Effectors and regulatory proteins interact with RAB proteins in a nucleotide-dependent manner through this region, and phosphorylation interferes with the ability of the RABs to bind to most of these proteins (3). spotlight the possibility that either centrosomal cohesion and/or ciliogenesis alterations may serve as cellular biomarkers for LRRK2-related PD. Introduction Autosomal-dominant point mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common cause of familiar Parkinsons disease (PD), and protein coding as well as non-coding variants HBX 41108 at the LRRK2 locus are major genetic susceptibility factors for sporadic PD (1). These genetic findings point towards a key role for LRRK2 in the entire PD disease spectrum. Recent mass spectroscopy studies have revealed that LRRK2 is able to phosphorylate a small subset of RAB proteins and (2C5), with HBX 41108 their phosphorylation enhanced by all pathogenic LRRK2 mutants in a cellular context (3). Current data suggest that RAB8 and RAB10 serve as the most prominent LRRK2 kinase substrates, and their phosphorylation is usually detectable in various cells and tissues including brain (6C8). Therefore, and given the relevance of LRRK2 for PD, it is crucial to determine the cellular processes which are most significantly affected by an increase in LRRK2 kinase activity via RAB8 and/or RAB10 phosphorylation. RAB GTPases are key regulators of all eukaryotic vesicular membraneCtrafficking events (9,10). LRRK2 phosphorylates a crucial region within RAB proteins, whose conformation changes dependent on the nucleotide-bound state. Effectors and regulatory proteins interact with RAB proteins in a nucleotide-dependent manner through this region, and phosphorylation interferes with the ability of the RABs to bind to most of these proteins (3). This is expected to lead to a loss of function in terms of RAB-mediated membrane-trafficking events, as we have recently shown HBX 41108 for the LRRK2-mediated phosphorylation of RAB8A (11). Recent studies also spotlight additional, gain-of-function mechanisms for phosphorylated RAB8 and RAB10. Our data show that phosphorylated RAB8A accumulates in a pericentrosomal/centrosomal area to cause deficits in centrosomal positioning with effects on neurite outgrowth, cell polarization and directed migration (12), all cellular phenotypes previously HBX 41108 reported to be impaired by pathogenic LRRK2 (13C18). The LRRK2-mediated pericentrosomal/centrosomal accumulation of phospho-RAB8 further causes deficits in centrosomal cohesion in dividing cells, including peripheral LRRK2 PD patient-derived cells, in a manner dependent upon LRRK2 kinase activity (12). Surprisingly, HBX 41108 Rabbit Polyclonal to PDRG1 whilst the phosphorylated RABs drop their interactions with their effector and regulatory proteins, they were reported to specifically gain the ability to interact with RILPL1 (2), a poorly characterized protein which localizes to the mother centriole and regulates ciliogenesis (19). The primary cilium emerges from the basal body, which is a special form of the mother centriole, and a recent study reports that pathogenic LRRK2 interferes with ciliogenesis in a manner dependent on both phospho-RAB10 and RILPL1 (20). Ciliogenesis deficits were observed in various cell types, including the somatosensory cortex and the small populace of cholinergic neurons present in the striatum of LRRK2 transgenic mice (20). The latter neurons require cilia to sense Sonic hedgehog signalling (21,22), which provides a neuroprotective circuit to support dopaminergic neurons (23). In this manner, ciliogenesis deficits may contribute to PD pathogenesis in a non-cell-autonomous manner. However, it remains unknown whether the reported LRRK2-mediated centrosomal and ciliogenesis deficits are distinct cellular reflections of the same phospho-RAB8/10-RILPL1 pathway. Here, we show that centrosomal cohesion deficits are mediated by both RAB8A/B and RAB10 and correlate with the centrosomal accumulation of both phospho-RAB proteins. The pathogenic LRRK2-mediated centrosomal cohesion alterations are abolished in RAB8A, RAB10 or RILPL1 knockout cells. In addition, the pathogenic LRRK2-mediated ciliogenesis deficits also correlate with the centrosomal accumulation of.