4 YEAR PhD IN NEUROSCIENCE
Department of Cell and Developmental Biology
Neuronal calcium signalling by NAADP
Although entry of calcium into neurons from the extracellular space through plasma membrane ion channels is a major mechanism that raises calcium concentration in neurons, the release of calcium from intracellular calcium stores is also intimately involved in neuronal calcium homeostasis. A precise definition of how calcium levels are modulated is vital since loss of calcium homeostasis is implicated in a variety of neurodegenerative diseases, including Alzheimer’s and Parkinson’s Diseases.
Our lab focuses on the actions of the novel calcium mobilizing messenger, nicotinic acid adenine dinucleotide phosphate (NAADP). NAADP is unusual in that it activates calcium channels expressed not on the endoplasmic reticulum (an established calcium store) but instead on acidic organelles  such as endosomes and lysosomes. NAADP is produced by neurotransmitters including glutamate  and we have recently identified the target channel at the molecular level as members of the two-pore channel (TPC) family . The sub-cellular location of TPCs is particularly important since the endo-lysosomal system is remarkably mobile and de-regulated in certain neuronal disorders , and there is good evidence to implicate this pathway in Parkinson’s Disease. Our lab uses a variety of techniques including digital imaging, protein chemistry and molecular biology.
Subcellular dynamics of TPCs in neurons. The endo-lysosomal system is a highly dynamic system of organelles. Its endowment with calcium channels raises the possibility that the calcium signals maybe be strategically targeted to different subcellular locations. In this project, you will express fluorescently tagged TPC constructs in cell lines and neurons and perform real-time imaging of TPC distribution in both un-stimulated and stimulated cells.
Defining the role of NAADP in lysosomal disorders (in collaboration with Michael Duchen). Mutations in several mitochondrial genes have been linked to Parkinson’s Disease. Recent studies have also associated Parkinson’s Disease with mutations in glucocerebrosidase (GBA), a lysosomal enzyme deficient in the lysosomal disorder Gaucher’s disease. In this project, you will use single cell imaging techniques to characterize mitochondrial and lysosomal function in neuronal preparations in which GBA function is compromised.
Dickinson,G.D., Churchill,G.C., Brailoiu,E. and Patel,S. (2010)
Deviant NAADP-mediated Ca2+-signalling upon lysosome proliferation.
J.Biol.Chem., 285, 13321-13325.
Pandey,V., Chuang,C.C., Lewis,A.M., Aley,P., Brailoiu,E., Dun,N., Churchill,G.C. and Patel,S. (2009)
Recruitment of NAADP-sensitive acidic Ca2+ stores by glutamate.
Biochem.J., 422, 503-512.
Brailoiu,E., Churamani,D., Cai,X., Schrlau,M.G., Brailoiu,G.C., Gao,X., Hooper,R., Boulware,M.J., Dun,N.J., Marchant,J.S. and Patel,S. (2009)
Essential requirement for two-pore channel 1 in NAADP-mediated calcium signaling.
J.Cell Biol., 186, 201-209.
Churchill,G.C., Okada,Y., Thomas,J.M., Genazzani,A.A., Patel,S. and Galione,A. (2002)
NAADP mobilizes Ca2+ from reserve granules, lysosome-related organelles, in sea urchin eggs.
Cell, 111, 703-708.