PhD
PhD Vacancies in 2012
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Self Funded Studentships
Physiological roles of voltage gated potassium channels in cardiac disease and cancer
Modulation of synaptic interactions by nitric oxide
Prostaglandin receptors and pain
Regulation of ribosomal protein S6 phosphorylation by incretins and nutrients in pancreatic ß-cells
Tissue plasminogen activator as a mediator of neuronal and behavioural effects of stress
Cellular signalling and processing of neuromedin U
The role of the ß2-AR in angiogenesis and wound healing
Ion channels in platelets and megakaryocytes
Membrane invagination systems of the platelet and megakaryoctye
To apply to study for a PhD in Cell Physiology and Pharmacology please click here (and see right hand side of new page):
http://www2.le.ac.uk/study/research/phd/cell-physiology
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Physiological roles of voltage gated potassium channels in cardiac disease and cancer
Supervisor: Dr J S Mitcheson - jm109@le.ac.uk
Click here for Dr Mitcheson's research page
Summary of the Project
hERG (human ether-ago-go related gene) postassium channels have important roles in the repolarisation of cardiac muscle, pacemaker activity and protection of the heart from arrhythmias. Inherited mutations of hERG and block of the channel by numerous medications induce Long QT syndrome, which can cause arrhythmias and sudden cardiac death. Projects are available to investigate regulation of hERG channels by G-protein coupled receptor pathways and the structural basis for hERG channel voltage dependence and pharmacology.
In addition to important physiological roles in the heart, hERG channels also appear to have a role in the development of certain cancers such as leukemia, colon and breast cancer. hERG channels are expressed in tumour cells and absent in the healthy tissue. Expression in cell lines leads to cell transformation, including changes in morphology, adhesion independent growth, increases in migration rates and uncontrolled proliferation. Projects are available to determine the structural domains of hERG and signalling pathways that mediate these effects.
Techniques used in the laboratory include electrophysiology approaches for measuring channel activity in single cells, macropatches or at the single channel level, molecular biology techniques, establishment of stable cell lines and primary cultures, western blotting, phosphorylation assays, and cell growth and migration measurements.
For more information please contact Dr Mitcheson at the email address above.
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Modulation of synaptic interactions by nitric oxide
Supervisor: Dr V Straub - vs64@le.ac.uk
Click here for Dr Straub's research page
Summary of the Project
Neuromodulation is essential for nervous system function. It provides the nervous system with the ability to adapt to changes in internal and external demands by adjusting cellular and synaptic properties, neuronal network function and behaviour. It is well established that the gaseous neurotransmitter nitric oxide (NO) modulates a variety of nervous system functions and behaviours. Nevertheless, it is considerably less well understood how NO affects specific synaptic interactions and how these changes are related to effects at the system and behavioural level. This project aims to investigate the effects of NO on specific synapses in the nervous system of the pond snail Lymnaea stagnalis. The use of this model organism has the advantage that studies at the cellular and synaptic level can readily be related to complex network functions and behaviour. Importantly, results obtained in an invertebrate model system are also relevant to vertebrate nervous system function as cellular signalling mechanisms are highly conserved across the animal kingdom. Work in my laboratory has already demonstrated that NO has significant modulatory effects on 5-HT receptor function. This project will build on these results and further investigate the mechanisms of synaptic modulation by NO. The project will provide the opportunity to gain experience in a variety of different techniques including electrophysiological methods (intercellular and extracellular recording techniques, voltage-clamp techniques etc), cell culture techniques, imaging techniques (eg Ca++ sensitive dyes) and behaviour methods.
For further information please contact Dr Straub at the email address above.
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Prostaglandin receptors and pain
Supervisor: Dr B D Grubb - bdg1@le.ac.uk
Click here for Dr Grubb's research page
Summary of the Project
Prostaglandin receptors play an important role in modulating the excitation of nociceptive nerve endings and thus have an important role in pain perception. The aim of the proposed project is to identify which prostaglandin receptors and subtypes underly sensitisation and to etablish whether the expression of the cognate receptors is altered in models of inflammatory and neuropathic pain. The project will use a range of neuroanatomical (immunoctochemistry, morphometry), electrophysiological (single fibre recordings from skin-nerve preparation, patch clamp recordings) and cell imaging techniques (real time confocal imaging) to achieve these goals. It is hoped that the findings of this research will identify putative targets for the treatment of pain.
For further information please contact Dr Grubb at the email address above.
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Regulation of ribosomal protein S6 phosphorylation by incretins and nutrients in pancreatic ß-cells
Supervisor: Dr T P Herbert - tph4@le.ac.uk
Click here for Dr Herbert's research page
Summary of the Project
p70 ribosomal protein S6 kinase 1 and 2 kinase (S6K1/2) are critical downstream effectors of mTOR, a protein kinase that is able to integrate signals from hormones and nutrients to co-ordinate changes in cell growth and proliferation. Importantly, recent studies have demonstrated that S6K1/2 and the phosphorylation of ribosomal protein S6 (rpS6) play a particularly important role in regulating pancreatic ß-cell size. It has also been reported that nutrients, such as glucose and amino acids, and the incretin, glucagon like peptide-1 (GLP1), modulate S6 phosphorylation in pancreatic ß-cells. The aim of this project is to investigate, in pancreatic ß-cells, the signalling pathways that regulate rpS6 phosphorylation in response to nutrients and GLP1 and to determine the mechanism by which rpS6 phosphorylation regulates pancreatic ß-cell growth and proliferation.
For further information please contact Dr Herbert at the email address above.
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Tissue plasminogen activator as a mediator of neuronal and behavioural effects of stress
Supervisor: Dr R Pawlak - rp135@le.ac.uk
Click here for Dr Pawlak's research page
Summary of the Project
Psychological stress induces neuronal responses that can be either adaptive and directed toward maintaining homeostasis, or maladaptive and leading to severe behavioral abnormalities. Post-traumatic stress disorder is a devastating disease triggered by traumatic event(s), and characterized by cognitive impairments, depression, fear, and anxiety. We have recently shown that tissue plasminogen activator is a critical mediator of stress-induced biochemical and behavioural changes. To elucidate the molecular mechanisms by which tPA facilitates stress-induced anxiety we propose to explore the involvement of two major putative patways: activation of protease-activated receptors (PARs) and regulation of the main excitatory (NMDA, AMPA) and inhibitory (GABAA) receptors. We will examine the role of these molecules in the hippocampus and amygdala during psychological stress using genetic, cell biological and pharmacological approaches. First, we will examine spatial and temporal regulation of PARs, NMDA, AMPA and GABAA receptors after stress. To this end we will perform immunohistochemistry and Western blotting to determine the levels and distribution of active (cleaved or phosphorylated) or native forms of the above receptors in wild-type mice and animals in which tPA or PARs have been disrupted. Second, we will correlate these studies with behavioural experiments in tPA- and PAR-deficient mice. To accomplish that we will measure unconditioned fear in the elevated-plus maze, and learned fear using Pavlovian fear conditioning. Finally, once the mechanism(s) are determined, we will attempt to attenuate anxiety by pharmacologically disrupting critical elements of the pathway. These experiments will add to our knowledge about mechanisms of stress-related diseases, and may lead to the development of better therapies against anxiety disorders.
Recent Publications:
Matys, T., Pawlak, R., Matys, E., Pavlides, C., McEwen, B.S., Strickland, S. Tissue plasminogen activator promotes the effects of corticotropin-releasing factor on the amygdala and anxiety-like behavior. Proc Natl Acad Sci U S A 2004, 101(46), 16345-16350
Pawlak, R., Magarinos, A.M., Melchor, J.P., McEwen, B., Strickland, S. Tissue-plasminogen activator in the amygdala is critical for anxiety-like behavior. Nature Neuroscience 2003, 6(2):168-174
Pawlak, R., B.S. Shankaranarayana Rao, Melchor, J.P., Chattarji, S., McEwen, B., Strickland, S. Tissue plasminogen activator and plasminogen mediate stress-induced decline of neuronal and cognitive functions in the mouse hippocampus. Proc Natl Acad Sci U S A 2005, 112(50): 18201-18206.
For further information please contact Dr Pawlak at the email address above.
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Cellular signalling and processing of neuromedin U
Supervisor: Dr G B Willars - gbw2@le.ac.uk
Click here for Dr Willars' research page
Summary of the Project
Neuromedin U (NmU) belongs to a family of peptides termed neuromedins. It is highly conserved across species and ubiquitously expressed, with highest levels found in the gastrointestinal tract and pituitary. Although the precise patho-physiological roles have yet to be defined, NmU has been implicated in the regulation of smooth-muscle contraction, local blood flow, blood pressure, ion transport in the gut, gastric acid secretion and cancer. In the central nervous system, NmU is pro-nociceptive and plays a key role in the central regulation of the stress response, feeding behavior and energy expenditure. In mammals, the biological effects of NmU are mediated via two recently identified G-protein-coupled receptors (NmU-R1 and NmU-R2). We have recently characterised many aspects of the signalling and regulation of recombinantly expressed human NmU-R1 and NmU-R2. This project will seek to extend these studies, in particular to examine the cellular processing of NmU and its receptors and to define the signalling properties of endogenously expressed NmU-Rs. Further, we have shown that NmU binds essentially irreversibly to recombinant receptors, preventing repetitive functional responses but that in the more physiological context of isolated intact smooth-muscle, repetitive contractions are easily achieved. This project will examine this paradox to test if this is a consequence of either the proteolytic degradation of NmU or differences in the cellular processing of NmU and/or its receptor. This project will require the use of a broad variety of techniques in pharmacology/cell biology including: culture of primary cells and established cell lines; biochemical measurements of cell signalling (eg. phospholipid metabolism, Ca2+ signalling, cAMP); ligand binding; confocal microscopy; molecular biology; in vitro pharmacology; immunoblotting and immunocytochemistry.
Recent Publications:
Brighton, P.J., Szekeres, P.G. & Willars, G.B. (2004a) Pharmacol. Revs. 56, 231-248.
Brighton, P.J. et al., (2004b) Mol. Pharmacol. 66, 1544-1556.
For further information please contact Dr Willars at the email address above.
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The role of the ß2-AR in angiogenesis and wound healing
Supervisor: Dr C E Pullar - cp161@le.ac.uk
Click here for Dr Pullar's research page
Summary of the Project
Wound healing is a complex biological process requiring the orchestration of numerous processes and cell types to repair the wound. Recent work has identified the ß2-AR as a modulator of keratinocyte migration, wound re-epithelialisation and fibroblast-mediated wound contraction (1-5). Angiogenesis, the development of new blood vessels from existing vasculature, is essential for wound repair. Projects are available to investigate if ß2-AR activation or blockade alters endothelial cell pre-angiogenic responses including migration, proliferation, elongation and re-orientation and to delineate the signalling pathways that mediate these effects. Techniques used in the laboratory include primary cell culture; single cell migration, directional migration and proliferation assays; western blotting and immunocytochemistry.
Recent Publications:
Pullar, C. E., Grahn, J. C., Liu, W., and Isseroff, R. R. (2006) Faseb J 20(1), 76-86
Pullar, C. E., and Isseroff, R. R. (2005) J Cell Sci 118(Pt 9), 2023-2034
Pullar, C. E., and Isseroff, R. R. (2005) Wound Repair Regen 13(4), 405-411
Pullar, C. E., and Isseroff, R. R. (2006) J Cell Sci 119(Pt 3), 592-602
Pullar, C. E., Rizzo, A., and Isseroff, R. R. (2006) J Biol Chem 281(30), 21225-21235
For further information please contact Dr Pullar at the email address above.
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Ion channels in platelets and megakaryocytes
Supervisor: Professor M Mahaut-Smith - mpms1@le.ac.uk
Click here for Professor Mahaut-Smith's research page
Summary of the Project
Ion channels play important roles in all cell types, yet their study has proven difficult in the small and fragile blood platelet. Recent work has shown that the large platelet precursor cell, the megakaryocyte, can be employed as a bona fide model of platelet function and thus facilitate direct electrophysiological studies of this cell type. Using a combination of patch clamp and molecular tools, we have identified new candidate pathways for Ca2+ entry in the platelet (Carter et al., 2006; Mahaut-Smith et al., 2004; Tolhurst et al., 2008). This project will examine the mechanism of activation and role of these and other channels in platelet and megakaryocyte function, that is haemostasis, thrombosis and thrombopoiesis.
Techniques: Patch clamp, fluorescent Ca2+ measurements, RT-PCR, functional platelet assays, confocal microscopy, megakaryocyte culture, interference RNA
References:
Carter, R. N., Tolhurst, G., Walmsley, G., Vizuete-Forster, M., Miller, N., & Mahaut-Smith, M. P. (2006). Molecular and electrophysiological characterization of transient receptor potential ion channels in the primary murine megakaryocyte. J.Physiol 576, 151-162.
Mahaut-Smith, M. P., Tolhurst, G., & Evans, R. J. (2004). Emerging roles for P2X1 receptors in platelet activation. Platelets. 15, 131-144.
Tolhurst, G., Carter, R. N., Amisten, S., Holdich, J., Erlinge, D., & Mahaut-Smith-M.P. (2008). Expression profiling and electrophysiological studies suggest a major role for Orai1 in the store-operated Ca2+ influx pathway of platelets and megakaryocytes. Platelets In press.
For further information please contact Professor Mahaut-Smith at the email address above.
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Membrane invagination systems of the platelet and megakaryoctye
Supervisor: Professor M Mahaut-Smith - mpms1@le.ac.uk
Click here for Professor Mahaut-Smith's research page
Summary of the Project
The platelet and megakaryocyte possess unique plasma membrane invagination systems, referred to as the open canalicular system and demarcation membrane system, respectively (Mahaut-Smith et al., 2003; White & Clawson, 1980). Very little is known about how these invaginations develop during megakaryocytopoiesis and their contribution to cellular responses. This project will use patch clamp, molecular biology, electron microscopy and confocal fluorescence microscopy to investigate the properties and importance of membrane invaginations to platelet and megakaryocyte function, namely haemostasis, thrombosis and thrombopoiesis.
Techniques: Patch clamp, confocal microscopy, electron microscopy, megakaryocyte culture, stem cells, molecular biology, platelet functional assays.
References:
Mahaut-Smith, M. P., Thomas, D., Higham, A. B., Usher-Smith, J. A., Hussain, J. F., Martinez-Pinna, J., Skepper, J. N., & Mason, M. J. (2003). Properties of the demarcation membrane system in living rat megakaryocytes. Biophys.J. 84, 2646-2654.
White, J. G. & Clawson, C. C. (1980). The surface-connected canalicular system of blood platelets--a fenestrated membrane system. Am J Pathol 101, 353-364.
For further information please contact Professor Mahaut-Smith at the email address above.
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Visualising memory
Supervisor: Professor N Hartell - nh88@le.ac.uk
Click here for Professor Hartell's research page
Summary of the Project
How does the brain acquire information and store memories? One way is by an alteration in the strength of signalling at synapses, the electro-chemical junction formed between neurones. Changes in synaptic strength can arise from changes in the amount of neurotransmitter released or in the way receptors on the post-synaptic side of the junction respond to the transmitter. In this laboratory, we are interested in how synapses “learn” and we use a combination of electrophysiological recording and imaging techniques to study this. Our long-term goal is to be able to understand how the brain learns so that we can combat disease states that lead to memory loss such as dementias including Alzheimer’s disease.
Current projects are aimed at developing and using fluorescent protein based sensors that allow us to visualise cell communication directly. By targeting pH sensitive fluorescent proteins to presynaptic proteins involved in transmitter release, we will characterise the release characteristics of synapses as they learn. We will also use similar techniques to observe the regulation of surface expressed receptors on the post-synaptic membrane.
Our laboratory uses in vitro electrophysiology, laser scanning confocal and CCD based microscopy and molecular biological methods to address these questions. As well as offering projects aimed towards postgraduate students with backgrounds in Biological Sciences, we can also offer projects aimed towards the development of new types of high speed digital microscopes. These would suit students with interests in Physics, Biophysics or Bioengineering. As well as offering PhD projects, we occasionally host MSc or Erasmus students from other European Universities.
For further information please contact Professor Hartell at the email address above.
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Molecular genetic characterization of P2X receptor function in the model eukaryotic organism Dictyostelium discoideum
Supervisor: Dr S J Ennion - se15@le.ac.uk
Click here for Dr Ennion's research page
In addition to its central role in cell metabolism, ATP also acts as an extracellular signalling molecule with important functions in a diverse range of physiological and pathophysiological processes. P2X receptors facilitate the ionotropic component of ATP mediated signalling acting as extracellular ATP gated ion channels. Understanding the molecular function of P2X receptors is therefore of significant importance to human health. A current handicap is the lack of a simple model system to provide a fast and convenient test-bed for rapid genetic manipulation and functional screens probing the molecular function of P2X receptors. The recent identification of a family of P2X-like proteins in the model eukaryotic organism Dictyostelium discoideum has now opened a unique opportunity to address fundamental questions regarding the molecular mechanisms governing P2X receptor function in a relatively simple model system that offers a range of powerful molecular genetic and functional screening techniques. This project aims to characterise the molecular properties of Dictyostelium P2X-like receptors by genetic and electrophysiological methods. Homologous recombination will be used to “knock out” individual Dictyostelium P2X genes and effects on endogenous purinergic responses will be determined utilizing the calcium sensing protein aequorin. Green fluorescent protein (GFP) tagged receptors will also be generated and used to determine subcellular localization. Cloned Dictyostelium P2X receptors will also be expressed in Xenopus oocytes to enable electrophysiological characterization of ion channel function. This project will provide an excellent integrated training in genetic manipulation, molecular biology and electrophysiology. The research will take place in the laboratory of Dr Steve Ennion in the Department of Cell Physiology and Pharmacology, which has broad interests in cell signalling, ion channels, and molecular biology.
Background references:
K.C. Agboh, T.E. Webb, R.J. Evans, S.J. Ennion, Functional characterization of a P2X receptor from Schistosoma mansoni, J Biol Chem. 279 (2004) 41650-7.
S. Ennion, S. Hagan, R.J. Evans, The role of positively charged amino acids in ATP recognition by human P2X(1) receptors, J Biol Chem. 275 (2000) 29361-7.
S.J. Fountain, K. Parkinson, M.T. Young, L. Cao, C.R. Thompson, R.A. North, An intracellular P2X receptor required for osmoregulation in Dictyostelium discoideum, Nature. 448 (2007) 200-3.
For further information please contact Dr Ennion at the email address above.
