LSSP Symposium highlights epigenetics of the womb and how parental stress can change genetic makeup
Could a stressful day during pregnancy change the future of a developing child nestled in the womb?
Experts in the epigenetic research field are saying yes.
This weekend the 11th annual Life Sciences and Society Program will kick off “Epigenetic Revolution: Nature, Nurture and What Lies Ahead,” bringing experts on environmental influences on offspring to the stage.
Two speakers will focus their talks on the period of time developing mammals spend in the womb and what factors could trigger changes in their genetics. Tracy Bale, from the University of Pennsylvania, and Irva Hertz-Picciotto., from UC Davis, promise to draw the largest crowds.
“I heard great things about Tracy Bale’s innovative research — several senior colleagues called her a rising star in the field — so we were keen to invite her,” said LSSP Symposium Director Mary Shenk. “The connection to neurodevelopmental disorders like autism was of strong interest on campus.”
Epigenetic research has could provide answers to some of our longest standing questions.
Epigeneticists reason that the nature versus nurture development notion doesn’t consider their overlap. The premise is that our future is not only influenced by the genetics of our parents, but also tweaked further down the line by environmental factors.
Don’t miss it: Stress Parents
Tracy Bale, professor of neuroscience and animal biology at the University of Pennsylvania, will present “Stress Parents: Maternal and Paternal Epigenetic Programming of the Developing Brain” in Monsanto Auditorium at 9 am on Saturday.
Tracy Bale will speak in Bond Life Sciences Center’s Monsanto Auditorium at 9 a.m. Saturday. Her talk, “Stress Parents: Maternal and paternal epigenetic programming of the developing brain,” will cover cutting-edge research at the University of Pennsylvania where she linked parental stress, infection and malnutrition to an increased risk for the childhood development of neurodevelopmental disorders, like autism and schizophrenia.
Bale’s research provides tools to better understand how parental experiences trigger changes in their future offspring’s brain, and they could play an important role in disease risk and resilience.
She tests her theories in mice, finding epigenetic marks that were changed by male mice stress experiences. She said the research could one day translate to humans.
“If we can identify epigenetic marks in mice that are important in how their offspring develop, we might be able to understand more about human lifetime exposures to things like stress and how important such marks are in germ cells,” Bale said.
The bottom line is epigenetics can do what evolution does, but much more quickly. Bale wants the audience to walk away from her talk on Saturday morning understanding the importance of germ cells and how the influence of the environment can impact future offspring.
“This field helps to explain how an organism can rapidly respond to a changing environment and pass on potentially beneficial traits to future generations without the length of time evolution would require for such fitness,” Bale said.
Don’t miss it: Epigenetics and autism
Hertz-Picciotto will turn our discussion toward the topic of Autism: Past Evidence, Current Research and future quandaries” at 2:15 p.m. Saturday.
Her research began with three clues about autism: it tended to run in families, children with rubella had a high rate of autistic symptoms and children exposed prenatally to the drug thalidomide, show symptoms, as well.
Irva Hertz-Picciotto, professor of public health sciences at the University of California — Davis, will present “Environment and Autism: Past Evidence, Current Research and Future Quandaries” at 2:15 pm on Saturday.
“This is a controversial topic, but also an important one to learn more about given how many people’s lives are touched by autism,” Shenk said. “Dr. Hertz-Picciotto’s research and outreach work are very widely respected.”
Hertz-Picciotto, an environmental epidemiologist and professor of public health sciences at UC Davis, will highlight epigenetic studies being conducted, and key gaps, persistent myths and enigmas that still need to be solved during her talk on Saturday.
Bale and Hertz-Picciotto join many other speakers as part of this year’s LSSP Epigenetic Revolution Symposium.
The symposium begins Friday, March 13, with talks and presentations extending through March 15. Affiliated events will be going on the entire weekend, extending through March 17.
To introduce our 11th Annual Life Sciences and Society Program, The Epigenetics Revolution: Nature, Nurture and What Lies Ahead that runs at the University of Missouri March 13-15, we figured it would be nice to define the term epigenetics. Spoiler: It’s amazing and it could change everything.
According to Merriam-Webster Dictionary, epigenetics is “the study of heritable changes in gene function that do not involve changes in the DNA sequence.”
Let’s break that down.
We can inherit something that changes what our genes do, but don’t actually change the code of our DNA.
So what sort of things do genes do?
It might be easier to think about it like this: Genes are like ingredients that make up a recipe which concocts a specific function. Each individual ingredient adds to the bigger picture. Say the recipe is our height. There are many, many genes involved in myself standing at 5 feet 6 inches and my sister towering over me at 5 feet 10 inches.
Though it’s not epigenetics that makes my sister taller than me, epigenetics could help help explain why identical twins exposed to different conditions over their lifetimes, may eventually produce offspring with extreme differences in height, as just one example.
Yesterday, Jack C. Schultz, director of the Christopher S. Bond Life Sciences Center, explained epigenetics to me this way:
“We are not simply the sum of the genes we have, but rather which ones are on or off,” Schultz said. “Those differences in gene activity explain why even identical twins are not totally identical.”
Mary Shenk, the director of this year’s LSSP symposium, said epigenetics is a revolutionary area of research that changes the way we think about genetic effects. Epigenetics research makes it clear that many aspects of the environment—including the social environment—can affect how genes are expressed, she said.
“We have always known that some traits—height, for instance—were strongly influenced by the environment through diet,” Shenk said. “But new research makes it clear just how many ‘genetic’ traits are subject to either environmental influences and/or other influences such as the sex of the parent a gene is inherited from.”
“This is a real game-changer in terms of how we see the world of genes, and makes notions of simple genetic determinism of complex traits increasingly unrealistic,” Shenk added.
The key to understanding epigenetics, is to consider the capabilities of the environment to “switch on or off” the expression of our genes.
Let’s reflect on something you may have (or haven’t) heard about: “Hogerwinter,” more well known as the Dutch Hunger Winter. The historic famine from the winter of 1944 to the spring of 1945, has been the focal point in some of the most infamous epigenetic research.
Investigators wanted to know if prolonged famine conditions could have an effect on the offspring of pregnant mothers during that time.
“The Epigenetics Revolution: How Modern Biology Is Rewriting Our Understanding of Genetics, Disease, and Inheritance,” by Nessa Carey published by Columbia University Press in 2012, makes a compelling argument about the famine effect on gene expression in subsequent generations.
The research looked at children who were in the second trimester of their mother’s pregnancy during the winter of 1944-1945, and they found an increased incidence of schizophrenia in those children.
Carey’s research suggests epigenetics could explain effects of famine, on the expression of certain genes of the offspring of mothers pregnant during that time.
Illustration by Paige Blankenbuehler/Bond Life Sciences Center
Epigenetics are the nucleus of the 11th Annual Life Sciences and Society Program held at the University of Missouri next weekend, March 13-15. The field has the potential to unlock some of our longest standing questions about who we are and why we are this way, scientists say. The event is a great opportunity to learn more about “The Epigenetics Revolution.”
Schultz says the field of epigenetics is exploding, and it’s important to us for three big reasons.
One: Epigenetics helps us understand how we – or any organism – can cope with changing conditions even though we can’t change our genetic makeup.
Two: Epigenetics explains how traits can be passed from parent to offspring without changing genetic makeup.
Three: Many human diseases, including cancer, seem to involve epigenetic activity. Experiences of the parents, or of developing embryos in the womb could be responsible for difficult-to-understand problems in the offspring, such as cognitive disorders including autism spectrum disorders.
“Discovering how epigenetics works is like discovering an entirely new language,” Schultz said. “That language links our experiences – even emotional ones – to the way we are and the way our offspring look and behave.”
Schultz said exploring those links can help us understand how our environment shapes us and our societies.
According to Shenk, director of the Life Sciences and Society Program, the nine speakers coming to the MU campus all bring their own expertise to epigenetics. As far as picking a speaker, Shenk said it’s hard to choose just one.
Nonetheless, here are a few to keep on your radar, according to Shenk:
“I am especially looking forward to hearing Annie Murphy Paul talk about her experiences writing about maternal effects for a general audience.
“Tracy Bale and Oliver Rando discuss their work on paternal effects in mice (most recent focuses on mothers instead of fathers so this is especially interesting).
“I am also excited to hear Ted Koditschek from Mizzou discuss the history of the classic Lamarckian idea of the “inheritance of acquired characteristics” and how it relates to findings from modern epigenetics,” Shenk said.
Schedule of events
The location of all speakers and affiliated events will be announced at lssp.missouri.edu or on the Life Sciences and Society Program — University of Missouri Facebook page.
Friday
6:30 p.m. — Topic of the talk: Sharing epigenetic research with the public. Speaker: Annie Murphy Paul, science writer and author of Origins: How the Nine Months Before Birth Shape the Rest of Our Lives.
Saturday
9 a.m. — Topic of the talk: Stress Parents: Maternal and paternal epigenetic programming of the developing brain. Speaker: Tracy Bale, professor of neuroscience and animal biology at the University of Pennsylvania.
10:30 a.m. — Topic of the talk: You are what your father ate. Speaker: Oliver Rando, professor of biochemistry and molecular pharmacology at the University of Massachusetts Medical School.
11:30 a.m. — Topic of the talk: Epigenetic inheritance and evolutionary theory: the resurgence of natural philosophy. Speaker: Massimo Pigliucci, professor of philosophy at the City University of New York.
2:15 p.m. — Topic of the talk: Environment and Autism: Past evidence, current research and future quandaries. Speaker: Irva Hetz-Picciotto, professor of public health sciences at UC Davis.
3:15 p.m. — Topic of the talk: Prenatal stress modifies the impact of phthalates on boys’ reproductive tract development. Speaker: Shanna Swan, professor of preventative medicine at Mount Sinai School of Medicine.
4:30 p.m. — Panel Session with all Saturday speakers.
Sunday
9 a.m. — Topic of the talk: DOHaD, epigenetics and cancer. Speaker: Suh-mei Ho, director of the University of Cincinnati Cancer Center, and chair of the department of environmental health.
10:30 a.m. — Topic of the talk: The epigenetics of pediatric cancers. Speaker: Joya Chandra, associate professor of pediatrics at the University of Texas MD Anderson Cancer Center.
11:30 a.m. — Topic of the talk: Before epigenetics: Early ideas about the inheritance of acquired characteristics. Speaker: Ted Koditschek, professor of history at the University of Missouri.
Affiliated events:
Exhibit running March 5-30 at the Ellis Library Collonnade. Exhibit: Generations: Reproduction, heredity and epigenetics.
1 p.m. March 9, at the Ellis Library Government Documents Section. Topic of the talk: Genes, culture and evolution. Speaker: Karthik Panchanathan, department of anthropology, University of Missouri.
3:30 o.m. March 17, at Jesse Wrench Auditorium. Topic of the talk: Profound global institutional deprivation: the example of the English and Romanian adoptee study. Speaker: Sir Michael Rutter, professor of developmental psychology at the Institute of Psychiatry at King’s College in London.
Bond LSC’s Jack Schultz and Heidi Appel hold model Arabidopsis plants used in many of their experiments. Roger Meissen/Bond LSC
We often think of damage on a surface level.
But for plants, much of the important response to an insect bite takes place out of sight. Over minutes and hours, particular plant genes are turned on and off to fight back, translating into changes in its defenses.
In one of the broadest studies of its kind, scientists at the University of Missouri Bond Life Sciences Center recently looked at all plant genes and their response to the enemy.
“There are 28,000 genes in the plant, and we detected 2,778 genes responding, depending on the type of insect,” said Jack Schultz, Bond LSC director and study co-author. “Imagine you only look at a few of these genes, you get a very limited picture and possibly one that doesn’t represent what’s going on at all. This is by far the most comprehensive study of its type, allowing scientists to draw conclusions and get it right.”
Their results showed that the model Arabidopsis plant recognizes and responds differently to four insect species. The insects cause changes on a transcriptional level, triggering proteins that switch on and off plant genes to help defend against more attacks.
The difference in the insect
“It was no surprise that the plant responded differently to having its leaves chewed by a caterpillar or pierced by an aphid’s needle-like mouthparts,” said Heidi Appel, Bond LSC Investigator and lead author of the study. “But we were amazed that the plant responded so differently to insects that feed in the same way.”
Plants fed on by caterpillars – cabbage butterfly and beet armyworms – shared less than a quarter of their changes in gene expression. Likewise, plants fed on by the two species of aphids shared less than 10 percent of their changes in gene expression.
These Venn diagrams show the number of genes expressed due to each treatment and their overlap. Upward pointing arrows indicate upregulated genes, downward pointing arrows indicate downregulated genes. For example, beet armyworm (S. exigua) shared 21 percent of upregulated genes expressed with cabbage butterfly caterpillar (P. rapae). M. persicae and B. brevicoryne are the two types of aphids compared in the study. Courtesy of Heidi Appel
The plant responses to caterpillars were also very different than the plant response to mechanical wounding, sharing only about 10 percent of their gene expression changes. The overlap in plant gene responses between caterpillar and aphid treatments was also only 10 percent.
“The important thing is plants can tell the insects apart and respond in significantly different ways,” Schultz said. “And that’s more than most people give plants credit for.”
A sister study explored this phenomena further, led by former MU doctoral student Erin Rehrig.
It showed feeding of both caterpillars increased jasmonate and ethylene – well-known plant hormones that mediate defense responses. However, plants responded quicker and more strongly when fed on by the beet armyworm than by the cabbage butterfly caterpillar in most cases, indicating again that the plant can tell the two caterpillars apart.
The result is that the plant turns defense genes on earlier for beet armyworm.
In ecological terms, a quick defense response means the caterpillar won’t hang around very long and will move on to a different meal source.
More questions
A study this large has potential to open up a world of questions begging for answers.
“Among the genes changed when insects bite are ones that regulate processes like root growth, water use and other ecologically significant process that plants carefully monitor and control,” Schultz said. “Questions about the cost to the plant if the insect continues to eat would be an interesting follow-up study for doctoral students to explore these deeper genetic interactions.”
Frontiers in Plant Science published the primary study in its November 2014 issue. The sister study can be read here.
Adeno-associated virus type 2 at 3.0 A (xie, et al, Proc Natl Acad Sci U S A. 2002; 99:10405-10.) Courtesy David Pintel
It’s an understatement to say viruses are small.
But an average virus dwarfs the diminutive variety known as parvoviruses, which are among the most minuscule pathogens known to science.
Tucked inside a protective protein shell, or capsid, parvoviruses contain a single DNA strand of about 5,000 nucleotides. If parvo’s genetic material is like an hour-long stroll around your neighborhood, a bigger virus like herpes is equivalent to walking from St. Louis to Columbia, Missouri.
Dr. David Pintel stands next to a scan in his lab in Bond Life Sciences Center on Tuesday, Feb. 3, 2015. Hannah Baldwin/Bond LSC.
“I joke that we can do the whole parvovirus genome project in an afternoon, because it’s just taking it downstairs and having it sequenced,” said David Pintel, a Bond Life Sciences Center virologist and Dr. R. Phillip and Diane Acuff endowed professor in medical research at the University of Missouri. “It’s the size of one gene in the mammalian chromosome.”
But that little stretch of DNA still has plenty of tricks up its sleeve.
Pintel has spent nearly 35 years studying parvo and is one of the world’s foremost experts on the virus, but he’s still plumbing the tiny pathogen’s depths.
His lab focuses on unraveling how parvo interferes with a host cell’s lifecycle and understanding the virus’ quirky RNA processing strategies.
“Even though the virus is small, it’s not simple,” David Pintel said. “Otherwise we’d be out of business.”
Over the last two decades, parvo has become an important tool for gene therapy, an experimental technique that fights a disease by inactivating or replacing the genes that cause it. Researchers enlist a kind of parvovirus known as adeno-associated virus as a gene therapy vector, the vehicle that delivers a new gene to a cell’s nucleus. Pintel helped suss out the virus’ basic biology, an important step for developing effective gene therapy.
A varied virus
The name ‘parvo’ comes from the Latin word for ‘small.’ But the virus’ size makes it a resourceful, versatile enemy and a valuable model for understanding viruses and how they interact with hosts.
Parvoviruses fall into five main groups. They infect a broad swath of animal species from mammals such as humans and mice to invertebrates such as insects, crabs and shrimp.
Canine Parvovirus at 2.9 A (Tsao, et al, Science. 1991; 251:1456-65.) Courtesy David Pintel.
Canine parvovirus, or CPV, is perhaps the best-known type.
It targets the rapidly dividing cells in a dog’s gastrointestinal tract and causes lethargy, vomiting, extreme diarrhea and sometimes death. In humans, Fifth disease, caused by parvovirus B19, is the most common. This relatively innocuous virus usually infects children and causes cold-like symptoms followed by a “slapped cheek” rash. There is no vaccine for Fifth disease, but infections typically resolve without intervention.
Reading the transcript
Pintel surveyed the whole parvo family to understand its idiosyncrasies.
To study bocavirus – a kind of parvo recently linked to a human disease – Pintel looked closely at the dog version, minute virus of canines (MVC). MCV serves as a good model for the human disease-causing virus. While examining MVC, he noticed an unexpected signal in the center of the viral genome. The signal terminates RNA encoding proteins for the virus’ shell, a vital part of the pathogen.
Finding such a misplaced signal in the middle of a stretch of RNA is like coming across a paragraph break in the middle of a sentence.
Pintel knew the virus bypassed this stop sign somehow, because the blueprint for the viral capsid lies further down the genome.
To overcome this stop sign, this particular parvovirus makes a protein found in no other virus. The protein performs double-duty for the virus: It suppresses the internal termination signal and splices together two introns, or segments of RNA that do not directly code information but whose removal is necessary for protein production. Splicing the introns together ensures that the gene responsible for producing the viral capsid is interpreted correctly.
Viruses and hosts: a game of cat and mouse
The conflict between a virus and a host is a constantly escalating battle of assault and deception.
Viruses need a host cell’s infrastructure to replicate, but have to fool or outmaneuver its defenses.
Pintel discovered one example of this trickery in mice, where parvo triggers a cellular onslaught known as the DNA damage response, or DDR. This type of parvo co-opts that defense. Normally DDR pauses the cell cycle to keep damaged DNA from being passed on to the next generation of cells, but parvo exploits that delay, buying time for the virus to multiply.
“For many, many hours the cells are just held there by the virus while the virus continues to replicate,” Pintel said. “And then that cell never survives; the virus kills the cell. It’s that holding of the cell cycle — which is part of the DNA damage response — that the virus hijacks to hold the cell cycle. It’s really cool.”
Parvo’s small size makes it especially beholden to their hosts. But that can make them particularly revelatory for researchers.
Parvovirus samples from an experiment labeled by Femi Fasina, a postdoc in Pintel’s lab. Caleb O’Brien/Bond LSC.
“It’s a twofold thing,” Pintel said, “Because it’s a virus that’s dependent on the cell, when you learn how the virus is doing these things, you learn how the cell does those basic processes. If we’re looking at a viral-cell interaction, yes, we’re looking at it from a viral point of view, but on the other hand we’re trying to understand the basic cellular process.”
Uncovering such nuanced interactions is a painstaking, laborious process that often goes unheralded by mass media. But those fundamental discoveries provide the building blocks upon which other researchers depend, said Femi Fasina, a postdoc in Pintel’s lab.
“When you understand basic biology, people can walk on those advancements. Although we don’t see the impact immediately, such things lead to breakthroughs that will revolutionize a lot of things.”
A small question
Despite his deepening understanding of how parvo works, there remains one debate about the virus that Pintel deems beyond the scope of his research: Are the tiny slivers of DNA that comprise parvoviruses even alive?
“I think that’s a crazy question,” he said. “It’s semantics. The virus is a genome. It goes into a cell, it doesn’t do anything until it’s inside of a cell and then it does stuff.” So whether you write parvoviruses into the book of life depends entirely on how you define the word ‘alive.’
“I put that in the realm of philosophy,” Pintel said, “not the realm of science.”
Faculty and students crowded the hallways at Bond Life Sciences Center for an interdisciplinary poster session on Saturday. About 40 prospective graduate students listened to faculty and current graduate students from the biochemistry, interdisciplinary plant group, plant sciences, molecular pathogenesis and therapeutics (MPT), genetics area program and the life sciences fellowship program discuss their work.
The poster session was part of the 2015 Graduate Life Sciences Joint Recruitment Weekend, an event aimed at helping prospective graduate students determine if MU is the right place for them to continue their education. About 175 people participated, including current graduate students and faculty.
MU biochemistry senior Flore N’guessan said she applied to the MPT program because of her interest in virology.
“I’ve always wanted to do research,” she said.
N’guessan is currently a researcher in the Burke lab, which works on testing potential antiviral therapeutics on HIV. N’guessan has applied to other graduate programs but said that the interdisciplinary and collaborative nature of MU’s life sciences program appeals to her because it allows her to gain skills from other labs.
“It’s a collaborative and interdisciplinary university,” Dr. Jay Thelen, an associate professor of biochemistry, said. “That’s what this weekend highlights.”
Thelen emphasized that the benefit of events like the interdisciplinary poster session allows prospective students to see the diversity of science studied at Bond LSC and in labs throughout MU. And, he said, “It’s exciting to see how many students there are.”
Protein specimens are prepared here in a Bond Life Sciences lab. Bond LSC’s Mark Hannink recently identified a protein pathway could be useful in restoring mitochondrial recycling in certain cells, a problem that leads to familial Parkinson’s Disease.
It’s as if your recycling man quit his job and never came back.
Bags pile up to unexpected heights as waste continues to be generated and brought out to the curb. Day after day, the waste builds up as no one comes to pick them up.
For individuals with Parkinson’s disease, an accumulation of waste causes specific brain cells to die. The result is the onset of the disease.
But, instead of aluminum cans, plastics and paper, the waste that builds up in the brain cells of individuals with Parkinson’s is damaged mitochondria. Mitochondria are the cellular components that generate energy needed to keep cells alive.
When mitochondria is damaged and is no longer capable of making energy, it must be sent to the recycling center of a cell (called the lysosome).
Mark Hannink, a scientist at the Bond Life Sciences Center and professor of biochemistry at the University of Missouri, is peeling away the layers of this onion, one at a time.
His new research on a novel protein called PGAM5 (phosphoglycerate mutase family member 5) is pointing the way to finding a drug that can treat the disease.
Mitochondria suffer “wear and tear,” just like old cars
Mitochondria are endlessly helpful to a cell.
These powerhouses produce energy for a cell, control the cell division cycle and help regulate synapses. However, the mitochondrial proteins that produce energy eventually become damaged and no longer function properly.
“That’s part of the normal life cycle of mitochondria,” Hannink said. “Just like when the motor in an old car gives out due to wear and tear, that motor needs to be taken out and sent to the scrap dealer to be recycled and a new motor needs to be put in the car to keep it running.”
When mitochondria wear out they need to be sent to “recycling.”
“If that recycling pathway doesn’t work, the defective mitochondria will build up and will disrupt cell physiology, ultimately causing that cell to die” Hannink said.
Parkinson’s Disease is the clearest example of this recycling failure.
In early onset Parkinson’s, mutated proteins “forget” to take damaged mitochondria to the recycling center, resulting in build-up of toxic waste and, eventually, early onset of the disease.
“If the recycling mechanism isn’t functioning properly, those neurons die,” Hannink said.
Mark Hannink, lead investigator of the study, sits in his lab at the MU Bond Life Sciences Center. | Photo by Paige Blankenbuehler
Peptides behave like drug molecules
Hannink recently published research on the PGAM5 pathway in the Journal of Biological Chemistry along with MU graduate students Jordan M. Wilkins and Cyrus McConnell and fellow Biochemistry faculty member, Peter Tipton.
While its basic nature hides it from the view from the general public, this research takes a large step in the science of Parkinson’s disease.
Beyond defining the regulation of a pathway largely unstudied, their work discovered that a peptide regulates the pathway. Importantly, this peptide is able to alter the activity of the PGAM5 protein and stimulate an alternative recycling pathway for mitochondria.
Peptides are a clear signpost on a path toward drug development.
“Any time you can identify a biological process that is regulated by a peptide, that peptide becomes a lead candidate in the search for small, drug-like molecules that will act the same way,” Hannink said.
For Parkinson’s Disease, the goal is to find ways to repair the mitochondria recycling process.
“We propose that, by regulating PGAM5, it may be possible to restore mitochondrial quality control to dopaminergic neurons of patients with Parkinson’s and lessen the severity of the disease,” Hannink said.
What’s next?
While Hannink’s findings are exciting, there are also nuances to consider.
His research focuses on familial Parkinson’s disease, and it remains unknown whether sporadic Parkinson’s is also due to a defective mitochondrial recycling pathway. Sporadic Parkinson’s accounts for the vast majority of cases and typically affects older people.
It’s not clear if the PGAM5 pathway is also defective in those cases, Hannink said.
The next step of his research is to identify a small molecule that can regulate the PGAM5 protein in cells, just as the peptide did in his test-tube experiments.
Hannink thinks that development of a drug based on the PGAM5 pathway could be useful in restoring mitochondrial recycling in certain cells – like neurons affected in Parkinson’s – while blocking this recycling pathway in other cells, — like cancer cells.
The idea also needs to be tested using mice as a model system. The goal of those experiments will be to determine if the PGAM5 protein can stimulate alternative recycling pathways that can clean up and recycle damaged mitochondria pathway in neurons of mice.
Mutant arabidopsis models under lamps in Shuqun Zhang's lab.
Three-month-old mutant arabidopsis models are used to study the function of pollen.
The thought of pollen dispersed throughout the air might trigger horrific memories of allergies, but the drifting dander is absolutely essential to all life.
Science has long linked this element of reproduction with environmental conditions, but the reasons why and how pollen functions were less understood. Now lingering questions about the nuanced control of plants are being answered.
“Pollen is a very important part of the reproductive process and if we understand how pollen develops and how environmental stresses impinge on this process, we might be able to prevent crop loss due to high temperature or drought stress etc.,” said Shuqun Zhang, a Bond Life Sciences Center investigator.
Zhang has developed a new line of seeds that helped him and his lab identify an influential signaling pathway that triggers a chain reaction associated with normal pollen formation and function.
This research could lead to improvement to a plant’s response to disastrous environmental variables like drought to optimize pollen production and increase the production of food crops.
Left: Pollen grains genotypes MAPK3 and MAPK6 are illuminated by red and yellow dye using a fluorescent microscope. RIGHT: Normally developed pollen grains shown by an electronic microscope scan. | Credit: Shuqun Zhang
Seeds of success
Mutant seeds are the key to this work.
Instead of glowing green in the soil like you might see in a science fiction movie, they are providing important insight on plant reproduction and stress tolerance.
Zhang developed these plants from a mutant strain of Arabidopsis, a model plant used in scientific research. Certain genes were “switched off”to pinpoint where important pollen functions were signaled.
Using this mutant plant and seed system, Zhang found that WRKY34and WRKY2, two proteins that turn on/off genes, are regulated by MPK3and MPK6 “signaling” enzymes. These enzymes basically transform proteins from a non-functional state to a functional state, turning on specific duties or functions. Zhang, a professor of biochemistry at MU, began tinkering with the MPK3 and MKP6 pathways more than twenty years ago during his post-doc at Rutgers University.
Zhang’s research shows the newly identified MPK3/MPK6-WRKY34/WRKY2 pathway is a key switch in the hierarchy of the signaling system in pollen formation.
The research showed that the plant’s defense/stress response and reproductive process are linked, and the influential proteins MPK3 and MPK6 were part of the bigger WRKY34/WRKY2control pathway, which is activated in early pollen production.
The system is so useful that researchers across the country won’t stop asking for the seeds, Zhang said.
“We have a lot of requests for seeds,” Zhang said. “This is a very nice system to study pollen formation and function.”
The cascade of control
The functions of MPK3/MPK6 in plants can be compared to a “mother board” switch. The pathway — MPK3 and MPK6 —are part of a hierarchy of response, turning functions on or off. In other words, it’s a switch that controls a lot of different things. Controlling WRKY34/WRKY2 is one of the many roles played by MPK3 and MPK6.
Shuqun Zhang, University of Missouri Bond Life Sciences investigator.
“Whatever is plugged into it is what comes on,” Zhang said. “We are actually very, very interested in the evolutionarily context, how this came to be.”
This signaling process is just one of many in plants. MPK3 and MPK6 are two out the 20 MPKs, or MAPKs (abbreviated from Mitogen-Activated Protein Kinases) in Arabidopsis. They control plant defense, stress tolerance, growth, and development including pollen formation and functions.
“We determined that this MAPK-WRKY signaling module functions at the early stage of pollen development,” Zhang said.
The “loss of function of this pathway reduces pollen viability, and the surviving pollen has poor germination and reduced pollen tube growth, all of which reduce the transmission rate of the mutant pollen,” according to the research.
Zhang and his lab worked with the MU Division of Biochemistry and Interdisciplinary Plant Group on the research, which published in PLoS Genetics in June of this year.
A world without pollen production and defense
Without pollen, plants would not reproduce — there aren’t any Single Bars in the plant world (that we know of) — and if plant generations don’t propagate, there would be no air or food for human life to sustain.
“The factors such as heat and drought stresses cause problems to the plant’s normal developmental process and that’s how pollen fails to develop,” Zhang said. “If we understand the process, and know how environmental factors impact negatively the process, we can then make plants that can handle environmental stress better.”
Zhang and his lab continue to research the complexities of these pathways. Next on the quest is to answer how MPK3/MPK6 are involved in pollen functions such as guiding the pollen tube growth towards ovule to complete the sexual reproduction process in plants.
“It is possible that MPK3 and MPK6 are activated quickly in response to the guidance signals,” he said. “There’s still a long way to go because very few players in this process have been identified, we try to understand the biological process how they work together.” This research is in collaboration with Dr. Bruce McClure, also professor of Division of Biochemistry.
Read more:
1. PLoS Genetics (May 2014): Phosphorylation of a WRKY Transcription Factor by MAPKs is Required for Pollen Development and Function in Arabidopsis — Funded by a Hughes Research Fellowship and grants from the National Science Foundation.
2. Plant Physiology (June 2014): Two Mitogen-Activated Protein Kinases, MPK3 and MPK6, are required for Funicular Guidance of Pollen Tubes in Arabidopsis — Funded by a National Science Foundation grant and a NSF Young Investigator Award.
This collection of Science Haikus were inspired by the #sciku Twitter campaign by Popular Science, which highlighted a few science haikus from readers. As a response, I rallied some of the scientists at the Bond Life Sciences Center to come up with haikus relating to their discipline of science.
The response was wonderful — Dr. Burke, of the immunology and virology core sent me a whopping 26 haikus — and many more scientists participated than I originally anticipated.
A haiku is a rigid form. It’s also a famously concise rhetoric, forcing the author to condense their meaning into the designated number of syllables (not always an easy task).
The funding environment in sciences is becoming tighter and tighter all of the time, too. There’s less money to go around and scientist are more than ever being asked to condense their grant proposals down to two or three pages (a contrast to the 15 page proposals of the 1990s).
Could it only be a matter of time until the National Institutes of Health will be giving money to research based on haiku proposals?
Jingyou Yu, a graduate student, does cell surface staining in Shan-Lu Liu’s virology lab. The staining illuminates cell marker expressions in experiments that deduce how viruses spread once they are contracted. | Paige Blankenbuehler
News headlines seem to feverishly spread as if they were a pandemic of the brain.
Ebola hemorrhagic fever has been the most talked about disease of the year, appearing in thousands of headlines across the world since May. Through the noise of misinformation and sensationalism, fundamental information about the pandemic becomes harder to distinguish.
In an interview with Decoding Science on Tuesday, Shan-Lu Liu, MD, PhD, a Bond Life Sciences Center investigator who studies Ebola, weighed in on the latest news.
Liu, also an associate professor in the MU School of Medicine’s Department of Molecular Microbiology and Immunology, and his lab are particularly interested in the early behaviors of the virus in transmission and how it can navigate around the host immune response.
Shan-Lu Liu, Bond Life Sciences scientists and associate professor in the MU School of Medicine department of molecular microbiology and immunology.
Q: Talk about the transmission. Ebola doesn’t spread through air, but how easily can it be transmitted through fluids?
A: It’s hard to say. It’s really not like: touch an infected person and you got it. I don’t see that could happen so easily. As an RNA virus, it’s not that stable outside of the body, unlike hepatitis B virus (HBV) where you need to boil the virus for 10 minutes and it becomes not infectious. Because Ebola is not that stable, that should not be the reason why it’s so efficient to transmit.
I think the transmission is one of the biggest things it’s, you know, I don’t think we have a complete understanding. We do know that it spreads by contact through body fluids and many people don’t realize that the handling of the deceased — that’s very dangerous. Touching broken skin or mucous membranes like the nose and mouth is dangerous.
Q: Talk about the incubation period and how that relates to symptoms and spreading of the virus.
A: The incubation time is 2-21 days. At first, the person will have flu-like symptoms, so you know, that’s why it’s hard to notice in the early stages. Some doctors or nurses say ‘just give him antibiotics send him home.’ But in stage two, you get the hemorrhage and it gets serious. The mortality rate is high, from 50 to 90 percent.
I think the fatality is definitely related to the late stages of the disease, especially with the hemorrhaging fever. The early stages are almost unnoticeable but that’s the time transmission might spread easier through contact with an infected person’s fluid. Before symptoms, the virus doesn’t spread.
Q: Last week, an article seemed to contradict with the CDC estimate. The headline: “Some good news about Ebola: It won’t spread nearly as fast as other epidemics.“ What do you make of that?
I don’t know, it’s hard for me to make a comment. Nobody knows. Things can always change. We didn’t expect to see a diagnosis in the United States — like this you know, this patient from Liberia was able to travel on a plane from virus country. Who can expect that? Anything can happen. There seem to have been some mishaps because he came from that area, right? Communication is more important now but it’s hard to predict because anything could happen.
Q: How has the Ebola virus behaved in previous outbreaks?
A: The first outbreak was in 1976 in Sudan and Congo — (Democratic Republic of Congo, known as Zaire at the time). It was from contaminated needles in a hospital and originally came from fruit bats — they are one of those animals that could transmit Ebola from animals to humans. The fruit bats transmitted the virus to primates, primates transmit to humans. It’s hard to notice in the early stages. Editor’s note: The 1976 outbreak was the first occurrence of Ebola in humans. The outbreak affected one village, infecting 318 people that resulted in 280 deaths.
Q: Much of the media has reported a vaccine for ebola was delayed. How could this happen?
A: Drugs and vaccines are a little different. The Ebola vaccine was delayed, that’s for sure. That’s because, the vaccine on trial has to go through tedious steps to get approval and so thats why when this outbreak occurs the NIH (National Institutes of Health) decides to go ahead quickly. One of the things for ebola vaccine is um, the pharmaceutical companies and the industries are not interested in developing vaccines. Do you know why? It is not a big market. Only a hundred — or a thousand or more — people will be infected by ebola, unlike other vaccines like the HPV vaccination where 200 million people need it. The companies are not interested in developing it, because there’s no money in it.
A company needs to spend a lot of money to develop a vaccine, but they don’t see the market — the market can’t do it. But somebody needs to do it. Imagine if, if the virus spread like this, you know, unpredictable, it could be worse. In terms of therapy, the drugs and antibodies, we know they are really effective. And they are specific, so they can reach the market effectively.
Q: Will a drug be enough to prevent wide spreading of Ebola?
I think the companies and governments are speeding up to make those available. To see this prediction (the CDC 1.4 million estimate), they have to be prepared. People have put increasing attention on antibodies because a vaccine is not in the near future. So what’s the approach? A “therapeutic vaccine.” The so-called therapeutic vaccine is an antibody so you engineer, you use you know, molecular engineering technique to generate those antibodies and they can neutralize and block viral infection. It’s more realistic for Ebola and even for HIV. The HIV vaccine has failed so many times. So that’s why I think one of the new approaches is to use a new broad neutralizing antibody.
Q: Does Ebola stay in the body, like chicken pox?
A: Ebola do not cause latent infection. HIV can become latent and become chronic. So influenza virus, ebola viral infection and others normally do not lead to latency. I think for Ebola — for this type of infection — once you block the patient and clear the virus it should be good.
Q: Has the media done a good job in educating the public?
I think in terms of news coverage they are pretty careful. I looked at the news conference by the CDC director and by those doctors in Dallas, and when they make statements they are careful not to exaggerate and also give very cautious measurements. The news media need to be aware of the danger of the virus. In the meantime, you have to be aware of the possibility of being affected.
Again, I think it is a very important problem. It’s important to let the public know the situation. If you see people who have recently traveled from those West African countries, you have to be cautious — air travel is so common. But I think the media have generally done a good job.
Q: Has the government done a good job keeping the pandemic under control?
I don’t know what they do. The air travel is a problem. Intensified screening process, that should definitely be done. It’s very bad for people from the outbreak area, and I just hope that this community won’t be affected.
To control, they should be careful. A person with any sign of the disease — they need to be quickly monitored and treated.
Q: What’s the most important take-away message for the public?
A: I think it’s an important problem and we need to solve it urgently. I hope this outbreak will teach us a lesson in terms of how important emerging infectious viruses are as it comes and goes is to public health. Based on literature and reports, if people do not have obvious symptoms, they do not produce an infectious virus. The incubation time has a big range but again, we are still trying to understand the process better. Infection is a complex process. We need to better understand the viral transmission so I think for now, we need to be very cautious.
Liu and his lab do not work with the contagious Ebola virus on University of Missouri campus. All of the studies involve use of a recombinant or pseudotyped Ebola virus which is not infectious.
