Abstract
Parkinson’s Disease (PD) is the second most common neurodegenerative disease world-wide. Mutations in the multidomain protein Leucine Rich Repeat Kinase 2 (LRRK2) are the most frequent cause of hereditary PD. Furthermore, recent data suggest that independent of mutations, increased kinase activity of LRRK2 plays an essential role in PD pathogenesis. Isolated mitochondria of tissue samples from PD patients carrying LRRK2 mutations display a significant impairment of mitochondrial function. However, due to the complexity of the mitochondrial signaling network, the role of LRRK2 in mitochondrial metabolism is still not well understood. Previously we have shown that D. discoideum Roco4 is a suitable model to study the activation mechanism of LRRK2 in vivo. To get more insight in the LRRK2 pathways regulating mitochondrial activity we used this Roco4 model system in combination with murine RAW macrophages. Here we show that both Dictyostelium roco4 knockout and cells expressing PD-mutants show behavioral and developmental phenotypes that are characteristic for mitochondrial impairment. Mitochondrial activity measured by Seahorse technology revealed that the basal respiration of D. discoideum roco4- cells is significantly increased compared to the WT strain, while the basal and maximal respiration values of cells overexpressing Roco4 are reduced compared to the WT strain. Consistently, LRRK2 KO RAW 264.7 cells exhibit higher maximal mitochondrial respiration activity compared to the LRRK2 parental RAW264.7 cells. Measurement on isolated mitochondria from LRRK2 KO and parental RAW 264.7 cells revealed no difference in activity compared to the parental cells. Furthermore, neither D. discoideum roco4- nor LRRK2 KO RAW 264.7 showed a difference in either the number or the morphology of mitochondria compared to their respective parental strains. This suggests that the observed effects on the mitochondrial respiratory in cells are indirect and that LRRK2/Roco proteins most likely require other cytosolic cofactors to elicit mitochondrial effects.
Highlights
Neurological disorders pose an increasing societal and economic burden within our aging population
We investigated the effect of mutated Roco proteins on mitochondrial functioning in an in vivo model system
We showed that D. discoideum cells lacking Roco4 and cells expressing the conserved Parkinson’s Disease (PD) mutation G1179S display strong phenotypes associated with mitochondrial malfunction: a delayed development, affected phototaxis and impaired stalk formation
Summary
Neurological disorders pose an increasing societal and economic burden within our aging population. PD-associated mutations have been found in 23 genes or loci, including SNCA (α-synuclein), PARK2 (parkin), PINK1, PARK7 (DJ-1) and LRRK2 (leucine-rich repeat kinase 2) (Healy et al, 2008). Mutations in LRRK2 genes cause an autosomal dominant hereditary type of PD and accounts for 5% of the cases among European and North American PD patients (Li et al, 2015). It was shown recently that LRRK2 kinase activity was enhanced in post-mortem brain tissue from patients with idiopathic PD (iPD), suggesting that independent of mutations, wild-type LRRK2 plays a role in PD pathology as well (Di Maio et al, 2018)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
