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Xiang G, Pan L, Xing W, Zhang L, Huang L, Yu J, Zhang R, Wu J, Cheng J, Zhou Y. Identification of activity-dependent gene expression profiles reveals specific subsets of genes induced by different routes of Ca(2+) entry in cultured rat cortical neurons. J Cell Physiol 2007; 212:126-36. [PMID: 17443680 DOI: 10.1002/jcp.21008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Neuronal activity-dependent gene transcription is a key feature of long-lasting synaptic strengthening associated with learning and memory, as well as activity-dependent neuroprotection. To comprehensively determine the molecular alterations, we carried out genome-wide microarray analysis in cultured rat cortical neurons treated with specific pharmacological agents, a model with alterations in neuronal activity, which were monitored by multi-site electrophysiological recordings. Of the approximately 27,000 genes, the expression of 248 genes was strongly changed in response to enhanced activity. These genes encompass a large number of members of distinct families, including synaptic vesicle proteins, ion channels, signal transduction molecules, synaptic growth regulators, and others. Two subsets of these genes were further confirmed to be specifically induced by Ca(2+) influx through N-methyl-D-aspartate (NMDA) receptors and L-type voltage-gated Ca(2+) channels (VGCCs). In addition, those genes dynamically regulated by the enhanced activity were also elucidated, as well as those candidate genes associated with synaptic plasticity and neuroprotection. Our findings therefore would help define the molecular mechanisms that occur in response to neuronal activity and identify specific clusters of genes that contribute to activity-dependent and Ca(2+)-inducible modulation of brain development and function.
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Affiliation(s)
- Guangxin Xiang
- Medical Systems Biology Research Center, Tsinghua University, Beijing, China
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52
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Mattaliano MD, Montana ES, Parisky KM, Littleton JT, Griffith LC. The Drosophila ARC homolog regulates behavioral responses to starvation. Mol Cell Neurosci 2007; 36:211-21. [PMID: 17707655 PMCID: PMC2094000 DOI: 10.1016/j.mcn.2007.06.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 05/19/2007] [Accepted: 06/29/2007] [Indexed: 11/15/2022] Open
Abstract
The gene encoding dARC1, one of three Drosophila homologs of mammalian activity-regulated cytoskeleton-associated protein (ARC), is upregulated in both seizure and muscular hypercontraction mutants. In this study we generate a null mutant for dArc1 and show that this gene is not involved in synaptic plasticity at the larval neuromuscular junction or in formation or decay of short-term memory of courtship conditioning, but rather is a modifier of stress-induced behavior. dARC1 is expressed in a number of neurosecretory cells and mutants are starvation-resistant, exhibiting an increased time of survival in the absence of food. Starvation resistance is likely due to the fact that dArc1 mutants lack the normal hyperlocomotor response to starvation, which is almost universal in the animal kingdom. dARC1 acts in insulin-producing neurons of the pars intercerebralis to control this behavior, but does not appear to be a general regulator of insulin signaling. This suggests that there are multiple modes of communication between the pars and the ring gland that control starvation-induced behavioral responses.
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Affiliation(s)
- Mark D Mattaliano
- Department of Biology and National Center for Behavior Genomics, Brandeis University, Waltham, MA 02454-9110, USA
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53
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Gorokhova S, Bibert S, Geering K, Heintz N. A novel family of transmembrane proteins interacting with beta subunits of the Na,K-ATPase. Hum Mol Genet 2007; 16:2394-410. [PMID: 17606467 DOI: 10.1093/hmg/ddm167] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We characterized a family consisting of four mammalian proteins of unknown function (NKAIN1, 2, 3 and 4) and a single Drosophila ortholog dNKAIN. Aside from highly conserved transmembrane domains, NKAIN proteins contain no characterized functional domains. Striking amino acid conservation in the first two transmembrane domains suggests that these proteins are likely to function within the membrane bilayer. NKAIN family members are neuronally expressed in multiple regions of the mouse brain, although their expression is not ubiquitous. We demonstrate that mouse NKAIN1 interacts with the beta1 subunit of the Na,K-ATPase, whereas Drosophila ortholog dNKAIN interacts with Nrv2.2, a Drosophila homolog of the Na,K-ATPase beta subunits. We also show that NKAIN1 can form a complex with another beta subunit-binding protein, MONaKA, when binding to the beta1 subunit of the Na,K-ATPase. Our results suggest that a complex between mammalian NKAIN1 and MONaKA is required for NKAIN function, which is carried out by a single protein, dNKAIN, in Drosophila. This hypothesis is supported by the fact that dNKAIN, but not NKAIN1, induces voltage-independent amiloride-insensitive Na(+)-specific conductance that can be blocked by lanthanum. Drosophila mutants with decreased dNKAIN expression due to a P-element insertion in the dNKAIN gene exhibit temperature-sensitive paralysis, a phenotype also caused by mutations in the Na,K-ATPase alpha subunit and several ion channels. The neuronal expression of NKAIN proteins, their membrane localization and the temperature-sensitive paralysis of NKAIN Drosophila mutants strongly suggest that this novel protein family may be critical for neuronal function.
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Affiliation(s)
- Svetlana Gorokhova
- Laboratory of Molecular Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA
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54
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Rogers SM, Krapp HG, Burrows M, Matheson T. Compensatory plasticity at an identified synapse tunes a visuomotor pathway. J Neurosci 2007; 27:4621-33. [PMID: 17460075 PMCID: PMC6672987 DOI: 10.1523/jneurosci.4615-06.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We characterized homeostatic plasticity at an identified sensory-motor synapse in an insect, which maintains constant levels of motor drive as locusts transform from their solitarious phase to their gregarious swarming phase. The same mechanism produces behaviorally relevant changes in response timing that can be understood in the context of an animal's altered behavioral state. For individual animals of either phase, different looming objects elicited different spiking responses in a visual looming detector interneuron, descending contralateral movement detector (DCMD), yet its synaptic drive to a leg motoneuron, fast extensor tibiae (FETi), always had the same maximum amplitude. Gregarious locust DCMDs produced more action potentials and had higher firing frequencies, but individual postsynaptic potentials (PSPs) elicited in FETi were half the amplitude of those in solitarious locusts. A model suggested that this alone could not explain the similarity in overall amplitude, and we show that facilitation increased the maximum compound PSP amplitude in gregarious animals. There was the same linear relationship between times of peak DCMD firing before collision and the size/velocity of looming objects in both phases. The DCMD-FETi synapse transformed this relationship nonlinearly, such that peak amplitudes of compound PSPs occurred disproportionately earlier for smaller/faster objects. Furthermore, the peak PSP amplitude occurred earlier in gregarious than in solitarious locusts, indicating a differential tuning. Homeostatic modulation of the amplitude, together with a nonlinear synaptic transformation of timing, acted together to tune the DCMD-FETi system so that swarming gregarious locusts respond earlier to small moving objects, such as conspecifics, than solitarious locusts.
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Affiliation(s)
- Stephen M Rogers
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom.
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A comparative genomics approach to identifying the plasticity transcriptome. BMC Neurosci 2007; 8:20. [PMID: 17355637 PMCID: PMC1831778 DOI: 10.1186/1471-2202-8-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 03/13/2007] [Indexed: 02/04/2023] Open
Abstract
Background Neuronal activity regulates gene expression to control learning and memory, homeostasis of neuronal function, and pathological disease states such as epilepsy. A great deal of experimental evidence supports the involvement of two particular transcription factors in shaping the genomic response to neuronal activity and mediating plasticity: CREB and zif268 (egr-1, krox24, NGFI-A). The gene targets of these two transcription factors are of considerable interest, since they may help develop hypotheses about how neural activity is coupled to changes in neural function. Results We have developed a computational approach for identifying binding sites for these transcription factors within the promoter regions of annotated genes in the mouse, rat, and human genomes. By combining a robust search algorithm to identify discrete binding sites, a comparison of targets across species, and an analysis of binding site locations within promoter regions, we have defined a group of candidate genes that are strong CREB- or zif268 targets and are thus regulated by neural activity. Our analysis revealed that CREB and zif268 share a disproportionate number of targets in common and that these common targets are dominated by transcription factors. Conclusion These observations may enable a more detailed understanding of the regulatory networks that are induced by neural activity and contribute to the plasticity transcriptome. The target genes identified in this study will be a valuable resource for investigators who hope to define the functions of specific genes that underlie activity-dependent changes in neuronal properties.
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Peng IF, Wu CF. Drosophila cacophony channels: a major mediator of neuronal Ca2+ currents and a trigger for K+ channel homeostatic regulation. J Neurosci 2007; 27:1072-81. [PMID: 17267561 PMCID: PMC6673189 DOI: 10.1523/jneurosci.4746-06.2007] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 12/20/2006] [Accepted: 12/21/2006] [Indexed: 11/21/2022] Open
Abstract
The cacophony (cac) locus in Drosophila encodes a Ca2+ channel alpha subunit, but little is known about properties of cac-mediated currents and functional consequences of cac mutations in central neurons. We found that, in Drosophila cultured neurons, Ca2+ currents were mediated predominantly by the cac channels. The cac channels contribute to low- and high-threshold, fast- and slow-inactivating types of Ca2+ currents, take part in membrane depolarization, and strongly activate Ca2+-activated K+ current [I(K(Ca))]. In cac neurons, unexpectedly, voltage-activated transient K+ current I(A) is upregulated to a level that matches I(K(Ca)) reduction, implicating a homeostatic regulation that was mimicked by chronic pharmacological blockade of Ca2+ currents in wild-type neurons. Among K+ channel transcripts, Shaker mRNA levels were preferentially increased in cac flies. However, Ca2+ current expression levels remained unaltered in several K+ channel mutants, illustrating a key role of cac in developmental regulation of Drosophila neuronal excitability.
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Affiliation(s)
- I-Feng Peng
- Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
| | - Chun-Fang Wu
- Department of Biological Sciences, University of Iowa, Iowa City, Iowa 52242
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Weston AJ, Baines RA. Translational regulation of neuronal electrical properties. INVERTEBRATE NEUROSCIENCE 2007; 7:75-86. [PMID: 17221234 DOI: 10.1007/s10158-006-0037-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 12/12/2006] [Indexed: 12/01/2022]
Abstract
The nervous system has an in-built capability to adjust its responsiveness to excitation according to the history of electrical activity faced by the neurons embedded within its networks. This control over excitability represents a form of homeostasis and is exhibited at multiple stages in the flow of information from the genome to the expression and modification of protein products. Information on the nature of the homeostatic phenomenon at some of these stages is still limited and emerging. This article outlines the various stages at which such neuronal intrinsic plasticity has been observed and draws particular attention to the role of the translation repressor protein, Pumilio, as an important factor in the process. The study of this protein is providing insights into the regulation of neuronal excitability and offers an important research target with benefits to investigators in many areas of neuroscience.
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Affiliation(s)
- Andrew J Weston
- Department of Biological Sciences, University of Warwick, Coventry, UK
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58
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Peng IF, Wu CF. Differential contributions of Shaker and Shab K+ currents to neuronal firing patterns in Drosophila. J Neurophysiol 2006; 97:780-94. [PMID: 17079336 DOI: 10.1152/jn.01012.2006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Different K(+) currents participate in generating neuronal firing patterns. The Drosophila embryonic "giant" neuron culture system has facilitated current- and voltage-clamp recordings to correlate distinct excitability patterns with the underlying K(+) currents and to delineate the mutational effects of identified K(+) channels. Mutations of Sh and Shab K(+) channels removed part of inactivating I(A) and sustained I(K), respectively, and the remaining I(A) and I(K) revealed the properties of their counterparts, e.g., Shal and Shaw channels. Neuronal subsets displaying the delayed, tonic, adaptive, and damping spike patterns were characterized by different profiles of K(+) current voltage dependence and kinetics and by differential mutational effects. Shab channels regulated membrane repolarization and repetitive firing over hundreds of milliseconds, and Shab neurons showed a gradual decline in repolarization during current injection and their spike activities became limited to high-frequency, damping firing. In contrast, Sh channels acted on events within tens of milliseconds, and Sh mutations broadened spikes and reduced firing rates without eliminating any categories of firing patterns. However, removing both Sh and Shal I(A) by 4-aminopyridine converted the delayed to damping firing pattern, demonstrating their actions in regulating spike initiation. Specific blockade of Shab I(K) by quinidine mimicked the Shab phenotypes and converted tonic firing to a damping pattern. These conversions suggest a hierarchy of complexity in K(+) current interactions underlying different firing patterns. Different lineage-defined neuronal subsets, identifiable by employing the GAL4-UAS system, displayed different profiles of spike properties and K(+) current compositions, providing opportunities for mutational analysis in functionally specialized neurons.
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Affiliation(s)
- I-Feng Peng
- Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA
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Montana ES, Littleton JT. Expression profiling of a hypercontraction-induced myopathy in Drosophila suggests a compensatory cytoskeletal remodeling response. J Biol Chem 2006; 281:8100-9. [PMID: 16415344 DOI: 10.1074/jbc.m512468200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations that alter muscle contraction lead to a large array of diseases, including muscular dystrophies and cardiomyopathies. Although the molecular lesions underlying many hereditary muscle diseases are known, the downstream pathways that contribute to disease pathogenesis and compensatory muscle remodeling are poorly defined. We have recently identified and characterized mutations in Myosin Heavy Chain (Mhc) that lead to hypercontraction and subsequent degeneration of flight muscles in Drosophila. To characterize the genomic response to hypercontraction-induced myopathy, we performed expression analysis using Affymetrix high density oligonucleotide microarrays in Drosophila Mhc hypercontraction alleles. The altered transcriptional profile of dystrophic Mhc muscles suggests an actin-dependent remodeling of the muscle cytoskeleton. Specifically, a subset of the highly up-regulated transcripts is involved in actin regulation and structural support for the contractile machinery. In addition, we identified previously uncharacterized proteins with putative actin-interaction domains that are up-regulated in Mhc mutants and differentially expressed in muscles. Several of the up-regulated proteins, including the dystrophin-related protein, MSP-300, and the homolog of the neuronal activity-regulated protein, ARC, localize to specific subcellular muscle structures that may provide key structural sites for cytoskeletal remodeling in dystrophic muscles. Defining the genome-wide transcriptional response to muscle hypercontraction in Drosophila has revealed candidate loci that may participate in the pathogenesis of muscular dystrophy and in compensatory muscle repair pathways through modulation of the actin cytoskeleton.
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Affiliation(s)
- Enrico S Montana
- Department of Biology, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge 02139, USA
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Sanyal S, Ramaswami M. Activity-dependent regulation of transcription during development of synapses. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2006; 75:287-305. [PMID: 17137933 DOI: 10.1016/s0074-7742(06)75013-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Subhabrata Sanyal
- Department of Molecular and Cellular Biology, Life Sciences South, University of Arizona Tucson, Arizona 85721, USA
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Ruiz-Cañada C, Budnik V. Introduction on the use of the Drosophila embryonic/larval neuromuscular junction as a model system to study synapse development and function, and a brief summary of pathfinding and target recognition. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2006; 75:1-31. [PMID: 17137921 DOI: 10.1016/s0074-7742(06)75001-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Catalina Ruiz-Cañada
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts, Medical School, Massachusetts 01605, USA
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