The Roc domain of LRRK2 as a hub for protein-protein interactions: a focus on PAK6 and its impact on RAB phosphorylation

• Published in: Brain research Vol. 1778; p. 147781
• Main Authors: Cogo, Susanna, Ho, Franz Y., Tosoni, Elena, Tomkins, James E., Tessari, Isabella, Iannotta, Lucia, Montine, Thomas J., Manzoni, Claudia, Lewis, Patrick A., Bubacco, Luigi, Chartier Harlin, Marie-Christine, Taymans, Jean-Marc, Kortholt, Arjan, Nichols, Jeremy, Cendron, Laura, Civiero, Laura, Greggio, Elisa
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2022
• Subjects: 14-3-3 proteins; 14-3-3 Proteins - metabolism; GTP Phosphohydrolases - metabolism; GTPase; Humans; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 - metabolism; LRRK2; Neurology; p21-Activated Kinases - metabolism; PAK6; Parkinson Disease - metabolism; Parkinson’s disease; Phosphorylation; Protein Interaction Domains and Motifs; Protein-protein interactions; 14-3-3 proteins; PAK6; GTPase; LRRK2; Parkinson’s disease; Protein-protein interactions
• ISSN: 0006-8993; 1872-6240; 1872-6240
• DOI: 10.1016/j.brainres.2022.147781

The Roc domain of LRRK2 is a hub for protein-protein interaction. Among Roc interactors, PAK6 can modulate LRRK2 cellular phosphorylation by directly phosphorylating 14-3-3 proteins. Our present findings indicate that this pathway is impaired in the presence of the Roc pathogenic mutation R1441G LRRK2, whose Ser935 is basally dephosphorylated, and thus insensitive to PAK6-mediated effects on RAB10 phosphorylation. Based on these novel and previous findings, we also predict that the protective effects of PAK6 toward increased LRRK2 activity can be achieved only if 14-3-3s are bound to LRRK2, a condition satisfied in G2019S but not in Roc mutants. [Display omitted] •The Roc/GTPase domain of LRRK2 is a biochemical and molecular signaling hub.•Most of LRRK2 interactome binds Roc.•The spatial separation of binding partners within the LRRK2 structure correlates with a functional specialization.•PAK6 is a GTP-dependent Roc interactor able to modulate LRRK2-mediated RAB phosphorylation.•Parkinson’s mutations within Roc impair the ability of PAK6 to regulate LRRK2 activity. Leucine-rich repeat kinase 2 (LRRK2) has taken center stage in Parkinson’s disease (PD) research as mutations cause familial PD and more common variants increase lifetime risk for disease. One unique feature in LRRK2 is the coexistence of GTPase/Roc (Ras of complex) and kinase catalytic functions, bridged by a COR (C-terminal Of Roc) platform for dimerization. Multiple PD mutations are located within the Roc/GTPase domain and concomitantly lead to defective GTPase activity and augmented kinase activity in cells, supporting a crosstalk between GTPase and kinase domains. In addition, biochemical and structural data highlight the importance of Roc as a molecular switch modulating LRRK2 monomer-to-dimer equilibrium and building the interface for interaction with binding partners. Here we review the effects of PD Roc mutations on LRRK2 function and discuss the importance of Roc as a hub for multiple molecular interactions relevant for the regulation of cytoskeletal dynamics and intracellular trafficking pathways. Among the well-characterized Roc interactors, we focused on the cytoskeletal-related kinase p21-activated kinase 6 (PAK6). We report the affinity between LRRK2-Roc and PAK6 measured by microscale thermophoresis (MST). We further show that PAK6 can modulate LRRK2-mediated phosphorylation of RAB substrates in the presence of LRRK2 wild-type (WT) or the PD G2019S kinase mutant but not when the PD Roc mutation R1441G is expressed. These findings support a mechanism whereby mutations in Roc might affect LRRK2 activity through impaired protein-protein interaction in the cell.