2009 ASF Funded Research
Principle Investigator: Benjamin Philpot, PhD
Institution: University of North Carolina, Chapel Hill
Chapel Hill, NC
Study Title: Novel therapeutics for Angelman syndrome by manipulating Ube3a expression
$200,000 (2-year award)
There is currently no therapy for Angelman syndrome. One treatment strategy is to activate UBE3A from the normally silenced paternal allele. By identifying pharmacological interventions that upregulate paternal expression of UBE3A through a large scale drug screen, our findings are expected to provide the prototype of therapy for AS. By discovering molecules that epigenetically activate paternal Ube3a, we will also
gain insights into the normal molecular mechanism for silencing paternal Ube3a and will thus pinpoint additional strategies for the treatment of Angelman syndrome. We will focus our initial screen on neuroactive drugs that are already approved by the Food and Drug Administration (FDA), as this research approach holds promise for identifying small molecules that could be rapidly accelerated towards the treatment of Angelman syndrome.
Principle Investigator: John Marshall, PhD
Institution: Brown University
Study Title: Rescue of Angelman Syndrome Learning Deficits by an Investigational New Drug
$198,899 (2-year award)
This proposal is built upon the evidence that has been uncovered by investigations into AS, the use of CN 2097 specifically targets the cellular mechanisms and biochemistry that has been demonstrated to be crucial in this disease. By specifically targeting a single downstream target of the underlying UB3E genetic cause of the disease, we can demonstrate that manipulations of NMDA?dependent synaptic plasticity can effectively treat AS. UB3E misregulation may have many effects on the patient, but by selectively targeting the underlying cause of the cognitive symptoms we can ensure that the treatment is effective. The availability of a highly selective PDZ ligand, in the form of CN 2097, allows us to rigorously test the scientific basis of AS syndrome and gauge the effectiveness this type of treatment strategy. The effect of CN 2097 on WT compared to AS mice will also give insights into the uni? or multi?factorial nature of AS deficits. If the disorder is uni?factorial, then we would expect to see AS mice recover to the same extent not only as WT control but as WT mice under the influence of CN 2097. If AS is multi?factorial then we would predict only a partial therapeutic effect. Hopefully, our therapeutic strategy will be a complete treatment but even a partial effect would still have profound clinical implications. These research questions will be answered in phase 2 clinical trials or a proof of concept study after this pre?clinical stage is complete and the IND application is approved by the FDA.
The potential impact of this treatment strategy is enormous. Our commercialization plan envisages AS patients being early identified through genetic screening and behavioral diagnosis. Once patients have been identified, they will receive an orally active drug, which is easy to administer and taken chronically to rescue the cognitive defects that prevent normal brain development in response to sensory experience, learning and memory. Patients who undergo treatment will be dependent upon this medication in order to continue to develop and as such it is not envisaged as a one?treatment cure. However, this treatment will largely eradicate the symptomatology of the disease in a manner that will be as manageable as any other chronic disease that can be presently from birth, such as asthma and diabetes. We are also investigating the possibility of formulating this drug into a depot intra?muscular injection for ease of administration. We plan to complete this feasibility study within two years using support from the AS foundation whilst simultaneously satisfying the regulatory requirements for a successful IND registration with the FDA and Clinical trials. This will be funded through our industrial partner, Ardane Therapeutics (See letter of support). It is our desire that we can continue to work with the ASF, especially in the Phase 2 clinical trials for the identification and recruitment of patients.
Principle Investigator: Eric Klann, PhD
Institution: New York University
New York, NY
Study Title: NRB-a/ErbB4 and Dopamine D4 Receptors as Therapeutic Targets to Treat Cognitive Deficits in Angelman Syndrome
$196,788 (2-year award)
Angelman syndrome (AS) is a human neurological disorder that is associated with symptoms that include severe autism, motor abnormalities, and epilepsy. In most cases, AS is caused by the deletion of small portions on chromosome 15, which includes the UBE3A gene. The UBE3A gene encodes an enzyme termed ubiquitin ligase E3A (also termed E6-AP), which is one of a family of enzymes (E3 ubiquitin ligases) that is required to degrade proteins. A mouse model of AS has been generated and these mice exhibit seizures, impaired motor function, and cognitive deficits that correlate with neurological alterations observed in humans with AS. Many of these alterations are found in the hippocampus and prefrontal cortex in the brain. Hippocampus-dependent learning and memory is impaired in AS model mice, as is long-term potentiation (LTP), which is a cellular model for memory formation. We recently found that a protein called neuregulin-1 (NRG-1) is significantly enhanced in the hippocampus of AS model mice. NRG-1 has been shown previously to decrease the strength of the connections between neurons (synapses). Thus, we hypothesized that the increased levels of NRG-1 in the hippocampus of the AS model mice contribute to their LTP and memory impairments. Indeed, we found that inhbiting NRG-1 function reversed the LTP impairments displayed by the AS model mice. Therefore, we will now determine wehther inhibiting NRG-1 function can reverse memory impairments displayed by the AS model mice. If this is the case, it would indicate that targeting NRG-1 function is viable therapeutic target for the treatment of those with AS.
It was found recently that the ability of NRG-1 to inhibit LTP is mediated via dopamine D4 receptors (D4Rs). Therefore, we will determine whether drugs that block D4Rs can reverse the LTP and memory impairments exhibited by the AS model mice. If this is the case, it would have an enormous impact on AS research, as well as the care and treatment of people with AS. This is because D4R antagonists such as clozapine already are used extensively in the clinic to treat people with schizophrenia. Thus, our experiments should provide critical information concerning the therapeutic potential of approved pharmaceuticals such as clozapine for treating those with AS.
Principle Investigator: Peter Howley, MD
Institution: Harvard Medical School
Study Title: Identification of UBE3A Ligase Substrates
$200,000 (2-year award)
Angelman Syndrome is a genetic, neurodevelopmental disease involving the maternally inherited UBE3A gene. Defects of the maternal UBE3A allele therefore result in the lack of UBE3A ubiquitin-ligase activity in the regions of the brain in which the expression is imprinted. The pathogenic mechanisms that underlie Angelman Syndrome due to the lack of UBE3A activity in the affected neurons however are unknown. Central to understanding these pathogenic mechanisms is the identification of the substrates of UBE3A in neural cells, and the identification of the pathways that could be targeted in treating this disease. This proposal is designed to identify the a high confidence interaction network of proteins that complex UBE3A including proteins that are E3 ligase substrates of UBE3A in human neuroblastoma cells, and then validated in primary neurons. It is hypothesized that abnormal levels of proteins that are not properly ubiquitylated and degraded due to the lack of the UBE3A E3-ligase machinery is responsible for the neuronal pathogenesis underlying Angelman syndrome. The identification of these substrates and the pathways in which they function has the potential to lead to novel therapeutic approaches in the treatment and amelioration of the symptoms of the disease.
Principle Investigator: Yong-Jui Jiang, MD, PhD
Institution: Duke University
Study Title: Novel Ube3a Isoform and Angelman Syndrome
$99,425 (1-year award)
The Angelman mouse model has played a very important role in dissecting and understanding the pathogenesis of human Angelman syndrome since I reported first time a decade ago. One of the most remarkable findings in the AS mouse model is impaired synaptic plasticity. It is believed that the fully understanding of molecular pathway leading into abnormal synaptic plasticity in AS mouse model is the key to uncover the pathogenesis of AS and develop a targeted therapeutic strategy for human AS. AS mouse model will also be the only choce to test various candidate drugs to treat the AS. There are two mouse models currelty available to all investigators who are interested in Angelman syndrome research. One is I generated in Dr. Arthur Beaudet’s lab in Houston in which the exon 2 of Ube3a was deleted and other was produced in Joe Wagstaff’s lab in which the exon 10 of Ube3a was deleted. Our finding of novel and short isoforms of Ube3a indicates that these two different mutant mice represent isoform-specific knockout of Ube3a gene in mice. We immediately realized that these two mice provide an unique opportunity to dissect an extremely important question to understand the pathogenesis of AS: ”is ubiquitin protein ligase or coactivator, or both important for the pathogenesis of AS?” The understanding whether ubiqution or coactivator function is implicated in impaired synaptic plasticity will certainly dictate the research effort to search treatment strategy.
These new and unexpected findings also raise many other interesting questions regarding the difference between these two different lines of Ube3a mutant mice. It is critical important to understand the difference between these two mutant mice so other investigators can make an informed decision and have appropriate design when they plan to use these mice. Furthermore, understanding the function of these new isoforms will help to define genotype phenotype correlation in humans and help to make a prediction for the clinical presentations based the position of DNA mutation in UBE3A gene. It will enhance the care of AS patients. Because of the involvement of PI3K/AKT in the mTOR pathway, a possibility of modifying the PI3k/AKT/mTOR pathway by a known drug Rapamycin may be explored to search the treatment strategy.
Principle Investigator: Scott Dindot, PhD
Institution: Texas A&M University
College Station, TX
Study Title: Determining the Role of the E6-AP Isoforms in Synaptic Maturation
$93,063 (1-year award)
The behavioral and cognitive phenotypes present in Angelman syndrome (AS) patients are thought to arise through impaired experience dependent synaptic plasticity. What is unknown about AS is the function of the AS gene protein product, E6-AP, in the brain. This is complicated by the fact that the AS gene, UBE3A, encodes for at least three imprinted isoforms that are expressed in the brain. In mice, E6-AP is highly expressed in neurons where it is present in the nucleus, cell soma and synapse. Furthermore, studies have shown that E6-AP functions independently as an ubiquitin ligase and as a transcriptional coactivator. Thus, E6-AP appears to function in neurons where it is present in different cellular compartments, and has the potential to ubiquitinate proteins and to regulate gene expression. The cellular compartment in neuronal cells (i.e., synapse or nucleus) as well as the cellular mechanisms (i.e., ligase or coactivator) that lead to the AS phenotype in the absence of E6-AP are currently unknown. We have presented data that the UBE3A isoforms in conjunction with post-translational modifications to the N-terminus are at least two mechanisms that modulate E6-AP’s differential cellular localization and functional properties. In this project, we have proposed to determine the UBE3A isoform that regulates synaptic maturation, and to investigate post-translational signaling of E6-AP in response to synaptic activity. The potential impact of this project is that it will provide key insights into the function of E6-AP in synaptic plasticity.
2009 Behavorial Research Awards
Dr. Sarika Peters
Baylor College of Medicine
Use of Conventional and Complementary and Alternative Treatments for Problem Behaviors in Angelman Syndrome
The primary goal of this study is to examine the prevalence of use for different types of conventional as well as complementary and alternative medicine (CAM) therapies for the treatment of problem behaviors among individuals diagnosed with Angelman Syndrome (AS). Conventional treatments include psychopharmacological medications, behavioral therapy, physical therapy, and speech therapy, for example. Examples of CAM therapies may include: vitamins, special diets, antifungals, and developmental optometry. By conducting an anonymous, web-based survey, we will examine what factors contribute to the use of these treatments, how effective parents think these treatments may be, and any correlations with severity of problem behaviors in AS. This survey will be advertised nationally and internationally through Angelman syndrome organizations, and will also be translated into Spanish. Parents will be asked to complete the survey as long as their son/daughter with Angelman syndrome is age 2 and older. This study will yield preliminary information that can be used in the management of patients with AS and their difficult behaviors, and in assisting families in how to objectively evaluate treatments and treatment response.
Dr. Keith Allen
Evaluation of a Standard Behavioral Protocol in the Treatment of Sleep Problems in Young Children with Angelman Syndrome
Previous studies have provided extensive evidence that sleep problems are a common characteristic of the behavioral phenotype of Angelman Syndrome. In addition, these are most common in young children. Caregivers unanimously report persistent fatigue and reduced quality of life as a result. Yet, few parents receive help in treating these problems. Sadly, although behavior management is currently the most widely recommended approach in pediatric sleep medicine, there is a dearth of data to support its use in addressing sleep problems in Angelman Syndrome and this is likely the most significant obstacle to providing parents with the help they need.
While no structured protocol can be expected to address all sleep problems in children with Angelman Syndrome, the current research project has the potential to significantly impact the clinical management of sleep problems in children with Angelman Syndrome by providing a direct evaluation of a protocol of practical behavioral strategies that have been demonstrated effective other populations of children with sleep problems.
The current proposed project also has the potential to stimulate additional research on sleep problems in children with Angelman Syndrome, regardless of the outcomes. Positive outcomes will likely evoke additional studies designed to test the generalizability of the results or to conduct individual component analyses of the protocol to minimize response effort required of parents.
Total General Research Awarded: $988,175
Behavioral Research Awards: $104,538
2009 Total Research Awards: $1,092,713