Other meanings of Alpha-synuclein
Neuroscience
Alpha-synuclein is a small, intrinsically disordered neuronal protein that is central to the pathogenesis of Parkinson's disease and other synucleinopathies. Encoded by the SNCA gene, it is abundant in the brain, particularly at presynaptic terminals, where it is thought to regulate synaptic vesicle trafficking and neurotransmitter release. Misfolding and aggregation of alpha-synuclein into insoluble fibrils is a hallmark of several neurodegenerative disorders, including dementia with Lewy bodies and multiple system atrophy.
Alpha-synuclein is a 140-amino-acid protein with three distinct domains: an N-terminal amphipathic region, a central hydrophobic NAC (non-amyloid-β component) domain, and an acidic C-terminus. In solution, it is intrinsically disordered, but it adopts an alpha-helical conformation upon binding to lipid membranes. Its primary function is thought to involve synaptic vesicle trafficking and the regulation of neurotransmitter release, possibly by promoting SNARE complex assembly. It is also implicated in dopamine metabolism and in the maintenance of synaptic plasticity. Knockout studies in mice show subtle phenotypes, suggesting functional redundancy with other synucleins (beta- and gamma-synuclein).
Misfolding and aggregation of alpha-synuclein into amyloid fibrils is a pathological hallmark of Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. These aggregates form Lewy bodies and Lewy neurites, which are found in surviving neurons. The aggregation process is thought to be initiated by oxidative stress, mitochondrial dysfunction, or post-translational modifications such as phosphorylation at Ser129. Genetic mutations in SNCA (e.g., A53T, A30P) and multiplications of the gene cause familial forms of Parkinson's disease, underscoring the protein's causal role. The prion-like propagation of alpha-synuclein aggregates between cells is a growing area of research, explaining the spread of pathology through the brain.
Given its central role, alpha-synuclein is a prime target for disease-modifying therapies. Strategies include reducing its production via antisense oligonucleotides or small interfering RNAs, inhibiting aggregation with small molecules or peptides, and enhancing clearance through autophagy or the ubiquitin-proteasome system. Immunotherapy approaches, using antibodies that target aggregated forms, have shown promise in preclinical models and are in clinical trials. However, challenges remain, including the blood-brain barrier, the lack of reliable biomarkers, and the risk of off-target effects. Recent advances in cryo-electron microscopy have revealed the atomic structures of alpha-synuclein fibrils, which may inform rational drug design.
Beyond neurodegeneration, alpha-synuclein is expressed in other tissues, including the gut, where it may play a role in the enteric nervous system and in the gut-brain axis. It is also found in red blood cells, where its function is unclear. The protein's name derives from its initial discovery in the electric organ of the Pacific electric ray (Torpedo californica) and its later localization to the synapse and nucleus. Alpha-synuclein can exist in different conformations, including a tetrameric form that may be the native state, challenging the monomeric paradigm. Additionally, it interacts with lipids and membranes, and its aggregation is influenced by lipid composition. Some studies suggest a role in cancer, though this is controversial.
Alpha-synuclein was first identified in 1988 by Maroteaux and colleagues in the electric organ of the Pacific electric ray.
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