Strange K.,MDI Biological Laboratory
ILAR Journal | Year: 2016
Nonmammalian model organisms such as the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the zebrafish Danio rerio provide numerous experimental advantages for drug discovery including genetic and molecular tractability, amenability to high-throughput screening methods and reduced experimental costs and increased experimental throughput compared to traditional mammalian models. An interdisciplinary approach that strategically combines the study of nonmammalian and mammalian animal models with diverse experimental tools has and will continue to provide deep molecular and genetic understanding of human disease and will significantly enhance the discovery and application of new therapies to treat those diseases. This review will provide an overview of C. elegans, Drosophila, and zebrafish biology and husbandry and will discuss how these models are being used for phenotype-based drug screening and for identification of drug targets and mechanisms of action. The review will also describe how these and other nonmammalian model organisms are uniquely suited for the discovery of drug-based regenerative medicine therapies. © The Author 2016.
Lisse T.S.,MDI Biological Laboratory |
Lisse T.S.,The Jackson Laboratory |
Rieger S.,MDI Biological Laboratory
Journal of Cell Science | Year: 2017
Although the functions of H2O2 in epidermal wound repair are conserved throughout evolution, the underlying signaling mechanisms are largely unknown. In this study we used human keratinocytes (HEK001) to investigate H2O2-dependent wound repair mechanisms. Scratch wounding led to H2O2 production in two or three cell layers at the wound margin within ~30 min and subsequent cysteine modification of proteins via sulfenylation. Intriguingly, exogenous H2O2 treatment resulted in preferential sulfenylation of keratinocytes that adopted a migratory phenotype and detached from neighboring cells, suggesting that one of the primary functions of H2O2 is to stimulate signaling factors involved in cell migration. Based on previous findings that revealed epidermal growth factor receptor (EGFR) involvement in H2O2-dependent cell migration, we analyzed oxidation of a candidate upstream target, the inhibitor of κB kinase α (IKKα encoded by CHUK), as a mechanism of action. We show that IKKα is sulfenylated at a conserved cysteine residue in the kinase domain, which correlates with de-repression of EGF promoter activity and increased EGF expression. Thus, this indicates that IKKa promotes migration through dynamic interactions with the EGF promoter depending on the redox state within cells.
News Article | May 23, 2017
Cut off the head of a planarian flatworm, and a new one will grow in its place. The worm is one of many creatures that have some kind of memory for lost limbs, enabling them to regenerate what was there before. Now it seems that this memory can be altered by meddling with the electrical activity of the animals’ cells. Shifting the bioelectric current at the site of the cut changes the type of appendage regenerated – allowing a head to be regrown in place of a tail, for instance. Michael Levin at Tufts University in Medford, Massachusetts, and his colleagues have shown that after changing the electrical current of the cells once, the animals will continue to randomly regrow a head or a tail. The findings suggest that an animal’s body plan is not just down to its genes and environment – electricity plays a key role, too. “It’s pretty profound,” says Levin. His team has long been trying to understand how electric currents in the body’s cells affect health and the ability to regenerate damaged tissues – what Levin calls the “bioelectric code”. Charged ions are constantly moving in and out of cells, giving cells a natural electrical charge. The patterns of electrical activity are thought to have an important role in controlling how embryos develop limbs. Levin wants to find out whether they might work in adult animals – and potentially humans – too. Drugs, including commonly used anaesthetics, can destabilise the electrical charge of cells. In a recent experiment, Levin’s team took this approach to see if altering the electrical charge in worms that had had their heads and their tails cut off might encourage them to grow two heads or tails instead of one head and one tail. The team found that about 70 per cent of the worms regrew a second tail or head instead of the “correct” body part. The rest appeared to be unaffected. To probe further, Levin’s student Fallon Durant re-cut the worms that had regenerated the normal body part without giving them any other treatment. She saw the same trend – 70 per cent regrew the wrong part, while 30 per cent looked the same as they had originally. The team repeated the experiment, and saw the same outcome over and over again. After destabilising a worm’s electrical current once, it is as if each end of the worm makes its own decision – with a preference for the wrong part – as to whether it will develop a head or a tail whenever it is cut, says Levin. By altering the bioelectric code, the animal’s body plan can be permanently rewritten, he says. “A totally normal-looking worm with a normal gene expression and stem cell distribution can in fact be harbouring a [body plan] that’s quite different,” says Levin. “That information is stored in a bioelectric pattern – it’s not in the distribution of tissues or stem cells, it’s electrical.” “It’s provocative,” says Voot Yin at the MDI Biological Laboratory in Bar Harbor, Maine. The findings suggest that electrical changes might somehow change the way genes work, he says. The next step would be to test the approach in a mammal that can regenerate to the same extent as humans. Mice and humans are both able to regrow a small amount of a digit – such as a finger – if it is cut off. “We could see if we could boost mouse digit regeneration,” says Yin. On the other hand, the approach might also trigger the growth of other tissues at the mouse’s paw, such as a tail. “It is likely to trigger more unexpected changes,” says Yin. Levin hopes his findings might one day be useful in human health. People react differently to medicines and diseases – perhaps the electrical currents in our cells play a role in this variation, he says. Read more: I’m cracking the code to regrow human limbs; Cancer reversed in cells by hacking cells’ electricity with light; Grow with the flow: How electricity kicks life into shape
News Article | April 28, 2017
BAR HARBOR, MAINE -- The MDI Biological Laboratory has announced that Sandra Rieger, Ph.D., has been awarded a highly competitive grant from the National Cancer Institute, an institute of the National Institutes of Health (NIH), to study the molecular mechanisms underlying chemotherapy-induced peripheral neuropathy, a side effect of cancer chemotherapy causing symptoms such as pain, tingling, temperature sensitivity and numbness in the extremities. The grant will allow Rieger to continue her research on peripheral neuropathy caused by Taxol (paclitaxel), a chemotherapy agent used in the treatment of ovarian, breast, lung, pancreatic and other cancers. About 60 to 70 percent of patients receiving Taxol experience peripheral neuropathy. In severe cases, patients may be forced to reduce or curtail treatment, which deprives them of cancer treatment and may decrease chances of survival. Rieger's research also has potential applications in the treatment of peripheral neuropathies caused by other conditions, including diabetes, aging and antibiotic treatment. Neuropathy is a general term for peripheral nerve degeneration, which is believed to affect at least 20 million Americans, with some estimates as high as 40 million. No treatments are currently available, other than for symptoms such as pain. "This grant is an acknowledgement of the importance of Dr. Rieger's research," said Kevin Strange, Ph.D. president of the MDI Biological Laboratory. "Peripheral neuropathy is much more common than generally believed. Her research on the underlying molecular mechanisms of nerve regeneration opens the door to the development of new drug therapies to help the millions who suffer from this potentially debilitating condition." The five-year grant, which takes effect July 1, totals approximately $1.8 million over five years, with additional funding for facilities and administrative costs. The grant will fund Rieger's continuing research in the zebrafish and research with neurologist Nathan P. Staff, M.D., Ph.D. on skin samples from breast cancer patients undergoing Taxol treatment at the Mayo Clinic in Rochester, Minn. The research at the Mayo Clinic, which will take place over the first two years of the grant, will seek to determine if the same mechanisms that underlie Taxol-induced peripheral neuropathy in zebrafish are also linked to the condition in humans. "The research with Dr. Staff at the Mayo Clinic is the first step to developing a drug therapy to treat peripheral neuropathy in humans," Rieger said. "That's my major interest -- finding a therapy to cure this condition." The grant will allow Rieger to build on earlier research showing that Taxol-induced peripheral neuropathy is linked to the increased activity of a matrix-degrading enzyme, matrix metalloproteinase-13, or MMP-13, in the skin. The increase in MMP-13 activity leads to decreased skin resistance and the degeneration of sensory nerve endings, which in turn causes the symptoms of peripheral neuropathy. Rieger has also discovered two compounds that prevent or reverse chemotherapy-induced peripheral neuropathy in zebrafish by inhibiting the activity of MMP-13. The compounds are the subject of a provisional patent filed last year by the MDI Biological Laboratory for their use in the treatment of chemotherapy- and diabetes-induced peripheral neuropathy. The compounds have yet to be tested in humans. The ability offered by the grant to gain a deeper understanding of the mechanisms underlying peripheral neuropathy raises the prospect that other MMP-inhibiting drugs can be developed to treat peripheral neuropathy. Our scientists are pioneering new approaches to regenerative medicine focused on drugs that activate our natural ability to heal, and that slow age-related degenerative changes. Our unique approach has identified new drugs with the potential to treat major diseases, demonstrating that regeneration could be as simple as taking a pill. As innovators and entrepreneurs, we also teach what we know. Our Center for Science Entrepreneurship prepares students for 21st century careers and equips entrepreneurs with the skills and resources to turn great ideas into successful products. For more information, please visit mdibl.org.
News Article | February 16, 2017
BAR HARBOR, MAINE -- Scientists have known for decades that drastically restricting certain nutrients without causing malnutrition prolongs health and lifespan in a wide range of species, but the molecular mechanisms underlying this effect have remained a mystery. In a paper recently published in the journal Aging Cell, MDI Biological Laboratory scientist Aric Rogers, Ph.D., sheds light on an important genetic pathway underlying this process, raising the possibility that therapies can be developed that prolong the healthy years without having to suffering the consequences of a severely restricted diet. "It's tantalizing to think that we might be able to activate a protective response to enhance our own health without resorting to extreme dietary regimes," Rogers said. Rogers studies mechanisms important to the positive effects of dietary restriction in an intact organism -- the tiny roundworm, C. elegans -- as opposed to cells in a petri dish. C. elegans is an important model in aging research because it shares nearly half of its genes with humans and because of its short lifespan -- it lives for only two to three weeks -- which allows scientists to study many generations over a short period of time. "Aric's identification of a molecular mechanism governing the life-prolonging effects of dietary restriction is a validation of our unique approach to research in aging and regenerative biology," said Kevin Strange, Ph.D., president of the MDI Biological Laboratory. "Our use of whole organisms as research models provides greater insight into the many factors controlling physiological processes than the use of cells alone." Rogers studies the molecular mechanisms underlying aging at the MDI Biological Laboratory's Kathryn W. Davis Center for Regenerative Biology and Medicine. The laboratory is an independent, non-profit biomedical research institution located in Bar Harbor, Maine, focused on increasing healthy lifespan and increasing the body's natural ability to repair and regenerate tissues damaged by injury or disease. The life-prolonging effects of dietary restriction, also known as DR or CR (calorie restriction), occur in just about every animal tested. They are thought to be an evolutionary adaptation to harsh environmental conditions. In the absence of enough food to eat, evolution has programmed organisms to switch from a growth mode to a survival mode so they can live long enough to reproduce when conditions improve. The new study builds on Rogers' earlier research linking the effects of DR to the inhibition of genes governing the formation of proteins. In times of hardship, the body cuts back on the bulk of proteins synthesized, which are linked with growth and reproduction, in order to redirect the cell's energy toward stress-responsive proteins that help extend lifespan by maintaining cell balance and health. Specifically, the study found that the enhanced robustness associated with reducing the production of protein isn't from reduced protein synthesis per se, rather to the triggering of a stress response governing protein homeostasis -- or proteostasis -- a fancy word for the cell's quality control machinery. The stress response ensures that this quality control machinery keeps working optimally, despite harsh environmental conditions. The cell's quality control machinery is responsible for ensuring that newly synthesized proteins are properly shaped and that damaged proteins are quickly destroyed. Misshapen and damaged proteins can interfere with cell function, leading to disease and death. The identification of a mechanism underlying the protective effect of DR could lead to therapies for age-related diseases, including Alzheimer's and Parkinson's, that are associated with diminished cellular quality control. Alzheimer's, for instance, is associated with the build-up of a toxic protein, beta amyloid, in the brain, and Parkinson's with a build-up of a toxic protein called alpha synuclein. The link between aging and weakened cellular "housekeeping" functions raises the possibility that new drugs to prolong lifespan could also delay the onset of age-related degenerative diseases. Now that Rogers has identified a link, the next step is to investigate cause and effect by manipulating the genetic pathways that inhibit protein formation to see if the body's ability to clear molecular clutter is improved. "We think therapies to activate these protective pathways could not only prolong lifespan, but also delay the onset of age-related diseases," Rogers said. "Most older people suffer from multiple chronic diseases. Anti-aging procedures applied to disease models almost always delay disease onset and improve outcomes, which suggests that disease-suppressing benefits may be accessed to extend healthy human lifespan." Our scientists are pioneering new approaches to regenerative medicine focused on drugs that activate our natural ability to heal, and that slow age-related degenerative changes. Our unique approach has identified new drugs with the potential to treat major diseases, demonstrating that regeneration could be as simple as taking a pill. As innovators and entrepreneurs, we also teach what we know. Our new Center for Science Entrepreneurship prepares students for 21st century careers and equips entrepreneurs with the skills and resources to turn great ideas into successful products. For more information, please visit mdibl.org.
Henter H.J.,University of California at San Diego |
Imondi R.,Coastal Marine Biolabs |
James K.,MDI Biological Laboratory |
Spencer D.,Tulsa Community College |
Steinke D.,University of Guelph
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2016
Despite 250 years of modern taxonomy, there remains a large biodiversity knowledge gap. Most species remain unknown to science. DNA barcoding can help address this gap and has been used in a variety of educational contexts to incorporate original research into school curricula and informal education programmes. A growing body of evidence suggests that actively conducting research increases student engagement and retention in science. We describe case studies in five different educational settings in Canada and the USA: a programme for primary and secondary school students (ages 5-18), a year-long professional development programme for secondary school teachers, projects embedding this research into courses in a post-secondary 2-year institution and a degree-granting university, and a citizen science project. We argue that these projects are successful because the scientific content is authentic and compelling, DNA barcoding is conceptually and technically straightforward, the workflow is adaptable to a variety of situations, and online tools exist that allow participants to contribute high-quality data to the international research effort. Evidence of success includes the broad adoption of these programmes and assessment results demonstrating that participants are gaining both knowledge and confidence. There are exciting opportunities for coordination among educational projects in the future. © 2016 The Authors.
Bodnar A.G.,Bermuda Institute of Ocean Sciences |
Coffman J.A.,MDI Biological Laboratory
Aging Cell | Year: 2016
Aging in many animals is characterized by a failure to maintain tissue homeostasis and the loss of regenerative capacity. In this study, the ability to maintain tissue homeostasis and regenerative potential was investigated in sea urchins, a novel model to study longevity and negligible senescence. Sea urchins grow indeterminately, regenerate damaged appendages and reproduce throughout their lifespan and yet different species are reported to have very different life expectancies (ranging from 4 to more than 100 years). Quantitative analyses of cell proliferation and apoptosis indicated a low level of cell turnover in tissues of young and old sea urchins of species with different lifespans (Lytechinus variegatus, Strongylocentrotus purpuratus and Mesocentrotus franciscanus). The ability to regenerate damaged tissue was maintained with age as assessed by the regrowth of amputated spines and tube feet (motor and sensory appendages). Expression of genes involved in cell proliferation (pcna), telomere maintenance (tert) and multipotency (seawi and vasa) was maintained with age in somatic tissues. Immunolocalization of the Vasa protein to areas of the tube feet, spines, radial nerve, esophagus and a sub-population of circulating coelomocytes suggests the presence of multipotent cells that may play a role in normal tissue homeostasis and the regenerative potential of external appendages. The results indicate that regenerative potential was maintained with age regardless of lifespan, contrary to the expectation that shorter lived species would invest less in maintenance and repair. © 2016 The Anatomical Society and John Wiley & Sons Ltd.
Hartig E.I.,MDI Biological Laboratory |
Zhu S.,MDI Biological Laboratory |
King B.L.,MDI Biological Laboratory |
Coffman J.A.,MDI Biological Laboratory
Biology Open | Year: 2016
Chronic early-life stress increases adult susceptibility to numerous health problems linked to chronic inflammation. One way that this may occur is via glucocorticoid-induced developmental programming. To gain insight into such programming we treated zebrafish embryos with cortisol and examined the effects on both larvae and adults. Treated larvae had elevated whole-body cortisol and glucocorticoid signaling, and upregulated genes associated with defense response and immune system processes. In adulthood the treated fish maintained elevated basal cortisol levels in the absence of exogenous cortisol, and constitutively mis-expressed genes involved in defense response and its regulation. Adults derived from cortisol-treated embryos displayed defective tailfin regeneration, heightened basal expression of proinflammatory genes, and failure to appropriately regulate those genes following injury or immunological challenge. These results support the hypothesis that chronically elevated glucocorticoid signaling early in life directs development of a pro-inflammatory adult phenotype, at the expense of immunoregulation and somatic regenerative capacity. © 2016. Published by The Company of Biologists Ltd.
Arenas-Mena C.,CUNY - College of Staten Island |
Coffman J.A.,MDI Biological Laboratory
Developmental Dynamics | Year: 2015
It is proposed that the evolution of complex animals required repressive genetic mechanisms for controlling the transcriptional and proliferative potency of cells. Unicellular organisms are transcriptionally potent, able to express their full genetic complement as the need arises through their life cycle, whereas differentiated cells of multicellular organisms can only express a fraction of their genomic potential. Likewise, whereas cell proliferation in unicellular organisms is primarily limited by nutrient availability, cell proliferation in multicellular organisms is developmentally regulated. Repressive genetic controls limiting the potency of cells at the end of ontogeny would have stabilized the gene expression states of differentiated cells and prevented disruptive proliferation, allowing the emergence of diverse cell types and functional shapes. We propose that distal cis-regulatory elements represent the primary innovations that set the stage for the evolution of developmental gene regulatory networks and the repressive control of key multipotency and cell-cycle control genes. The testable prediction of this model is that the genomes of extant animals, unlike those of our unicellular relatives, encode gene regulatory circuits dedicated to the developmental control of transcriptional and proliferative potency. © 2015 Wiley Periodicals, Inc.