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Parkinson's Disease in Relation With Alpha-synuclein... Neurological diseases have eluded and frustrated both scientist and physicians for years. Little is know about the functions of the brain, and therefore, knowledge about neurological diseases is limited. One such disease, Parkinson's, has recently found its way back into the news thanks to Michael J. Fox and is being looked at more closely. However, the effects of Parkinson's and its exact pathological function have been studied for years. Since Parkinson's disease is so elusive and difficult to diagnose before the disease sets in, an early detection device was first looked at. It was found that there was a genetic effect. Genetic markers segregated with the disease in a family study of Italians. It was found that this gene is located on the long arm of chromosome 4 and is the alpha- synuclein gene. Through familiar examinations with genetic markers, the gene was found to be in 4q21-q22 region. Alpha-synuclein is a presynaptic nerve terminal protein and was originally associated with Alzheimer's disease. However, through further familiar studies, it was found that the majority of phenotypes of Parkinson's disease also had the alpha-synuclein gene of an earlier member with the disease (Polumeropoulos, Lavedan, Leroy, et al. 1997). Other studies were done to make sure that certain mutations in this gene was directly associated with Parkinson's. In zebra finches, the homolog to synuclein, synelfin, is thought to be involved in learning processes and memory. Also in rats, three members of the synuclein family have been identified at the time of this study. These genes bear a very close resemblance to human synuclein, 95% actually. These proteins were also found in abundance in the olfactory bulb and tract, hippocampus, dentate gyrus, habenula, amygdala, and piriform cortex, and trace amounts in other areas. This coincides directly with the loci a Lewy bodies found in human patients (Polumeropoulos, Lavedan, Leroy, et al. 1997). Lewy bodies are a defining characteristic of Parkinson's disease. They are also found in patients with Alzheimer's, but not in the same abundance. A study was performed in 1997 to determine if alpha- synuclein was involved in the formation of Lewy bodies since recent studies of the same time began linking Parkinson's to this protein. Six patients diagnosed with Parkinson's disease were chosen for the study. They were injected with various antibodies, affinity purified, anti-alpha- synuclein serum PER2 and PER1, which stained alpha-synuclein proteins. There was a strong immunological response in the brainstem- type and cortical Lewy bodies in the patients with Parkinson's. Unlike the previous familiar studies, none of these patients were related; therefore, the formation of Lewy bodies is not particular to one type of alpha-synuclein, but it was still involved in all the formations. With these results, it is reasonable to hypothesis that Parkinson's disease is directly related to alpha-synuclein (Spillantini 1997). Now that it was known that alpha-synuclein is directly involved with Lewy bodies and with Parkinson's disease, it was needed to know what mutations of the protein caused the greatest change. One such experiment was performed using the typical familiar variations of the gene: the wild type, A53T, and A30P. These variations of genes were extracted from the human gene library and were placed in bacterial genomes through an unnamed vector. The genes were extracted in cDNA and the genes were placed in the bacteria as the following: wild type, A53T, A30P, and A53T/A30P. The bacteria would make the protein and carry on. At various intervals the solutions were centrifuged and measurements of aggregates were made. The aggregates were fibrillar beta-sheets, which are now known to be a critical step in the formations of Lewy bodies (Narhi, Wood, Steavenson, et al. 1999). The results of this experiment produced results that confirmed the original suspicions that mutations in alpha-synuclein led to the formations of Lewy bodies. There was a lag time, however, that the proteins went through before they began to aggregate. Under the conditions tested, which were various times measured at 25 degrees Celsius, the wild type lag time was 280h, the A30P was about 180h, and A53T was about 100h. It is obvious from this that the A53T mutation causes the earliest aggregation and therefore, the earliest formations of Lewy bodies. It was also noted that shaking the test tubes made the aggregation occur faster. This was just noted as another possible path for the disease, however, it was not explored further (Narhi, Wood, Steavenson, et al. 1999). Mutations in alpha-synuclein is noted in familiar cases of Parkinson's disease; however, in cases that are not related the disease in many times linked with accumulations of the wild type alpha-synuclein. Because of this, further study was done into the effects of accumulation of alpha-synuclein, particularly on dopaminergic cells. In an experiment performed in February of 2000, mice were induced to display various productivity of human wild type alpha-synuclein (the exact mechanisms of this induction were not mentioned). The mice with the highest expression of human wild type aplha-synculein experienced the greatest effect. More cells in these mice had intraneuronal inclusions, both nuclear and cytomplasmic, that were reactive with an antibody for human alpha-synuclein, but not with mice. These cells that were most effected were also found in the regions of the brain that is most effect when a patient has Parkinson's disease (Masliah, Rockenstein, Veinbergs, et al. 2000). It is also known that patients with Parkinson's disease have a degeneration of dopaminergic neurons. To test this hypothesis and see if it correlated with the results received from the induction of wild type human alpha-synuclein, stains were introduced for both human alpha-synuclein and dopamine. The concentrations of these dopaminergic neurons were less in the mice with a higher expression rate, and also the concentration of dopaminergic neurons was less in the areas of the brain known to be most affected in Parkinson's disease. These findings substantiate, again, the hypothesis that accumulation of alpha-synuclein, in this case wild type, is directly related to Parkinson's, and further more, the degradation of dopaminergic neurons is also related to it (Masliah, Rockenstein, Veinbergs, et al. 2000). These findings definitely progressed the knowledge of Parkinson's disease, however, the exact pathway and growth of the disease is still unknown. Studies of this nature on humans is completely unfeasible, not to mention inhumane. Therefore, another method of study must be devised for these results. Feany and Bender looked for a new method by inducing Parkinson's disease in Drosophila or fruit flies (Feany and Bender 2000). They used the previous findings and decided to induce the mutations of alpha-synuclein in fruit flies. They used the wild type, A30P, and A53T variations of the gene. With inducing these genes through the use of a vector, the scientists were only looking to see if they could induce a disease resembling Parkinson's. To determine this, they ran several tests. First, a stain was used that targeted dopaminergic neurons and tested at intervals of 30 to 60 days. With the wild type, the neurons were decreased or gone, but in the A53T and A30P mutations, the nerons were all completely gone. They tested this method with another marker and the same results occurred (Feany and Bender 2000). Other reasons they believed they induced a Parkinson's like disease in the flies is that there were other symptoms. There was no lose of brain volume, therefore the neurological disorder was not caused by complete destruction. Also, there was no difference in any of the samples when stained for serotonin. This means that only neurons with dopamine were being effected. Microscopic analysis also showed that there were formations that appeared in every physical sense to be the same as the Lewy bodies found in human patients. They also ran tests for motor skills, the speed at which the flies flew away from danger, and this decreased as followed: A53T and wild type degenerated faster but A30P degenerated the fastest. All of these results concurred that the scientist were able to create a disease that very closely resembled Parkinson's in flies (Feany and Bender 2000). There have been giant leaps in the study of Parkinson's disease over the past few years. We now know major functions of the disease and what genes are involved, but the exact mechanism of the disease is still not known. With the advancements now, studies within the fruit flies have opened the door to our understanding of the methodology and pathology of this disease. Works Sited Feany, Mel B. and Bender, Welcome W. "A Drosophila Model of Parkinson's Disease." Nature, 23 March 2000. Masliah, Eliezer, Edward Rockenstein, Isaac Veinberg, et al. "Dopaminergic Loss and Inclusion Body Formation in Alpha-Synuclein Mice: Implications for Neurodegenerative Disorders." Science, 18 February 2000. Narhi, Linda, Stephen J. Wood, Shirley Steavenson, et al. "Both Familial Parkinson's Disease Mutations Accelerate Alpha-Synuclein Aggregation." The Journal of Biological Chemistry, 2 April 1999. Polymeropoulos, Miheal H. Christian Lavedan, Elisabeth Leroy, et al. "Mutation in the Alpha- Synuclein Gene Identified in Families with Parkinson's Disease." Science, 27 June 1997. Spillantini, Maria Grazia. "Alpha-Synuclein in Lewy Bodies." Nature, 28 August 1997. http://www.biol.sc.edu/~elygen/emery.html *************** [log in to unmask]