugs that are capable of augmenting function,” Lorson said.  “To have a rare disease that has so many shots on goals, so to speak is really exciting.”

“The SMA community is really a model for how foundations, families, patients and government agencies can come together,” Lorson said. He said families and government agencies are often in the same room as academics, biotechnology and pharmaceutical companies during meetings.

“The amount of support from the patients, the families and the non-profit world has really helped drive SMN research… I think that’s really helped push SMA from an unknown 20 years ago, to an approved drug.”

Christian Lorson is a professor of veterinary pathobiology at the Bond LSC. His research focuses on spinal muscular atrophy.
The results of this study were published in an article in JCI Insight, “Plastin-3 extends survival and reduces severity in mouse models of spinal muscular atrophy.” This work is partially funded by grants from the Muscular Dystrophy Association, FightSMA, the Gwendolyn Strong Foundation, and the Missouri Spinal Cord Injury/Disease Research Program. CureSMA provided the initial support for the development of the drug/antisense oligonucleotide used in these studies.

 

BPA rewires the sex of turtle brains

By Jinghong Chen | Bond Life Sciences Center

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Painted turtle eggs were brought from a hatchery in Louisiana, candled to ensure embryo viability and then incubated at male-permissive temperatures in a bed of vermiculite. Those exposed to BPA developed deformities to testes that held female characteristics.Photo by Roger Meissen | © 2015 – MU Bond Life Sciences Center

Cool dudes, hot mommas. This is the underlying concept behind sex development in painted turtles, a species that lacks sex chromosomes.

A painted turtle’s sex is determined by temperature at which the eggs are incubated at critical stages during early development. Eggs incubated at lower temperatures produce male turtles, while those incubated at higher temperatures results in females.

However, early exposure to certain environmental chemicals that mimic hormones naturally produced in individuals can override incubation temperature. Scientists at the Bond Life Sciences Center have teamed up to study how endocrine disrupting chemicals (EDCs), namely bisphenol A (BPA) and ethinyl estradiol (EE), result in irreversible sexual programming of the brain in painted turtles.

“Turtles do not have sex chromosomes. Instead, they demonstrate temperature sex determination. But if they are exposed to EDCs prior to when certain organs form, such chemicals can cause partial to full sex reversal to female both in terms of the gonad and brain,” said Cheryl Rosenfeld, a Bond Life Sciences Center investigator and an associate professor of biomedical sciences at the University of Missouri. “The males will essentially act like females in terms of their behavioral responses.”

The hormones Rosenfeld refers to are BPA and EE, two widely used EDCs. BPA is present in many commonly used household, such as plastic food storage containers, store receipts, and dental fillings. The EE is present in birth control pills and can accumulate in many aquatic environments. These chemicals have been identified in all aquatic environments tested to date, including rivers and streams. Thus, exposure of turtles and other species that inhabit such environments can potentially lead to irreversible effects.

Previously, Rosenfeld and colleagues had studied how these chemicals change behavior of painted turtles after treating the eggs with BPA and EE under male-promoting temperatures. They discovered that male turtles that are early exposed to chemicals exhibit greater spatial navigational ability and improved memory, which are considered female-typical behaviors.

Rosenfeld and colleagues postulated that if the behavioral patterns differ between those exposed to BPA and those who were not, the different behaviors may be due to underlying and persistent differences in the neural circuitry between these two groups.

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Cheryl Rosenfeld is a Bond Life Sciences Center investigator and an associate professor of biomedical sciences at the University of Missouri. | photo by Jinghong Chen, Bond LSC

A gene map for turtle

In order to address this possibility, Rosenfeld teamed up with Scott Givan, associate director of the Informatics Research Core Facility, to study the gene expression profiles of the turtles and potentially identify patterns of gene expression associated with the altered behaviors.

After Rosenfeld’s team tested the behavior of the turtles, they collected RNA from the turtle brains to perform a technique called RNAseq that isolates all of the transcripts expressed in this organ. RNA is a nucleic acid that carries genetic information and is indicative of the expression level of every gene in the turtle genome. Once these sequencing results were obtained, Givan had to align the results to the painted turtle genome that has been previously sequenced and annotated. He then determined the transcripts that were differentially expressed in turtles developmentally exposed to BPA or EE versus those unexposed individuals.

There are no existing turtle gene pathway profiles. Therefore, Givan had to analyze the turtle gene expression profiles based on those previously identified in human samples.

“[One] of the most important things in this paper is the linkage of the gene expression profile to behavior difference,” Givan said. “But the gene and metabolic pathway data don’t exist for turtles. We had to basically infer pathway modeling based on the human metabolic pathway maps.”

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Scott Givan is the associate director of Informatics Research Core Facility and research assistant professor of molecular microbiology and immunology. | photo by Jinghong Chen, Bond LSC

The results suggest that BPA and, to a much lesser extent, EE exposure overridden incubation temperature and altered the gene expression profile in the brain to potentially reprogram brain to the female rather than male pathway. Specifically, BPA exposure was associated with metabolic pathway alterations involving mitochondria, such as oxidative phosphorylation and influenced ribosomal function.

Mitochondrial activity provides energy. Up-regulation of metabolic pathways in mitochondria can lead to more energy in brain cells, which may have permitted BPA-exposed turtles to demonstrate faster responses and greater cognitive flexibility, including enhanced spatial navigational ability that was previously identified in this group.

The other changes — oxidative phosphorylation and ribosomal function — play key roles in protein synthesis. Specifically, oxidative phosphorylation generates is one of main pathways involved in generating ATP, which is considered an energy source. Ribosome functions to assemble amino acids together for the synthesis of proteins, including enzymes that may facilitate metabolic reactions.

Less appealing males

The possibility for shifting brain sex has a real impact in the wild.

In the beginning, a turtle’s brain is neutral, as it is requires hormones to sculpt and direct it to be male or female. However EDCs, such as BPA and EE, can usurp these normal pathways and cause the brain of otherwise male turtles to develop more feminine characteristics.

“There are certain programmed behaviors [male turtles] have to do to entice the female to select them as their reproductive partner, but if he is not demonstrating these male-typical behaviors, she will likely reject him,” Rosenfeld said. “Even if such chemicals reprogram the brain and subsequent adult behaviors without affecting the gonad, it could have individual and population consequences by reducing a male’s likelihood of breeding.”

Combined with possible shrinking and already inbred population, declines in male turtles or skewing of sex ratio to females that could originate due to EDC-exposure, could push turtle species that exhibit temperature-dependent sex determination (TSD) to the brink of extinction.

“The concern also with turtle species that exhibit TSD, climate change and exposure to EDCs can lead to detrimental and irreversible imbalances in sex ratio favoring females over males, and thereby compromising genetic diversity of the population as a whole,” Rosenfeld said.

Future studies in Rosenfeld’s lab plan to extend the research to female turtles to learn whether the chemicals have any effects on females derived based on TSD rather than those due to exposure to environmental chemicals that are similar to estrogen. She also hopes to look into individual brain regions, such as the forebrain and hippocampus that are essential for cognitive abilities.

 

Cheryl Rosenfeld is a Bond LSC investigator,associate professor of biomedical sciences, and research faculty member in the Thompson Center for Autism and Neurobehavioral Disorders. Scott Givan is the associate director of Informatics Research Core Facility and research assistant professor of molecular microbiology and immunology.

This research was funded by the Mizzou Advantage Program, the Bond Life Sciences Center and the University of Missouri Office of Research.

The next Martians: the common bean?

Researchers in the Mendoza-Cozatl lab grow beans in a soil that simulates Martian soil
By Eleanor C. Hasenbeck | Bond Life Sciences

As NASA works to send people to Mars, researchers at the Mendoza-Cozatl lab at Bond Life Sciences Center are exploring the possibility of sending beans to the red planet. The journey from Earth to Mars alone would take somewhere between 100 to 300 days. To feed astronauts on these longer missions, scientists are studying space horticulture.

Norma Castro, a research associate in the lab, studies how common beans grow in a soil that simulates Mars’ red soil. The common bean is a good candidate for interstellar cultivation. Beans are a very nutritious crop, and their affinity for nitrogen-fixing bacteria can improve soil health while requiring less fertilizer. Castro is trying to understand how different varieties of beans could grow in the soil.

“This kind of research not only will tell us the right plants to take to Mars, but also which kind of technology needs to be developed,” Castro said.

Why self-defense turns self-attack

Mahmoud Khalafalla

Mahmoud Khalafalla, a Ph.D. student at Weisman’s lab, is isolating RNA from salivary glands of Sjögren’s syndrome mouse model to look for the expression of pro-inflammatory genes. | photo by Jinghong Chen, Bond LSC

By Jinghong Chen | Bond Life Sciences Center

Our immune system is often the key to our health. Everyday, it works to protect us from foreign invaders such as bacteria and virus, but what happens when it attacks our own tissues?

Gary Weisman, a Curator’s Distinguished Professor of Biochemistry at the Bond Life Sciences Center, is working to advance our understanding of the mechanisms behind immune system function and autoimmune diseases such as Sjögren’s syndrome.

In our immune system, B cells are responsible for producing antibodies to recognize foreign invaders. However, in many autoimmune diseases, B cells produce autoantibodies that recognize our own proteins, causing inflammation and tissue damage. In Sjögren’s syndrome (SS), they attack the glands that produce saliva and tears.

Patients with SS often suffer chronic dry eyes and dry mouth, which might lead to bacterial infection, difficulties in swallowing and speech.

“The symptoms decrease the quality of life rather than the length of life,” said Lucas Woods, research lab manager in Weisman’s lab.

Although SS patients are at higher risk of developing lymphoma cancers and other concurrent autoimmune diseases that may increase mortality, Woods further explained.

According to the Sjögren’s Syndrome Foundation, there are an estimated four million people living with the disease in the U.S. For unknown reasons, 90 percent of them are female.

Yet, current clinical treatments only reduce symptoms by using artificial saliva and tears or cholinergic agents to promote fluid secretion, but there is no approved treatment to reduce the inflammation of the glands themselves. This is the focus of Weisman’s lab.

Sensor of danger

There are 15 different types of nucleotide receptors in humans that regulate numerous cell processes from inflammatory responses to tissue regeneration. Those receptors are stimulated by nucleotides such as ATP. In the past three and a half years, Mahmoud Khalafalla, a Ph.D. student in Weisman’s lab, has focused on one of them in particular – the P2X7 receptor.

Previous studies show increased P2X7 expression in salivary glands from SS patients, as compared to healthy individuals. To understand the reasons behind this, Weisman’s lab used genetically modified mice that develop disease traits similar to SS patients.

In this mouse model, Sjögren’s-like disease occurs when the immune cells invade salivary glands and damage the tissue, leading to decreased saliva production. The invasion of immune cells is triggered by proinflammatory cytokines, a type of signaling molecule that promotes the recruitment of immune cells to the inflamed areas.

But what induces those cytokines?

Weisman’s lab tries to piece together the answer. For the first time, they found that the P2X7 receptor is responsible for the release of these proinflammatory molecules from salivary gland epithelial cells.

To function, most cell-surface receptors require ligands that bind to the receptor to induce cellular responses. The ligand for the P2X7 receptor is ATP – the “energy currency inside of cells.” P2X7 receptors are activated when high concentrations of ATP are released to the outside of the cells, which typically occurs when the cells are injured during inflammation.

“P2X7 receptors [act like] the sensor of danger,” Khalafalla said.

After identifying the role of the P2X7 receptor, the lab then asked: if we stop its activation, what would happen?

Using a drug that inhibits P2X7 receptor activation, they blocked the receptor in their SS mouse model to determine its effect on the development of autoimmune disease. Interestingly, saliva secretion was restored when the P2X7 receptor is blocked while the levels of invading immune cells in salivary glands were dramatically reduced.

“This gives us the thought that [blockade of the] P2X7 receptor is really a promising strategy to reduce salivary inflammation. This may not only relate to Sjögren’s syndrome, but to other autoimmune diseases as well,” Khalafalla said.

Our receptor

Another similar receptor that plays a role in autoimmune diseases is the P2Y2 receptor, which has been referred to as “our receptor” by Weisman’s lab.

As one of the researchers who proved the existence of this receptor, Weisman has spent most of his career studying it.

One of his research projects investigating P2Y2 receptors in human disease recently gained a grant extension for another five years from the National Institutes of Health. The lab found that in a mouse model of SS, similar to the P2X7 receptor, the expression of P2Y2 receptors was increased in both the salivary gland epithelial cells and immune cells.

Furthermore, after they knocked out the P2Y2 receptor in the SS mouse model by breeding them with genetically-modified P2Y2 receptor knockout mice, the inflammation of salivary glands was dramatically reduced.

“The very next step is that we are going to isolate these immune cells out of the diseased mouse salivary glands, and characterize what kinds of cells they are. We want to know exactly which ones are controlling the development of autoimmune diseases, and how P2Y2 receptors and nucleotides like ATP in general are contributing to the diseases,” Woods said.

 

Gary Weisman is a Curator’s Distinguished Professor of Biochemistry at the Bond Life Sciences Center. His research focuses on the relationship between inflammatory diseases and nucleotide receptors. He currently works on a collaborative research project with Dr. Carisa Petris, an eye surgeon at the MU Hospital, to understand the mechanism of how Sjögren’s syndrome damages the tear-secreting lacrimal glands in mice.

 

Planting a seed for sciences

Rhizobia bacteria

Plants on the left grow with rhizobia bacteria, one type of fixing nitrogen bacteria, in the greenhouse, while the plants on the right grow without the bacteria. | photo by Jinghong Chen, Bond LSC

Jinghong Chen | Bond Life Sciences Center

Since eight years old, Beverly Agtuca knew she wanted to be a scientist.

A trip to Philippines changed Agtuca, an American-born Filipino, and inspired her passion on plants.

“My grandma always told me to work in the field all day so that they can have enough food for us to eat,” Agtuca said. “The life [in Philippines] is so different from here…I want to not just provide food but be that scientist trying to figuring something out, and hopefully saving the world.”

Agtuca is on her way to her dream. She is now a third year doctoral student in Gary Stacey’s lab at Bond Life Sciences Center with a focus on nitrogen-fixing bacteria.

Although she has been involved in research since high school, Agtuca recently faced a new challenge of telling people about her work. The Preparing Tomorrow’s Leaders of Science class tasked her with making a 90-second video to explain her two-year study to the general public.

Her team, “The A Team,” chose to go with the benefits of having nitrogen-fixing bacteria.

For decades, people have been adding nitrogen fertilizers to plants to improve yields, but this can lead to pollution in water systems and ecosystems. Scientists need to enhance plant productivity to meet a huge food demand by the year of 2050.

One little bacteria might make this possible and save the world. Rhizobia, a type of natural bacteria in soil, are able to fix nitrogen via biological nitrogen fixation. These bacteria can convert nitrogen gas into ammonia as a plant nutrient source, while the plants give all the carbon sources back to the bacteria.

“It is like a walky-talky,” Agtuca said. “They are communicating with each other.”

Yet before speaking to the public, Agtuca needs to explain the plant-bacteria interaction to her teammates. Students less well versed in science like Jessica Kaiser, a strategic communication student, thinks of science differently.

“The biggest issue we ran into is jargon, like basic science words that [my teammates] are so comfortable with,” Kaiser said. “We need to focus on what people care about instead of the technical sides, to focus on why it matters to anybody rather than just to a science person.”

Within two weeks, they produced the video “Good Microbes: reducing pollution one farm at a time.” Along with two other teams, their videos will be commented and judged by representatives from Monsanto.

"The A Team"

“The A Team” stands together at Bond Life Sciences Center. From left to right: Jessica Kaiser, Sven Nelson, Anna Glowinski, Eleni Galata and Beverly Agtuca. | photo by Jinghong Chen, Bond LSC

The 90-second video is just a glimpse of Agtuca’s study. In the last two years she has been focusing on the use of a new technique — laser ablation electrospray ionization mass spectrometry (LAESI-MS) — that does in situ metabolic profiling of tissues. The lab is using LAESI-MS to investigate the metabolites in a well-characterized model plant-rhizobium system, specifically nitrogen-fixing soybean nodules resulting from root infection by the symbiotic bacterium Bradyrhizobium japonicum.

This work includes a huge collaboration that was developed through a Department of Energy (DOE) grant involving the George Washington University, Washington D.C. and the Environmental Molecular Science Laboratory (EMSL), Pacific Northwest National Laboratory, Richland, WA.

LAESI-MS works like a superhero’s laser-like beams. You first aim the laser on the sample, which then heats it and causes neutral particles to be released into the air. This plume of neutrals is then captured and ionized by the electrospray, and finally analyzed by the spectrometer to figure out the exactly what metabolites in nodules are involved in biological nitrogen fixation.

“It takes about three seconds to analyze one sample using this LAESI-MS technique,” Agtuca said. Other metabolic techniques require extensive pre-treatment of the sample before analysis.

By analyzing the data collected via LAESI-MS, the lab is able to confirm that future plant studies could apply this new approach to understand the interactions between plant and bacteria.

Agtuca’s research is a long way from her first experiences with plants. She still remembers the moment she found her plants in her own garden died. She was less than 10 years old, yet devoted to taking care of her plants with water and fertilizers.

“I was really sad. I could not get my tomatoes, peppers and eggplants to live.…That makes me think that I want to answer why they didn’t grow,” Agtuca said.

More than ever, her future is helping her answer those question for herself.

 

Gary Stacey is a Bond LSC investigator and MU curators’ professor of plant science and MSMC endowed professor of soybean biotechnology. Read more here about Stacey lab.

Sven Nelson is a USDA/ARS postdoctoral research scientist at the University of Missouri. Anna Glowinski is a Ph.D. student in the USDA/ARS lab. Jessica Kaiser is a graduate student in strategic communication. Eleni Galata works as the team mentor and she is a Ph.D. student in agricultural and applied economics at MU.

Art of balance

Vinit Shanbhag

Vinit Shanbhag mixes the CRISPR plasmid DNA with cells. The lab will test whether the gene of interest has been knocked out of the cells later. | photo by Jinghong Chen, Bond LSC

Jinghong Chen | Bond Life Sciences Center

It might be strange to say, but in a way the Australian soil led scientist Michael Petris to where he is now.

In certain areas of Australia, soils suffer from extremely low level of copper bioavailability, resulting in poor growth and neurological problems on sheep.

Petris, a Bond LSC investigator and professor of biochemistry who was born in Australia, now spends his time studying how copper, an essential mineral in human body, works in cells to build and maintain essential functions.

Recently published work from his lab focuses on how the ATP7A protein, one of the major proteins, cycles within the cell.

“Copper is solely acquired from diet. The absorption of copper from the intestine in the blood needs ATP7A,” Vinit Shanbhag, a Ph.D. biochemistry student at Petris’ lab and an author of the study, said. “It transports copper to different copper dependent enzymes and exports free copper from the cell to the outside.”

After exporting copper at the cell membrane, ATP7A needs to come back to its steady-state location within the Golgi apparatus of cells – via a process called retrograde trafficking. But one question baffled scientists: what are the key elements that lead ATP7A coming back?

Back in the late 90s, Petris discovered the importance of one single di-leucine in retrograde trafficking of ATP7A. For those of you wondering, leucine is an amino acid that forms the building blocks of proteins like ATP7A, while di-leucine consists of two of them connected via a peptide bond.

His team wished to identify other signals for retrograde trafficking, but one technical hurdle stood in the way— the ATP7A gene is unstable when grown in bacterial plasmids, the traditional way of amplifying genes in the lab.

Commercial DNA synthesis was the answer. This method could create artificial genes in the laboratory.

“We reasoned that if we introduced enough silent mutations into a DNA sequence, we could avoid or change the region of instability in the native sequence without affecting the encoded protein,” Petris said.

To stabilize the gene, they changed more than 1,000 nucleotides within a 3,000 nucleotides segment, and thus solving the problem of instability of the ATP7A gene. In doing so, they subsequently found that in fact multiple di-leucines that are required for retrograde trafficking of ATP7A. This approach could be used by other laboratories whose gene of interest is also unstable.

An overlooked mineral

“If you ask [people], is it important to understand iron nutrition? Is it important to understand calcium nutrition? Most people would say of course! … But, perhaps you would not get the same answer for copper, despite the fact there is a little dispute that copper is important,” Petris said.

As an essential micronutrient, copper performs central functions to develop and maintain human skin, bones, brains and other organs.

“If you don’t have enough copper in your body, you cannot use oxygen to make energy,” Petris said. “If you don’t have copper, you would not survive.”

Pregnant women who carry a mutated ATP7A gene on their X chromosome can pass it on to their children in the form of Menkes disease.

Menkes disease is a genetic disorder that results in poor uptake and distribution of copper to cells. The incidence of this disease is estimated to be one in 100,000 newborns, according to U.S. National Library of Medicine.

Infants with Menkes disease typically begin to develop symptoms during infancy and rarely live past the first few years of life. Abnormally high accumulation of copper in kidneys and low-level accumulation in the liver and brain, cause visible symptoms like sparse hair, loose skin and failure to grow.

Despite copper’s importance, it also can be a potentially toxic nutrient.

“Copper deficiency can be a problem but too much copper is also a problem. There should be a balance,” Shanbhag explained.

The liver normally stores excessive copper and excretes it into bile to release it out of the body. Yet people with genetic disorders that preventing copper excretion might suffer Wilson’s disease, leading to life-threatening organ damage.

Shanbhag said people with Wilson’s disease accumulate toxic amounts of copper in liver and other organs, causing Kayser–Fleischer rings that encircle the pigmented regions of the eye, a hue caused by copper deposits in the cornea.

Its clinical consequences differ from chornic liver failure to neurological sysmptoms like tremors, dystonia, ataxia and cognitive deteriortation.

About one in 30,000 people have Wilson disease, according to National Institute of Diabetes and Digestive and Kidney Diseases.

Starving tumors

Vinit Shanbhag

Vinit Shanbhag mixes the CRISPR DNA with mammalian cells to specifically delete a gene in these cells in lab hood. | photo by Jinghong Chen, Bond LSC

In 2013, Petris’ lab published the first direct evidence suggesting ATP7A is essential for the dietary absorption of copper. Since then they have dug deeper into this copper transporter, and his lab now sets their sights on a greater enemy of human health — cancer.

Tumor growth requires access to large amounts of nutrients. Without an adequate supply of oxygen and nutrients, tumors fail to grow and survive. Scientists have identified that by preventing access to nutrients—for example by blocking the growth of new blood vessels—they could starve the tumor of nutrients.

Copper is a key nutrient for tumor growth. With the new-introduced system CRISPR-Cas9 — a genome editing tool to knock out specfic genes — his lab has explored how to exploit understanding of copper metabolic pathways to withhold copper from cancer cells.

“Copper starvation might be a good approach as an anti-cancer strategy,” Petris said.

Weapon of the immune system

Michael Petris and lab

Michael Petris, a professor of biochemistry at MU, stands with his lab. From left to right: Vinit Shanbhag, Nikita Gudekar, Michael Petris, Kimberly Jasmer-McDonald, Aslam Khan. | photo by Jinghong Chen, Bond LSC

Currently, four members study in Petris’ lab to tackle the relationship between copper and various diseases. Petris plans to expand his research to another area: the role of copper in innate immunity against bacterial pathogens.

This is the topic of Petris’ next grant. Nutritional immunity, which describes how the mammalian host withholds nutrients from the invading bacteria during infection, is very well-described for iron and zinc.

Yet copper performs differently.

During infection, the level of copper in blood actually goes up instead of going down. The immune system concentrates copper at sites of infection and within regions where the bacteria are engulfed.

“We speculate that copper is being used as weapon by the host to kill the bacteria,” Petris said. “That is the area we are trying to develop further.”

 

Michael Petris is a Bond LSC investigator and a professor of biochemistry. The study “Multiple di-leucines in the ATP7A copper transporter are required for retrograde trafficking to the trans-Golgi network” was published by The Royal Society of Chemistry in September 2016.

 

 

Chemical persuasion

Scientists prove parasite mimics key plant peptide to feed off roots
By Roger Meissen | Bond LSC

A nematode (the oblong object on the upper left) activates the vascular stem cell pathway in the developing nematode feeding site (syncytium) on a plant root. | contributed by Melissa Mitchum

A nematode (the oblong object on the left) activates the vascular stem cell pathway in the developing nematode feeding site (syncytium) on a plant root. | photo by Xiaoli Guo, MU post-doctoral research associate

When it comes to nematodes, unraveling the root of the issue is complicated.

These tiny parasites siphon off the nutrients from the roots of important crops like soybeans, and scientists keep uncovering more about how they accomplish this task.

Research from the lab of Bond LSC’s Melissa Mitchum recently pinpointed a new way nematodes take over root cells.

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Melissa Mitchum | photo by Roger Meissen, Bond LSC

“In a normal plant, the plant sends different chemical signals to form different types of structures for a plant. One of those structures is the xylem for nutrient flow,” said Mitchum, an associate professor in the Division of Plant Sciences at MU. “Plant researchers discovered a peptide signal for vascular stem cells several years ago, but this is the first time anyone has proven that a nematode is also secreting chemical mimics to keep these stem cells from changing into the plant structures they normally would.”

Stem cells? Xylem? Chemical mimics?

Let’s unpack what’s going on.

First, all plants contain stem cells. These are cells with unbridled potential and are at the growth centers in a plant. Think the tips of shoots and roots. With the right urging, plant stem cells can turn into many different types of cells.

That influence often comes in the form of chemicals. These chemicals are typically made inside the plant and when stem cells are exposed to them at the right time, they turn certain genes either on or off that in turn start a transformation of these cells into more specialized organs.

Want a leaf? Expose a stem cell to a particular combination of chemicals. Need a root? Flood it with a different concoction of peptides. The xylem — the dead cells that pipe water and nutrients up and down the plant — requires a particular type of peptide that connects with just the right receptor to start the process.

But for a nematode, the plan is to hijack the plant’s plan and make plant cells feed it. This microscopic worm attaches itself to a root and uses a needle-like mouthpiece to inject spit into a single root cell. That spit contains chemical signals of its own engineered to look like plant signals. In this case, these chemicals — B-type CLE peptides — and their purpose are just being discovered by Mitchum’s lab.

“Now a nematode doesn’t want to turn its feeding site into xylem because these are dead cells it can’t use, so they may be tapping into part of the pathway required to maintain the stems cells while suppressing xylem differentiation to form a structure that serves as a nutrient sink,” Mitchum said. “To me that’s really cool.”

This means these cells are free to serve the nematode. Many of their cell walls dissolve to create a large nutrient storage container for the nematode and some create finger-like cell wall ingrowths that increase the take up of food being piped through the roots. For a nematode, that’s a lifetime of meals for it while it sits immobile, just eating.

But how did scientists figure out and test that this nematode’s chemical was the cause?

Using next generation sequencing technologies that were previously unavailable, Michael Gardner, a graduate research assistant, and Jianying Wang, a senior research associate in Mitchum’s lab, compared the pieces of the plant and nematode genome and found nearly identical peptides in both — B-type CLE peptides.

“Everything is faster, more sensitive and we can detect things that had gone undetected through these technological advances that didn’t exist 10 years ago,” Mitchum said.

To test their theory, Xiaoli Guo, postdoctoral researcher and first author of the study in Mitchum’s lab synthesized the B-type CLE nematode peptide and applied it to vascular stem cells of the model plant Arabidopsis. They found that the nematode peptides triggered a growth response in much the same way as the plants own peptides affected development.

They used mutant Arabidopsis plants engineered to not be affected as much by this peptide to confirm their findings.

“We knocked out genes in the plant to turn off this pathway, and that caused the nematode’s feeding cell to be compromised. That’s why you see reduced development of the nematode on the plants.”

This all matters because these tiny nematodes cost U.S. farmers billions every year in lost yields from soybeans, and similar nematodes affect sugar beets, potatoes, corn and other crops.

While this discovery is just a piece of a puzzle, these pieces hopefully will come together to build better crops.

“You have to know what is happening before you can intervene,” Mitchum said. “Now our biggest hurdle is to figure out how to not compromise plant growth while blocking only the nematode’s version of this peptide.”

Mitchum is a Bond LSC investigator and an associate professor of Plant Sciences in the College of Agriculture, Food and Natural Resources. The study Identification of cyst nematode B-type CLE peptides and modulation of the vascular stem cell pathway for feeding cell formation” recently was published by the journal PLOS Pathogens in February 2017.

Cornelison receives highest honor from White House

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It feels good to get recognition, especially when it comes from the White House.

This week D Cornelison, a Bond Life Sciences Center researcher and associate professor of biological sciences found out she will receive a Presidential Early Career Award for Scientists and Engineers (PECASE). The award is the highest honor bestowed by the United States government on science and engineering professionals in the early stages of their independent research careers. She joins 102 researchers this year selected by the White House to receive this prestigious award.

This is a first for Missouri as a state as well as MU, making her the only scientist based in Missouri to ever be selected. Cornelison was nominated by her program officer at the National Institutes of Health, which funds her work on satellite cells.

Read more here from Melody Kroll on the Division of Biological Sciences website.

If you’d rather hear about it from her mouth, listen to Cornelison’s interview on KFRU Wednesday morning.

Live long and prosper: healthy mitochondria, healthy motor neurons?

Chris Lorson

Chris Lorson (front) and Mark Hannink (back) collaborate to study the role of mitochondria in motor neuron health, particularly in relation to spinal muscular atrophy, a neuromuscular disorder | photo by Jen Lu, Bond LSC

Chris Lorson, a professor of veterinary pathobiology, and Mark Hannink, a professor of biochemistry, want to find a new way to help motor neurons live a long and healthy life. Their question: what’s the relationship between motor neuron sruvival and a cellular component called mitochondria?

The two researchers at the Bond Life Sciences Center were awarded preliminary funding from the Bond LSC to pursue this question. Their findings could lead to new targets for therapies to treat a type of muscular dystrophy called spinal muscular atrophy, or SMA.

Spinal muscular atrophy, a genetic disease characterized by the death of motor neurons in the spinal cord, is caused by a mutation in the Survival Motor Neuron 1, or SMN1, gene. Patients with SMA develop muscle weakness and deterioration that spread inwards from the hands and feet, which progresses to interfere with mobility and breathing. The severity of symptoms and time of onset depend on how well a related gene is able to compensate for the lack of SMN1. As a result, treatment strategies usually focus on improving the activation of SMN1’s back-up gene.

Hannink and Lorson, however, are interested in a different pathway that is related to mitochondria dsyfunction.

Mitochondria are like the cell’s battery packs. Produced in the cell body, mitochondria migrate to the other end of the motor neuron to provide the energy to send electrochemical signals to recipient muscles and nerves. When mitochondria break down, the cell packs them into vacuoles that return to the cell body for recycling or removal.

“I saw a report that said that in SMA, there’s evidence for dysfunctional mitochondria in spinal motor neuron atrophy,” Hannink said. “My lab knows something about how mitochondria respond to stress.”

“There’s a lot of information out there that hints at it,” Lorson, an expert in SMA, said. “A number of the same responses you see in the stress pathway are also activated in neurodegeneration.”

To test their hypothesis, Hannink and Lorson plan to make motor neurons from pluripotent stem cells taken from people with and without SMA, and compare mitochondrial function and cell survival between the two groups. Then, they will test if a number of different genes that are known to be important for mitochondrial function will affect motor neuron health in both SMA and non-SMA derived cells.

“If you look at the tool chest of SMA therapeutics right now,” Lorson said, “you have a number of very obvious targets.”

Most approaches aim to boost the performance of the SMN or its back-up gene, but there are also options like neuroprotectants and skeletal muscle activators. Molecules that maintain healthy mitochondrial function could be another possibility.

“These are things that don’t worry about the state of the SMN gene and are targeting something in addition to, supplemental to or as an alternative to SMN,” Lorson said. “And that’s where this project would fall.”

This seed funding is one of seven awarded this year at the Bond Life Sciences Center. These awards, which range from $40,000 to $100,000 in funding, foster inter-laboratory collaboration and make possible the development of pilot projects.

The eyes have it

Carisa Petris

Dr. Carisa Petris stands in the McQuinn atrium of Bond Life Science Center. She and Bond LSC researcher Gary Weisman are using funding from a $100,000 Bond LSC grant to study the mechanisms of an auto-immune disease in the lacrimal glands of the eyes. They are hoping treatments for the disease in mice they study could be applied to humans. | photo by Phillip Sitter, Bond LSC

Bond LSC scientist works with MU eye surgeon to help people suffering from autoimmune-disease Sjögren’s syndrome

By Phillip Sitter | Bond LSC

They may not get much respect, but tears and spit are the products of a delicate secretive system that people would pay their respects to in mourning if they discovered that system was dying.

Gary Weisman and Dr. Carisa Petris are working together to help heal the damage caused by such a chronic lack of tears and saliva. The pair recently received a $100,000 Bond Life Sciences Center Grant for Innovative Collaborative Research to allow Bond LSC’s Weisman to partner with Petris, an eye surgeon working at MU Hospital.

They want to study the mechanism by which the auto-immune disease Sjögren’s syndrome cripples the glands of the eyes in mice. By comparing that mechanism to how it works in human eyes, they hope to examine if effective treatments for the mice could in turn help people.

“Dr. Weisman has characterized [Sjögren’s syndrome] in the salivary glands, and then there are similar glands in the eye called the lacrimal glands, and those are the tissues that we’re going to study,” she said of their collaboration.

Sjögren’s attacks the glands in our bodies that produce tears and saliva. Without tears and saliva, people suffer chronic dry mouth and eyes and are more susceptible to infections. Sjögren’s itself can also spread to other parts of the body, including the lungs, kidneys and digestive organs. An estimated four million people in the United States live with the disease, according to the Sjögren’s Syndrome Foundation.

Much of the grant money will go toward the costs of obtaining and housing new knockout mice for the study. These mice have a disabled, or knocked out, gene that causes them to express a certain trait like the dry eyes and development of Sjögren’s in this case.

“It takes a few weeks to a couple months for the disease to fully manifest itself, so we’ll house those mice for that time, and then of course, we’ll be treating them with the drug, and not with the drug, some for harvesting just the lacrimal glands and [studying] the surface of the eye,” Petris said.

Even though Sjögren’s syndrome and inflammation research are big topics, there’s just no good solution to the problems yet.

“There are a few [eye] drops that are used for Sjögren’s now, and they’re at best helpful, but they don’t cure the disease, so that would be the ultimate goal. They help decrease the inflammation that goes along with it and increase the tear production. The drops are also limited in their longevity too — you can only use them a certain length of time before they tend to not work so well anymore,” Petris said.

Petris referred to one drug that shows promise. The drug or another like it would interrupt the autoimmune response that causes the damaging inflammation that leads to Sjögren’s. It has already shown good results for reducing the symptom of dry mouth in mice, so Petris said she and Weisman will add it to some of the eyes of their mice and see if has any similar effect it reducing dryness there.

 

Gary Weisman was recently recognized for his career studying auto-immune responses with an award at an international conference in Seoul, Republic of Korea. Read more about Sjögren’s syndrome and Weisman’s work here.

This seed funding is one of seven awarded this year at the Bond Life Sciences Center. These awards, which range from $40,000 to $100,000 in funding, foster inter-laboratory collaboration and make possible the development of pilot projects. Read more about another Bond LSC seed funding grant-supported collaborative project here.