The application process for the 2009 Young Investigator Award program is NOW OPEN! Please note the deadlines below for the pre-application and full application. Be sure to carefully read the FULL RFA for updates to the YIA program.
2010 YIA Pre-Application - due February 5, 2010
(please email electronic version with signature to Min Wong at
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by 5PM EST.) 2010 YIA Full Application - due March 5, 2010
From Schwannomatosis Genes to New NF1 and NF2 Drug Therapies
Postdoctoral Awardees
Jody Fromm, Ph.D., Harvard Medical School/Brigham and Women’s Hospital To determine the therapeutic effects of combined sunitinib and rapamycin treatment on MPNSTs in a genetically engineered mouse model
The primary clinical feature of NF1 is the development of benign tumors in the nerve tissue, classified as either dermal or plexiform. Whereas dermal tumors develop progressively throughout life and are relatively small, plexiform tumors can form before birth, can grow to be quite large, and can develop into malignant peripheral nerve sheath tumors (MPNSTs). Those tumors that can be surgically removed unfortunately often regrow, and despite radiation and, in some cases chemotherapy, inoperable MPNSTs progress rapidly and are typically lethal; therefore identifying an effective alternative treatment for these tumors is critical. Previous studies carried out by Dr. Fromm’s lab revealed that human MPNST cells are extremely sensitive to mTOR inhibitors, such as rapamycin, which immediately halts tumor growth and prolongs the survival of a genetically engineered MPNST mouse model. However, as would be predicted from studies with other targeted therapies, they also found that the tumors in their mouse model ultimately become resistant to mTOR inhibitors. The present study will therefore take two distinct approaches to develop more effective combination therapies. First, Dr. Fromm proposes to investigate the mechanism by which tumors re-establish their blood vessel network after treatment with rapamycin and assess the therapeutic effects of anti-angiogenic agents in combination with rapamycin in vivo. Second, she will evaluate the mechanisms of rapamycin resistance by compiling gene expression profiles of pro-angiogenic factors in sensitive and resistant tumors. The findings from this study will hopefully develop into effective therapies for NF1 patients.
Wei Li, Ph.D., Memorial Sloan-Kettering Cancer Center Role of Merlin in the nucleus during tumor suppression
NF2 is a disorder characterized by the growth of tumors in the nervous system, and symptoms often manifest at an early age. Most of the tumors originate from Schwann cells, which surround and insulate nerve cells, but while local surgery and radiation are the primary treatments, they carry the risk of damaging the central nervous system. Determining the molecular pathology of this disorder would therefore help in the discovery of novel therapeutic approaches at the molecular level. This study seeks to understand how the absence of the Merlin protein, produced by the Neurofibromatosis type 2 (Nf2) gene, induces Schwann cells to overproliferate and to give rise to tumors. Although the exact molecular function of Merlin remains unknown, it is involved in controlling cell growth and division, cell movement, cell shape, and communication between cells. Additionally, Dr. Li’s laboratory recently discovered that Merlin interacts with and inhibits a novel E3 ubiquitin ligase, an enzyme found in cell nuclei. Members of this ligase family usually regulate protein functions and degradation, so our studies indicate that inhibition of this ligase is important to Merlin-mediated growth inhibition and tumor suppression. The goal of this research is to further study the role of Merlin in the nucleus during tumor suppression so as to provide a new horizon for understanding the mechanism by which Merlin suppresses tumorigenesis and to contribute to the development of new and more effective therapies for NF2.
Arkadiusz Piotrowski, Ph.D., University of Alabama at Birmingham DNA methylation and subchromosomal structural rearrangements as contributing causal factors in schwannomatosis
Point mutations, or single base pair changes in DNA, affecting the INI1 gene have recently been implicated as causal factors of Schwannomatosis; however, most phenotypic manifestations of this disorder have not been associated with specific point mutations in INI1. Furthermore, complete inactivation of INI1 is either lethal or leads to diseases different from Schwannomatosis. Structural rearrangements, i.e. losses or multiplications of segments in the human genome, are possible yet unexplored components that may decrease or increase activity of the INI1 gene and other genomic regions implicated in Schwannomatosis. Another factor that may lead to similar effects is DNA methylation. Methylation is an epigenetic alteration, which means modification of DNA without actual change in DNA sequence. Both structural rearrangements and DNA methylation may affect activity of genes in a subtle way that is required in the development of the disease. In order to address this issue, Dr. Piotrowski has designed experimental assays based on custom microarrays and complementary techniques, which his lab successfully validated in previous studies. These tools have been further tailored specifically to suit the analysis of Schwannomatosis-associated genes and genomic regions on chromosome 22. Finally, using genome-wide array-CGH, they will test the alternative hypothesis that there exist regions outside of chromosome 22 in the human genome that harbor deletions and/or duplications of genetic material that may contribute to the pathogenesis of Schwannomatosis. In the current project, Dr. Piotrowski plans to test the hypothesis of the involvement of DNA methylation and small structural rearrangements as contributing causal factors in Schwannomatosis.
Chunling Yi, Ph.D., The Wistar Institute Development of novel targets and therapeutics for the treatment of NF2
NF2 is caused by mutations of the Nf2 gene, which encodes a protein called Merlin. Merlin negatively regulates signaling by Rac/Ras, small proteins that control a wide array of cellular processes, including cell growth, by inhibiting Pak, a downstream signaling protein in the Rac/Ras pathway. Dr. Yi’s lab has recently shown that Pak is abnormally activated in schwannoma samples from NF2 patients and that Pak serves as a viable therapeutic target for NF2. In a collaboration effort, they have successfully developed highly specific and potent small-molecule Pak inhibitors. The first part of this proposal is aimed at further improving the specificity and potency of the Pak inhibitors and testing them in cellular and animal models of NF2. Should these inhibitors prove to alleviate tumor development in animal models, it would provide a novel therapeutic modality for NF2 patients. While Pak inhibitors show great promise, available evidence indicates that Merlin may target additional proteins within the cell. To identify new Merlin targets, preliminary studies were undertaken and resulted in the purification of a novel protein complex that is comprised of Merlin and associated proteins angiomotin, patj, and pals1. This preliminary study suggests that angiomotin also functions as a modulator of Rac signaling. The second half of this proposal will be devoted to the further investigation of the role of Merlin-angiomotin complex in cell signaling and schwannoma development. Taken together, these studies should provide novel compounds for development as therapeutics and should significantly further understanding regarding the disease mechanism of NF2.
Pre-Doctoral Awardee
Ana Oliveira, Duke University Medical Center The role of neurofibromin in spine morphology and plasticity
Learning disabilities are common in children with Neurofibromatosis type 1 (NF1), and these severely reduce the quality of life of many patients; however, the pathogenic process for NF1-associated learning disabilities has not been fully understood. The goal of this study, therefore, is to understand the role of Neurofibromin, the protein encoded by the Nf1 gene, in synaptic plasticity, the cellular basis of learning and memory. Neurofibromin regulates a protein called Ras, which is known for its role in initiating cell proliferation, but in NF1, Neurofibromin is mutated and cannot perform its normal function. The learning deficits in an animal model of NF1 are caused by the hyper-activation of Ras. This study will focus specifically on the role of Neurofibromin on Ras signaling in dendritic spines, protrusions from a neuron’s dendrites that receive input and transmit signals to the cell body of the neuron. Ras activation induced by NMDA receptors in dendritic spines is required for many forms of synaptic plasticity including long-term potentiation (LTP) and the formation of synapses. Because neurons communicate via synapses, and because it is believed that memory is stored in these synapses, LTP, which signifies enduring improvement in interneural communication, is considered to be a major mechanism of learning. Given that Neurofibromin is accumulated in dendritic spines and interacts with NMDA receptors, our central hypothesis is that Neurofibromin is important for the regulation of the NMDA receptor–Ras pathway in dendritic spines, and can thereby regulate the morphological and functional plasticity of dendritic spines. This project is expected to elucidate the molecular mechanisms of impaired synaptic plasticity and learning due to reduced level of Neurofibromin, and hopefully to facilitate the development of new therapeutics for ameliorating the learning disability of NF1 patients.
2008 Young Investigator Award Recipients
Postdoctoral Awardees
Sutapa Banerjee, Ph.D., Washington University School of Medicine Regulation and role of mTOR in neurofibromin growth control
Neurofibromatosis 1 (NF1) is a common cancer predisposition syndrome in which affected individuals are prone to the development of both benign and malignant tumors. In this regard, 15-20% of children with NF1 will develop a brain tumor involving the nerve that carries visual information from the eye to the brain (optic glioma). Studies from the awardees laboratory and others have shown that the NF1 protein, neurofibromin, controls the activity of the mammalian target of rapamycin (mTOR) molecule. It was recently shown that inhibition of mTOR activity in Nf1 mice with optic glioma results in tumor shrinkage. The overall objective of this proposal is to understand how neurofibromin controls mTOR pathway-mediated cell growth in vitro and in vivo. Specifically, Dr. Banerjee plans to determine precisely how mTOR activity is controlled by neurofibromin and how neurofibromin-mediated mTOR pathway activation controls the cancer-related properties of brain cells. These studies are aimed at defining the mechanism underlying neurofibromin growth control relevant to the design of more specific treatments for NF1-associated tumors.
Johanna Buchstaller, Ph.D., University of Michigan Tumor initiating cells in MPNSTs
About 10% of patients with NF1 develop malignant peripheral nerve sheath tumors (MPNSTs), soft tissue sarcomas, which are very aggressive and often withstand chemo- and radiotherapy. The awardee’s research group recently showed that plexiform neurofibromas and MPNSTs appear to arise from mature cells found in the nerve bundles of peripheral nerves. The goal for this project is to identify which cells within the tumor drive tumor growth. Previous studies have shown that brain tumor growth is driven by a small minority of cells, whereas the majority of cells within the tumor remain quiescent. This has led to idea that fighting this small subset of cells during cancer therapy might be sufficient to eliminate the cancer. The applicant wants to know if this also applies to MPNSTs and she is going to investigate this issue on mouse models of the disease and human tissue samples obtained by collaborating with the University of Michigan hospital. Preliminary results suggest that a high proportion of cells isolated from MPNSTs are responsible for tumor growth, suggesting that in these cancers all cells are equally able to grow and that tumor therapy will need to target and eliminate all cells. These results now need to be confirmed in a larger number of samples. Additionally, Dr. Buchstaller would like to find out why the tumor cells have the capacity to grow indefinitely. High mobility group a2 (Hmga2) is a molecule that is found in MPNST cells, but not in normal nerve tissue. The applicant will investigate the role of Hmga2 by monitoring tumor development and growth in mice deficient for Hmga2. If fewer and smaller tumors arise in these mice, this suggests that Hmga2 plays a role MPNST growth and that cell signaling pathways involving this molecule might be suitable targets for tumor therapy.
Annabel Parret, Ph.D, EMBL, Heidelberg, Germany Structure determination of neurofibromin by cryo-electron microscopy
NF1 is caused by alterations of a gene encoding a huge protein called neurofibromin that fulfills vital cellular functions and if not functional contributes to the symptoms of NF1, including learning disabilities and cancer related features. Previous work using structural investigation has already contributed and understanding how neurofibromin regulates intracellular signal transduction in order to avoid permanent activation of the cell division machinery and also the discovery of a novel two-component module in the protein whose presence was not detected by other research methods. The 3-dimensional organization of domains within neurofibromin is not known nor the shape of the unknown portions of the protein. One reason for this lack of knowledge is the fact that the full neurofibromin could not be routinely produced for biochemical or structural studies for a long time. The host laboratory has recently succeeded to solve this problem by using modern protein production tools along with the power of modern gene synthesis in vitro. In this study, Dr. Parret will use electron microscopy (EM) to obtain the first 3-dimensional structure of neurofibromin. While EM normally does not give high resolution information it will clearly reveal the shape of the molecule and most likely the locations and relative orientations of the previously structurally characterized portions. This may give insights into aspects of regulation of the protein and/or its binding partners. The study will also lay groundwork for subsequent work employing X-ray crystallography on the side of sample preparation but also by providing an initial model to solve the initial problems of X-ray structure determination.
Aaron Schindeler, Ph.D., The Children's Hospital at Westmead Mouse models of bone abnormalities in NF1
Congenital pseudarthrosis of the tibia (CPT) is a leading cause of leg amputation in children. Children who develop this condition have bony lesions in the tibia that make it prone to fracture. Once a fracture occurs the tibia fails to unite, leading to a pseudarthrosis or "false joint". Even with modern orthopaedic techniques, sound union is achieved in less than 50% of CPT patients. Permanent disability and/or amputation are common outcomes. At present, patients with CPT undergo demanding recurrent surgery, which is also a major demand on clinical resources. CPT is associated with a loss of the second copy of the Nf1 gene. NF1 is an autosomal dominant disease - the condition arises due to defects in one of two copies of the Nf1 gene. However, a recent clinical study has shown that pseudarthrotic tissues from NF1 patients have undergone a localized loss their second Nf1 gene. Dr. Schindeler will employ several strategies to investigate and model the loss of the second copy of an Nf1 gene in mice. He will make use of conditional knockout technology to delete both copies of the Nf1 gene in mouse tissues. Dr. Schindeler aims to better understand the role of NF1 in bone and in CPT:
· Examination of the mechanism underlying the role of Nf1 in bone cells
· Generation of a mouse model of CPT that reproduces the loss of the second Nf1 gene that occurs in a clinical setting. This model will be an important tool for understanding the pathology of NF1.
· Use current understanding of bone pharmaceutical therapies to develop and test treatments for CPT. This study is likely to significantly enhance our understanding of bone repair in NF1.
With the improved understanding gained from this collaborative research project it is hoped to translate some of the recent breakthroughs in NF1 bone biology to improved outcomes for this neglected patient group.
Weidong Li, Ph.D., University of California, Los Angeles Ritalin and the treatment of the neurological and cognitive deficits associated with neurofibromatosis type I
Approximately half of children with NF1 show learning disabilities and attention problems. The laboratory has been able to show that mice with a mutation akin to those found in NF1 patients also show learning and attention problems. NF1 mice, as NF1 patients have a molecule called Ras, which is overly active. The lab had previously found that correcting this problem led to a reversal of the learning deficits and attention problems of the mice. Methylphenidate, known commercially as Ritalin, is a central nervous system (CNS) stimulant and a medication prescribed for individuals (usually children) who have attention-deficit hyperactivity disorder (ADHD), which consists of a persistent pattern of abnormally high levels of activity, impulsivity, and/or inattention. Studies showed a high incidence of ADHD in NF1 and supported an association between ADHD and learning and social problems in children with NF1. One clinic report suggested that these NF1 children with ADHD might benefit from the use of Ritalin but the mechanism is unclear. The CNS stimulant role of Ritalin makes it big concern for the parents of NF1 children about the potential of drug abuse. To let the NF1 children get the possible benefits from this drug we need more scientific studies to investigate the effectiveness and mechanism of Ritalin in NF1.Their former studies demonstrated that the cognitive deficits including attention problems are caused by the disruption of neurofibromin function which leads to enhanced Ras-MAPK activities and normalize Ras-MAPK activities could rescue the deficits in NF1 mice. For the proposed study, Dr. Li would test the RAS-MAPK activities and behaviors in NF1 mice by treating with Ritalin. Amazingly, the preliminary studies showed the lower dose but not higher dose of Ritalin might decreases the abnormal higher MAPK activity in NF1 mice, which may account for the effectiveness of Ritalin in NF1. The studies will illustrate why Ritalin may help the cognitive deficits in NF1 and whether the dose is critics for the effectiveness of Ritalin in NF1.
Huarui Zheng, Ph.D., University of Michigan Therapeutic intervention of preclinical symptoms in a NF1 mouse model
The hallmark feature of NF1 is the development of multiple neurofibromas, which represents major morbidity of NF1 patients. Plexiform neurofibroma is the only type of neurofibroma that has the potential to be transformed to malignant peripheral nerve sheath tumor (MPNST). Currently, there is no effective drug treatment for plexiform neurofibroma. The major therapy strategy is surgical resection. However, plexiform neurofibromas often reside in deep sites of body and diffusely infiltrate through nerves, making it very difficult to resect completely and likely to recur. Therefore, it is urgent and critical for NF1 community to develop new therapeutic strategies based on most recent findings on molecular and cellular mechanisms of plexiform neurofibroma formation. Recently, the lab employed transgenic approaches to generate a mouse model recapitulating human plexiform neurofibromas. By detailed examination of early stage peripheral nerves during neurofibroma development, the group identified cellular mechanism for plexiform neurofibroma formation. Specifically, they found the earliest events of neurofibroma initiation are progressive dissociation of a subset of nonmyelinating Schwann cells (nmSCs) from axons and proliferation, accompanied by axonal degeneration and inflammatory response evidenced by mast cell infiltration. It was also observed elevated mTOR (mammalian target of rapamycin) activity at the stage of neurofibroma development, which suggests a molecular target for preventing neurofibroma initiation. In this proposal, Dr. Zheng will use mTOR inhibitor and mast cell inhibitor to treat the mutant mice from post natal stage to prevent nmSCs dissociation and proliferation, eventually inhibit neurofibroma formation.
Pre-Doctoral Awardees
Timmy Mani, University of Cincinnati The role of PIP2 binding and lipid raft association in merlin function
NF2 patients develop a variety of tumors in the brain, the most common being tumors associated with the nerves that are responsible for hearing and sense of balance, leading to difficulties in hearing, ringing in the ears and difficulty maintaining balance. In addition, NF2 patients can also develop several other tumors and the average survival from diagnosis for NF2 patients is 15 years. NF2 patients carry defects in a gene called Nf2, which in normal individuals, produces a protein called merlin. Since the loss of merlin results in tumor formation, the presence of merlin in normal cells is assumed to suppress abnormal cell growth and tumor formation. Experiments from several labs support this hypothesis. However, how merlin prevents abnormal cell growth is not fully understood. The group has shown that merlin is found in specialized regions within the cell membrane, called "lipid rafts", which contain many molecules involved in controlling cell growth and other cell functions. They have also shown that merlin binds to a particular molecule within the cell membrane called PIP2, and that this binding seems to be necessary for its localization to lipid rafts. The overall goals for this study are to determine if PIP2 binding to merlin is essential for the ability of merlin to prevent abnormal cell growth and to determine if PIP2 binding regulates other known modifications of the merlin protein that affect its activity. PIP2 binding represents an important potential mechanism of regulation of merlin function. Understanding the modification of merlin function by PIP2 binding will help facilitate the design of drugs for treating NF2 in future.
Linnea Vose, New York Medical College Pharmacological effects on cognition in a fly model of NF1
NF1 symptoms include disfiguring benign tumors, an increased risk for malignant tumors, and a high incidence of learning disabilities. Many drugs currently approved for use in humans have the potential to affect proteins in the cellular pathways involved in learning. Mice and flies have genes very similar to the human gene responsible for NF1, and mutations can cause learning defects similar to human patients, making these animals excellent models for research. One of these drugs, lovastatin, has been shown to increase learning in mice, but no comparable work has been done with flies. Ms. Vose proposes that treating flies with lovastatin and other approved drugs will improve their learning ability. If these experiments are successful, the Nf1 mutant flies can be used to screen for other useful drugs and novel compounds which can be further tested in mice and eventually clinical trials in humans suffering from this disease.
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