School of Chemistry - Research Publications

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    The hypoxia imaging agent CuII(atsm) is neuroprotective and improves motor and cognitive functions in multiple animal models of Parkinson's disease
    Hung, LW ; Villemagne, VL ; Cheng, L ; Sherratt, NA ; Ayton, S ; White, AR ; Crouch, PJ ; Lim, S ; Leong, SL ; Wilkins, S ; George, J ; Roberts, BR ; Pham, CLL ; Liu, X ; Chiu, FCK ; Shackleford, DM ; Powell, AK ; Masters, CL ; Bush, AI ; O'Keefe, G ; Culvenor, JG ; Cappai, R ; Cherny, RA ; Donnelly, PS ; Hill, AF ; Finkelstein, DI ; Barnham, KJ (ROCKEFELLER UNIV PRESS, 2012-04-09)
    Parkinson's disease (PD) is a progressive, chronic disease characterized by dyskinesia, rigidity, instability, and tremors. The disease is defined by the presence of Lewy bodies, which primarily consist of aggregated α-synuclein protein, and is accompanied by the loss of monoaminergic neurons. Current therapeutic strategies only give symptomatic relief of motor impairment and do not address the underlying neurodegeneration. Hence, we have identified Cu(II)(atsm) as a potential therapeutic for PD. Drug administration to four different animal models of PD resulted in improved motor and cognition function, rescued nigral cell loss, and improved dopamine metabolism. In vitro, this compound is able to inhibit the effects of peroxynitrite-driven toxicity, including the formation of nitrated α-synuclein oligomers. Our results show that Cu(II)(atsm) is effective in reversing parkinsonian defects in animal models and has the potential to be a successful treatment of PD.
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    An impaired mitochondrial electron transport chain increases retention of the hypoxia imaging agent diacetylbis(4-methylthiosemicarbazonato)copperII
    Donnelly, PS ; Liddell, JR ; Lim, S ; Paterson, BM ; Cater, MA ; Savva, MS ; Mot, AI ; James, JL ; Trounce, IA ; White, AR ; Crouch, PJ (NATL ACAD SCIENCES, 2012-01-03)
    Radiolabeled diacetylbis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] is an effective positron-emission tomography imaging agent for myocardial ischemia, hypoxic tumors, and brain disorders with regionalized oxidative stress, such as mitochondrial myopathy, encephalopathy, and lactic acidosis with stroke-like episodes (MELAS) and Parkinson's disease. An excessively elevated reductive state is common to these conditions and has been proposed as an important mechanism affecting cellular retention of Cu from Cu(II)(atsm). However, data from whole-cell models to demonstrate this mechanism have not yet been provided. The present study used a unique cell culture model, mitochondrial xenocybrids, to provide whole-cell mechanistic data on cellular retention of Cu from Cu(II)(atsm). Genetic incompatibility between nuclear and mitochondrial encoded subunits of the mitochondrial electron transport chain (ETC) in xenocybrid cells compromises normal function of the ETC. As a consequence of this impairment to the ETC we show xenocybrid cells upregulate glycolytic ATP production and accumulate NADH. Compared to control cells the xenocybrid cells retained more Cu after being treated with Cu(II)(atsm). By transfecting the cells with a metal-responsive element reporter construct the increase in Cu retention was shown to involve a Cu(II)(atsm)-induced increase in intracellular bioavailable Cu specifically within the xenocybrid cells. Parallel experiments using cells grown under hypoxic conditions confirmed that a compromised ETC and elevated NADH levels contribute to increased cellular retention of Cu from Cu(II)(atsm). Using these cell culture models our data demonstrate that compromised ETC function, due to the absence of O(2) as the terminal electron acceptor or dysfunction of individual components of the ETC, is an important determinant in driving the intracellular dissociation of Cu(II)(atsm) that increases cellular retention of the Cu.
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    Inhibition of TDP-43 Accumulation by Bis(thiosemicarbazonato)-Copper Complexes
    Parker, SJ ; Meyerowitz, J ; James, JL ; Liddell, JR ; Nonaka, T ; Hasegawa, M ; Kanninen, KM ; Lim, S ; Paterson, BM ; Donnelly, PS ; Crouch, PJ ; White, AR ; Kahle, PJ (PUBLIC LIBRARY SCIENCE, 2012-08-03)
    Amyotrophic lateral sclerosis (ALS) is a progressive, fatal, motor neuron disease with no effective long-term treatment options. Recently, TDP-43 has been identified as a key protein in the pathogenesis of some cases of ALS. Although the role of TDP-43 in motor neuron degeneration is not yet known, TDP-43 has been shown to accumulate in RNA stress granules (SGs) in cell models and in spinal cord tissue from ALS patients. The SG association may be an early pathological change to TDP-43 metabolism and as such a potential target for therapeutic intervention. Accumulation of TDP-43 in SGs induced by inhibition of mitochondrial activity can be inhibited by modulation of cellular kinase activity. We have also found that treatment of cells and animal models of neurodegeneration, including an ALS model, with bioavailable bis(thiosemicarbazonato)copper(II) complexes (Cu(II)(btsc)s) can modulate kinase activity and induce neuroprotective effects. In this study we examined the effect of diacetylbis(-methylthiosemicarbazonato)copper(II) (Cu(II)(atsm)) and glyoxalbis(-methylthiosemicarbazonato)copper(II) (Cu(II)(gtsm)) on TDP-43-positive SGs induced in SH-SY5Y cells in culture. We found that the Cu(II)(btsc)s blocked formation of TDP-43-and human antigen R (HuR)-positive SGs induced by paraquat. The Cu(II)(btsc)s protected neurons from paraquat-mediated cell death. These effects were associated with inhibition of ERK phosphorylation. Co-treatment of cultures with either Cu(II)(atsm) or an ERK inhibitor, PD98059 both prevented ERK activation and blocked formation of TDP-43-and HuR-positive SGs. Cu(II)(atsm) treatment or ERK inhibition also prevented abnormal ubiquitin accumulation in paraquat-treated cells suggesting a link between prolonged ERK activation and abnormal ubiquitin metabolism in paraquat stress and inhibition by Cu. Moreover, Cu(II)(atsm) reduced accumulation of C-terminal (219-414) TDP-43 in transfected SH-SY5Y cells. These results demonstrate that Cu(II)(btsc) complexes could potentially be developed as a neuroprotective agent to modulate neuronal kinase function and inhibit TDP-43 aggregation. Further studies in TDP-43 animal models are warranted.
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    The challenges of using a copper fluorescent sensor (CS1) to track intracellular distributions of copper in neuronal and glial cells
    Price, KA ; Hickey, JL ; Xiao, Z ; Wedd, AG ; James, SA ; Liddell, JR ; Crouch, PJ ; White, AR ; Donnelly, PS (ROYAL SOC CHEMISTRY, 2012)