Jan Teller - US grants

DESCRIPTION The long-range objective of this research is the precise biochemical elucidation of the structural components and mechanisms of formation of the initial amyloid beta-peptide deposits in the brain. In this pursuit several observations have been made that are the foundation of this proposal. First, the formation of parenchymal amyloid plaques in Down's syndrome (DS), is preceded by the presence of increased concentration of soluble, aggregated amyloid beta-peptide (A-beta), that ends at residue 42. Second, three major, N-terminally truncated A-beta peptides beginning at residues 1, 3 and 11 are the invariant components of the soluble A-beta aggregate and, subsequently, senile plaques. Third, all three A-beta forms are extensively modified at the N-termini: aspartate-1 is either isomerized or racemized, glutamates-3 and -11 are cyclized to pyroglutamates. Fourth, the same truncated A-beta peptides, although not aggregated, are also present in the cerebrospinal fluid. Fifth, brain concentration of the water-soluble, pyroglutamate-modified A-beta increases, relative to the full-length peptide, with age in DS and is dramatically increased in some familial Alzheimer's disease (AD), brains. Sixth, water-soluble A-beta aggregate is partially resistant to unspecific proteolysis. All these observations point to a critical role of the truncated A-beta peptides in the initiation of amyloid deposits. Therefore, it is proposed to determine the structural basis of the generation of major A-beta peptides present in the brain. Specifically we will a) determine the primary structure, molecular organization and quantity of major modified A-beta forms in non-AD aging brain, DS brain, and in transgenic animals; b) investigate if the N-terminally truncated A-beta are formed from A-beta aggregates and/or A-beta precursor protein (APP); C-terminal fragments (CTFs), isolated from brain; c) investigate if the truncated A-beta, in the form found in the brain, can be proteolytically generated in vitro from recombinant CTFs. The proposed studies will involve biochemical and enzymological techniques, mass spectrometric analysis and development of specific immunological and molecular biological reagents.

Using a yeast two-hybrid genetic screen we have isolated a novel cDNA that codes for a protein named XBP (X11 Binding Protein), which interacts with the PDZ region of X11. X11 is a brain specific protein interacting with the beta-amyloid precursor protein (APP). The putative carboxyl terminus of XBP contains a four amino acid motif - GTTV, matching a consensus sequence required for interaction with PDZ domains. XBP bears some sequence similarity to the moesin/ezrin/radixin family of proteins that cross-link and regulate actin-plasma membrane interactions. We hypothesize that XBP is a crosslinking adaptor-like protein which plays a role in organizing a multi-protein complex involving APP. XBP may participate in both structural and regulatory interactions of APP at the plasma membrane. Since X11 and another APP- interacting protein, Fe65 bind to the NPTY internalization motif on APP, it is likely that their interactions with other protein ligands will have direct consequences for the APP function. Given that the NPTY motif is a tyrosine-based internalization signal required for degradation of APP, specific interactions within the APP multi-protein complex may directly affect proteolytic processing of APP, and result in generation of beta-amyloid peptide (Abeta). Whether Abeta itself or rather aberrant processing of its precursor is responsible for AD pathogenesis, detailed knowledge of the APP organization at the plasma membrane is necessary to fully understand the molecular pathways of the disease. The overall goal of this research is to gain insight into the structural and functional interactions of APP with other neuronal proteins that may lead to elucidation of the normal function of APP in the brain. This proposal deals with a fundamental aspect of the APP function and regulation. Its objective is to extend our preliminary by documenting that XBP specifically interacts with X11. We propose to study the XBP protein by characterizing its ability to interact with functional fragments of X11 both in vitro and in vivo by using recombinant fusion proteins and specific antibodies.

[unreadable] DESCRIPTION (provided by applicant): Dystonia is a neurological disorder in which the muscles contract and spasm involuntarily forcing the body into abnormal movements and awkward, contorted postures. Dystonia causes varying degrees of disability and pain severely affecting an individual's quality of life and impacting a growing number of individuals in the United States and worldwide. During the last ten years substantial research progress has been made that "re-defined" numerous forms of dystonia in genetic and biochemical terms. Although pathophysiologically the dystonias are considered "circuit" disorders, identification of gene mutations in familial dystonias points to specific molecular pathomechanisms and potentially enables targeting cellular and biochemical with pharmacological agents. Despite this progress there is an urgent need to "translate" basic and clinical research results into therapeutics development. The goal of this project is to organize a workshop dedicated to the translational aspects of dystonia research. The proposed meeting will bring together key individuals actively involved in genetic, cellular, physiological and clinical research on dystonia to discuss existing and potential possibilities for accelerating the transfer of recent basic science findings to clinical practice. The major outcomes of the proposed meeting will be: a) arriving at a consensus position regarding the acceptability of identified molecular targets for dystonia drug development and additional research avenues necessary to provide "proof of concept" for each target; b) identification of research areas that need to be supported in order to develop more solid scientific basis for target validation; c) identification and evaluation of the current status of translational dystonia research; d) identification and recruitment of researchers with the potential to creatively contribute to the translational efforts; e) identification and critical evaluation of mechanisms needed to accelerate translational discoveries and implementations; f) identification of dystonia patients' therapeutic needs and assessment of clinical relevance of current and future translational studies. PUBLIC HEALTH RELEVANCE: The importance and relevance of this project stems from the fact that dystonia is considered the third major movement disorders affecting hundreds of thousands of Americans and that there is no cure for this disease. Moreover, dystonic symptoms are prevalent among patients suffering from other major neurological disease: Parkinson's disease, Huntington's disease, and many others. Advancing translational research in this field is desperately needed to facilitate and speed up therapeutics discovery. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Dystonia is a neurological disorder characterized by excessive involuntary muscle contractions leading to twisting movements and unnatural postures. It has many different clinical manifestations, and many different causes. Individually each subtype of dystonia is quite rare, but collectively there are more than three million affected people worldwide. Unfortunately, there are few effective medical treatments, and surgical interventions, while effective in some forms of dystonia, are not broadly indicated and carry the risks inherent to invasive procedures. Fortunately, however, several promising pharmacological agents recently have been discovered by laboratory screening programs and should be available for clinical evaluation in the near future. Moreover, several pharmaceutical companies also have expressed interest in clinically evaluating drug candidates in dystonia. A major barrier to moving forward with these potential new treatments is uncertainty regarding the most efficient designs for clinical trials in dystonia. This uncertainty exists in part because the term 'dystonia denotes a group of rare and heterogeneous disorders for which there is limited prior clinical trial experience. The goal of our workshop is to develop recommendations for clinical trial designs best-suited for the dystonias. The workshop will bring together clinicians involved in treating and studying dystonia, clinical trialists from other neurological disorders, biostatisticians, junior trainees, and experts from the FDA. The main outcome of the workshop will be a summary of the status of clinical trials for dystonia, identification of missing elements necessary for initiaing optimal clinical trials in dystonia, recommendations for future research needed to address any obstacles to clinical trials in dystonia, and one or more designs that may be appropriate for future trials. The results will be shared with the clinical research community in the form of a professional journal publication. PUBLIC HEALTH RELEVANCE: The importance and relevance of this project stems from the fact that dystonia is considered the third major movement disorder affecting hundreds of thousands of Americans and that there is no cure for this disease. Moreover, dystonic symptoms are prevalent among patients suffering from other major neurological disease: Parkinson's disease, Huntington's disease, and many others. Designing and conducting clinical trials in this field is desperately needed to facilitate and speed up therapeutics discovery.