Synuclein

Diffuse Lewy body Cerebrocortical regions, a-Synuclein Lewy bodies and neurites... 

Several pathological self-polymerizing systems have been biophysi-cally characterized sufficiently to permit identification of protein or peptide species that could serve as molecular targets in a structure-activity relationship. These include transthyretin (TTR) [73-76], serum amyloid A protein (SAA) [77], microtubule-associated protein tau [78-80], amylin or islet amyloid polypeptide (IAPP) [81,82], IgG light chain amyloidosis (AL) [83-85], polyglutamine diseases [9,86], a-synuclein [47,48] and the Alzheimer s (3 peptide [87-96]. A variety of A(3 peptide assay systems have been established at Parke-Davis to search for inhibitors of fibril formation that could be therapeutically useful [97]. 

Mice expressing high levels of human a-synuclein under the control of the human PDGF(5 promoter developed intracellular nuclear... 

Farrer M, Gwinn-Hardy K, Hutton M, Hardy J. The genetics of disorders with synuclein pathology and parkinsonism. Hum Mol Genet 1999 8 1901-1905. 

Polymeropoulos MH, Lavedan C, Leroy E, Ide SE, Dehejia A, Dutra A, Pike B, Root H, Rubenstein J, Boyer R, Stenroos ES, Chandrasekharappa S, Athanassiadou A, Papapetropoulos T, Johnson WG, Lazzarini AM, Duvoisin RC, Di Iorio G, Golbe LI, Nussbaum RL. Mutation in the alpha-synuclein gene identified in families with Parkinson s disease. Science 1997 276 2045-2047. 

Polymeropoulos MH. Autosomal dominant Parkinson s disease and alpha-synuclein. Ann Neurol 1998 44 S63-S64. 

Baba M, Nakajo S, Tu PH, Tomita T, Nakaya K, Lee VM, Trojanowski JQ, Iwatsubo T. Aggregation of alpha-synuclein in Lewy bodies of sporadic Parkinson s disease and dementia with Lewy bodies. Am J Pathol 1998 152 879-884. 

Spillantini MG, Crowther RA, Jakes R, Cairns NJ, Lantos PT, Goedert M. Filamentous a-synuclein inclusions link multiple system atrophy with Parkinson s disease and dementia with Lewy bodies. Neurosci Lett 1998 251 205-208. 

Synuclein fibrillogenesis is nucleation-dependent. Implications for the pathogenesis of Parkinson s disease. J Biol Chem 1999 274 19509-19512. 

Narhi L, Wood SJ, Steavenson S, Jiang Y, Wu GM, Anafi D, Kaufman SA, Martin F, Sitney K, Denis P, Louis JC, Wypych J, Biere AL, Citron M. Both familial Parkinson s disease mutations accelerate alpha-synuclein aggregation. J Biol Chem 1999 274 9843-9846. 

The ROA spectra of /Tcascin, y-synuclein, and the tau 46 P301L mutant are displayed in Figure 9 as typical examples. Although very similar overall, there are differences of detail between the three ROA spectra which reflect the different residue compositions and also differences in minor structural elements. The absence of a well-defined amide I ROA couplet in any of the spectra indicates that none of the proteins contains a significant quantity of well-defined secondary structure. 

These studies suggest that the caseins, synucleins, and tau have natively unfolded structures in which the sequences are based largely on the PPII conformation and are held together in a loose noncooperative fashion. However, rather than describing them as random coil ,... 

Fig. 9. Backscattered Raman and ROA spectra of the natively unfolded proteins bovine /1-casein (top pair) and human y-synuclein (middle pair) in aqueous buffer at pH 7.0, and of the human tau 46 P301L mutant at pH 4.3. 

The reason that the caseins, which constitute nearly 80% of bovine milk, are unfolded in their native states appears to be to facilitate digestion, since the open rheomorphic structures allow rapid and extensive degradation to smaller peptides by proteolytic enzymes. The natively unfolded structures of many cereal proteins may serve an analogous purpose since they provide nutrition for seedlings. The physiological function of the synucleins in the brain is as yet unclear, but tau is known to promote and stabilize the assembly of microtubules. 

The conformational plasticity supported by mobile regions within native proteins, partially denatured protein states such as molten globules, and natively unfolded proteins underlies many of the conformational (protein misfolding) diseases (Carrell and Lomas, 1997 Dobson et al., 2001). Many of these diseases involve amyloid fibril formation, as in amyloidosis from mutant human lysozymes, neurodegenerative diseases such as Parkinson s and Alzheimer s due to the hbrillogenic propensities of a -synuclein and tau, and the prion encephalopathies such as scrapie, BSE, and new variant Creutzfeldt-Jacob disease (CJD) where amyloid fibril formation is triggered by exposure to the amyloid form of the prion protein. In addition, aggregation of serine protease inhibitors such as a j-antitrypsin is responsible for diseases such as emphysema and cirrhosis. 

Rub U., Del Tredici K., Schultz C. et al (2002). Parkinson s disease the thalamic components of the limbic loop are severely impaired by alpha-synuclein immunopositive inclusion body pathology. Neurobiol. Aging 23, 245-54. 

The failure of proteins to fold into their functional forms can occasionally lead to "misfolding" or "conformational" diseases.140 Many of these diseases are associated with the formation of amyloid protein, an insoluble material that is deposited as fibrils or plaques in different tissues and organs of the body. They include amyloid Ap protein as the major constituent of the plaques in Alzheimer patients, PrPc associated with neuro-degenerative diseases, a-synuclein (AS) associated with Parkinson s diseases, transthyretin (TTR) as a homotetrameric protein that is involved in the transport of thyroid hormones and retinol in human serum. In particular, the Ap protein is a peptide of 39-43 amino acids that is the... 

The use of pairs of matched spectral variants of GFP, like cyan and yellow or GFP and mRed, to differentially tag proteins and look for interactions, is now in routine use. The approach can be readily applied to homodimerization of molecules that differ only by their living color or epitope tag. For example, homomultimer-ization of a viral coat protein can be observed by imaging a mixture of cyan and yellow tagged homomeric molecules [46], whereas oc-synuclein stacking can be detected by utilizing a-synuclein transcripts that encoded different epitope tags for detection by immunostaining [47],... 

Klucken, J., Outeiro, T. F., Nguyen, P., McLean, P. J. and Hyman, B. T. (2006). Detection of novel intracellular alpha-synuclein oligomeric species by fluorescence lifetime imaging. FASEB J. 20, 2050-7. 

McLean, P. J., Kawamata, H., Ribich, S. and Hyman, B. T. (2000). Membrane association and protein conformation of alpha-synuclein in intact neurons. Effect of Parkinson s disease-linked mutations. J. Biol. Chem. 275, 8812-6. 

Roberti, M. J., Bertoncini, C. W., Klement, R., Jares-Erijman, E. A. and Jovin, T. M. (2007). Fluorescence imaging of amyloid formation in living cells by a functional, tetracysteine-tagged ot-synuclein. Nat. Methods 4, 345-51. 

Alafuzoff I, Parkkinen L, Al-Sarraj S, et al. Assessment of [alpha]-synuclein pathology a study of the BrainNet Europe Consortium. I. Neuropathol. Exp. Neurol. 2008 67 125-143. 

Fig. 8 Pulse sequence for the measurement of homonuclear correlation spectra with 7 filtering. Narrows bars indicate 7t/2 pulses and broad bars indicate 71 pulses. Experimental conditions employed for a-synuclein fibrils samples static field strength 9.4 T temperature —5 °C spinning frequency 8 kHz T2 filter 100 ms CP contact time 2.5 ms TOBSY mixing time 6 ms. The rf phases can be found in the original figure and caption. (Figure and caption adapted from the Supporting Information of [134]. Copyright (2005) National Academy of Sciences, USA)...

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