The LRRK2 kinase substrates RAB8a and RAB10 contribute complementary but distinct disease-relevant phenotypes in...

Area of Science:

• Neuroscience
• Genetics
• Cell Biology

Background:

• Mutations in the Leucine-Rich Repeat Kinase 2 (LRRK2) gene are a significant cause of familial Parkinson's disease (PD).
• Pathogenic LRRK2 mutations lead to increased kinase activity, affecting cellular processes.
• Small RAB GTPases, including RAB8a and RAB10, are key substrates of LRRK2, and their phosphorylation by LRRK2 results in inactivation.

Purpose of the Study:

• To investigate the distinct roles of LRRK2 substrates RAB8a and RAB10 in neuronal function and pathology.
• To generate and characterize isogenic induced pluripotent stem cell (iPSC) lines lacking functional RAB8a or RAB10 using CRISPR-Cas9 genome editing.
• To understand how the inactivation of RAB8a and RAB10 by LRRK2 contributes to Parkinson's disease.

Main Methods:

• CRISPR-Cas9 genome editing was employed to create isogenic iPSC lines deficient in RAB8a and RAB10.
• These iPSC lines were differentiated into NGN2-induced neurons for detailed analysis.
• Neuropathological hallmarks, including lysosomal pH, Golgi organization, and the accumulation of α-synuclein and tau, were thoroughly characterized.

Main Results:

• Deficiency in RAB8a and RAB10 exhibited opposing effects on lysosomal pH and Golgi organization in neurons.
• RAB8a ablation specifically impacted α-synuclein levels, while RAB10 ablation affected tau levels.
• The genetic inactivation of RAB8a or RAB10 demonstrated largely antagonistic cellular consequences.

Conclusions:

• The study highlights the distinct and often opposing roles of RAB8a and RAB10 in neuronal homeostasis.
• These findings provide critical insights into the diverse neuropathological features associated with LRRK2 mutations in Parkinson's disease.
• Understanding the specific contributions of LRRK2 substrates offers potential avenues for targeted therapeutic strategies.