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Updated: May 30, 2025
Metabolic Labeling of Leucine Rich Repeat Kinases 1 and 2 with Radioactive Phosphate
Published on: September 18, 2013
Endogenous LRRK2 and PINK1 function in a convergent neuroprotective ciliogenesis pathway in the brain
Enrico Bagnoli1,2, Yu-En Lin2,3, Sophie Burel1
1Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
Abstract:
Mutations in Leucine-rich repeat kinase 2 (LRRK2) and PTEN-induced kinase 1 (PINK1) are associated with familial Parkinson's disease (PD). LRRK2 phosphorylates Rab guanosine triphosphatase (GTPases) within the Switch II domain while PINK1 directly phosphorylates Parkin and ubiquitin (Ub) and indirectly induces phosphorylation of a subset of Rab GTPases. Herein we have crossed LRRK2 [R1441C] mutant knock-in mice with PINK1 knock-out (KO) mice and report that loss of PINK1 does not impact endogenous LRRK2-mediated Rab phosphorylation nor do we see significant effect of mutant LRRK2 on PINK1-mediated Rab and Ub phosphorylation. In addition, we observe that a pool of the Rab-specific, protein phosphatase family member 1H phosphatase, is transcriptionally up-regulated and recruited to damaged mitochondria, independent of PINK1 or LRRK2 activity. Parallel signaling of LRRK2 and PINK1 pathways is supported by assessment of motor behavioral studies that show no evidence of genetic interaction in crossed mouse lines. Previously we showed loss of cilia in LRRK2 R1441C mice and herein we show that PINK1 KO mice exhibit a ciliogenesis defect in striatal cholinergic interneurons and astrocytes that interferes with Hedgehog induction of glial derived-neurotrophic factor transcription. This is not exacerbated in double-mutant LRRK2 and PINK1 mice. Overall, our analysis indicates that LRRK2 activation and/or loss of PINK1 function along parallel pathways to impair ciliogenesis, suggesting a convergent mechanism toward PD. Our data suggest that reversal of defects downstream of ciliogenesis offers a common therapeutic strategy for LRRK2 or PINK1 PD patients, whereas LRRK2 inhibitors that are currently in clinical trials are unlikely to benefit PINK1 PD patients.
Insights
Mutations in Leucine-rich repeat kinase 2 (LRRK2) and PTEN-induced kinase 1 (PINK1) impair ciliogenesis through parallel pathways, suggesting a common therapeutic strategy for Parkinson
Area of Science:
- Neuroscience
- Genetics
- Cell Biology
Background:
- Mutations in Leucine-rich repeat kinase 2 (LRRK2) and PTEN-induced kinase 1 (PINK1) are linked to familial Parkinson's disease (PD).
- LRRK2 and PINK1 regulate distinct phosphorylation events, including on Rab GTPases, Parkin, and ubiquitin.
- Understanding the interplay between LRRK2 and PINK1 is crucial for developing effective Parkinson's disease therapies.
Purpose of the Study:
- To investigate the functional interaction between LRRK2 and PINK1 in Parkinson's disease pathogenesis.
- To determine if loss of PINK1 affects LRRK2-mediated phosphorylation and vice versa.
- To explore the role of these proteins in ciliogenesis and identify potential convergent therapeutic strategies.
Main Methods:
- Generation of double-mutant mice combining LRRK2 [R1441C] knock-in and PINK1 knock-out.
- Assessment of Rab GTPase phosphorylation in response to LRRK2 and PINK1 mutations.
- Analysis of protein phosphatase 1H (PP1H) expression and localization.
- Evaluation of motor behavior in genetically modified mouse lines.
- Investigation of ciliogenesis defects in specific neuronal and glial cell types.
Main Results:
- Loss of PINK1 did not alter LRRK2-mediated Rab phosphorylation, and mutant LRRK2 did not significantly affect PINK1-mediated phosphorylation of Rab and ubiquitin.
- Protein phosphatase 1H (PP1H) was transcriptionally upregulated and recruited to damaged mitochondria independently of LRRK2 or PINK1 activity.
- Motor behavioral studies showed no genetic interaction between LRRK2 and PINK1 mutations.
- PINK1 knock-out mice exhibited ciliogenesis defects in striatal cholinergic interneurons and astrocytes, which were not exacerbated in double mutants.
Conclusions:
- LRRK2 and PINK1 function in parallel pathways to impair ciliogenesis, indicating a convergent mechanism in Parkinson's disease.
- Reversing defects downstream of ciliogenesis may offer a common therapeutic approach for both LRRK2 and PINK1 related Parkinson's disease.
- LRRK2 inhibitors are unlikely to benefit patients with PINK1-related Parkinson's disease.
