Jon Lindstrom

University of Pennsylvania, Philadelphia, Pennsylvania, United States

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Publications (266)1419.35 Total impact

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    ABSTRACT: Myasthenia gravis (MG) with antibodies against the acetylcholine receptor (AChR) is characterized by a chronic, fatigable weakness of voluntary muscles. The production of autoantibodies involves the dysregulation of T cells which provide the environment for the development of autoreactive B cells. The symptoms are caused by destruction of the postsynaptic membrane and degradation of the AChR by IgG autoantibodies, predominantly of the G1 and G3 subclasses. Active immunization of animals with AChR from mammalian muscles, AChR form Torpedo or Electrophorus electric organs, and recombinant or synthetic AChR fragments generates a chronic model of MG, termed experimental autoimmune myasthenia gravis (EAMG). This model covers cellular mechanisms involved in the immune response against the AChR, e.g. antigen presentation, T cell-help and regulation, B cell selection and differentiation into plasma cells. Our aim is to define standard operation procedures and recommendations for the rat EAMG model using purified AChR from the Torpedo californica electric organ, in order to facilitate more rapid translation of preclinical proof of concept or efficacy studies into clinical trials and, ultimately, clinical practice. Copyright © 2015. Published by Elsevier Inc.
    Experimental Neurology 03/2015; 14. DOI:10.1016/j.expneurol.2015.03.010 · 4.62 Impact Factor
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    ABSTRACT: Antibodies against the muscle acetylcholine receptor (AChR) are the most common cause of myasthenia gravis (MG). Passive transfer of AChR antibodies from MG patients into animals reproduces key features of human disease, including antigenic modulation of the AChR, complement-mediated damage of the neuromuscular junction, and muscle weakness. Similarly, AChR antibodies generated by active immunization in experimental autoimmune MG models can subsequently be passively transferred to other animals and induce weakness. The passive transfer model is useful to test therapeutic strategies aimed at the effector mechanism of the autoantibodies. Here we summarize published and unpublished experience using the AChR passive transfer MG model in mice, rats and rhesus monkeys, and give recommendations for the design of preclinical studies in order to facilitate translation of positive and negative results to improve MG therapies. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
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    ABSTRACT: Nicotinic acetylcholine receptors (nAChRs) are highly conserved between humans and non-human primates. Conservation exists at the level of genomic structure, protein structure and epigenetics. Overall homology of nAChRs at the protein level is 98% in macaques versus 89% in mice, which is highly relevant for evaluating subtype-specific ligands that have different affinities in humans versus rodents. In addition to conservation at the protein level, there is high conservation of genomic structure in terms of intron and exon size and placement of CpG sites that play a key role in epigenetic regulation. Analysis of single nucleotide polymorphisms (SNPs) shows that while the majority of SNPs are not conserved between humans and macaques, some functional polymorphisms are. Most significantly, cynomolgus monkeys express a similar α5 nAChR Asp398Asn polymorphism to the human α5 Asp398Asn polymorphism that has been linked to greater nicotine addiction and smoking related disease. Monkeys can be trained to readily self-administer nicotine, and in an initial study we have demonstrated that cynomolgus monkeys bearing the α5 D398N polymorphism show a reduced behavioral sensitivity to oral nicotine and tend to consume it in a different pattern when compared to wild-type monkeys. Thus the combination of highly homologous nAChR, higher cortical functions and capacity for complex training makes non-human primates a unique model to study in vivo functions of nicotinic receptors. In particular, primate studies on nicotine addiction and evaluation of therapies to prevent or overcome nicotine addiction are likely to be highly predictive of treatment outcomes in humans. Copyright © 2015. Published by Elsevier Ltd.
    Neuropharmacology 02/2015; DOI:10.1016/j.neuropharm.2015.01.023 · 4.82 Impact Factor
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    ABSTRACT: Nicotinic acetylcholine receptors (AChRs) are ACh-gated ion channels formed from five homologous subunits in subtypes defined by their subunit composition and stoichiometry. Some subtypes readily produce functional AChRs in Xenopus oocytes and transfected cell lines. α6β2β3* AChRs (subtypes formed from these subunits and perhaps others) are not easily expressed. This may be because the types of neurons in which they are expressed (typically dopaminergic neurons) have unique chaperones for assembling α6β2β3* AChRs, especially in the presence of the other AChR subtypes. Because these relatively minor brain AChR subtypes are of major importance in addiction to nicotine, it is important for drug development as well as investigation of their functional properties to be able to efficiently express human α6β2β3* AChRs. We review the issues and progress in expressing α6* AChRs. This article is part of a Special Issue entitled 'Nicotinic Acetylcholine Receptor'. Copyright © 2014. Published by Elsevier Ltd.
    Neuropharmacology 10/2014; DOI:10.1016/j.neuropharm.2014.10.009 · 4.82 Impact Factor
  • Jie Luo, Jon Lindstrom
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    ABSTRACT: Myasthenia gravis (MG) and experimental autoimmune myasthenia gravis (EAMG) are caused by Ab-mediated autoimmune responses to muscle nicotinic acetylcholine receptors (AChRs) that impair neuromuscular transmission, thereby causing muscle weakness. Previously, we discovered that i.p. injection of a therapeutic vaccine consisting of bacterially expressed cytoplasmic domains of human AChR subunits reduced the development of chronic EAMG in rats. In this article, we show that immunization with the therapeutic vaccine in adjuvants does not induce EAMG and, thus, is safe. The potency and efficacy of the therapeutic vaccine were greatly increased by s.c. administration of repeated low doses in IFA. Onset of chronic EAMG could be prevented. Established chronic EAMG could be rapidly reversed, modeling therapy of chronic MG. Therapy reduced pathological Abs assayed by immune precipitation of a main immunogenic region chimera. Successfully treated rats exhibited long-term resistance to reinduction of EAMG, suggesting a lasting cure of MG. A long-term effect of therapy was to change the isotype of the pathogenic Ab response from IgG2b, which fixes complement, to IgG1, which does not. Prevention and reversal of chronic EAMG was not caused by the isotype switch, but the isotype switch may contribute to resistance to reinduction of EAMG. Immunization with AChR cytoplasmic domains in adjuvant is promising as a safe, Ag-specific, potent, effective, rapidly acting, and long-lasting therapeutic approach to MG.
    The Journal of Immunology 10/2014; 193. DOI:10.4049/jimmunol.1401392 · 5.36 Impact Factor
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    ABSTRACT: Human (α6β2)(α4β2)β3 nicotinic acetylcholine receptors (AChRs) are essential for addiction to nicotine and a target for drug development for smoking cessation. Expressing this complex AChR is difficult, but has been achieved using subunit concatamers. In order to determine what limits expression of α6* AChRs and to efficiently express α6* AChRs using free subunits, we investigated expression of the simpler (α6β2)2β3 AChR. The concatameric form of this AChR assembles well, but is transported to the cell surface inefficiently. Various chimeras of α6 with the closely related α3 subunit increased expression efficiency with free subunits and produced pharmacologically equivalent functional AChRs. A chimera in which the large cytoplasmic domain of α6 was replaced with that of α3 increased assembly with β2 subunits and transport of AChRs to the oocyte surface. Another chimera replacing the unique methionine 211 of α6 with leucine found at this position in transmembrane domain 1 of α3 and other α subunits increased assembly of mature subunits containing β3 subunits within oocytes. Combining both α3 sequences in an α6 chimera increased expression of functional (α6β2)2β3 AChRs to 12-fold more than with concatamers. This is pragmatically useful, and provides insights on features of α6 subunit structure that limit its expression in transfected cells.
    PLoS ONE 07/2014; 9(7):e103244. DOI:10.1371/journal.pone.0103244 · 3.53 Impact Factor
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    ABSTRACT: In this study, we report a new protein involved in the homeostatic regulation of sleep in Drosophila. We conducted a forward genetic screen of chemically mutagenized flies to identify short-sleeping mutants and found one, redeye (rye) that shows a severe reduction of sleep length. Cloning of rye reveals that it encodes a nicotinic acetylcholine receptor α subunit required for Drosophila sleep. Levels of RYE oscillate in light-dark cycles and peak at times of daily sleep. Cycling of RYE is independent of a functional circadian clock, but rather depends upon the sleep homeostat, as protein levels are up-regulated in short-sleeping mutants and also in wild type animals following sleep deprivation. We propose that the homeostatic drive to sleep increases levels of RYE, which responds to this drive by promoting sleep. DOI: http://dx.doi.org/10.7554/eLife.01473.001.
    eLife Sciences 02/2014; 3:e01473. DOI:10.7554/eLife.01473 · 8.52 Impact Factor
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    ABSTRACT: Chronic nicotine administration increases the density of brain α4β2* nicotinic acetylcholine receptors (nAChRs), which may contribute to withdrawal symptoms associated with smoking cessation. Varenicline, a smoking cessation drug, also increases these receptors in rodent brain. The maintenance of this increase by varenicline as well as nicotine replacement may contribute to the high rate of relapse during the first year after smoking cessation. Recently we found that sazetidine-A, a potent partial agonist that desensitizes α4β2* nAChRs, does not increase the density of these receptors in brain at doses that decrease nicotine self-administration, increase attention in rats, and produce anxiolytic effects in mice. Here we investigated whether chronic sazetidine-A and varenicline maintain the density of nAChRs after their up-regulation by nicotine. In addition, we examined the effects of these drugs on a measure of anxiety in mice and weight gain in rats. After increasing nAChRs in the rodent brain with chronic nicotine, replacing nicotine with chronic varenicline maintained the increased nAChR binding, as well as the subunit proteins measured by western blots. In contrast, replacing nicotine treatments with chronic sazetidine-A resulted in the return of the density of nAChRs to the levels seen in saline controls. Nicotine, sazetidine-A and varenicline each demonstrated anxiolytic effects in mice, but only sazetidine-A and nicotine attenuated the gain of weight over a 6-week period in rats. These findings suggest that apart from its modest anxiolytic and weight control effects, sazetidine-A, or drugs like it, may be useful in achieving long-term abstinence from smoking. This article is protected by copyright. All rights reserved.
    Journal of Neurochemistry 01/2014; DOI:10.1111/jnc.12653 · 4.24 Impact Factor
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    ABSTRACT: Nicotine, the primary psychoactive component in tobacco smoke, produces its behavioral effects through interactions with neuronal nicotinic acetylcholine receptors (nAChRs). α4β2 nAChRs are the most abundant in mammalian brain, and converging evidence shows that this subtype mediates the rewarding and reinforcing effects of nicotine. A number of rare variants in the CHRNA4 gene that encodes the α4 nAChR subunit have been identified in human subjects and appear to be underrepresented in a cohort of smokers. We compared three of these variants (α4R336C, α4P451L and α4R487Q) to the common variant to determine their effects on α4β2 nAChR pharmacology. We examined [3H]-epibatidine binding, interacting proteins and phosphorylation of the α4 nAChR subunit with LC-MS/MS in HEK 293 cells, and voltage-clamp electrophysiology in Xenopus oocytes. We observed significant effects of the α4 variants on nAChR expression, subcellular distribution, and sensitivity to nicotine-induced receptor upregulation. Proteomic analysis of immunopurified α4β2 nAChRs incorporating the rare variants identified considerable differences in the intracellular interactomes due to these single amino acid substitutions. Electrophysiological characterization in Xenopus oocytes revealed alterations in the functional parameters of activation by nAChR agonists conferred by these α4 rare variants, as well as shifts in receptor function following incubation with nicotine. Taken together, these experiments suggest that genetic variation at CHRNA4 alters the assembly and expression of α4β2 nAChRs resulting in receptors that are more sensitive to nicotine exposure than those assembled with the common α4 variant. The changes in nAChR pharmacology could contribute to differences in responses to smoked nicotine in individuals harboring these rare variants.
    Journal of Pharmacology and Experimental Therapeutics 01/2014; 348(3). DOI:10.1124/jpet.113.209767 · 3.89 Impact Factor
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    ABSTRACT: The design and synthesis of a series of substituted heteroaromatic α4β2α5 positive allosteric modulators is reported. The optimization and development of the heteroaromatic series was carried out from NS9283, and several potent analogues, such as 3-(5-(pyridin-3-yl)-2H-tetrazol-2-yl)benzonitrile (5k) and 3,3'-(2H-tetrazole-2,5-diyl)dipyridine (12h) with good in vitro efficacy were discovered.
    Bioorganic & medicinal chemistry letters 11/2013; DOI:10.1016/j.bmcl.2013.11.049 · 2.65 Impact Factor
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    ABSTRACT: The behavioral effects of nicotine and other nicotinic agonists are mediated by AChRs in the brain. The relative contribution of acute activation versus chronic desensitization of AChRs is unknown. Sustained "smoldering activation" occurs over a range of agonist concentrations at which activated and desensitized AChRs are present in equilibrium. We used a fluorescent dye sensitive to changes in membrane potential to examine the effects of acute activation and chronic desensitization by nicotinic AChR agonists on cell lines expressing human α4β2, α3β4 and α7 AChRs. We examined the effects of acute and prolonged application of nicotine and the partial agonists varenicline, cytisine and sazetidine-A on these AChRs. The range of concentrations over which nicotine causes smoldering activation of α4β2 AChRs was centered at 0.13 µM, a level found in smokers. However, nicotine produced smoldering activation of α3β4 and α7 AChRs at concentrations well above levels found in smokers. The α4β2 expressing cell line contains a mixture of two stoichiometries, namely (α4β2)2β2 and (α4β2)2α4. The (α4β2)2β2 stoichiometry is more sensitive to activation by nicotine. Sazetidine-A activates and desensitizes only this stoichiometry. Varenicline, cytisine and sazetidine-A were partial agonists on this mixture of α4β2 AChRs, but full agonists on α3β4 and α7 AChRs. It has been reported that cytisine and varenicline are most efficacious on the (α4β2)2α4 stoichiometry. In this study, we distinguish the dual effects of activation and desensitization of AChRs by these nicotinic agonists and define the range of concentrations over which smoldering activation can be sustained.
    PLoS ONE 11/2013; 8(11):e79653. DOI:10.1371/journal.pone.0079653 · 3.53 Impact Factor
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    ABSTRACT: Selected nicotinic agonists were used to activate and desensitize high-sensitivity (HS; (α4)2(β2)3) or low-sensitivity (LS; (α4)3(β2)2) isoforms of human α4β2-nicotinic acetylcholine receptors (nAChR). Function was assessed using (86)Rb(+) efflux in a stably-transfected SH-EP1-hα4β2 human epithelial cell line, and two-electrode voltage-clamp electrophysiology in Xenopus oocytes expressing concatenated pentameric HS or LS α4β2-nAChR constructs (HSP and LSP). Unlike previously-studied agonists, desensitization bythe highly-selective agonists A-85380 and sazetidine-A (Saz-A) preferentially reduced α4β2-nAChR HS-phase vs. LS-phase responses. The concatenated-nAChR experiments confirmed that ≈20% of LS-isoform ACh-induced function occurs in an HS-like phase, which is abolished by Saz-A preincubation. Six mutant LSP were generated, each targeting a conserved agonist-binding residue within the LS-isoform-only α4(+)/(-)α4 interface agonist binding site. Every mutation reduced the percentage of LS-phase function, demonstrating that this site underpins LS-phase function. Oocyte-surface expression of the HSP and each of the LSP constructs was statistically indistinguishable, as measured using β2-subunit-specific [(125)I]mAb295 labeling. However, maximum function is approximately 5x greater on a "per receptor" basis for unmodified-LSP vs. HSP α4β2-nAChR. Thus, recruitment of the α4(+)/(-)α4 site at higher agonist concentrations appears to augment otherwise-similar function mediated by the pair of α4(+)/(-)β2 sites shared by both isoforms. These studies elucidate the receptor-level differences underlying the differential pharmacology of the two α4β2-nAChR isoforms, and demonstrate that HS vs. LS α4β2-nAChR activity can be selectively manipulated using pharmacological approaches. Since α4β2 nAChR are the predominant neuronal subtype these discoveries likely have significant functional implications, and may provide important insights for drug discovery and development.
    Journal of Pharmacology and Experimental Therapeutics 11/2013; 348(1). DOI:10.1124/jpet.113.208389 · 3.89 Impact Factor
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    ABSTRACT: Neuronal nicotinic acetylcholine receptors (nAChRs) containing α4 and β2 subunits are the principal receptors in the mammalian central nervous system that bind nicotine with high affinity. These nAChRs are involved in nicotine dependence, mood disorders, neurodegeneration and neuroprotection. However, our understanding of the interactions between α4β2-containing (α 4 β2∗) nAChRs and other proteins remains limited. In this study, we identified proteins that interact with α 4 β2∗ nAChRs in a gene-dose dependent pattern by immunopurifying β2∗ nAChRs from mice that differ in α4 and β2 subunit expression and performing proteomic analysis using isobaric tags for relative and absolute quantitation (iTRAQ). Reduced expression of either the α4 or the β2 subunit results in a correlated decline in the expression of a number of putative interacting proteins. We identified 208 proteins co-immunoprecipitated with these nAChRs. Furthermore, stratified linear regression analysis indicated that levels of 17 proteins was correlated significantly with expression of α4 β2 nAChRs, including proteins involved in cytoskeletal rearrangement and calcium signaling. These findings represent the first application of quantitative proteomics to produce a β2∗ nAChR interactome and describe a novel technique used to discover potential targets for pharmacological manipulation of α4 β2 nAChRs and their downstream signaling mechanisms.
    07/2013; DOI:10.1016/j.gpb.2013.05.005
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    ABSTRACT: Synthesis of acetylcholine (ACh) by non-neuronal cells is now well established and plays diverse physiologic roles. In neurons, the Na(+) -dependent, high affinity choline transporter (CHT1) is absolutely required for ACh synthesis. By contrast, some non-neuronal cells synthesize ACh in the absence of CHT1 indicating a fundamental difference in ACh synthesis compared to neurons. The aim of this study was to identify choline transporters, other than CHT1, that play a role in non-neuronal ACh synthesis. ACh synthesis was studied in lung and colon cancer cell lines focusing on the choline transporter-like proteins, a five gene family (CTL1-5). Supporting a role for CTLs in choline transport in lung cancer cells, choline transport was Na(+) -independent and CTL1-5 were expressed in all cells examined. CTL1,2,&5 were expressed at highest levels and knockdown of CTL1,2&5 decreased choline transport in H82 lung cancer cells. Knockdowns of CTL1,2,3&5 had no effect on ACh synthesis in H82 cells. By contrast, knockdown of CTL4 significantly decreased ACh secretion by both lung and colon cancer cells. Conversely, increasing expression of CTL4 increased ACh secretion. These results indicate that CTL4 mediates ACh synthesis in non-neuronal cell lines and presents a mechanism to target non-neuronal ACh synthesis without affecting neuronal ACh synthesis. This article is protected by copyright. All rights reserved.
    Journal of Neurochemistry 05/2013; DOI:10.1111/jnc.12298 · 4.24 Impact Factor
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    ABSTRACT: Functional α7 nicotinic acetylcholine receptors (AChRs) do not assemble efficiently in cells transfected with α7 subunits unless the cells are also transfected with the chaperone protein RIC-3. Despite the presence of RIC-3, large amounts of these subunits remain improperly assembled. Thus, additional chaperone proteins are probably required for efficient assembly of α7 AChRs. Cholinergic ligands can act as pharmacological chaperones to promote assembly of mature AChRs and upregulate the amount of functional AChRs. In addition, we have found that the chemical chaperones 4-phenylbutyric acid (PBA) and valproic acid (VPA) greatly increase the amount of functional α7 AChRs produced in a cell line expressing both α7 and RIC-3. Increased α7 AChR expression allows assay of drug action using a membrane potential-sensitive fluorescent indicator. Both PBA and VPA also increase α7 expression in the SH-SY5Y neuroblastoma cell line that endogenously expresses α7 AChRs. VPA increases expression of endogenous α7 AChRs in hippocampal neurons but PBA does not. RIC-3 is insufficient for optimal assembly of α7 AChRs, but provides assay conditions for detecting additional chaperones. Chemical chaperones are a useful pragmatic approach to express high levels of human α7 AChRs for drug selection and characterization and possibly to increase α7 expression in vivo.
    PLoS ONE 04/2013; 8(4):e62246. DOI:10.1371/journal.pone.0062246 · 3.53 Impact Factor
  • Jon Lindstrom, Jie Luo
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    ABSTRACT: In myasthenia gravis (MG) and experimental autoimmune MG (EAMG), many pathologically significant autoantibodies are directed to the main immunogenic region (MIR) of muscle nicotinic acetylcholine receptors (AChRs), a conformation-dependent region at the extracellular tip of α1 subunits of AChRs. Human muscle AChR α1 MIR sequences were integrated into Aplesia ACh-binding protein (AChBP). The chimera potently induced EAMG, while AChBP induced EAMG much less potently. AChBP is a water-soluble protein resembling the extracellular domain of AChRs; yet, rats immunized with chimeras developed autoantibodies to both extracellular and cytoplasmic domains of muscle AChRs. We propose that an initial autoimmune response directed at the MIR leads to an autoimmune response sustained by muscle AChRs. Autoimmune stimulation sustained by endogenous muscle AChR may be a target for specific immunosuppression. These studies show that the α1 MIR is highly myasthenogenic, and that AChR-like proteins distantly related to muscle AChR can induce EAMG and, potentially, MG.
    Annals of the New York Academy of Sciences 12/2012; 1274(1):9-13. DOI:10.1111/j.1749-6632.2012.06766.x · 4.38 Impact Factor
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    ABSTRACT: Several mutations in α4 or β2 nicotinic receptor subunits are linked to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). One such missense mutation in the gene encoding the β2 neuronal nicotinic acetylcholine receptor (nAChR) subunit (CHRNB2) is a valine-to-leucine substitution in the second transmembrane domain at position 287 (β2VL). Previous studies indicated that the β2VL mutation in mice alters circadian rhythm consistent with sleep alterations observed in ADNFLE patients (Xu et al., 2011). The current study investigates changes in nicotinic receptor function and expression that may explain the behavioral phenotype of β2VL mice. No differences in β2 mRNA expression were found between wild-type (WT) and heterozygous (HT) or homozygous mutant (MT) mice. However, antibody and ligand binding indicated that the mutation resulted in a reduction in receptor protein. Functional consequences of the β2VL mutation were assessed biochemically using crude synaptosomes. A gene-dose dependent increase in sensitivity to activation by acetylcholine and decrease in maximal nAChR-mediated [(3)H]-dopamine release and (86)Rb efflux were observed. Maximal nAChR-mediated [(3)H]-GABA release in the cortex was also decreased in the MT, but maximal [(3)H]-GABA release was retained in the hippocampus. Behaviorally both HT and MT mice demonstrated increased sensitivity to nicotine-induced hypolocomotion and hypothermia. Furthermore, WT mice display only a tonic-clonic seizure (EEG recordable) 3min after injection of a high dose of nicotine, while MT mice also display a dystonic arousal complex (non-EEG recordable) event 30s after nicotine injection. Data indicate decreases in maximal response for certain measures are larger than expected given the decrease in receptor expression.
    Pharmacology Biochemistry and Behavior 11/2012; DOI:10.1016/j.pbb.2012.10.014 · 2.82 Impact Factor
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    ABSTRACT: Nicotinic acetylcholine receptors (nAChRs) containing α6 and β2 subunits modulate dopamine release in the basal ganglia and are therapeutically relevant targets for treatment of neurological and psychiatric disorders including Parkinson's disease and nicotine dependence. However, the expression profile of β2 and β4 subunits overlap in a variety of tissues including locus ceruleus, retina, hippocampus, dorsal root ganglia, and adrenal chromaffin cells. Ligands that bind α6β2 nAChRs also potently bind the closely related α6β4 subtype. To distinguish between these two subtypes, we synthesized novel analogs of a recently described α-conotoxin, PeIA. PeIA is a peptide antagonist that blocks several nAChR subtypes, including α6/α3β2β3 and α6/α3β4 nAChRs, with low nanomolar potency. We systematically mutated PeIA and evaluated the resulting analogs for enhanced potency and/or selectivity for α6/α3β2β3 nAChRs expressed in Xenopus oocytes (α6/α3 is a subunit chimera that contains the N-terminal ligand-binding domain of the α6 subunit). On the basis of these results, second-generation analogs were then synthesized. The final analog, PeIA[S9H,V10A,E14N], potently blocked acetylcholine-gated currents mediated by α6/α3β2β3 and α6/α3β4 nAChRs with IC(50) values of 223 pM and 65 nM, respectively, yielding a >290-fold separation between the two subtypes. Kinetic studies of ligand binding to α6/α3β2β3 nAChRs yielded a k(off) of 0.096 ± 0.001 min(-1) and a k(on) of 0.23 ± 0.019 min(-1) M(-9). The synthesis of PeIA[S9H,V10A,E14N] demonstrates that ligands can be developed to discriminate between α6β2 and α6β4 nAChRs.
    Molecular pharmacology 08/2012; 82(5):972-82. DOI:10.1124/mol.112.080853 · 4.12 Impact Factor
  • Jon Lindstrom
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    ABSTRACT: Autoantibodies directed at the extracellular domain of skeletal muscle nicotinic acetylcholine receptors (AChRs), especially those directed at the main immunogenic region (MIR) at the extracellular tip of α1 subunits, mediate the immune assault that impairs neuromuscular transmission, thereby causing the weakness and fatigability characteristic of myasthenia gravis (MG).(1) Immunizing animals with AChRs purified from fish electric organs, or mammalian muscle, or with chimeras of human α1 subunits in AChR-related mollusk acetylcholine binding proteins, or with the mollusk protein itself, initiates an animal model of MG.(2).
    Neurology 06/2012; 79(4):304-5. DOI:10.1212/WNL.0b013e318260cdc7 · 8.30 Impact Factor
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    Jie Luo, Jon Lindstrom
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    ABSTRACT: In myasthenia gravis (MG) and experimental autoimmune MG (EAMG), many pathologically significant autoantibodies are directed at the main immunogenic region (MIR), a conformation-dependent region at the extracellular tip of α1 subunits of muscle nicotinic acetylcholine receptors (AChRs). Human muscle AChR α1 MIR sequences were integrated into Aplysia ACh-binding protein (AChBP). The chimera was potent in inducing both acute and chronic EAMG, though less potent than Torpedo electric organ AChR. Wild-type AChBP also induced EAMG but was less potent, and weakness developed slowly without an acute phase. AChBP is more closely related in sequence to neuronal α7 AChRs that are also homomeric; however, autoimmune responses were induced to muscle AChR, but not to neuronal AChR subtypes. The greater accessibility of muscle AChRs to antibodies, compared to neuronal AChRs, may allow muscle AChRs to induce self-sustaining autoimmune responses. The human α1 subunit MIR is a potent immunogen for producing pathologically significant autoantibodies. Additional epitopes in this region or other parts of the AChR extracellular domain contribute significantly to myasthenogenicity. We show that an AChR-related protein can induce EAMG. Thus, in principle, an AChR-related protein could induce MG. AChBP is a water-soluble protein resembling the extracellular domain of AChRs, yet rats that developed EAMG had autoantibodies to AChR cytoplasmic domains. We propose that an initial autoimmune response, directed at the MIR on the extracellular surface of muscle AChRs, leads to an autoimmune response sustained by muscle AChRs. Autoimmune stimulation sustained by endogenous muscle AChR may be a target for specific immunosuppression.
    Autoimmunity 09/2011; 45(3):245-52. DOI:10.3109/08916934.2011.622015 · 2.75 Impact Factor

Publication Stats

12k Citations
1,419.35 Total Impact Points

Institutions

  • 1991–2014
    • University of Pennsylvania
      • • Department of Medicine
      • • Department of Neuroscience
      • • The Mahoney Institute of Neurological Sciences
      Philadelphia, Pennsylvania, United States
  • 1992–2013
    • Hospital of the University of Pennsylvania
      • Department of Neuroscience
      Filadelfia, Pennsylvania, United States
    • Saint Catherine University
      Minneapolis, Minnesota, United States
  • 2011
    • University of Colorado at Boulder
      • Institute for Behavioral Genetics (IBG)
      Boulder, Colorado, United States
  • 2009
    • National University of General San Martín
      San Martín, San Juan, Argentina
  • 2008–2009
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 2005–2009
    • Louisiana State University Health Sciences Center New Orleans
      • Center for Neuroscience
      New Orleans, LA, United States
  • 1976–2007
    • Salk Institute
      La Jolla, California, United States
  • 2004
    • Wisconsin National Primate Research Center
      Madison, Wisconsin, United States
    • University of Utah
      • Department of Biology
      Salt Lake City, Utah, United States
  • 2003
    • University of the Sciences in Philadelphia
      Philadelphia, Pennsylvania, United States
    • University of Cologne
      Köln, North Rhine-Westphalia, Germany
  • 2000
    • University of Alabama at Birmingham
      • Vision Science Research Center
      Birmingham, Alabama, United States
    • The Children's Hospital of Philadelphia
      • Department of Neurology
      Philadelphia, Pennsylvania, United States
  • 1991–1992
    • University of Minnesota Duluth
      • Department of Chemistry and Biochemistry
      Duluth, MN, United States
  • 1990
    • Nara Medical University
      • Department of Pharmacology
      Nara-shi, Nara, Japan
  • 1989
    • University of California, Riverside
      • Division of Biomedical Sciences
      Riverside, CA, United States
  • 1987
    • Howard Hughes Medical Institute
      Ashburn, Virginia, United States
  • 1986
    • Stanford University
      Palo Alto, California, United States
  • 1980–1986
    • University of California, San Diego
      San Diego, California, United States
  • 1984
    • Abbott Laboratories
      North Chicago, Illinois, United States
  • 1978
    • University of California, Los Angeles
      • Department of Medicine
      Los Angeles, California, United States