Professor Miratul Muqit FRSE
My laboratory focuses on elucidating signal transduction pathways that are linked to neurodegeneration in Parkinson’s disease. Over the last decade, spectacular genetic breakthroughs have uncovered nearly 20 genes or loci linked to rare inherited forms of Parkinson’s disease including mutations in key signaling molecules such as protein kinases and ubiquitin ligases (Table 1). These discoveries provide an exciting platform for biochemical analysis since understanding the function of the proteins encoded by these genes is likely to lead to fundamental insights into the major mechanisms underlying neuronal loss in Parkinson’s. This will undoubtedly drive new ideas into how to better diagnose and treat this devastating condition.
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Mutations in PTEN-induced kinase 1 (PINK1) lead to autosomal recessive Parkinson’s disease . PINK1 is unique amongst all protein kinases since it contains a mitochondrial targeting domain and also three loop insertions within its catalytic domain (Figure 1). Whilst we could show very quickly that PINK1 was indeed localized at the mitochondria (Figure 2), for many years little was known about the catalytic properties of PINK1 since the human enzyme displays very low kinase activity in vitro. We discovered active insect orthologues of PINK1 and deployed these to establish the first PINK1 kinase activity in the field . This enabled us to determine that the majority of PINK1 disease-associated mutations lead to inactivation of the kinase activity .
Figure 1. Domain outline of PINK1. MTS – mitochondrial targeting sequence, TM – transmembrane region; INS – insertion, CTD – C-terminal domain.
Figure 2. PINK1 is localized to mitochondria in neuronal SH-SY5Y cells.
We recently made major advances in understanding the regulation and downstream function of PINK1. We discovered that human PINK1 can be activated in cells upon mitochondrial depolarization that can be induced artificially by mitochondrial uncoupling agents such as CCCP. Upon activation, we found that PINK1 becomes autophosphorylated at Threonine 257 and can phosphorylate another Parkinson’s-linked protein, Parkin at Serine 65 . Parkin belongs to the family of RING-IBR-RING E3 ubiquitin ligases and our work demonstrated that phosphorylation at Serine 65 was critical for activation of Parkin E3 ligase activity . Our work has elucidated a signaling pathway for the PINK1 kinase and provides a solid platform for future exciting research questions (Figure 3). Our work also suggests that small molecule activators of PINK1 that mimic PINK1 phosphorylation could be therapeutically beneficial and this has opened up a new area of drug discovery research in Parkinson’s.
Figure 3. PINK1 signaling pathway.
My laboratory is utilizing state of the art biochemical, proteomic, transgenic and structural methodologies to address the next major questions for understanding the PINK1 signaling pathway. We wish to understand in more detail how PINK1 activity is regulated by mitochondrial depolarization and identify novel regulatory molecules of PINK1 activity. We are also very interested in determining the mechanism of how Serine 65 phosphorylation leads to activation of the Parkin E3 ligase activity and identifying key substrates of Parkin whose ubiquitylation is critically dependent on Serine 65 phosphorylation.
- Valente, E.M., Abou-Sleiman, P.M., Caputo, V.*, Muqit, M.M.K.*, Harvey K., Gispert S., Ali Z. et al. (2004) Hereditary early onset Parkinson’s disease is caused by mutations in PINK1. Science 304: 1158-1160. (*Joint 2nd authorship)
- Woodroof, H.I., Pogson, J.H., Begley M., Cantley, L.C., Deak, M., Campbell, D.G., van Aalten, D.M.F., Whitworth, A.J., Alessi, D.R., and Muqit, M.M.K. (2011) Discovery of catalytically active orthologues of the Parkinson’s disease kinase PINK1: analysis of substrate specificity and impact of mutations. Open Biology 1: 110012
- Kondapalli, C., Kazlauskaite, A.Z., Campbell, D.G., Gourlay, R., Burchell, L., Walden, H., McCartney, T., Deak, M., Alessi, D.R., and Muqit, M.M.K. (2012) The Parkinson’s disease associated kinase PINK1 is activated by mitochondrial uncoupler, CCCP, and phosphorylates Parkin at Ser65. Open Biology 2: 120080
Top 10 research papers with up to date citations (December 10th 2013)
Iovino M, Pfisterer U, Holton JL, Lashley T, Swingler RJ, Calo L, Treacy R, Revesz T, Parmar M, Goedert M, Muqit MMK*, Spillantini MG* (2013)
The novel MAPT mutation K298E: mechanisms of mutant tau toxicity, brain pathology and tau expression in induced fibroblast-derived neurons.
Acta Neuropath in press DOI: 10.1007/s00401-013-1219-1 (*Joint Senior Authors)
Kondapalli C, Kazlauskaite A, Zhang N, Woodroof HI, Campbell DG, Gourlay R, Burchell L, Walden H, Macartney TJ, Deak M, Knebel A, Alessi DR, & Muqit MMK (2012)
PINK1 is activated by mitochondrial membrane potential depolarization and stimulates Parkin E3 ligase activity by phosphorylating Serine 65.
Open Biol 2, 120080 (30 citations)
Woodroof HI, Pogson JH, Begley M, Cantley LC, Deak M, Campbell DG, van Aalten DM, Whitworth AJ, Alessi DR, & Muqit MMK. (2011)
Discovery of catalytically active orthologues of the Parkinson’s disease kinase PINK1: analysis of substrate specificity and impact of mutations.
Open Biol 1, 11001. (9 citations)
Sleiman, PM*, Healy DG*, Muqit MMK*, Yang YX, Van Der Brug M, Holton JL, et al. (2009)
Characterisation of a novel NR4A2 mutation in Parkinson’s disease brain.
Neurosci Lett 457: 75-79. (*Joint 1st Author) (13 citations)
Moran NF, Banin MD, Muqit MMK, Bax BE. (2008)
Carrier erythrocyte entrapped thymidine phosphorylase therapie for mngie.
Neurology 71: 686-688 (30 citations)
Abou-Sleiman PM, Muqit MMK, McDonald NQ et al. (2006)
A heterozygous effect for PINK1 mutations in Parkinson’s disease; low frequency low penetrance?
Ann Neurol 60, 414-419 (93 citations)
Muqit MMK, Abou-Sleiman PM, Saurin A, et al. (2006)
Altered cleavage and localisation of PINK1 in the presence of proteasomal stress.
J Neurochem 98, 156-169 (83 citations)
Gandhi S, Muqit MMK, Healy DG et al. (2006)
PINK1 protein in normal human brain and Parkinson’s disease.
Brain 129, 1720-1731 (172 citations)
Valente EM, Abou-Sleiman PM, Caputo V*, Muqit MMK*, Harvey K, Gispert S, Ali Z et al. (2004)
Hereditary early onset Parkinson’s disease is caused by mutations in PINK1.
Science 304, 1158-1160. (*Joint 2nd author) (1193 citations)
Muqit MMK, Davidson SM, Payne-Smith MD, MacCormac LP, Wood NW, Latchman DS. (2004)
Parkin is recruited into aggresomes in a stress specific manner: over-expression of parkin reduces aggresome formation but can be dissociated from parkin's effect on neuronal survival.
Hum Mol Genet 13, 117-135 (58 citations)
In collaboration with the pharmaceutical industry via the Division of Signal Transduction Therapy collaboration with AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Janssen Pharmaceutica, Merck Serono and Pfizer the research ouptuts from my group contribute to accelerating the development of company drug development programmes through access to research data and reagents. Reagents are also commercialised to provide access to the wider scientific community via license arrangements with companies such as Millipore, AbCam and Ubiquigent.
Impact of research since 2008
- Competitive funding obtained from the Wellcome Trust as a Senior Research Fellow in Clinical Science (2013).
- 2 papers published in Open Biology in 2011 and 2012.