Bandopadhyay, R., R. de Silva, et al. (2001). "No pathogenic mutations in the synphilin-1 gene in Parkinson's disease." Neurosci Lett 307(2): 125-7.
alpha-Synuclein is mutated in rare autosomal dominant forms of Parkinson's disease and is a major component of Lewy bodies and neurites. Synphilin-1, a novel protein interacts in vivo and co-localises with alpha-synuclein in Lewy bodies. We analysed the synphilin-1 gene in familial Parkinson's disease by single-strand conformation polymorphism (SSCP) and automated sequencing but found no coding mutations. However, we identified two novel intronic polymorphisms; an A/T polymorphism in intron 2, resulting in the introduction of an Alu1 site and a second G/T polymorphism in intron 4. We analysed the intron 2 polymorphism for allelic association as it was conducive to rapid screening but observed no changes in frequency between Parkinson's disease cases and controls.

Barbieri, S., K. Hofele, et al. (2001). "Mouse models of alpha-synucleinopathy and Lewy pathology. Alpha-synuclein expression in transgenic mice." Adv Exp Med Biol 487: 147-67.

Bonifati, V., G. De Michele, et al. (2001). "The parkin gene and its phenotype. Italian PD Genetics Study Group, French PD Genetics Study Group and the European Consortium on Genetic Susceptibility in Parkinson's Disease." Neurol Sci 22(1): 51-2.
Mutations of the parkin gene on chromosome 6 cause autosomal recessive, early onset parkinsonism. This is the most frequent form of monogenic parkinsonism so far identified. The associated phenotypical spectrum encompasses early onset, levodopa-responsive parkinsonism (average onset in the early 30s in Europe), and it overlaps with dopa-responsive dystonia in cases with the earliest onset, and with clinically typical Parkinson's disease in cases with later onset. Despite clinical features, Lewy bodies are not found at autopsy in brains of patients with parkin mutations. The parkin protein possesses ubiquitin ligase activity, which is abolished by the pathogenic mutations.

Chung, K. K., Y. Zhang, et al. (2001). "Parkin ubiquitinates the alpha-synuclein-interacting protein, synphilin-1: implications for Lewy-body formation in Parkinson disease." Nat Med 7(10): 1144-50.
Parkinson disease is a common neurodegenerative disorder characterized by the loss of dopaminergic neurons and the presence of intracytoplasmic-ubiquitinated inclusions (Lewy bodies). Mutations in alpha-synuclein (A53T, A30P) and parkin cause familial Parkinson disease. Both these proteins are found in Lewy bodies. The absence of Lewy bodies in patients with parkin mutations suggests that parkin might be required for the formation of Lewy bodies. Here we show that parkin interacts with and ubiquitinates the alpha-synuclein-interacting protein, synphilin-1. Co-expression of alpha-synuclein, synphilin-1 and parkin result in the formation of Lewy-body-like ubiquitin-positive cytosolic inclusions. We further show that familial-linked mutations in parkin disrupt the ubiquitination of synphilin-1 and the formation of the ubiquitin-positive inclusions. These results provide a molecular basis for the ubiquitination of Lewy-body-associated proteins and link parkin and alpha-synuclein in a common pathogenic mechanism through their interaction with synphilin-1.

Ebadi, M., P. Govitrapong, et al. (2001). "Ubiquinone (coenzyme q10) and mitochondria in oxidative stress of parkinson's disease." Biol Signals Recept 10(3-4): 224-53.
Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease affecting approximately1% of the population older than 50 years. There is a worldwide increase in disease prevalence due to the increasing age of human populations. A definitive neuropathological diagnosis of Parkinson's disease requires loss of dopaminergic neurons in the substantia nigra and related brain stem nuclei, and the presence of Lewy bodies in remaining nerve cells. The contribution of genetic factors to the pathogenesis of Parkinson's disease is increasingly being recognized. A point mutation which is sufficient to cause a rare autosomal dominant form of the disorder has been recently identified in the alpha-synuclein gene on chromosome 4 in the much more common sporadic, or 'idiopathic' form of Parkinson's disease, and a defect of complex I of the mitochondrial respiratory chain was confirmed at the biochemical level. Disease specificity of this defect has been demonstrated for the parkinsonian substantia nigra. These findings and the observation that the neurotoxin 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP), which causes a Parkinson-like syndrome in humans, acts via inhibition of complex I have triggered research interest in the mitochondrial genetics of Parkinson's disease. Oxidative phosphorylation consists of five protein-lipid enzyme complexes located in the mitochondrial inner membrane that contain flavins (FMN, FAD), quinoid compounds (coenzyme Q10, CoQ10) and transition metal compounds (iron-sulfur clusters, hemes, protein-bound copper). These enzymes are designated complex I (NADH:ubiquinone oxidoreductase, EC 1.6. 5.3), complex II (succinate:ubiquinone oxidoreductase, EC 1.3.5.1), complex III (ubiquinol:ferrocytochrome c oxidoreductase, EC 1.10.2.2), complex IV (ferrocytochrome c:oxygen oxidoreductase or cytochrome c oxidase, EC 1.9.3.1), and complex V (ATP synthase, EC 3.6.1.34). A defect in mitochondrial oxidative phosphorylation, in terms of a reduction in the activity of NADH CoQ reductase (complex I) has been reported in the striatum of patients with Parkinson's disease. The reduction in the activity of complex I is found in the substantia nigra, but not in other areas of the brain, such as globus pallidus or cerebral cortex. Therefore, the specificity of mitochondrial impairment may play a role in the degeneration of nigrostriatal dopaminergic neurons. This view is supported by the fact that MPTP generating 1-methyl-4-phenylpyridine (MPP(+)) destroys dopaminergic neurons in the substantia nigra. Although the serum levels of CoQ10 is normal in patients with Parkinson's disease, CoQ10 is able to attenuate the MPTP-induced loss of striatal dopaminergic neurons.

Ellis, C. E., P. L. Schwartzberg, et al. (2001). "alpha-synuclein is phosphorylated by members of the Src family of protein-tyrosine kinases." J Biol Chem 276(6): 3879-84.
alpha-Synuclein (alpha-Syn) is implicated in the pathogenesis of Parkinson's Disease, genetically through missense mutations linked to early onset disease and pathologically through its presence in Lewy bodies. alpha-Syn is phosphorylated on serine residues; however, tyrosine phosphorylation of alpha-Syn has not been established (, ). A comparison of the protein sequence between Synuclein family members revealed that all four tyrosine residues of alpha-Syn are conserved in all orthologs and beta-Syn paralogs described to date, suggesting that these residues may be of functional importance (). For this reason, experiments were performed to determine whether alpha-Syn could be phosphorylated on tyrosine residue(s) in human cells. Indeed, alpha-Syn is phosphorylated within 2 min of pervanadate treatment in alpha-Syn-transfected cells. Tyrosine phosphorylation occurs primarily on tyrosine 125 and was inhibited by PP2, a selective inhibitor of Src protein-tyrosine kinase (PTK) family members at concentrations consistent with inhibition of Src function (). Finally, we demonstrate that alpha-Syn can be phosphorylated directly both in cotransfection experiments using c-Src and Fyn expression vectors and in in vitro kinase assays with purified kinases. These data suggest that alpha-Syn can be a target for phosphorylation by the Src family of PTKs.

Farrer, M., P. Chan, et al. (2001). "Lewy bodies and parkinsonism in families with parkin mutations." Ann Neurol 50(3): 293-300.
Previous work has established that compound mutations and homozygous loss of function of the parkin gene cause early-onset, autosomal recessive parkinsonism. Classically, this disease has been associated with loss of dopaminergic neurons in the substantia nigra pars compacta and locus ceruleus, without Lewy body pathology. We have sequenced the parkin gene of 38 patients with early-onset Parkinson's disease (<41 years). Two probands with mutations were followed up. Clinical evaluation of their families was performed, blinded to both genetic and pathological findings. Chromosome 6q25.2-27 haplotype analysis was carried out independently of the trait; parkin gene expression was examined at both the RNA and protein levels. Haplotype analysis of these families revealed a common chromosome 6, with a novel 40 bp exon 3 deletion that cosegregated with disease. In the proband of the smaller kindred, an exon 7 R275W substitution was identified in addition to the exon 3 deletion; RNA analysis demonstrated that the mutations were on alternate transcripts. However, Lewy body pathology typical of idiopathic Parkinson's disease was found at autopsy in the proband from the smaller kindred. These data suggest that compound heterozygous parkin mutations and loss of parkin protein may lead to early-onset parkinsonism with Lewy body pathology, while a hemizygous mutation may confer increased susceptibility to typical Parkinson's disease.

Farrer, M., A. Destee, et al. (2001). "Genetic analysis of synphilin-1 in familial Parkinson's disease." Neurobiol Dis 8(2): 317-23.
alpha-Synuclein is present in Lewy bodies of patients with both sporadic and familial Parkinson's disease. However, pathogenic mutations Ala30Pro and Ala53Thr in alpha-synuclein are rare causes of disease. Synphilin-1 has been demonstrated to associate with alpha-synuclein and promote the formation of cytosolic inclusions in vitro. Two-point genetic linkage analysis of a dinucleotide repeat within the synphilin-1 gene initially implicated this locus as a cause of Parkinson's disease in three of nine families. However, subsequent haplotype, sequencing, and association analyses in these three families and an independent case-control series suggest that variability within the locus does not confer susceptibility to Parkinson's disease. Copyright 2001 Academic Press.

Galvin, J. E., T. M. Schuck, et al. (2001). "Differential expression and distribution of alpha-, beta-, and gamma-synuclein in the developing human substantia nigra." Exp Neurol 168(2): 347-55.
Although the functions of alpha-, beta-, and gamma-synuclein (alphaS, betaS, gammaS, respectively) are unknown, these synaptic proteins are implicated in the pathogenesis of Parkinson's disease (PD) and related disorders. For example, alphaS forms Lewy bodies (LBs) in substantia nigra (SN) neurons of PD. However, since it is not known how these hallmark PD lesions contribute to the degeneration of SN neurons or what the normal function of alphaS is in SN neurons, we studied the developing human SN from 11 weeks gestational age (GA) to 16 years of age using immunohistochemistry and antibodies to alphaS, betaS, gammaS, other synaptic proteins, and tyrosine hydoxylase (TH). SN neurons expressed TH at 11 weeks GA and alphaS, betaS, and gammaS appeared initially at 15, 17, and 18 weeks GA, respectively. These synucleins first appeared in perikarya of SN neurons after synaptophysin, but about the same time as synaptotagmin and synaptobrevin. Redistribution of alphaS from perikarya to processes of SN neurons occurred by 18 weeks GA in parallel with synaptophysin, while betaS and synaptotagmin were redistributed similarly between 20 and 28 weeks GA and this also occurred with gammaS and synaptobrevin between 33 weeks GA and 9 months postnatal. These data suggest that alphaS, betaS, and gammaS may play a functional role in the development and maturation of SN neurons, but it remains to be determined how sequestration of alphaS as LBs in PD contributes to the degeneration of SN neurons.

Gasser, T. (2001). "Genetics of Parkinson's disease." J Neurol 248(10): 833-40.
Over the past few years, several genes for monogenically inherited forms of Parkinson's disease (PD) have been mapped and/or cloned. In a small number of families with autosomal dominant inheritance and typical Lewy-body pathology, mutations have been identified in the gene for alpha-synuclein. Aggregation of this protein in Lewy-bodies may be a crucial step in the molecular pathogenesis of familial and sporadic PD. On the other hand, mutations in the parkin gene cause autosomal recessive parkinsonism of early onset. In this form of PD, nigral degeneration is not accompanied by Lewy-body formation. Parkin-mutations appear to be a common cause of PD in patients with very early onset. Parkin has been implicated in the cellular protein degradation pathways, as it has been shown that it functions as a ubiquitin ligase. The potential importance of this pathway is also highlighted by the finding of a mutation in the gene for ubiquitin C-terminal hydrolase L1 in another small family with PD. Other loci have been mapped to chromosome 2p and 4p, respectively, in a small number of families with dominantly inherited PD, but those genes have not yet been identified. These findings prove that there are several genetically distinct forms of PD that can be caused by mutations in single genes. On the other hand, there is at present no direct evidence that any of these genes have a direct role in the aetiology of the common sporadic form of PD. Epidemiological, case control, and twin studies, although supporting a genetic contribution to the development of PD, all suggest a clear familial clustering only in a minority of cases. It is therefore widely believed that a combination of interacting genetic and environmental causes may be responsible in this majority of PD-cases. However, studies of gene-environment interactions have not yet produced any convincing results. Nevertheless, the elucidation of the molecular sequence of events leading to nigral degeneration in clearly inherited cases is likely to shed light also on the molecular pathogenesis of the common sporadic form of this disorder.

Gasser, T. (2001). "Molecular genetics of Parkinson's disease." Adv Neurol 86: 23-32.
Over the last few years, several genes for monogenically inherited forms of Parkinson's disease have been mapped and/or cloned. In a large family with autosomal dominant inheritance and typical Lewy-body pathology, a first gene locus has been mapped to the long arm of chromosome 4, and mutations in this and a few other families linked to this locus have been identified in the gene for alpha-synuclein. Aggregation of this protein in Lewy bodies may be a crucial step in the molecular pathogenesis of familial and sporadic Parkinson's disease. A gene causing autosomal recessive parkinsonism of juvenile onset has been mapped to chromosome 6, and the causative gene has been identified and named parkin. A third locus, again in families with dominant inheritance, typical Lewy-body pathology, and late onset, has been mapped to chromosome 2p13, and two additional genes on chromosome 4p have been linked to other dominantly inherited forms of the disease. At present, there is no direct evidence that any of the genes for familial parkinsonian syndromes has a direct role in the etiology of the common sporadic form of PD. However, the elucidation of the molecular sequence of events leading to nigral degeneration in these inherited cases is likely also to shed light on the molecular pathogenesis of the common sporadic disorder.

Goedert, M. (2001). "Alpha-synuclein and neurodegenerative diseases." Nat Rev Neurosci 2(7): 492-501.

Goedert, M. (2001). "Parkinson's disease and other alpha-synucleinopathies." Clin Chem Lab Med 39(4): 308-12.
Parkinson's disease is the most common movement disorder and the second most common neurodegenerative disease. Neuropathologically, it is characterized by the degeneration of nerve cells that develop filamentous inclusions in the form of Lewy bodies and Lewy neurites. Recent work has shown that rare, familial forms of Parkinson's disease are caused by missense mutations in the alpha-synuclein gene and that the filamentous lesions of Parkinson's disease are made of alpha-synuclein. The same is true of the Lewy body pathology that is associated with other neurodegenerative diseases, such as dementia with Lewy bodies. The filamentous inclusions of multiple system atrophy have also been found to be made of alpha-synuclein, thus providing an unexpected molecular link with Lewy body diseases. Recombinant alpha-synuclein assembles into filaments with similar morphologies to those found in the human diseases and with a cross-beta diffraction pattern characteristic of amyloid. The related proteins beta-synuclein and gamma-synuclein are poor at assembling into filaments. They are not present in the pathological filamentous lesions and have not been found to be linked to genetic disease. The new work has established the alpha-synucleinopathies as a major class of neurodegenerative disease.

Iwata, A., S. Miura, et al. (2001). "alpha-Synuclein forms a complex with transcription factor Elk-1." J Neurochem 77(1): 239-52.
alpha-Synuclein has been identified as a component of Lewy bodies in Parkinson's disease and diffuse Lewy body disease, and glial cytoplasmic inclusions (GCIs) in multiple system atrophy (MSA). To explore the role of alpha-synuclein in the pathogenesis, we searched for molecules interacting with alpha-synuclein and discovered that GCIs are stained by anti-Elk-1 antibody. To seek the role of Elk-1 in synucleinopathies, we cotransfected alpha-synuclein and Elk-1 to cultured cells, and found small granular structure complexes where the two molecules colocalized. Moreover, alpha-synuclein and Elk-1 were co-immunoprecipitated from the cell lysates. For formation of the complex, the presence of both ETS and B-box domains of Elk-1 was required. Although there was no evidence of direct binding between alpha-synuclein and Elk-1, we discovered that alpha-synuclein and Elk-1 both bind to ERK-2, a MAP kinase. The effect of alpha-synuclein on the MAP kinase pathway was assessed using the Pathdetect system, which showed prominent attenuation of Elk-1 phosphorylation with alpha-synuclein, and especially A53T mutant. Our results suggest that alpha-synuclein reacts with the MAP kinase pathway, which might cause dysfunction of neurons and oligodendrocytes and lead to neurodegeneration in Parkinson's disease and MSA.

Kawamata, H., P. J. McLean, et al. (2001). "Interaction of alpha-synuclein and synphilin-1: effect of Parkinson's disease-associated mutations." J Neurochem 77(3): 929-34.
alpha-Synuclein is a major component of Lewy bodies, a neuropathological feature of Parkinson's disease. Two alpha-synuclein mutations, Ala53Thr and Ala30Pro, are associated with early onset, familial forms of the disease. Recently, synphilin-1, a protein found to interact with alpha-synuclein by yeast two hybrid techniques, was detected in Lewy bodies. In this study we report the interaction of alpha-synuclein and synphilin-1 in human neuroglioma cells using a sensitive fluorescence resonance energy transfer technique. We demonstrate that the C-terminus of alpha-synuclein is closely associated with the C-terminus of synphilin-1. A weak interaction occurs between the N-terminus of alpha-synuclein and synphilin-1. The familial Parkinson's disease associated mutations of alpha-synuclein (Ala53Thr and Ala30Pro) also demonstrate a strong interaction between their C-terminal regions and synphilin-1. However, compared with wild-type alpha-synuclein, significantly less energy transfer occurs between the C-terminus of Ala53Thr alpha-synuclein and synphilin-1, suggesting that the Ala53Thr mutation alters the conformation of alpha-synuclein in relation to synphilin-1.

Li, J., V. N. Uversky, et al. (2001). "Effect of familial Parkinson's disease point mutations A30P and A53T on the structural properties, aggregation, and fibrillation of human alpha-synuclein." Biochemistry 40(38): 11604-13.
Parkinson's disease involves the loss of dopaminergic neurons in the substantia nigra, leading to movement disorders. The pathological hallmark of Parkinson's disease is the presence of Lewy bodies and Lewy neurites, which are intracellular inclusions consisting primarily of alpha-synuclein. Although essentially all cases of sporadic and early-onset Parkinson's disease are of unknown etiology, two point mutations (A53T and A30P) in the alpha-synuclein gene have been identified in familial early-onset Parkinson's disease. Previous reports have shown that mutant alpha-synuclein may form fibrils more rapidly than wild-type protein. To determine the underlying molecular basis for the enhanced fibrillation of the mutants, the structural properties, responses to changes in the environment, and propensity to aggregate of wild-type, A30P, and A53T alpha-synucleins were systematically investigated. A variety of biophysical methods, including far-UV circular dichroism, FTIR, small-angle X-ray scattering, and light scattering, were employed. Neither the natively unfolded nor the partially folded intermediate conformations are affected by the familial Parkinson's disease point mutations. However, both mutants underwent self-association more readily than the wild type (i.e., at much lower protein concentration and more rapidly). We attribute this effect to the increased propensity of their partially folded intermediates to aggregate, rather than to any changes in the monomeric natively unfolded species. This increased propensity of these mutants to aggregate, relative to wild-type alpha-synuclein, would account for the correlation of these mutations with Parkinson's disease.

Mark, M. H. (2001). "Lumping and splitting the Parkinson Plus syndromes: dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration." Neurol Clin 19(3): 607-27, vi.
The atypical parkinsonian or Parkinson Plus syndromes are often difficult to differentiate from Parkinson's disease and each other. In this article, the clinicopathological characteristics of dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration are discussed. These disorders, although clinically distinct, may have more similarities than previously thought, based on modern immunocytochemical techniques and new genetic findings. These intriguing interconnections at a basic molecular level have provided the scientific rationale for lumping these diseases into two groups, the synucleinopathies and the tauopathies.

Matsuoka, Y., M. Vila, et al. (2001). "Lack of nigral pathology in transgenic mice expressing human alpha-synuclein driven by the tyrosine hydroxylase promoter." Neurobiol Dis 8(3): 535-9.
alpha-Synuclein has been identified as a major component of Lewy body inclusions, which are one of the pathologic hallmarks of idiopathic Parkinson's disease. Mutations in alpha-synuclein have been found to be responsible for rare familial cases of Parkinsonism. To test whether overexpression of human alpha-synuclein leads to inclusion formation and neuronal loss of dopaminergic cells in the substantia nigra, we made transgenic mice in which the expression of wild-type or mutant (A30P and A53T) human alpha-synuclein protein was driven by the promoter from the tyrosine hydroxylase gene. Even though high levels of human alpha-synuclein accumulated in dopaminergic cell bodies, Lewy-type-positive inclusions did not develop in the nigrostriatal system. In addition, the number of nigral neurons and the levels of striatal dopamine were unchanged relative to non-transgenic littermates, in mice up to one year of age. These findings suggest that overexpression of alpha-synuclein within nigrostriatal dopaminergic neurons is not in itself sufficient to cause aggregation into Lewy body-like inclusions, nor does it trigger overt neurodegenerative changes. Copyright 2001 Academic Press.

McLean, P. J., H. Kawamata, et al. (2001). "Alpha-synuclein-enhanced green fluorescent protein fusion proteins form proteasome sensitive inclusions in primary neurons." Neuroscience 104(3): 901-12.
Alpha-synuclein accumulates in the brains of sporadic Parkinson's disease patients as a major component of Lewy bodies, and mutations in alpha-synuclein are associated with familial forms of Parkinson's disease. The pathogenic mechanisms that precede and promote the aggregation of alpha-synuclein into Lewy bodies in neurons remain to be determined. Here, we constructed a series of alpha-synuclein-enhanced green fluorescent protein (alpha-synucleinEGFP, SynEGFP) fusion proteins to address whether the Parkinson's disease-associated mutations alter the subcellular distribution of alpha-synuclein, and to use as a tool for experimental manipulations to induce aggregate formation. When transfected into mouse cultured primary neurons, the 49-kDa alpha-synucleinEGFP fusion proteins are partially truncated to a approximately 27-kDa form. This non-fluorescent carboxy-terminally modified fusion protein spontaneously forms inclusions in the neuronal cytoplasm. A marked increase in the accumulation of inclusions is detected following treatment with each of three proteasome inhibitors, n-acetyl-leu-leu-norleucinal, lactacystin and MG132. Interestingly, Ala30Pro alpha-synucleinEGFP does not form the cytoplasmic inclusions that are characteristic of wild-type and Ala53Thr alpha-synucleinEGFP, supporting the idea that the Ala30Pro alpha-synuclein protein conformation differs from wild-type alpha-synuclein. Similar inclusions are formed if alpha-synuclein carboxy-terminus is modified by the addition of a V5/6xHistidine epitope tag. By contrast, overexpression of unmodified alpha-synuclein does not lead to aggregate formation. Furthermore, synphilin-1, an alpha-synuclein interacting protein also found in Lewy bodies, colocalizes with the carboxy-terminally truncated alpha-synuclein fusion protein in discrete cytoplasmic inclusions.Our finding that manipulations of the carboxy-terminus of alpha-synuclein lead to inclusion formation may provide a model for studies of the pathogenic mechanisms of alpha-synuclein aggregation in Lewy bodies.

McNaught, K. S. and P. Jenner (2001). "Proteasomal function is impaired in substantia nigra in Parkinson's disease." Neurosci Lett 297(3): 191-4.
The accumulation of alpha-synuclein, ubiquitin and other proteins in Lewy bodies in degenerating dopaminergic neurones in substantia nigra in idiopathic Parkinson's disease (PD) suggest that inhibition of normal/abnormal protein degradation may contribute to neuronal death. We now show for the first time that the chymotrypsin- (39%), trypsin- (42%) and postacidic-like (33%) hydrolysing activities of 20/26S proteasome are impaired in substantia nigra in PD. Proteasome inhibition does not appear to result from drug treatment since high concentrations of L-3,4-dihydroxyphenylalanine had no effect on enzymatic activity in vitro. These observations provide the first direct evidence that inhibition of the ubiquitin-proteasome pathway leading to altered protein handling and Lewy body formation may be responsible for degeneration of the nigrostriatal pathway in idiopathic PD.

McNaught, K. S., C. W. Olanow, et al. (2001). "Failure of the ubiquitin-proteasome system in Parkinson's disease." Nat Rev Neurosci 2(8): 589-94.

Mizuno, Y., N. Hattori, et al. (2001). "Parkin and Parkinson's disease." Curr Opin Neurol 14(4): 477-82.
Parkin is the causative gene for an autosomal recessive form of Parkinson's disease. The gene was discovered in 1998. The parkin gene is a novel gene containing 12 exons spanning over 1.5 Mb and encodes a protein of 465 amino acids with a molecular mass of approximately 52,000 M(r). Various deletion mutations and point mutations have been discovered in patients with autosomal recessive Parkinson's disease. The substantia nigra and the locus coeruleus selectively undergo neurodegeneration without forming Lewy bodies. The parkin gene product, Parkin protein, has a unique structure with a ubiquitin-like domain in the amino-terminus and a RING finger motif in the carboxy terminus. The function of Parkin was not known until recently. During the year 2000, great progress was made in defining its function. First of all, Parkin was found to be a ubiquitin-protein ligase (E3), a component of the ubiquitin system, which is an important adenosine triphosphate-dependent protein degradation machinery. In addition, CDCrel-1, a synaptic vesicle associated protein, was found to be a substrate for Parkin as an E3. Although many studies still need to be performed to elucidate the molecular mechanism of the selective nigral neurodegeneration in this form of familial Parkinson's disease, it will not be too long before this is accomplished. In this review article, we evaluate the developments in this area published since 1 February 2000.

Nielsen, M. S., H. Vorum, et al. (2001). "Ca2+ binding to alpha-synuclein regulates ligand binding and oligomerization." J Biol Chem 276(25): 22680-4.
alpha-Synuclein is a protein normally involved in presynaptic vesicle homeostasis. It participates in the development of Parkinson's disease, in which the nerve cell lesions, Lewy bodies, accumulate alpha-synuclein filaments. The synaptic neurotransmitter release is primarily dependent on Ca(2+)-regulated processes. A microdialysis technique was applied showing that alpha-synuclein binds Ca(2+) with an IC(50) of about 2-300 microm and in a reaction uninhibited by a 50-fold excess of Mg(2+). The Ca(2+)-binding site consists of a novel C-terminally localized acidic 32-amino acid domain also present in the homologue beta-synuclein, as shown by Ca(2+) binding to truncated recombinant and synthetic alpha-synuclein peptides. Ca(2+) binding affects the functional properties of alpha-synuclein. First, the ligand binding of (125)I-labeled bovine microtubule-associated protein 1A is stimulated by Ca(2+) ions in the 1-500 microm range and is dependent on an intact Ca(2+) binding site in alpha-synuclein. Second, the Ca(2+) binding stimulates the proportion of (125)I-alpha-synuclein-containing oligomers. This suggests that Ca(2+) ions may both participate in normal alpha-synuclein functions in the nerve terminal and exercise pathological effects involved in the formation of Lewy bodies.

Sherer, T. B., R. Betarbet, et al. (2001). "Pathogenesis of Parkinson's disease." Curr Opin Investig Drugs 2(5): 657-62.
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by degeneration of the nigrostriatal dopaminergic pathway and the appearance of cytoplasmic proteinaceous aggregates known as Lewy bodies. Studies of familial PD have uncovered rare causative mutations in genes, including alpha-synuclein. Mutations or oxidative modification of alpha-synuclein causes it to aggregate; alpha-synuclein is a major component of the Lewy body in both familial and sporadic PD. Biochemical analysis has implicated mitochondrial dysfunction in PD. Epidemiological studies indicate a role of exposure to pesticides, some of which are mitochondrial toxins. Mitochondrial dysfunction, resulting from genetic defects, environmental toxins, or a combination of the two, may cause alpha-synuclein aggregation and produce selective neurodegeneration through mechanisms involving oxidative stress and excitotoxicity. Efforts to better define PD pathogenesis should reveal novel therapeutic targets.

Shimo, Y., M. Takanashi, et al. (2001). "[A-56-year-old woman with parkinsonism, whose mother had Parkinson's disease]." No To Shinkei 53(5): 495-505.
We report a 56-year-old woman with progressive gait disturbance. Her mother had Parkinson's disease with onset at age 70. She died at age 74 and the post-mortem examination confirmed the diagnosis of Lewy body positive Parkinson's disease. The patient was well until the age of 50(1995) when she noted an onset of resting tremor and difficulty of gait. She also developed delusional ideation and was admitted to a psychiatric service of another hospital, where a major tranquilizer was given. The delusion disappeared but she developed marked rigidity. The major tranquilizer was discontinued and an anticholinergic and amantadine HCl were given. She showed marked improvement to Hoehn and Yahr stage II and was discharged. In 1995, when she was 52 years of the age, she developed delusion again and a major tranquilizer was given. She developed marked parkinsonism again and became Hoehn and Yahr stage V. The major tranquilizer was discontinued and she was treated with levodopa/carbidopa, trihexyphenidyl, bromocriptine, and dops. She improved remarkably to stage II. She was admitted to our service on October 8, 1996 for drug adjustment. She was alert and not demented. She was anxious but delusion or hallucination was noted. Higher cerebral functions were intact. Cranial nerve functions were also intact except for masked face and small voice. Her posture was stooped and steps were small. She showed retropulsion and moderate bradykinesia. Resting tremor was noted in her left hand. Rigidity was noted in both legs. No cerebellar ataxia or weakness was noted. Deep tendon reflexes were within normal range and sensation was intact. Her cranial MRI revealed some atrophic changes in the putamen, in which a T 2-high signal linear lesion was seen along the lateral border of the putamen bilaterally. In addition, posterior part of the putamen showed T 2-low signal intensity change. She was treated with 1.6 mg of talipexole, 6 mg of trihexyphenidyl, and 100 mg of L-dops. She was in stage III of Hoehn and Yahr. She developed neurogenic bladder with a large amount of residual urine for which she required catheterization. She was transferred to another hospital. Despite drug adjustment, she lost response to levodopa and her parkinsonism deteriorated gradually. She also developed syncope orthostatic hypotension. In April of 1998, she developed intracerebral hemorrhage and was admitted again on April 19, 1998. She was unable to stand and showed marked akinesia and rigidity. She was in stage V of Hoehn and Yahr. Her cranial CT scan revealed bilateral high-density lesions in the posterior parietal lobes. She developed dysphagia for which she required gastrostomy. She was transferred to another hospital but her clinical condition deteriorated further. On December 22, 1999, she developed fever and dyspnea and was admitted to our service again. She developed cardial arrest at the emergency room from hypoxia. She was resuscitated; however, she was comatose with loss of brain stem reflexes. Later on she developed generalized myoclonus. She developed cardiac arrest and pronounced dead on December 28, 1999. The patient was discussed in a neurological CPC. The chief discussant arrived at the conclusion that the patient had striatonigral degeneration because of poor response to levodopa in the later course, autonomic failures, and MRI changes. Some other participants thought that the patient had a form of familial Parkinson's disease. Opinions were divided into these two possibilities. Post-mortem examination revealed that the substantia nigra showed intense neuronal loss and gliosis, however, no Lewy bodies were seen. In addition, intracytoplasmic inclusions were seen in oligodendrocytes. The putamen was markedly atrophic in its posterior part with marked gliosis and neuronal loss. The ventromedial part of the pontine nucleus also showed neuronal loss and intracytoplasmic glial inclusions. Pathologic diagnosis was multiple system atrophy. In the parietal lobe, an arteriovenous malformation with bleeding was noted. This is very unique case. Although her mother had Lewy body-positive Parkinson's disease, the patient had Lewy body-negative multiple system atrophy with a-synuclein-positive glial inclusions. Whether this is just a coincidental occurrence or the presence of a genetic load for Parkinson's disease might triggered her multiple system atrophy is an interesting question to be answered in future.

Shimura, H., M. G. Schlossmacher, et al. (2001). "Ubiquitination of a new form of alpha-synuclein by parkin from human brain: implications for Parkinson's disease." Science 293(5528): 263-9.
Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the progressive accumulation in selected neurons of protein inclusions containing alpha-synuclein and ubiquitin. Rare inherited forms of PD are caused by autosomal dominant mutations in alpha-synuclein or by autosomal recessive mutations in parkin, an E3 ubiquitin ligase. We hypothesized that these two gene products interact functionally, namely, that parkin ubiquitinates alpha-synuclein normally and that this process is altered in autosomal recessive PD. We have now identified a protein complex in normal human brain that includes parkin as the E3 ubiquitin ligase, UbcH7 as its associated E2 ubiquitin conjugating enzyme, and a new 22-kilodalton glycosylated form of alpha-synuclein (alphaSp22) as its substrate. In contrast to normal parkin, mutant parkin associated with autosomal recessive PD failed to bind alphaSp22. In an in vitro ubiquitination assay, alphaSp22 was modified by normal but not mutant parkin into polyubiquitinated, high molecular weight species. Accordingly, alphaSp22 accumulated in a non-ubiquitinated form in parkin-deficient PD brains. We conclude that alphaSp22 is a substrate for parkin's ubiquitin ligase activity in normal human brain and that loss of parkin function causes pathological alphaSp22 accumulation. These findings demonstrate a critical biochemical reaction between the two PD-linked gene products and suggest that this reaction underlies the accumulation of ubiquitinated alpha-synuclein in conventional PD.

Stefanis, L., N. Kholodilov, et al. (2001). "Synuclein-1 is selectively up-regulated in response to nerve growth factor treatment in PC12 cells." J Neurochem 76(4): 1165-76.
Mutations in the alpha-synuclein gene have recently been identified in families with inherited Parkinson's disease and the protein product of this gene is a component of Lewy bodies, indicating that alpha-synuclein is involved in Parkinson's disease pathogenesis. A role for normal alpha-synuclein in synaptic function, apoptosis or plasticity responses has been suggested. We show here that in rat pheochromocytoma PC12 cells synuclein-1, the rat homolog of human alpha-synuclein, is highly and selectively up-regulated at the mRNA and protein levels after 7 days of nerve growth factor treatment. Synuclein-1 expression appears neither sufficient nor necessary for the neuritic sprouting that occurs within 1-2 days of nerve growth factor treatment. Rather, it likely represents a component of a late neuronal maturational response. Synuclein-1 redistributes diffusely within the cell soma and the neuritic processes in nerve growth factor-treated PC12 cells. Cultured neonatal rat sympathetic neurones express high levels of synuclein-1, with a diffuse intracellular distribution, similar to neuronal PC12 cells. These results suggest that levels of synuclein-1 may be regulated by neurotrophic factors in the nervous system and reinforce a role for alpha-synuclein in plasticity-maturational responses. In contrast, there is no correlation between synuclein expression and apoptotic death following trophic deprivation.

Stefanova, N., L. Klimaschewski, et al. (2001). "Glial cell death induced by overexpression of alpha-synuclein." J Neurosci Res 65(5): 432-8.
alpha-Synuclein is present in intracellular protein aggregates that are hallmarks of common neurodegenerative disorders including Parkinson disease, dementia with Lewy bodies, and multiple system atrophy. alpha-Synuclein is localized in neurons and presynaptic terminals. Under pathological conditions, however, it is also found in glia. The role of alpha-synuclein in glial cells and its relevance to the molecular pathology of neurodegenerative diseases is presently unclear. To investigate the consequence of alpha-synuclein overexpression in glia, we transfected U373 astrocytoma cells with vectors encoding wild-type human alpha-synuclein or C-terminally truncated synuclein fused to red fluorescent protein. alpha-synuclein immunocytochemistry of transfected astroglial cells revealed diffuse cytoplasmic labeling associated with discrete inclusions both within cell bodies and processes. Susceptibility to oxidative stress was increased in astroglial cells overexpressing alpha-synuclein, particularly in the presence of cytoplasmic inclusions. Furthermore, overexpression of alpha-synuclein induced apoptotic death of astroglial cells as shown by TUNEL staining. Our in vitro model is the first to replicate salient features of the glial pathology associated with alpha-synucleinopathies. It provides a simple testbed to further explore the cascade of events that leads to apoptotic glial cell death in some of these disorders; it may also be useful to assess the effects of therapeutic interventions including antioxidative and antiapoptotic strategies.

Sung, J. Y., J. Kim, et al. (2001). "Induction of neuronal cell death by Rab5A-dependent endocytosis of alpha-synuclein." J Biol Chem 276(29): 27441-8.
The presynaptic alpha-synuclein is a prime suspect for contributing to Lewy pathology and clinical aspects of diseases, including Parkinson's disease, dementia with Lewy bodies, and a Lewy body variant of Alzheimer's disease. Here we examined the pathogenic mechanism of neuronal cell death induced by alpha-synuclein. The exogenous addition of alpha-synuclein caused a marked decrease of cell viability in primary and immortalized neuronal cells. The neuronal cell death appeared to be correlated with the Rab5A-specific endocytosis of alpha-synuclein that subsequently caused the formation of Lewy body-like intracytoplasmic inclusions. This was further supported by the fact that the expression of GTPase-deficient Rab5A resulted in a significant decrease of its cytotoxicity as a result of incomplete endocytosis of alpha-synuclein.

Vaughan, J. R., M. B. Davis, et al. (2001). "Genetics of Parkinsonism: a review." Ann Hum Genet 65(Pt 2): 111-26.
Idiopathic Parkinson's disease (IPD), a progressive neurodegenerative disorder, is a common cause of disability. No current therapies modify disease progression. The pathological hallmarks are the presence of Lewy bodies and massive loss of dopaminergic neurons in the pars compacta of the substantia nigra. Two genes (SNCA and parkin) as well as two gene loci have now been implicated in the pathogenesis of familial PD. These represent significant progress in our understanding of the disease, considering the rarity of large families, low heritability in the general population and genetic heterogeneity. Mutations in a further gene, UCHL1, have been described in familial PD although the evidence for its role in PD is less clear. Knowledge of the genes described in PD to date should help to define molecular mechanisms of neurodegeneration in PD, as well as in other diseases where defects in protein handling may be a common feature. Nigral degeneration with Lewy body formation and the resulting clinical picture of PD may represent a final common pathway of a multifactorial disease process in which both environmental and genetic factors have a role. This review discusses the major advances in the field to date and illustrates how the existence of genetic factors has now become firmly established.