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Neuroscience Graduate Program at UCSF
Biology and Therapeutics for Neurodegenerative Diseases that Derive from Abnormal Protein Conformation
Many human neurodegenerative diseases are derived from proteins that can assume alternative, pathogenic conformations. My laboratory focuses on the biological basis and development of therapies for polyglutamine diseases such as Huntington disease (HD) and spinobulbar muscular atrophy (SBMA), and diseases related to the microtubule associated protein tau. Each condition derives from protein misfolding that leads to intracellular accumulation of soluble and insoluble aggregated species. We use biochemistry, cell and molecular biology, and animal models to address basic questions about molecular mechanisms, and to identify genetic and pharmacologic modifiers of pathogenesis. In additional work we are studying the molecular mechanisms and developing novel pharmacologic inhibitors of androgen receptor (AR) activation, which initiates pathology in SBMA and prostate cancer (PCa).
1. Polyglutamine Disease. We have created cellular models of pathogenesis that reflect a critical conformational change in a target protein that leads to intracellular aggregation. SBMA is caused by a polyglutamine expansion in the AR protein. Using biochemistry and atomic force microscopy, we have linked the development of soluble AR N-terminal oligomers of AR to its toxic effects in the brain of a mouse model of SBMA. To develop therapies, we have used fluorescence resonance energy transfer (FRET) to create a high throughput cellular assay of polyglutamine protein aggregation. We have used the FRET-based assay to identify small molecule inhibitors of this process. We have pursued in detail the molecular mechanism of one compound (Y-27632), an inhibitor of the rho-associated kinase p160ROCK. Y-27632 inhibits polyglutamine aggregation by modulating intracellular F-actin assembly. F-actin binds AR and huntingtin (the causative protein in HD), and we are testing the hypothesis that this interaction stabilizes the mutant proteins, preventing subsequent aggregation and toxicity. We have used genetic approaches in Drosophila to test in vivo the cellular pathways implicated by our cellular studies. Future work is directed towards identifying the molecular mechanism by which actin regulates polyglutamine protein aggregation and toxicity, testing the effects of Y-27632 in transgenic mouse models, and the developing novel therapies.
2. Tauopathy. The microtubule associated protein tau underlies a large group of neurodegenerative diseases that includes Alzheimer disease and the frontotemporal dementias, collectively termed the tauopathies. Like other amyloid proteins such as Aß, synuclein, and prion protein, in disease states tau is capable of spontaneously forming ordered fibrillar arrays. These fibrils are tightly linked to pathology, but many questions remain unanswered. For example, it is unknown why distinct disease syndromes are produced from a single protein, and why the spread of degeneration begins in one group of cells and subsequently spreads to adjacent cells, or those with strong synaptic connectivity. We are testing the hypothesis that self-propagating tau fibrils might spread disease through the brain via cell-cell transmission of misfolded protein. This hypothesis is supported by two observations. First, we have found that extracellular tau fibrils, but not unpolymerized monomer, can enter and accumulate in cultured cells. Second, using biochemistry and CD-spectroscopy, we have found that a wild-type tau monomer may assume multiple self-propagating conformations. We are now testing the idea that tau might act as a self-propagating pathogenic agent, much like a classical prion. We are also exploring molecular mechanisms of cell entry, and developing therapeutic approaches designed to inhibit tau misfolding.
3. AR Inhibitors. Both SBMA and PCa are initiated by ligand binding to AR, and could be blocked by novel inhibitors. We have developed FRET-based assays to directly measure ligand-induced conformational change in nuclear receptors such as AR. We have used this technology to develop cell-based assays that enable screening for novel inhibitors, and we have identified several lead compounds that have potential as novel therapeutics. Ongoing work is testing the effect of these compounds in animal models, and determining their molecular mechanism of action.1. Molecular mechanisms of pathogenesis and therapeutic development for polyglutamine diseases.
2. Molecular basis of tauopathy.
3. Molecular mechanisms of nuclear receptor activation, and development of novel inhibitors.
Suzanne Angeli
BMS Graduate Student
Shweta Chandra, Ph.D.
Postdoctoral Fellow
Bess Frost
BMS Graduate Student
Anthony Gerber, M.D., Ph.D.
Postdoctoral Fellow
Rachel Jacks
BMS Graduate Student
Jeremy Jones, Ph.D.
Postdoctoral Fellow
Mei Li, M.D., Ph.D.
Postdoctoral Fellow
Victoria Lyo
Medical Student
Aye Aye Ma
Research Associate
Jieya Shao, Ph.D.
Postdoctoral Fellow
1. Diamond, MI; Miner, JN; Yoshinaga, SK and Keith R Yamamoto "Transcription Factor Interactions: Selectors of Positive or Negative Regulation from a Single DNA Element" Science 1990; 249:1266-1272
2. Diamond, MI; Robinson, MR and Keith R Yamamoto “Glucocorticoid Regulation of Polyglutamine Protein Aggregation and Nuclear Localization” Proceedings of the National Academy of Sciences, 2000; 97(2):657-61.
3. Welch, WJ and Marc I. Diamond: “Glucocorticoid Modulation of Androgen Receptor Nuclear Aggregation and Cellular Toxicity is Associated with Distinct Forms of Soluble Expanded Polyglutamine Protein” Human Molecular Genetics, 2001; 10(26):3063-3074
4. Cowan, KJ, Diamond, MI, and William J. Welch: “Polyglutamine protein aggregation and toxicity are linked to the cellular stress response” Human Molecular Genetics, 2003; 12(12):1377-91.
5. Pollitt, SK, Pallos, J, Shao, J, Desai, UA, Ma, AK, Thompson, LM, Marsh, JL, and Marc I Diamond: “A rapid cellular FRET assay of polyglutamine aggregation identifies a novel inhibitor” Neuron, 2003; 40:685-94
6. Schaufele, F; Carbonell, X; Guerbadot, M; Borngraeber, S; Ma, AK; Chapman, MS; Miner, JN; and Marc I. Diamond: “The structural basis of AR activation: intramolecular and intermolecular amino-carboxy interactions” PNAS, 2005; 102(28):9802-7
7. Desai UA, Pallos J, Ma AA, Stockwell BR, Thompson LM, Marsh JL, and Marc I Diamond: “Biologically active molecules that reduce polyglutamine aggregation and toxicity” Human Molecular Genetics 2006 Jul 1;15(13):2114-24Marc Diamond, M.D.
Phone
415-514-3646
Physical Address
S572B
Genentech Hall
600 16th Street
Mission Bay Campus
Mailing Address
GH-S572B
600 16th Street
San Francisco, CA 94143-2280
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