Veronique Daniëls

The Parkinson Disease-associated Leucine-rich Repeat Kinase 2 (LRRK2) Is a Dimer That Undergoes Intramolecular Autophosphorylation

Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of familial and apparently sporadic Parkinson disease. LRRK2 is a multidomain protein kinase with autophosphorylation activity. It has previously been shown that the kinase activity of LRRK2 is required for neuronal toxicity, suggesting that understanding the mechanism of kinase activation and regulation may be important for the development of specific kinase inhibitors for Parkinson disease treatment. Here, we show that LRRK2 predominantly exists as a dimer under native conditions, a state that appears to be stabilized by multiple domain-domain interactions. Furthermore, an intact C terminus, but not N terminus, is required for autophosphorylation activity. We identify two residues in the activation loop that contribute to the regulation of LRRK2 autophosphorylation. Finally, we demonstrate that LRRK2 undergoes intramolecular autophosphorylation. Together, these results provide insight into the mechanism and regulation of LRRK2 kinase activity.

Insight into the mode of action of the LRRK2 Y1699C pathogenic mutant

J. Neurochem. (2011) 116, 304–315.

Inhibition of FK506 Binding Proteins Reduces α-Synuclein Aggregation and Parkinson's Disease-Like Pathology

α-Synuclein (α-SYN) is a key player in the pathogenesis of Parkinsons disease (PD). In pathological conditions, the protein is present in a fibrillar, aggregated form inside cytoplasmic inclusions called Lewy bodies. Members of the FK506 binding protein (FKBP) family are peptidyl-prolyl isomerases that were shown recently to accelerate the aggregation of α-SYN in vitro. We now established a neuronal cell culture model for synucleinopathy based on oxidative stress-induced α-SYN aggregation and apoptosis. Using high-content analysis, we examined the role of FKBPs in aggregation and apoptotic cell death. FK506, a specific inhibitor of this family of proteins, inhibited α-SYN aggregation and neuronal cell death in this synucleinopathy model dose dependently. Knockdown of FKBP12 or FKBP52 reduced the number of α-SYN aggregates and protected against cell death, whereas overexpression of FKBP12 or FKBP52 accelerated both aggregation of α-SYN and cell death. Thus, FK506 likely targets FKBP members in the cell culture model. Furthermore, oral administration of FK506 after viral vector-mediated overexpression of α-SYN in adult mouse brain significantly reduced α-SYN aggregate formation and neuronal cell death. Our data explain previously described neuroregenerative and neuroprotective effects of immunophilin ligands and validate FKBPs as a novel drug target for the causative treatment of PD.

On the Road to Leucine-Rich Repeat Kinase 2 Signalling: Evidence from Cellular and in vivo Studies

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder. Although PD has long been considered a purely sporadic disorder, genetic research has revealed an underlying genetic cause in at least 10% of all PD cases. To date, mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common cause of familial PD. Moreover, given the strong clinical and neuropathological similarities between LRRK2 PD and the sporadic forms of the disease, the notion is supported that the unravelling of the molecular pathways underlying LRRK2 PD will greatly contribute to our general understanding of PD. Therefore, intense research efforts have been focused on the understanding of the physiological function of LRRK2 and its relation to PD. To date, progress has been made in these fields based on the study of LRRK2 cell culture models, the identification of LRRK2 interaction partners and kinase substrates and the generation of LRRK2 animal models. In this review, the current insights into the cellular role of LRRK2 are discussed. The overview reveals a potential involvement of LRRK2 in major cell signalling pathways including apoptosis, cytoskeleton dynamics, protein translation, mitogen-activated protein kinase signalling and specific dopaminergic functions, consistent with its proposed role as a signal transduction protein.