Parkinson’s disease

Parkinson’s disease

What is Parkinson’s disease?

Parkinson’s disease (PD) is movement disorder of the nervous system that worsens over time. As nerve cells (neurons) in parts of the brain weaken or are damaged or die, people may begin to notice problems with movement, tremor, stiffness in the limbs or the trunk of the body, or impaired balance. As these symptoms become more obvious, people may have difficulty walking, talking, or completing other simple tasks. Not everyone with one or more of these symptoms has PD, as the symptoms appear in other diseases as well.

No cure for PD exists today, but research is ongoing and medications or surgery can often provide substantial improvement with motor symptoms.

Degenerate α-synuclein causes the disease

Protein aggregates have been observed in the nerve tissue of patients with Parkinson’s disease which consist of induvidual components (monomers) of  the protein alpha-synuclein. These assemble into what are referred to as amyloid fibrils. Similar deposits are also found in the case of other neurodegenerative diseases such as Alzheimer’s. Researchers are looking for approaches to prevent fibril formation and potentially cure the diseases.

Aggregates of amyloid proteins characterize many neurodegenerative disorders including Alzheimer’s disease (AD) and Parkinson’s disease (PD). Formation of pathological inclusions occurs by a multistep process including the misfolding of normal soluble proteins and their association into higher order oligomers, followed by their assembly into amyloid fibrils (figure 5) that form disease specific inclusions. 

Native α-synuclein 
H. Lundbeck A/S

Degenerate α-synucleinH. Lundbeck A/S

Fibrils precipitated on a ProPhyl Air gel (Coomassie stain)

Large amounts of insoluble aggregated fibrils (left+right), caused by a degenerative α-synuclein can be found on the application point on a gel. Causally responsible for Parkinson’s disease.  
The size of the fibrils can be well over 2 Megadalton (2MDa) and thus no longer accessible for electrophoresis

Fibrils precipitated on a ProPhyl Air gel (Coomassie stain)
α-Synuclein fibrils are a major component of the intracellular Lewy bodies that are associated with Parkinson's disease, Lewy body dementia, and multiple system atrophy (see below)
figure 1

Fig.1 left
Sample A,B,C,D

α-synuclein in different aggregation stages of fibril production (intermediate fibrils). 
Sample C + D
Large amounts of insoluble aggregated fibrils can be found on the application point (below).

Sample S
monomeric α-synuclein
Fig.1 right
Sample A,B,C,D,S
previously unknown proteins in the high pH range (> pH 8,5)

The formation of intermediate  fibril aggregation shown in the fig. 1 left could be an indication that one or more of misfolding isoforms of the α-synuclein shown in the IEF (fig. 2) could be the cause of the production of macromolecular amyolid fibrils the leads to Parkinson’s. When α-syn is incubated in vitro at a high concentration under shaking conditions, it undergoes a conformational change and turns into fibrils within a few days.

In contrast, little or no fibrils form at a lower α-syn concentration without shaking, and the protein needs more time to assemble.​ Studies indicate that α-syn exists in secretory vesicles of neurons and multifarious biological fluids such as CSF and plasma, implying that α-syn may be secreted via exocytosis.Interestingly, they found CSF α-synuclein levels at 12 months were lower in people with PD treated with dopamine replacement therapy, especially dopamine agonists.

α-synuclein is expressed principally in the nervous system, but it is also produced in the other tissues, including the skin. In the brain, the protein is primarily neuronal, but it is also present in glia. Neuronal α-synuclein is concentrated in the presynaptic nerve terminals, interacts with plasma membrane phospholipids, and is also present in the nuclei and mitochondria. At least  six synuclein bands of unknown origin (fig. 2). The most common isoform is a 140 amino acid-long transcript. Other isoforms are α-synuclein-126, lacking residues 41-54; and α-synuclein-112, which lacks residues 103-130. α-synuclein’s physiological role is poorly understood, but the protein has been implicated in regulating dopamine release and transport, synaptic vesicle clustering, and functioning as a SNARE-complex chaperone.

figure 3

Sample A,B,C,D
α-synuclein in different stages of fibril aggregation (intermediate fibrils). 
Sample hu-α-synuclein
Human monomeric synuclein checked with FPLC and SDS electrophoresis (figure 2+4). Several bands were identified in the IEF with ProPhyl Air that could result from the protein fragmentation into subunits. This finding is new and needs further investigation.

α-synuclein fibrils are a major component of the intracellular Lewy bodies that are associated with Parkinson’s disease, Lewy body dementia, and multiple system atrophy (see below)

figure 6

ProPhyl Air made a decisive contribution to the discovery of α-synuclein in cerebrospinal fluid using the isoelectric focusing method