Reduced LRRK2 in association with retromer dysfunction in post-mortem brain tissue from LRRK2 mutation carriers

Area of Science:

• Neuroscience
• Genetics
• Biochemistry

Background:

• Missense mutations in leucine-rich repeat kinase 2 (LRRK2) are a known cause of familial Parkinson's disease.
• The impact of these mutations on LRRK2 protein levels in the brain remains largely uncharacterized.

Purpose of the Study:

• To investigate LRRK2 protein levels in the brain tissue of individuals with LRRK2 mutations.
• To explore the relationship between LRRK2 protein levels and other genetically associated Parkinson's disease proteins.

Main Methods:

• Utilized brain tissue from 17 LRRK2 mutation carriers (G2019S and I2020T) and matched controls/idiopathic Parkinson's disease cases.
• Employed immunoblot assays to quantify protein levels of LRRK2, VPS35, GBA, and MPR300 (IGF2R).

Main Results:

• LRRK2 protein levels were significantly reduced in LRRK2 mutation carriers compared to controls and idiopathic Parkinson's disease cases.
• Decreased levels of vacuolar protein sorting associated protein 35 (VPS35) and glucocerebrosidase (GBA) were observed.
• Cation-independent mannose-6-phosphate receptor (MPR300) levels were also reduced and correlated with LRRK2 levels.

Conclusions:

• This study provides novel data on LRRK2 protein expression in the brains of LRRK2 mutation carriers.
• Findings suggest a potential link between LRRK2 dysfunction and retromer pathway impairment in LRRK2-associated Parkinson's disease.