Cell biological mechanisms underlying neuronal excitability and synaptic plasticity
Professor Josef Kittler
|Tel: +44 (0)20 7679 3218|
Professor Josef Kittler graduated in 1996 with a degree in Biochemistry from the University of Bath. He carried out PhD and postdoctoral studies with Stephen Moss at the MRC Laboratory for Molecular Cell Biology, UCL. Following a Wellcome Trust Advanced Training Fellowship with David Attwell in the Department of Physiology at UCL he was awarded in 2005 an MRC Career Development Award to establish his independent research group. He is currently an editor of the Journal of Biological Chemistry.
Overview Nerve cells in the brain have a highly spatially diverse cellular and subcellular architecture including axon, cell body, and dendrites as major cellular compartments, in addition to subcellular membrane microdomains such as spines, synapses and the secretory and endosomal networks. To ensure efficient signaling between neurons, and to ensure that the correct levels of neuronal activity are maintained, it is critical that mechanisms exist to tightly regulate the selective transport and localisation of ion channels, receptors and organelles to these specific neuronal subdomains. We are interested in understanding the contribution played by intracellular transport and membrane trafficking of proteins and organelles in regulating the activity and plasticity of synapses.
We focus on three major research themes: Firstly, we are studying the molecular and cellular mechanisms regulating the function and membrane trafficking of neurotransmitter receptors and transporters and the role this plays in controlling synaptic transmission and hence the levels of neuronal excitability in the brain. We are similarly interested in how the function of synapses can be controlled by the regulated trafficking of organelles such as mitochondria. Secondly, we concentrate on how intracellular transport is regulated by post-translational modifications such as phosphorylation, palmitoylation and ubiquitination. Thirdly, we wish to understand better how the trafficking of receptors, transporters and other cargo may be altered in neurological and neuropsychiatric diseases. We combine the use of various techniques, including molecular and cell biology, protein biochemistry, patch clamp electrophysiology, neuronal transfection, and fixed and live cell confocal and CCD imaging. We also use fluorescent protein and Quantum Dot labeling approaches to study the membrane dynamics of proteins of interest.
GABAA receptor trafficking and the molecular mechanisms that regulate the plasticity of inhibitory synapses
|Synaptic GABAA receptor clusters imaged by immunofluorescence and confocal microscopy||Structure of a GABAAR endocytosis motif complexed with the clathrin adaptor AP2 (from Kittler et al., 2008)|
GABAA receptors are ligand-gated ion channels that mediate the majority of fast inhibitory neurotransmission in the central nervous system. We are interested in the mechanisms that regulate the number of GABAA receptors at inhibitory synapses to control the strength and plasticity of these synapses. In particular we focus on identifying and characterising protein complexes important for regulating receptor anchoring at synapses and receptor transport through the secretory and endocytic compartments. We also study the cross-talk between post-translational modification of the GABAA receptor (by phosphorylation, ubiquitination and palmitoylation) and receptor membrane trafficking and in particular how phosphorylation can act as regulatory switch for the regulated membrane trafficking of receptors towards and away from synapses.
GABAA receptor membrane dynamics imaged in live neurons using semi-conductor nanocrystals (Quantum Dots)
Glutamate transporter trafficking
Maintaining the correct levels of extracellular glutamate is crucial for the control of cell and network activity in the brain and for nerve cell survival. Glutamate uptake is controlled by glutamate transporters present on both neurons and glia, which play a critical role in shaping synaptic transmission and in keeping extracellular glutamate below excitotoxic levels. the dysfunction of these transporters is implicated in several neurological diseases including epilepsy, stroke and motor neuron disease. Understanding how neurons and glial cells regulate glutamate transporter function has important implications for understanding of how neuronal activity is controlled and how disrupted glutamate uptake may contribute to pathology. We are interested in understanding better the role of glutamate transporter associated proteins (or modifying enzymes) in regulating transporter activity and trafficking under normal and pathological conditions.
|Live cell imaging of the membrane trafficking of GFP-glutamate transporter containing vesicles in transfected cells|
Organellar trafficking in neurons
We are interested in the mechanisms that underlie the activity dependent transport and localisation or organelles within neurons under normal conditions and during excitotoxicity. In particular we focus on the mechanisms that regulate the transport and morphology of mitochondria and endocytic compartments within dendrites and the role of motor proteins and adaptors in this process. We are also investigating how proteins implicated in pathology, such as the schizophrenia protein disc1, are involved in intracellular transport in neurons.
Live cell confocal imaging of mitochondrial transport dynamics in a hippocampal neuron
For additional information on our research interests and a full publication list with links to pubmed please also visit:
1: Smith KR, Davenport EC, Wei J, Li X, Pathania M, Vaccaro V, Yan Z, Kittler JT. GIT1 and βPIX are essential for GABA(A) receptor synaptic stability and inhibitory neurotransmission. Cell Rep. 2014 Oct 9;9(1):298-310.
2: Birsa N, Norkett R, Wauer T, Mevissen TE, Wu HC, Foltynie T, Bhatia K, Hirst WD, Komander D, Plun-Favreau H, Kittler JT. Lysine 27 ubiquitination of the mitochondrial transport protein Miro is dependent on serine 65 of the Parkin ubiquitin ligase. J Biol Chem. 2014 May 23;289(21):14569-82.
3: Pathania M, Davenport EC, Muir J, Sheehan DF, López-Doménech G, Kittler JT. The autism and schizophrenia associated gene CYFIP1 is critical for the maintenance of dendritic complexity and the stabilization of mature spines. Transl Psychiatry. 2014 Mar 25;4:e374.
4: Smith KR, Muir J, Rao Y, Browarski M, Gruenig MC, Sheehan DF, Haucke V, Kittler JT. Stabilization of GABA(A) receptors at endocytic zones is mediated by an AP2 binding motif within the GABA(A) receptor β3 subunit. J Neurosci. 2012 Feb 15;32(7):2485-98.
5: Atkin TA, Brandon NJ, Kittler JT. Disrupted in Schizophrenia 1 forms pathological aggresomes that disrupt its function in intracellular transport. Hum Mol Genet. 2012 May 1;21(9):2017-28.
6: Atkin TA, MacAskill AF, Brandon NJ, Kittler JT. Disrupted in Schizophrenia-1 regulates intracellular trafficking of mitochondria in neurons. Mol Psychiatry. 2011 Feb;16(2):122-4, 121.
7: Muir J, Arancibia-Carcamo IL, MacAskill AF, Smith KR, Griffin LD, Kittler JT. NMDA receptors regulate GABAA receptor lateral mobility and clustering at inhibitory synapses through serine 327 on the γ2 subunit. Proc Natl Acad Sci USA. 2010 Sep 21;107(38):16679-84.
8: Twelvetrees AE, Yuen EY, Arancibia-Carcamo IL, MacAskill AF, Rostaing P, Lumb MJ, Humbert S, Triller A, Saudou F, Yan Z, Kittler JT. Delivery of GABAARs to synapses is mediated by HAP1-KIF5 and disrupted by mutant huntingtin. Neuron. 2010 Jan 14;65(1):53-65.
9: Macaskill AF, Rinholm JE, Twelvetrees AE, Arancibia-Carcamo IL, Muir J, Fransson A, Aspenstrom P, Attwell D, Kittler JT. Miro1 is a calcium sensor for glutamate receptor-dependent localization of mitochondria at synapses. Neuron. 2009 Feb 26;61(4):541-55.
The Dynamic Synapse Kittler JT and Moss SJ Eds (2006)
- The Dynamic Synapse: Molecular Methods In Ionotropic Receptor Biology Frontiers in Neuroscience, CRC Press