New brain-specific beta-synuclein isoforms show expression ratio changes in Lewy body diseases

Area of Science:

• Neuroscience
• Genetics
• Pathology

Background:

• Lewy body diseases (LBDs), including dementia with Lewy bodies (DLB) and Parkinson disease (PD), are characterized by alpha-synuclein (AS) aggregation.
• Beta-synuclein (BS) inhibits AS aggregation and may be protective.
• A subset of DLB patients shows a lack of BS in cortical regions.

Purpose of the Study:

• To characterize new BS transcript variants.
• To analyze BS expression in neuronal and non-neuronal tissues.
• To investigate differential BS expression in brain samples from LBD patients and controls.

Main Methods:

• Characterization of four novel BS transcript variants.
• Real-time PCR analysis of mRNA expression in brain tissue.
• Quantification using neuron-specific enolase 2 and synaptophysin as housekeeping genes.
• Evaluation of expression changes using the ΔΔCt method.

Main Results:

• All BS isoforms were significantly reduced in the cortex of patients with pure Lewy body pathology (LBP) presenting as DLB.
• A shift in BS isoform expression ratios was observed in the temporal cortex of all LBD cases.
• Minor BS isoforms, typically absent in the midbrain, were detected in the caudate nucleus of DLB samples.

Conclusions:

• BS isoforms are diminished in the cortex of DLB patients, supporting a role in LBD pathogenesis.
• Shifts in BS isoform expression and detection of minor isoforms in specific brain regions offer new insights into LBD mechanisms.
• These findings highlight the potential involvement of minor transcript variants in complex neurological diseases like LBDs.