Novel LRRK2 GTP-binding inhibitors reduced degeneration in Parkinson's disease cell and mouse models

Abstract

Mutations in the leucine-rich repeat kinase-2 (LRRK2) gene cause autosomal-dominant Parkinson's disease (PD) and contribute to sporadic PD. LRRK2 contains Guanosine-5'-triphosphate (GTP) binding, GTPase and kinase activities that have been implicated in the neuronal degeneration of PD pathogenesis, making LRRK2, a potential drug target. To date, there is no disease-modifying drug to slow the neuronal degeneration of PD and no published LRRK2 GTP domain inhibitor. Here, the biological functions of two novel GTP-binding inhibitors of LRRK2 were examined in PD cell and mouse models. Through a combination of computer-aided drug design (CADD) and LRRK2 bio-functional screens, two novel compounds, 68: and 70: , were shown to reduce LRRK2 GTP binding and to inhibit LRRK2 kinase activity in vitro and in cultured cell assays. Moreover, these two compounds attenuated neuronal degeneration in human SH-SY5Y neuroblastoma cells and mouse primary neurons expressing mutant LRRK2 variants. Although both compounds inhibited LRRK2 kinase activity and reduced neuronal degeneration, solubility problems with 70: prevented further testing in mice. Thus, only 68: was tested in a LRRK2-based lipopolysaccharide (LPS)-induced pre-inflammatory mouse model. 68: reduced LRRK2 GTP-binding activity and kinase activity in brains of LRRK2 transgenic mice after intraperitoneal injection. Moreover, LPS induced LRRK2 upregulation and microglia activation in mouse brains. These findings suggest that disruption of GTP binding to LRRK2 represents a potential novel therapeutic approach for PD intervention and that these novel GTP-binding inhibitors provide both tools and lead compounds for future drug development.

WD40 repeat domain proteins: a novel target class?

“…Mutations driving Parkinson’s disease augment the kinase activity of LRRK2, and the neuronal toxicity of mutant LRRK2 can be reduced by alterations that decrease its kinase activity 70,71 , placing the catalytic activity at root of the pathology. Chemical inhibitors targeting the kinase or GTP binding domains of LRRK2 protect against models of Parkinson’s disease, further supporting mutated LRRK2 as a target for therapy 72–74 . An LRKK2 construct that lacks the WDR domain is unable to auto-phosphorylate, and loss of the WDR domain blocks the neurotoxicity of multiple LRRK2 mutations 75,76 .…”

Inhibition of TLR2 signaling by small molecule inhibitors targeting a pocket within the TLR2 TIR domain

“…CADD screening was performed as described previously (42)(43)(44) to identify small molecule inhibitors of TLR2 signaling. Briefly, CADD analysis required the following steps: (i) visual identification of a putative "pocket" in the 3D structure of the TLR2 TIR domain (Fig.…”

The function of orthologues of the human Parkinson's disease gene LRRK2 across species: implications for disease modelling in preclinical research

“…However, other LRRK2 mutations apparently have kinase activity similar to wild type protein or even diminished phosphorylation activity [136,137] and therefore may require alternative pharmacological approaches [134]. For example, mutations in the ROC domain (R1441C/G/H) may be targeted with compounds that interfere with GTP binding [138,139]. Importantly for the current discussion, the optimal choice of animal models for each treatment modality stratified by pathogenic mutation would allow estimating in vivo efficacy of the drugs as well as revealing potential side effects more effectively during preclinical research prior to human trials.…”