Five Questions with Louis-Jan “LJ” Pilaz

In this continuing “Five questions with…” series, Sharlini Sankaran talks with Louis-Jan “LJ” Pilaz, Regeneration Next Postdoctoral Fellow from the Silver Lab at Duke, about his recently-published paper in the journal Current Biology.

What excites you about your work?
I have always been fascinated by the brain, this incredibly complex organic machine. The developing brain contains these cool radial glial cells that give rise to our “thinking units”, our neurons. But radial glial cells do so much more. They generate specialized brain cells such as astrocytes. They form a barrier between the brain and the rest of the body during development, and they also serve as a scaffold for migrating neurons.

They can do all this thanks to their unique morphology. Radial glial cells, are absolutely gorgeous and remain full of mysteries. I love to spend time thinking about them and I’m driven by the need to know more about them. Anything impacting their functioning can have devastating impacts on brain development and eventually lead to neurodevelopmental diseases. The more we know about them, the more likely we will be able to find cures for those diseases.

Can you describe the breakthrough discovery that led to the publication of this paper?

Click image to play a live video of messenger RNAs moving along the radial glial cell’s basal process. The messenger RNA can be seen as a bright spot moving from the bottom of the image to the top.

Radial glial cells bear two long protrusions, called processes, emanating from their cell body. These processes end with structures called “endfeet” because of the way they look. One of these processes spans the whole brain radially, going from the center outwards. It is called the basal process and ends with basal endfeet tightly connected to the “roof” of the brain. In the mouse the basal process can have a length of several hundred microns, in the human several millimeters. If the basal process is not properly maintained, neurons will not properly migrate to their final destination. If the connection between radial glial endfeet and the roof of the brain is altered, neurons will migrate too far away and will end up outside the brain. Despite the importance of those structures, little is known about what is going on inside them.

In our latest paper, we show that the basal process is a highway for molecular transport. We uncovered some fascinating functions taking place in the basal endfeet: we imaged messenger RNAs being transported at high speed from the cell body to the basal endfeet within living brain tissue (see video). With the help of Ashley Lennox, a graduate student in the lab, we showed that these basal endfeet RNAs can locally produce proteins, far away from the cell body. We discovered 115 different RNAs that accumulate in the basal endfeet. Importantly about 30% of those RNAs have been implicated in neurological diseases and might play a significant role during brain development. We also show that RNA transport may be influenced by FMRP, an RNA-binding protein linked to Fragile X Syndrome, the most common cause of autism caused by a mutation of a single gene.

Why is this discovery important to the field of regenerative medicine?
Neural stem cells receive a lot of attention in the field of regeneration in the nervous system. In some areas of the adult brain, stem cells and progenitors are still proliferating and differentiating. There is hope that one day we will be able to harness those neural stem cells already in place to produce neurons that were lost after a stroke or injury. Another strategy would be to grow neural stem cells in a dish and then introduce them into damaged brains to produce new neurons. Our paper uncovers completely novel mechanisms at play in radial glial cells. This is yet another piece of the neural stem cell “puzzle” that scientists need to consider when attempting either strategy to stimulate regeneration of injured or lost neurons in the brain.

Our paper establishes radial glial cells as a model of choice to study RNA localization and local protein production in distant areas of a cell. These two mechanisms are implicated in the regeneration of axons after injury. For that reason, future studies of RNA localization in radial glial cells may yield findings critical to better understand how it plays a role in the regenerating axon.

What comes next in this research?
Scientists do not know why radial glial cells spend so much energy to transport RNAs across such long distances and what that means for normal brain function. We are now actively trying to uncover the function(s) of those localized RNAs during brain development.

Is there anything else you want to share about your work?
I feel very fortunate to be working in Debby Silver’s lab and to be part of the Duke community. All this work would not have been possible without the support of core facilities and lively discussions with other labs. Duke is an amazing place to do science!

L-J’s work was recently featured in the Duke Med School Blog. You can read more about his discoveries here.

Mouse vouchers awarded to six investigators

house_mouseRegeneration Next supports expansion of animal models at Duke for the purposes of regenerative biology research. As such, RNI has awarded six new vouchers of up to $5,000 for new transgenic or genetically modified mice that will be used for tissue regeneration and/or stem cell research. The vouchers are redeemable for provision of services at the Duke School of Medicine Transgenic and Knockout Mouse Shared Resource. Congratulations to the PIs and their trainees!


  • Blanche Capel: Role of Lamin B Receptor in Male Germ Cell Differentiation and Epigenetic Regulation and Identification of Lamin Associated Domains During Male Germ Cell Differentiation and Epigenetic Programming Regeneration
  • Charles Gersbach: Generation of dCas9-­KRAB transgenic mouse line for screening of genes and enhancers during regeneration
  • Dwight Koeberl: Genome editing in a humanized mouse model of Pompe Disease
  • Ruorong Yan: Modulation of heart regeneration by enhancer-delivered factors
  • Eda Yildirim: Nucleoporin 153: Regulation of gene expression during specification of hematopoietic stem cell fate and
    embryonic development

The next callout for vouchers will be posted in early 2017 with an anticipated start date of June 1.

Duke PhD Students Win Grant to Study Science & Technology Policy Fellowship Feasibility in NC

Two Duke University PhD candidates have been awarded a $25,000 grant to study the feasibility of establishing a North Carolina Science and Technology Policy Fellowship Program. ccst-grant-award-featureThe California Council on Science and Technology (CCST) in partnership with the Gordon and Betty Moore Foundation and Simons Foundation is funding multiple grants to support planning processes for creating immersive science and technology policy fellowship programs in state legislature. The Fellowship Program would provide the state legislature with non-partisan science PhDs to assist them in grappling with the complex issues of science underlying many legislative initiatives.

Andrew George and Dan Keeley, researchers in the Duke Biology PhD program, won their bid for North Carolina with support from Science & Society, the Sanford School for Public Policy, the Duke Government Affairs Office, and the North Carolina Sea Grant Program. George and Keeley are mentored by Drs. Dave Sherwood and Dave McClay respectively. Sherwood is co-director of Regeneration Next and McClay is a Regeneration Next-affiliated faculty member. For more information on the grant>

Five questions with Michel Bagnat


Michel Bagnat

In this second installment of the series “Five Questions With,” Sharlini Sankaran talked with Dr. Michel Bagnat, Associate Professor of Cell Biology, about his recently announced selection as a prestigious Howard Hughes Medical Institute (HHMI) Scholar.

What excites you about your work?
Our work takes many months and when you first plan the research, you don’t always know how things are going to pan out. I get excited when we plan things well in advance, and everything falls into place when you see your research design work exactly how you expected. I find it exciting to make new tools that may later enable researchers to discover new mechanisms of regeneration and healing.

In our work, we get to open new directions for research, and we often see things come together in ways we were not anticipating. For example, we started off pursuing projects that were seemingly unrelated in the notochord (the zebrafish equivalent of the spinal cord) and intestine. We discovered some basic commonalities in the way the notochord and the intestine develop – it is exciting to see that


A cross-section of a zebrafish gut (image courtesy Bagnat Lab)

many systems are related, and understanding one may help in understanding of other systems.

What interests you about this particular area of regenerative biology?
Many of the basic biological processes we study happen to play a role in regeneration. I was interested in looking at basic biological process such as fluid secretion in various parts of the body. We know that in the intestine for example, tubes transport and secrete fluid, but we found that the same process of fluid transportation is responsible for also opening the lumen (gut) during zebrafish development. Basically, these cells secrete fluid that generates hydrostatic pressure that “pushes” lumen opening to form an intestinal tube during development. Hydrostatic pressure within a structure causes it to open and expand – picture a water balloon filling up and expanding.

In the notochord a similar process also takes place within lysosomes, large fluid-filled structures inside cells. These fluid-filled structures in the notochord were so big and so “there” that nobody looked at them, sort of like the elephant in the room. We found that a similar process, where lysosomes use hydrostatic pressure to “push” cells during morphogenesis (development of shape and structure), is also responsible for developing the shape and form of the notochord and the long axis of the trunk. We know that certain cells of the intestine also contain lysosomes with similar structural and genetic properties, but in the intestine these lysosomes play a different role: they are involved in nutrition rather than in morphogenesis.

Tell me about the breakthrough discovery that led to the HHMI award.
HHMI tends to fund a very diverse set of projects and investigators. I really don’t know exactly which discovery led to the award, but I can say that our work is very different than what other researchers are doing and I am grateful for the award.

Why is this work important?
The connections and similarities that we find along the way are important – we learn from these connections and can use them to find genes and mutations that are related to a human disease or condition. For example, we were studying the defects of intestinal barrier function in zebrafish and found a mutation that was related to regulation of a protein call TNF (tumor necrosis factor). Regulation of TNF is known to be a factor in irritable bowel syndrome in humans, so we looked for similar mutations in patients – and we found them.

The same thing happened when we were looking at notochord formation. We didn’t start out looking for a connection to scoliosis, but we found one. When we started studying lysosomes in zebrafish notochords, we found that certain genetic mutations cause impaired lysosome functions which cause the spine to be kinked. This is similar to what happens in scoliosis in humans.  Of course, there are many other factors involved in scoliosis, but this finding brings us closer to an understanding of what could cause it.

What comes next for you?
Every time we look into a basic problem, we end up finding new ones. Our work in both areas has opened up new research questions we want to pursue further. The difficulty for us is that the research tools to enable the work we want to do are not there, and we have to make them as we go. I don’t think my lab has ever worked on anything that has already been established!

On one hand it is exciting and an advantage to be the first to accomplish something in the field. But on the other hand, it is harder to get other people excited about work that is so new.  I hope that as we progress in our work, other researchers will get excited and contribute to understanding of the connection between developmental processes, disease, and regeneration.

Five questions with Mayssa Mokalled


Dr. Mayssa Mokalled

We are beginning a new feature called “Five Questions” to highlight breakthrough research and achievements in regeneration research in Duke. Sharlini Sankaran talked with Dr. Mayssa Mokalled, a postdoctoral fellow in Ken Poss’ lab, about her newly-published paper in the journal Science.

1.       What excites you about your work?
How could the spinal cord be rebuilt after injury or disease? How could function be regained after paralysis?  Why can zebrafish regrow their spinal cord, but not mammals? These are the big questions that keep me excited about my work. At the same time, the experimental aspects of my work keep me excited on a day-to-day basis. Overall, I feel privileged that my research is truly my most favorite hobby. I enjoy having the intellectual freedom to ask the questions I am most excited about, the significance and potential applications of making biological discoveries, and the continually renewed excitement about the next questions.

A zebrafish spine in the process of self-healing. The green indicates the bridging glial cells during regeneration.

A zebrafish spine in the process of self-healing. The green indicates the bridging glial cells during regeneration.

2.       Tell me about why you chose to study zebrafish regeneration.
Having trained as a developmental biologist and mouse geneticist, I have a fascination for the questions and possible applications of tissue regeneration.  Intrigued by the uneven distribution of regenerative capacity across species, I decided to investigate a regenerative model system.  As a highly regenerative, vertebrate, genetic model organism, zebrafish were the obvious choice.  Joining the Poss lab was an unmatched opportunity to train in adult zebrafish regeneration. My long-term plan is to gain expertise and knowledge of the zebrafish model system to understand the bases for the differential regenerative capacity between zebrafish and mammals.

3.       Briefly describe your breakthrough discovery that led to the publication of this paper.
Our goal is to explore what enables spinal cord regeneration in zebrafish. To do this, we identified the connective tissue growth factor (ctgfa) gene, and activated it in zebrafish with complete spinal transections.  Characterizing the expression and function of ctgfa during spinal cord regeneration revealed a number of findings that led to the publication of this paper. We found that ctgfa expression marks the bridging glial cells that connect the severed cord. Functionally, ctgfa is a pro-regenerative factor that is necessary and sufficient to stimulate regeneration and functional recovery after spinal cord injury.

4.       Why is this discovery important to the field of Regenerative Biology?
Developing means to treat and reverse spinal cord injury is a pressing need in regenerative medicine. Zebrafish glial cells display a unique, yet poorly understood, bridging response that could account for their remarkable regenerative capacity. Our findings present a major step towards understanding the mechanisms of glial bridging.  We generated fundamental discoveries about how zebrafish regrow their spinal cord – we now have a model that we can use to further explore how to boost the regenerative potential of the mammalian spinal cord.

5.       What comes next in this research?
Our findings stimulated a number of directions that we are eager to pursue. In the course of our work, we generated unique tools to further investigate the mechanisms of spinal cord bridging in zebrafish.  A natural future direction for our study is to characterize the expression and function of the ctgf gene after mammalian spinal cord injury.  Identifying the type of glial cells that can produce CTGF or are competent to respond to it could inform new methods to repair the mammalian spinal cord after injury.

Mayssa’s work has been featured in international news outlets and science blogs. Read more about this groundbreaking work here and here.

Sherwood named co-director of Woods Hole Embryology Course

David-Sherwood-copy1Regeneration Next Co-Director Dr. Dave Sherwood has been appointed as one of the new co-directors for the Embryology Course at the Marine Biological Laboratory at Woods Hole, Massachusetts. The course is an intensive six-week laboratory and lecture format for advanced graduate students, postdoctoral fellows, and more senior researchers who seek a broad and balanced view of the modern issues of developmental biology. Along with University of California-San Francisco’s Dr. Rich Schneider, Dave will co-lead the course six weeks each summer for the next five years.

The Woods Hole Embryology course was founded in 1893 and has been going strong for over 120 years— before the digital age, through both world wars, and the turn of two new centuries! It is the oldest lab course in the United States and is world renowned. Well over half of the students are from other countries. Dave says, “It’s a huge honor for me to be appointed as a co-director, and it further elevates Duke’s reputation as a leader in developmental biology.”




Mouse vouchers: deadline extended to Nov 4

house_mouseThe deadline to apply for the Regeneration Next Mouse Vouchers has been extended to 11:59 pm, Nov 4th. This new voucher program is aimed at stimulating new research reagent creation at Duke by subsidizing creation of transgenic or genetically modified mouse strains. We will be offering vouchers of up to $5,000 to Duke investigators for this purpose. Full callout>

Researchers identify protein that may regulate microcephaly in mammals


Dr. Debby Silver (R) participates in a panel session on Communicating your Science during the Regeneration Next annual retreat.

Dr. Debby Silver, a faculty member in the department of Molecular Genetics and Microbiology, studies neural stem cells of the developing brain as well as causes of small brain size (micocephaly) in mammals. Microcephaly causes stunted brain development and intellectual disabilities, for example in some babies with rare genetic disorders and in babies born to mothers who have been exposed to the Zika virus. Researchers like Dr. Silver are getting closer to pinpointing what genes and proteins control development of neurons during the early stages of brain development in embryos. Dr. Silver and her colleagues recently published a paper in the journal PLOS Genetics that examines how mutation of three genes cause microcephaly in mammals.

Dr. Silver and colleagues found that mice embryos that are lacking any of these three genes develop microcephaly. Further, they found that there is a common protein called p53, that is over-abundant in mice lacking the three key genes that regulate neuron development. By removing p53 in each of the 3 mouse mutants, the researchers were able to partially rescue  the microcephaly. They predict that p53 signaling plays a role in stem cell divisions, causing many of the stem cells that will become neurons to die out. Having too few stem cells in turn results in fewer brain cells, and thus, microcephaly.

This discovery gets us closer to understanding the mechanisms that are key to brain development in the early stages of pregnancy, and may provide a key to future in utero treatments to prevent microcephaly in some babies. Read more on Debby’s work here:

Space: The Cardiac Frontier

A guest post by Arun Sharma


Arun Sharma speaks at a NASA press conference. (Photo credit: NASA/Kim Shiflett)

My passions for the very large (outer space) and the very small (stem cells) came together in ways that I could have never predicted this summer when I sent patient-specific, beating human heart cells, to the International Space Station aboard a SpaceX Falcon 9 rocket. As mankind spends more time in space, with the imminent goal of traveling to Mars, we need to better understand how human cells function in a nearly weightless, or microgravity, environment. Recent scientific advances have made it possible to mass-produce long-lasting, stable human heart muscle cells (cardiomyocytes). My colleagues and I have spent several years working to generate these cells from stem cells, and our efforts paid off when we recently sent a sample of cardiomyocytes to the International Space Station to study cardiac function.

My interest in cardiovascular regenerative medicine was born when I was an undergraduate student at Duke University, after learning about the work being conducted in the labs of Dr. Ken Poss and Dr. Gerry Blobe. I devoted myself to cardiovascular regenerative medicine, trying to understand ways that the human heart might be able to restore lost cells similarly to how a zebrafish can regrow heart muscle. At Duke, I was fascinated to learn about induced pluripotent stem cells (iPSCs), a type of stem cell derived directly from adult cells. I could see the potential that these cells hold to treat cardiovascular disease. At the Harvard Stem Cell Institute’s summer internship program, I got my first hands-on experience with making beating cardiomyocytes from iPSCs.

My summer stem cell experience, while exhilarating, left me thirsting for more. So, I enrolled in the Stanford University’s new PhD program in Stem Cell Biology and Regenerative medicine. Over the past four years at Stanford, I have devoted my scientific studies to making stable, long-lasting cardiomyocytes from iPSCs. With this new cell system, we can better model cellular changes in the human cardiomyocyte’s response to microgravity.

Astronaut Dr. Kate Rubins changes nutrients for space-flown iPSC-CMs. (Photo credit: Arun Sharma)

Astronaut Dr. Kate Rubins changes nutrients for space-flown iPSC-CMs. (Photo credit: Arun Sharma)

In the past few months, I have had the chance to interact with astronauts, aerospace engineers, and fellow biologists, all of whom are passionate about space science and understanding how the human body functions in space. With the aid of biologist and astronaut Dr. Kate Rubins, who is currently aboard the International Space Station, we have been able to examine iPSC-cardiomyocyte changes in form and beating rate using short video clips taken aboard the station’s light microscopy module. Dr. Rubins also preserved a small sample of cells for gene expression analysis and “fed” the cells to keep them healthy. Another sample of cells was recently returned to us alive, and I’m happy to say, they are still beating. Heart cells are certainly tough, even in the face of adverse conditions such as low gravity!

We are very excited to see what our further analyses of these space-flown heart cells will reveal. Our studies may uncover novel insight into how the heart functions in a unique environment such as microgravity, and hopefully, our work can aid humanity as it pushes further into the stars. Ultimately, my experience this summer would not have been possible without the opportunities I had at Duke almost a decade ago that led me down the path towards a career in regenerative medicine. The sky is not the limit for regenerative medicine at Duke University!

Beating heart cells aboard the International Space Station (Courtesy Arun Sharma)

Beating heart cells aboard the International Space Station (Courtesy Arun Sharma; click to play)

Arun Sharma (Duke Trinity Class of 2012) holds the BS from Duke University and is currently a PhD student at the Stanford University Stem Cell Biology and Regenerative Medicine program under the mentorship of Drs Sean Wu and Joseph Wu. He is a graduate of the Harvard Stem Cell Institute’s Summer internship program.

Waves of chemical activity influence fruitfly embryo development


Images of the fruitfly embryo showing waves of cell differentiation. Credit: Stefano DiTalia

Scientists have discovered that traveling “waves” of chemicals can quickly transfer information from cell to cell in a synchronized way. These synchronized waves of protein activity are emerging as an important form of cell communication that regulates embryonic development. These waves are also involved in adult cell functions, such as heart contractions and in the transmission of signals in the brain.

However, very few scientists have been able to image, quantify and mathematically describe these waves. In a recent paper, Duke University assistant professor Stefano Di Talia, Ph.D. student Victoria Deneke, and colleagues did just that. They show that waves of protein activity that spread across the fruit fly embryo synchronize its rapid cellular divisions. When they introduced a physical barrier halfway along the embryo, the wave of division did not go through the barrier, demonstrating that the activity is dependent on a signal that diffuses through the embryo. The behavior of stem cells must be coordinated across the whole tissue or organ for maintaining stability.

Their findings may hold the key to understanding how and when cells communicate during different stages of tissue development, and may be important to help understand how cells behave during tissue repair and regrowth. This finding may even lead to a better future understanding of why cancerous cells are not stable and multiply so rapidly. The paper was published in Developmental Cell on August 22nd, 2016. Read it here: