Professor Dario Alessi

Understanding the LRRK2 Signalling pathway in Parkinson’s Disease

Much of Dario’s current work is focused on deciphering how autosomal dominant missense mutations that hyper-activate the LRRK2 protein kinase, predispose humans to Parkinson's disease.

LRRK2 mutations are the most frequent cause of inherited Parkinson's disease, accounting for at least 5% of familial and 1-2% of idiopathic Parkinson’s disease. Parkinson's disease affects an estimated 7 million people worldwide and all attempts to slow the progression of Parkinson’s have thus far failed.

The cardinal symptoms, shaking, rigidity, and slowness of movement arise from degeneration of dopaminergic neurons located within the substantia nigra. Dementia and behavioural disorders are unfortunately also common in the advanced stages of the disease.

The therapeutic efficacy of LRRK2 inhibitors are currently being tested in clinical trials. They represent one of the most promising therapeutic strategies currently under evaluation for slowing Parkinson’s disease progression, at least for patients possessing LRRK2 mutations.

Dario’s research focuses on understanding how LRRK2 is regulated and functions and how mutations in this protein kinase lead to Parkinson’s disease.

Dario’s lab in collaboration with Matthias Mann showed that LRRK2 phosphorylates a subgroup of Rab proteins (Rab3A/B/C/D, Rab8A/B, Rab10, Rab12, Rab29, Rab35, and Rab43) at a conserved Thr/Ser residue (Thr73 for Rab10), located at the centre of the effector binding switch-II motif [1, 2].

Consistent with Rab proteins comprising disease-relevant substrates, Dario's lab have demonstrated that all established pathogenic mutations enhance LRRK2 mediated Rab protein phosphorylation in a manner that is blocked by diverse LRRK2 inhibitors [1-3].

LRRK2 phosphorylation of Rab proteins blocks the ability of Rab proteins to interact with cognate effectors such as GDI and guanine nucleotide exchange factors, thereby trapping the phosphorylated Rab protein in the GTP bound state on the membrane where it has been phosphorylated [1, 2].

Recent work identified a novel group of effectors including RILPL1, RILPL2, JIP3 and JIP4 that bind preferentially to LRRK2 phosphorylated Rab8 and Rab10 [2, 4]. The work of Dario’s collaborator Suzanne Pfeffer at Stanford University (https://biochemistry.stanford.edu/suzanne-pfeffer) has revealed that LRRK2 phosphorylated Rab8A and Rab10, in complex with RILPL1/RILPL2, inhibit the formation of primary cilia that are implicated in controlling a Sonic hedgehog-driven neuroprotective pathway that could provide a mechanism by which LRRK2 is linked to Parkinson’s disease [5].

Dario's research has also revealed that other proteins encoded by genes implicated in Parkinson’s disease including Rab29 [6] and VPS35 [7], regulate phosphorylation of Rab proteins via LRRK2. They have also developed new methods to interrogate LRRK2 pathway activity in cell and mouse models [8] as well as humans [9]. They have recently identified a novel protein phosphatase termed PPM1H that counteracts LRRK2 signaling by selectively dephosphorylating Rab proteins [10].

Key gaps remain in our knowledge of how LRRK2 is regulated and functions that Dario's laboratory is working hard to address. These include understanding how Rab29, VPS35, the immune system, and other Parkinson’s disease genes and risk variants impact on the LRRK2 pathway. Individual functions of the different Rab proteins that are phosphorylated by LRRK2 and the effectors that interact with these after they are phosphorylated need to be identified, as well as establishing how this impacts downstream biology. It will be important to comprehend what are the most relevant Rab substrates that link LRRK2 to Parkinson’s disease. Much evidence suggests that LRRK2 regulates the endo-lysosomes through an unknown pathway that Dario's lab aims to decipher. Understanding how PPM1H and other protein phosphatases control the LRRK2 pathway is also an important question.

Impact

Dario's research has contributed to advancing our understanding of the roles that protein phosphorylation and ubiquitylation play in regulating key areas of cell function, and to investigate how derailment of these pathways causes disease. 

Dario is the Director of a flagship partnership between the University of Dundee and a group of pharmaceutical companies termed the “Division-of-Signal-Transduction-Therapy”, a collaboration that has run for over 20 years. This collaboration has supported the development of numerous clinically approved drugs and accelerated the advance of LRRK2 inhibitors.

Dario places strong emphasis on collaboration and rigorous methodologies to produce robust data of the highest quality to move a field forward. Dario believes in the importance of freely sharing knowledge, reagents and materials early on in projects to benefit the field at large. The discovery of the physiological substrates of LRRK2 has been hailed as an exemplar for how international collaboration can accelerate breakthroughs.

Dario is also an associate member of the UK Dementia-Research-Initiative advising on neurodegeneration research in the UK.

Dario has advocated for patient-public-involvement in Parkinson’s research and given multiple talks to patients both locally and nationally. He has recently aided establishment of a collaboration termed the “Edinburgh-Dundee-Parkinson's-Research-Initiative” to foster interactions between Parkinson’s researchers, clinicians and patients based in Scotland.

Approaching 70 protein kinase inhibitor drugs have now been approved for the treatment of disease (https://www.ppu.mrc.ac.uk/list-clinically-approved-kinase-inhibitors) and Dario’s research together with other MRC PPU staff members research and collaborations with companies has contributed to this field of medicine. He hopes that LRRK2 inhibitors might one day be approved for the treatment of Parkinson’s.

Selected Recent Publications

1          Steger, M., Tonelli, F., Ito, G., Davies, P., Trost, M., Vetter, M., Wachter, S., Lorentzen, E., Duddy, G., Wilson, S., Baptista, M. A., Fiske, B. K., Fell, M. J., Morrow, J. A., Reith, A. D., Alessi, D. R. and Mann, M. (2016) Phosphoproteomics reveals that Parkinson's disease kinase LRRK2 regulates a subset of Rab GTPases. Elife. 5,e12813

https://elifesciences.org/articles/12813

2          Steger, M., Diez, F., Dhekne, H. S., Lis, P., Nirujogi, R. S., Karayel, O., Tonelli, F., Martinez, T. N., Lorentzen, E., Pfeffer, S. R., Alessi, D. R. and Mann, M. (2017) Systematic proteomic analysis of LRRK2-mediated Rab GTPase phosphorylation establishes a connection to ciliogenesis. Elife. 6,e31012

https://elifesciences.org/articles/31012

3          Ito, G., Katsemonova, K., Tonelli, F., Lis, P., Baptista, M. A., Shpiro, N., Duddy, G., Wilson, S., Ho, P. W., Ho, S. L., Reith, A. D. and Alessi, D. R. (2016) Phos-tag analysis of Rab10 phosphorylation by LRRK2: a powerful assay for assessing kinase function and inhibitors. Biochem J. 473, 2671-2685

https://portlandpress.com/biochemj/article-lookup/doi/10.1042/BCJ20160557

4          Waschbüsch, D., Purlyte, E., Pal, P., McGrath, E., Alessi, D. R. and Khan, A. R. (2019) Structural basis for Rab8a GTPase recruitment of RILPL2 via LRRK2 phosphorylation of switch 2. bioRxiv, 739813

https://www.biorxiv.org/content/10.1101/739813v1

5          Dhekne, H. S., Yanatori, I., Gomez, R. C., Tonelli, F., Diez, F., Schule, B., Steger, M., Alessi, D. R. and Pfeffer, S. R. (2018) A pathway for Parkinson's Disease LRRK2 kinase to block primary cilia and Sonic hedgehog signaling in the brain. Elife. 7, e40202

https://elifesciences.org/articles/40202

6          Purlyte, E., Dhekne, H. S., Sarhan, A. R., Gomez, R., Lis, P., Wightman, M., Martinez, T. N., Tonelli, F., Pfeffer, S. R. and Alessi, D. R. (2018) Rab29 activation of the Parkinson's disease-associated LRRK2 kinase. EMBO J. 37, 1-18

https://www.embopress.org/doi/full/10.15252/embj.201798099

7          Mir, R., Tonelli, F., Lis, P., Macartney, T., Polinski, N. K., Martinez, T. N., Chou, M.-Y., Howden, A. J. M., König, T., Hotzy, C., Milenkovic, I., Brücke, T., Zimprich, A., Sammler, E. and Alessi, D. R. (2018) The Parkinson's disease VPS35[D620N] mutation enhances LRRK2-mediated Rab protein phosphorylation in mouse and human. Biochem J. 475, 1861-1883

https://portlandpress.com/biochemj/article-lookup/doi/10.1042/BCJ20180248

8          Lis, P., Burel, S., Steger, M., Mann, M., Brown, F., Diez, F., Tonelli, F., Holton, J. L., Ho, P. W., Ho, S. L., Chou, M. Y., Polinski, N. K., Martinez, T. N., Davies, P. and Alessi, D. R. (2018) Development of phospho-specific Rab protein antibodies to monitor in vivo activity of the LRRK2 Parkinson's disease kinase. Biochem J. 475, 1-22

https://portlandpress.com/biochemj/article-lookup/doi/10.1042/BCJ20170802

9          Fan, Y., Howden, A. J. M., Sarhan, A. R., Lis, P., Ito, G., Martinez, T. N., Brockmann, K., Gasser, T., Alessi, D. R. and Sammler, E. M. (2018) Interrogating Parkinson's disease LRRK2 kinase pathway activity by assessing Rab10 phosphorylation in human neutrophils. Biochem J. 475, 23-44

https://portlandpress.com/biochemj/article-lookup/doi/10.1042/BCJ20170803

10        Berndsen, K., Lis, P., Yeshaw, W. M., Wawro, P. S., Nirujogi, R. S., Wightman, M., Macartney, T., Dorward, M., Knebel, A., Tonelli, F., Pfeffer, S. R. and Alessi, D. R. (2019) PPM1H phosphatase counteracts LRRK2 signaling by selectively dephosphorylating Rab proteins. Elife. 8, e50416

https://elifesciences.org/articles/50416

For an up to date list of Dario’s publications, click here https://scholar.google.co.uk/citations?hl=en&user=9gPyVfsAAAAJ&view_op=list_works&sortby=pubdate