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Jocelyn E Shaw - One of the best experts on this subject based on the ideXlab platform.
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Interactions between Innexins UNC-7 and UNC-9 mediate electrical synapse specificity in the Caenorhabditis elegans locomotory nervous system
Neural Development, 2009Co-Authors: Todd A Starich, I Martha Skerrett, Bruce J Nicholson, Jocelyn E ShawAbstract:Background Approximately 10% of Caenorhabditis elegans nervous system synapses are electrical, that is, gap junctions composed of Innexins. The locomotory nervous system consists of several pairs of interneurons and three major classes of motor neurons, all with stereotypical patterns of connectivity that include gap junctions. Mutations in the two Innexin genes unc-7 and unc-9 result in identical uncoordinated movement phenotypes, and their respective gene products were investigated for their contribution to electrical synapse connectivity. Results unc-7 encodes three Innexin isoforms. Two of these, UNC-7S and UNC-7SR, are functionally equivalent and play an essential role in coordinated locomotion. UNC-7S and UNC-7SR are widely expressed and co-localize extensively with green fluorescent protein-tagged Innexin UNC-9 in the ventral and dorsal nerve cords. A subset of UNC-7S/SR expression visualizes gap junctions formed between the AVB forward command interneurons and their B class motor neuron partners. Experiments indicate that expression of UNC-7S/SR in AVB and expression of UNC-9 in B motor neurons is necessary for these gap junctions to form. In Xenopus oocyte pairs, both UNC-7S and UNC-9 form homomeric gap junctions, and together they form heterotypic channels. Xenopus oocyte studies and co-localization studies in C. elegans suggest that UNC-7S and UNC-9 do not heteromerize in the same hemichannel, leading to the model that hemichannels in AVB:B motor neuron gap junctions are homomeric and heterotypic. Conclusion UNC-7S and UNC-9 are widely expressed and contribute to a large number of the gap junctions identified in the locomotory nervous system. Proper AVB:B gap junction formation requires UNC-7S expression in AVB interneurons and UNC-9 expression in B motor neurons. More broadly, this illustrates that Innexin identity is critical for electrical synapse specificity, but differential (compartmentalized) Innexin expression cannot account for all of the specificity seen in C. elegans , and other factors must influence the determination of synaptic partners.
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interactions between Innexins unc 7 and unc 9 mediate electrical synapse specificity in the caenorhabditis elegans locomotory nervous system
Neural Development, 2009Co-Authors: Todd A Starich, Bruce J Nicholson, Martha I Skerrett, Jocelyn E ShawAbstract:Approximately 10% of Caenorhabditis elegans nervous system synapses are electrical, that is, gap junctions composed of Innexins. The locomotory nervous system consists of several pairs of interneurons and three major classes of motor neurons, all with stereotypical patterns of connectivity that include gap junctions. Mutations in the two Innexin genes unc-7 and unc-9 result in identical uncoordinated movement phenotypes, and their respective gene products were investigated for their contribution to electrical synapse connectivity. unc-7 encodes three Innexin isoforms. Two of these, UNC-7S and UNC-7SR, are functionally equivalent and play an essential role in coordinated locomotion. UNC-7S and UNC-7SR are widely expressed and co-localize extensively with green fluorescent protein-tagged Innexin UNC-9 in the ventral and dorsal nerve cords. A subset of UNC-7S/SR expression visualizes gap junctions formed between the AVB forward command interneurons and their B class motor neuron partners. Experiments indicate that expression of UNC-7S/SR in AVB and expression of UNC-9 in B motor neurons is necessary for these gap junctions to form. In Xenopus oocyte pairs, both UNC-7S and UNC-9 form homomeric gap junctions, and together they form heterotypic channels. Xenopus oocyte studies and co-localization studies in C. elegans suggest that UNC-7S and UNC-9 do not heteromerize in the same hemichannel, leading to the model that hemichannels in AVB:B motor neuron gap junctions are homomeric and heterotypic. UNC-7S and UNC-9 are widely expressed and contribute to a large number of the gap junctions identified in the locomotory nervous system. Proper AVB:B gap junction formation requires UNC-7S expression in AVB interneurons and UNC-9 expression in B motor neurons. More broadly, this illustrates that Innexin identity is critical for electrical synapse specificity, but differential (compartmentalized) Innexin expression cannot account for all of the specificity seen in C. elegans, and other factors must influence the determination of synaptic partners.
Jennifer Zimmermann - One of the best experts on this subject based on the ideXlab platform.
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Gap junctions in the ovary of Drosophila melanogaster: localization of Innexins 1, 2, 3 and 4 and evidence for intercellular communication via Innexin-2 containing channels
BMC Developmental Biology, 2008Co-Authors: Johannes Bohrmann, Jennifer ZimmermannAbstract:Background In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the Innexin family. In order to reveal the role that Innexins play in cell-cell communication during oogenesis, we investigated the localization of Innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade. Results We found Innexin 1 predominantly localized to the baso-lateral domain of follicle cells, whereas Innexin 2 is positioned apico-laterally as well as apically between follicle cells and germ-line cells. Innexin 3 was observed laterally in follicle cells and also in nurse cells, and Innexin 4 was detected in the oolemma up to stage 8 and in nurse-cell membranes up to stage 12. In order to test whether Innexins form channels suitable for intercellular communication, we microinjected Innexin antibodies in combination with a fluorescent tracer into the oocyte of stage-10 follicles. We found that dye-coupling between oocyte and follicle cells was largely reduced by Innexin-2 antibodies directed against the intracellular C-terminus as well as against the intracellular loop. Analyzing in vitro, between stages 10 and 14, the developmental capacities of follicles following microinjections of Innexin-2 antibodies revealed defects in follicle-cell differentiation, nurse-cell regression, oocyte growth and choriogenesis. Conclusion Our results suggest that all analyzed Innexins are involved in the formation of gap junctions in the ovary. While Innexins 2 and 3 are colocalized between soma cells, Innexins 2 and 4 are colocalized between soma and germ-line cells. Innexin 2 is participating in cell-cell communication via hemichannels residing in the oolemma. It is obvious that gap-junctional communication between germ-line and soma cells is essential for several processes during oogenesis.
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gap junctions in the ovary of drosophila melanogaster localization of Innexins 1 2 3 and 4 and evidence for intercellular communication via Innexin 2 containing channels
BMC Developmental Biology, 2008Co-Authors: Johannes Bohrmann, Jennifer ZimmermannAbstract:Background In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the Innexin family. In order to reveal the role that Innexins play in cell-cell communication during oogenesis, we investigated the localization of Innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade.
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BMC Developmental Biology BioMed Central
2008Co-Authors: Johannes Bohrmann, Jennifer ZimmermannAbstract:Research article Gap junctions in the ovary of Drosophila melanogaster: localization of Innexins 1, 2, 3 and 4 and evidence for intercellular communication via Innexin-2 containing channel
Todd A Starich - One of the best experts on this subject based on the ideXlab platform.
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Interactions between Innexins UNC-7 and UNC-9 mediate electrical synapse specificity in the Caenorhabditis elegans locomotory nervous system
Neural Development, 2009Co-Authors: Todd A Starich, I Martha Skerrett, Bruce J Nicholson, Jocelyn E ShawAbstract:Background Approximately 10% of Caenorhabditis elegans nervous system synapses are electrical, that is, gap junctions composed of Innexins. The locomotory nervous system consists of several pairs of interneurons and three major classes of motor neurons, all with stereotypical patterns of connectivity that include gap junctions. Mutations in the two Innexin genes unc-7 and unc-9 result in identical uncoordinated movement phenotypes, and their respective gene products were investigated for their contribution to electrical synapse connectivity. Results unc-7 encodes three Innexin isoforms. Two of these, UNC-7S and UNC-7SR, are functionally equivalent and play an essential role in coordinated locomotion. UNC-7S and UNC-7SR are widely expressed and co-localize extensively with green fluorescent protein-tagged Innexin UNC-9 in the ventral and dorsal nerve cords. A subset of UNC-7S/SR expression visualizes gap junctions formed between the AVB forward command interneurons and their B class motor neuron partners. Experiments indicate that expression of UNC-7S/SR in AVB and expression of UNC-9 in B motor neurons is necessary for these gap junctions to form. In Xenopus oocyte pairs, both UNC-7S and UNC-9 form homomeric gap junctions, and together they form heterotypic channels. Xenopus oocyte studies and co-localization studies in C. elegans suggest that UNC-7S and UNC-9 do not heteromerize in the same hemichannel, leading to the model that hemichannels in AVB:B motor neuron gap junctions are homomeric and heterotypic. Conclusion UNC-7S and UNC-9 are widely expressed and contribute to a large number of the gap junctions identified in the locomotory nervous system. Proper AVB:B gap junction formation requires UNC-7S expression in AVB interneurons and UNC-9 expression in B motor neurons. More broadly, this illustrates that Innexin identity is critical for electrical synapse specificity, but differential (compartmentalized) Innexin expression cannot account for all of the specificity seen in C. elegans , and other factors must influence the determination of synaptic partners.
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interactions between Innexins unc 7 and unc 9 mediate electrical synapse specificity in the caenorhabditis elegans locomotory nervous system
Neural Development, 2009Co-Authors: Todd A Starich, Bruce J Nicholson, Martha I Skerrett, Jocelyn E ShawAbstract:Approximately 10% of Caenorhabditis elegans nervous system synapses are electrical, that is, gap junctions composed of Innexins. The locomotory nervous system consists of several pairs of interneurons and three major classes of motor neurons, all with stereotypical patterns of connectivity that include gap junctions. Mutations in the two Innexin genes unc-7 and unc-9 result in identical uncoordinated movement phenotypes, and their respective gene products were investigated for their contribution to electrical synapse connectivity. unc-7 encodes three Innexin isoforms. Two of these, UNC-7S and UNC-7SR, are functionally equivalent and play an essential role in coordinated locomotion. UNC-7S and UNC-7SR are widely expressed and co-localize extensively with green fluorescent protein-tagged Innexin UNC-9 in the ventral and dorsal nerve cords. A subset of UNC-7S/SR expression visualizes gap junctions formed between the AVB forward command interneurons and their B class motor neuron partners. Experiments indicate that expression of UNC-7S/SR in AVB and expression of UNC-9 in B motor neurons is necessary for these gap junctions to form. In Xenopus oocyte pairs, both UNC-7S and UNC-9 form homomeric gap junctions, and together they form heterotypic channels. Xenopus oocyte studies and co-localization studies in C. elegans suggest that UNC-7S and UNC-9 do not heteromerize in the same hemichannel, leading to the model that hemichannels in AVB:B motor neuron gap junctions are homomeric and heterotypic. UNC-7S and UNC-9 are widely expressed and contribute to a large number of the gap junctions identified in the locomotory nervous system. Proper AVB:B gap junction formation requires UNC-7S expression in AVB interneurons and UNC-9 expression in B motor neurons. More broadly, this illustrates that Innexin identity is critical for electrical synapse specificity, but differential (compartmentalized) Innexin expression cannot account for all of the specificity seen in C. elegans, and other factors must influence the determination of synaptic partners.
Zhao-wen Wang - One of the best experts on this subject based on the ideXlab platform.
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Expression patterns of Innexins functioning in C. elegans body-wall muscle.
2013Co-Authors: Ping Liu, Zeynep F. Altun, Bojun Chen, David H. Hall, Maegan J. Gross, Alan Shan, Benjamin Schuman, Zhao-wen WangAbstract:Expression patterns were assessed by analyzing GFP signal in live worms expressing Innexin promoter and GFP transcriptional fusions. Body-wall muscle expression (indicated by arrows) was observed for four of the six Innexins important to muscle electrical coupling, including unc-9, inx-10, inx-11 and inx-18. The unc-9 expression data were shown previously [33,34].
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Junctional conductance (Gj) of C. elegans body-wall muscle was significantly decreased in mutants of six Innexins.
2013Co-Authors: Ping Liu, Zeynep F. Altun, Bojun Chen, David H. Hall, Maegan J. Gross, Alan Shan, Benjamin Schuman, Zhao-wen WangAbstract:A. Diagram showing ventral body-wall muscle cells. Ventral muscles include the left and right quadrants with each quadrant consisting of two rows of muscle cells in a monolayer. The highlighted cell pairs (L1/L2 and R1/R2) represent those used for electrophysiological analyses. B. Gj was indistinguishable between wild type (WT) and mutants of 16 Innexins. C. Mutants of 6 Innexins showed significantly lower Gj when compared with WT, and the coupling defect was rescued completely by expressing a wild-type Innexin in each corresponding mutant. The asterisk (*) indicates a statistically significant difference compared with WT. The number on each bar represents the number (N) of cell pairs analyzed.
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low conductance gap junctions mediate specific electrical coupling in body wall muscle cells of caenorhabditis elegans
Journal of Biological Chemistry, 2006Co-Authors: Qiang Liu, Bojun Chen, Eric D Gaier, Jaya Joshi, Zhao-wen WangAbstract:Abstract Invertebrate Innexins and their mammalian homologues, the pannexins, are gap junction proteins. Although a large number of such proteins have been identified, few of the gap junctions that they form have been characterized to provide combined information of biophysical properties, coupling pattern, and molecular compositions. We adapted the dual whole cell voltage clamp technique to in situ analysis of electrical coupling in Caenorhabditis elegans body-wall muscle. We found that body-wall muscle cells were electrically coupled in a highly organized and specific pattern. The coupling was characterized by small (350 pS or less) junctional conductance (Gj), which showed a bell-shaped relationship with junctional potential (Vj) but was independent of membrane potential (Vm). Injection of currents comparable to the junctional current (Ij) into body-wall muscle cells caused significant depolarization, suggesting important functional relevance. The Innexin UNC-9 appeared to be a key component of the gap junctions. Both Myc- and green fluorescent protein-tagged UNC-9 was localized to muscle intercellular junctions. Gj was greatly inhibited in unc-9(fc16), a putative null mutant. Specific inhibition of UNC-9 function in muscle cells reduced locomotion velocity. Despite UNC-9 expression in both motor neurons and body-wall muscle cells, analyses of miniature and evoked postsynaptic currents in the unc-9 mutant showed normal neuromuscular transmission. These analyses provide a relatively detailed description of Innexin-based gap junctions in a native tissue and suggest that Innexin-based small conductance gap junctions can play an important role in processes such as locomotion.
Johannes Bohrmann - One of the best experts on this subject based on the ideXlab platform.
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Gap junctions in the ovary of Drosophila melanogaster: localization of Innexins 1, 2, 3 and 4 and evidence for intercellular communication via Innexin-2 containing channels
BMC Developmental Biology, 2008Co-Authors: Johannes Bohrmann, Jennifer ZimmermannAbstract:Background In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the Innexin family. In order to reveal the role that Innexins play in cell-cell communication during oogenesis, we investigated the localization of Innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade. Results We found Innexin 1 predominantly localized to the baso-lateral domain of follicle cells, whereas Innexin 2 is positioned apico-laterally as well as apically between follicle cells and germ-line cells. Innexin 3 was observed laterally in follicle cells and also in nurse cells, and Innexin 4 was detected in the oolemma up to stage 8 and in nurse-cell membranes up to stage 12. In order to test whether Innexins form channels suitable for intercellular communication, we microinjected Innexin antibodies in combination with a fluorescent tracer into the oocyte of stage-10 follicles. We found that dye-coupling between oocyte and follicle cells was largely reduced by Innexin-2 antibodies directed against the intracellular C-terminus as well as against the intracellular loop. Analyzing in vitro, between stages 10 and 14, the developmental capacities of follicles following microinjections of Innexin-2 antibodies revealed defects in follicle-cell differentiation, nurse-cell regression, oocyte growth and choriogenesis. Conclusion Our results suggest that all analyzed Innexins are involved in the formation of gap junctions in the ovary. While Innexins 2 and 3 are colocalized between soma cells, Innexins 2 and 4 are colocalized between soma and germ-line cells. Innexin 2 is participating in cell-cell communication via hemichannels residing in the oolemma. It is obvious that gap-junctional communication between germ-line and soma cells is essential for several processes during oogenesis.
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gap junctions in the ovary of drosophila melanogaster localization of Innexins 1 2 3 and 4 and evidence for intercellular communication via Innexin 2 containing channels
BMC Developmental Biology, 2008Co-Authors: Johannes Bohrmann, Jennifer ZimmermannAbstract:Background In the Drosophila ovary, germ-line and soma cells are interconnected via gap junctions. The main gap-junction proteins in invertebrates are members of the Innexin family. In order to reveal the role that Innexins play in cell-cell communication during oogenesis, we investigated the localization of Innexins 1, 2, 3 and 4 using immunohistochemistry, and analyzed follicle development following channel blockade.
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BMC Developmental Biology BioMed Central
2008Co-Authors: Johannes Bohrmann, Jennifer ZimmermannAbstract:Research article Gap junctions in the ovary of Drosophila melanogaster: localization of Innexins 1, 2, 3 and 4 and evidence for intercellular communication via Innexin-2 containing channel