Publications (24) View all
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Article: CLC-3 chloride channels moderate LTP at Schaffer collateral-CA1 synapses.
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ABSTRACT: CLC-3 is expressed in the brain on synaptic vesicles and postsynaptic membranes. Although CLC-3 is broadly expressed throughout the brain, the CLC-3 knockout mouse shows complete, selective postnatal neurodegeneration of the hippocampus, suggesting a crucial role for the channel in maintaining normal brain function. CLC-3 channels are functionally linked to NMDARs in the hippocampus: NMDAR-dependent Ca2+ entry, activation of CaMKII, and subsequent gating of CLC-3 links the channels via a Ca2+-mediated feedback loop. We demonstrate that loss of CLC-3 at mature synapses increases LTP from 135 ± 4% in the wildtype slice to 154 ± 7% above baseline (p < 0.001) in the knockout; therefore, the contribution of CLC-3 is to reduce synaptic potentiation by ~40%. In addition, we show that phosphorylation of CLC-3 is required for its regulatory function in LTP using a decoy peptide representing the CaMKII phosphorylation site on CLC-3. CLC-3 is also expressed on synaptic vesicles, however, our data suggest functionally separable pre- and postsynaptic roles. Thus CLC-3 confers Cl--sensitivity to excitatory synapses, controls the magnitude of LTP and may provide a protective limit on Ca2+ influx.The Journal of Physiology 11/2012; · 4.72 Impact Factor -
Article: Presynaptic CLC-3 determines quantal size of inhibitory transmission in the hippocampus.
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ABSTRACT: The absence of the chloride channel CLC-3 in Clcn3(-/-) mice results in hippocampal degeneration with a distinct temporal-spatial sequence that resembles neuronal loss in temporal lobe epilepsy. We examined how the loss of CLC-3 might affect GABAergic synaptic transmission in the hippocampus. An electrophysiological study of synaptic function in hippocampal slices taken from Clcn3(-/-) mice before the onset of neurodegeneration revealed a substantial decrease in the amplitude and frequency of miniature inhibitory postsynaptic currents compared with those in wild-type slices. We found that CLC-3 colocalized with the vesicular GABA transporter VGAT in the CA1 region of the hippocampus. Acidification of inhibitory synaptic vesicles induced by Cl(-) showed a marked dependence on CLC-3 expression. The decrease in inhibitory transmission in Clcn3(-/-) mice suggests that the neurotransmitter loading of synaptic vesicles was reduced, which we attribute to defective vesicular acidification. Our observations extend the role of Cl(-) in inhibitory transmission from that of a postsynaptic permeant species to a presynaptic regulatory element.Nature Neuroscience 03/2011; 14(4):487-94. · 15.53 Impact Factor -
Article: Response to Jentsch et al.
Cell metabolism 10/2010; 12(4):310. · 17.35 Impact Factor -
Article: Bepridil and amiodarone simultaneously target the Alzheimer's disease beta- and gamma-secretase via distinct mechanisms.
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ABSTRACT: The two proteases beta-secretase and gamma-secretase generate the amyloid beta peptide and are drug targets for Alzheimer's disease. Here we tested the possibility of targeting the cellular environment of beta-secretase cleavage instead of the beta-secretase enzyme itself. beta-Secretase has an acidic pH optimum and cleaves the amyloid precursor protein in the acidic endosomes. We identified two drugs, bepridil and amiodarone, that are weak bases and are in clinical use as calcium antagonists. Independently of their calcium-blocking activity, both compounds mildly raised the membrane-proximal, endosomal pH and inhibited beta-secretase cleavage at therapeutically achievable concentrations in cultured cells, in primary neurons, and in vivo in guinea pigs. This shows that an alkalinization of the cellular environment could be a novel therapeutic strategy to inhibit beta-secretase. Surprisingly, bepridil and amiodarone also modulated gamma-secretase cleavage independently of endosomal alkalinization. Thus, both compounds act as dual modulators that simultaneously target beta- and gamma-secretase through distinct molecular mechanisms. In addition to Alzheimer's disease, compounds with dual properties may also be useful for drug development targeting other membrane proteins.Journal of Neuroscience 06/2010; 30(26):8974-83. · 7.11 Impact Factor -
Article: Compartmentalized cyclic adenosine 3',5'-monophosphate at the plasma membrane clusters PDE3A and cystic fibrosis transmembrane conductance regulator into microdomains.
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ABSTRACT: Formation of multiple-protein macromolecular complexes at specialized subcellular microdomains increases the specificity and efficiency of signaling in cells. In this study, we demonstrate that phosphodiesterase type 3A (PDE3A) physically and functionally interacts with cystic fibrosis transmembrane conductance regulator (CFTR) channel. PDE3A inhibition generates compartmentalized cyclic adenosine 3',5'-monophosphate (cAMP), which further clusters PDE3A and CFTR into microdomains at the plasma membrane and potentiates CFTR channel function. Actin skeleton disruption reduces PDE3A-CFTR interaction and segregates PDE3A from its interacting partners, thus compromising the integrity of the CFTR-PDE3A-containing macromolecular complex. Consequently, compartmentalized cAMP signaling is lost. PDE3A inhibition no longer activates CFTR channel function in a compartmentalized manner. The physiological relevance of PDE3A-CFTR interaction was investigated using pig trachea submucosal gland secretion model. Our data show that PDE3A inhibition augments CFTR-dependent submucosal gland secretion and actin skeleton disruption decreases secretion.Molecular biology of the cell 03/2010; 21(6):1097-110. · 5.98 Impact Factor
