Expression of Multiple UNC-13 Proteins in theCaenorhabditis elegans Nervous System

The Caenorhabditis elegans UNC-13 protein and its mammalian homologues are important for normal neurotransmitter release. We have identified a set of transcripts from the unc-13locus in C. elegans resulting from alternative splicing and apparent alternative promoters. These transcripts encode proteins that are identical in their C-terminal regions but that vary in their N-terminal regions. The most abundant protein form is localized to most or all synapses. We have analyzed the sequence alterations, immunostaining patterns, and behavioral phenotypes of 31 independentunc-13 alleles. Many of these mutations are transcript-specific; their phenotypes suggest that the different UNC-13 forms have different cellular functions. We have also isolated a deletion allele that is predicted to disrupt all UNC-13 protein products; animals homozygous for this null allele are able to complete embryogenesis and hatch, but they die as paralyzed first-stage larvae. Transgenic expression of the entire gene rescues the behavior of mutants fully; transgenic overexpression of one of the transcripts can partially compensate for the genetic loss of another. This finding suggests some degree of functional overlap of the different protein products.

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Global regulatory features of alternative splicing across tissues and within the nervous system of C. elegans

Genome Research ◽

10.1101/gr.267328.120 ◽

2020 ◽

Vol 30 (12) ◽

pp. 1766-1780

Author(s):

Bina Koterniak ◽

Pallavi P. Pilaka ◽

Xicotencatl Gracida ◽

Lisa-Marie Schneider ◽

Iva Pritišanac ◽

...

Keyword(s):

Nervous System ◽

Alternative Splicing ◽

C Elegans

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Neuronal post-developmentally acting SAX-7S/L1CAM can function as cleaved fragments to maintain neuronal architecture in C. elegans

Genetics ◽

10.1093/genetics/iyab086 ◽

2021 ◽

Author(s):

Virginie E Desse ◽

Cassandra R Blanchette ◽

Malika Nadour ◽

Paola Perrat ◽

Lise Rivollet ◽

...

Keyword(s):

Nervous System ◽

System Architecture ◽

Null Allele ◽

Neuronal Organization ◽

C Elegans ◽

The Face ◽

L1 Protein ◽

Neuronal Maintenance

Abstract Whereas remarkable advances have uncovered mechanisms that drive nervous system assembly, the processes responsible for the lifelong maintenance of nervous system architecture remain poorly understood. Subsequent to its establishment during embryogenesis, neuronal architecture is maintained throughout life in the face of the animal’s growth, maturation processes, the addition of new neurons, body movements, and aging. The C. elegans protein SAX-7, homologous to the vertebrate L1 protein family of neural adhesion molecules, is required for maintaining the organization of neuronal ganglia and fascicles after their successful initial embryonic development. To dissect the function of sax-7 in neuronal maintenance, we generated a null allele and sax-7S-isoform-specific alleles. We find that the null sax-7(qv30) is, in some contexts, more severe than previously described mutant alleles, and that the loss of sax-7S largely phenocopies the null, consistent with sax-7S being the key isoform in neuronal maintenance. Using a sfGFP::SAX-7S knock-in, we observe sax-7S to be predominantly expressed across the nervous system, from embryogenesis to adulthood. Yet, its role in maintaining neuronal organization is ensured by post-developmentally acting SAX-7S, as larval transgenic sax-7S(+) expression alone is sufficient to profoundly rescue the null mutants' neuronal maintenance defects. Moreover, the majority of the protein SAX-7 appears to be cleaved, and we show that these cleaved SAX-7S fragments together, not individually, can fully support neuronal maintenance. These findings contribute to our understanding of the role of the conserved protein SAX-7/L1CAM in long-term neuronal maintenance, and may help decipher processes that go awry in some neurodegenerative conditions.

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Tissue-specific isoforms of the single C. elegans Ryanodine receptor gene unc-68 control specific functions

PLoS Genetics ◽

10.1371/journal.pgen.1009102 ◽

2020 ◽

Vol 16 (10) ◽

pp. e1009102

Author(s):

Filipe Marques ◽

Saurabh Thapliyal ◽

Avelino Javer ◽

Priyanka Shrestha ◽

André E. X. Brown ◽

...

Keyword(s):

Alternative Splicing ◽

Receptor Gene ◽

Ryanodine Receptors ◽

Computer Assisted ◽

Alternative Promoters ◽

Tissue Specific ◽

C Elegans ◽

Specific Alternative ◽

And Function ◽

Different Tissues

Ryanodine receptors (RyR) are essential regulators of cellular calcium homeostasis and signaling. Vertebrate genomes contain multiple RyR gene isoforms, expressed in different tissues and executing different functions. In contrast, invertebrate genomes contain a single RyR-encoding gene and it has long been proposed that different transcripts generated by alternative splicing may diversify their functions. Here, we analyze the expression and function of alternative exons in the C. elegans RyR gene unc-68. We show that specific isoform subsets are created via alternative promoters and via alternative splicing in unc-68 Divergent Region 2 (DR2), which actually corresponds to a region of high sequence variability across vertebrate isoforms. The expression of specific unc-68 alternative exons is enriched in different tissues, such as in body wall muscle, neurons and pharyngeal muscle. In order to infer the function of specific alternative promoters and alternative exons of unc-68, we selectively deleted them by CRISPR/Cas9 genome editing. We evaluated pharyngeal function, as well as locomotor function in swimming and crawling with high-content computer-assisted postural and behavioral analysis. Our data provide a comprehensive map of the pleiotropic impact of isoform-specific mutations and highlight that tissue-specific unc-68 isoforms fulfill distinct functions. As a whole, our work clarifies how the C. elegans single RyR gene unc-68 can fulfill multiple tasks through tissue-specific isoforms, and provide a solid foundation to further develop C. elegans as a model to study RyR channel functions and malfunctions.

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Neuronal post-developmentally acting SAX-7S/L1CAM can function as cleaved fragments to maintain neuronal architecture in C. elegans

10.1101/2021.01.25.428117 ◽

2021 ◽

Author(s):

V.E. Desse ◽

C.R. Blanchette ◽

P. Perrat ◽

C.Y. Bénard

Keyword(s):

Nervous System ◽

System Architecture ◽

Null Allele ◽

Neuronal Organization ◽

C Elegans ◽

The Face ◽

L1 Protein ◽

Neuronal Maintenance

ABSTRACTWhereas remarkable advances have uncovered mechanisms that drive nervous system assembly, the processes responsible for the lifelong maintenance of nervous system architecture remain poorly understood. Subsequent to its establishment during embryogenesis, neuronal architecture is maintained throughout life in the face of the animal’s growth, maturation processes, the addition of new neurons, body movements, and aging. The C. elegans protein SAX-7, homologous to the vertebrate L1 protein family, is required for maintaining the organization of neuronal ganglia and fascicles after their successful initial embryonic development. To dissect the function of sax-7 in neuronal maintenance, we generated a null allele and sax-7S-isoform-specific alleles. We find that the null sax-7(qv30) is, in some contexts, more severe than previously described mutant alleles, and that the loss of sax-7S largely phenocopies the null, consistent with sax-7S being the key isoform in neuronal maintenance. Using a sfGFP::SAX-7S knock-in, we observe sax-7S to be predominantly expressed across the nervous system, from embryogenesis to adulthood. Yet, its role in maintaining neuronal organization is ensured by post-developmentally acting SAX-7S, as larval transgenic sax-7S(+) expression alone is sufficient to profoundly rescue the null mutants’ neuronal maintenance defects. Moreover, the majority of the protein SAX-7 appears to be cleaved, and we show that these cleaved SAX-7S fragments together, not individually, can fully support neuronal maintenance. These findings contribute to our understanding of the role of the conserved protein SAX-7/L1CAM in long-term neuronal maintenance, and may help decipher processes that go awry in some neurodegenerative conditions.

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A genome-wide analysis of alternative splicing in tissues and distinct neuronal subtypes in C. elegans

10.26226/morressier.5ebd45acffea6f735881af04 ◽

2020 ◽

Author(s):

Bina Koterniak

Keyword(s):

Alternative Splicing ◽

Genome Wide Analysis ◽

C Elegans ◽

Genome Wide ◽

A Genome

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Behavioral Effects of Volatile Anesthetics in Caenorhabditis elegans

Anesthesiology ◽

10.1097/00000542-199610000-00027 ◽

1996 ◽

Vol 85 (4) ◽

pp. 901-912 ◽

Cited By ~ 38

Author(s):

Michael C. Crowder ◽

Laynie D. Shebester ◽

Tim Schedl

Keyword(s):

Nervous System ◽

Caenorhabditis Elegans ◽

Time Course ◽

Model Organism ◽

Volatile Anesthetic ◽

Volatile Anesthetics ◽

Effective Concentration ◽

Forward Genetics ◽

C Elegans ◽

Median Effective Concentration

Background The nematode Caenorhabditis elegans offers many advantages as a model organism for studying volatile anesthetic actions. It has a simple, well-understood nervous system; it allows the researcher to do forward genetics; and its genome will soon be completely sequenced. C. elegans is immobilized by volatile anesthetics only at high concentrations and with an unusually slow time course. Here other behavioral dysfunctions are considered as anesthetic endpoints in C. elegans. Methods The potency of halothane for disrupting eight different behaviors was determined by logistic regression of concentration and response data. Other volatile anesthetics were also tested for some behaviors. Established protocols were used for behavioral endpoints that, except for pharyngeal pumping, were set as complete disruption of the behavior. Time courses were measured for rapid behaviors. Recovery from exposure to 1 or 4 vol% halothane was determined for mating, chemotaxis, and gross movement. All experiments were performed at 20 to 22 degrees C. Results The median effective concentration values for halothane inhibition of mating (0.30 vol%-0.21 mM), chemotaxis (0.34 vol%-0.24 mM), and coordinated movement (0.32 vol% - 0.23 mM) were similar to the human minimum alveolar concentration (MAC; 0.21 mM). In contrast, halothane produced immobility with a median effective concentration of 3.65 vol% (2.6 mM). Other behaviors had intermediate sensitivities. Halothane's effects reached steady-state in 10 min for all behaviors tested except immobility, which required 2 h. Recovery was complete after exposure to 1 vol% halothane but was significantly reduced after exposure to immobilizing concentrations. Conclusions Volatile anesthetics selectively disrupt C. elegans behavior. The potency, time course, and recovery characteristics of halothane's effects on three behaviors are similar to its anesthetic properties in vertebrates. The affected nervous system molecules may express structural motifs similar to those on vertebrate anesthetic targets.

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Complementary RNA amplification methods enhance microarray identification of transcripts expressed in the C. elegans nervous system

BMC Genomics ◽

10.1186/1471-2164-9-84 ◽

2008 ◽

Vol 9 (1) ◽

Cited By ~ 24

Author(s):

Joseph D Watson ◽

Shenglong Wang ◽

Stephen E Von Stetina ◽

W Clay Spencer ◽

Shawn Levy ◽

...

Keyword(s):

Nervous System ◽

Rna Amplification ◽

C Elegans

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Regulation of Multiple Core Spliceosomal Proteins by Alternative Splicing-Coupled Nonsense-Mediated mRNA Decay

Molecular and Cellular Biology ◽

10.1128/mcb.00361-08 ◽

2008 ◽

Vol 28 (13) ◽

pp. 4320-4330 ◽

Cited By ~ 126

Author(s):

Arneet L. Saltzman ◽

Yoon Ki Kim ◽

Qun Pan ◽

Matthew M. Fagnani ◽

Lynne E. Maquat ◽

...

Keyword(s):

Gene Expression ◽

Alternative Splicing ◽

Mrna Decay ◽

Splice Variants ◽

Cellular Functions ◽

Regulate Gene Expression ◽

Premature Termination Codons ◽

Microarray Profiling ◽

Nonsense Mediated Mrna Decay ◽

Regulate Gene

ABSTRACT Alternative splicing (AS) can regulate gene expression by introducing premature termination codons (PTCs) into spliced mRNA that subsequently elicit transcript degradation by the nonsense-mediated mRNA decay (NMD) pathway. However, the range of cellular functions controlled by this process and the factors required are poorly understood. By quantitative AS microarray profiling, we find that there are significant overlaps among the sets of PTC-introducing AS events affected by individual knockdown of the three core human NMD factors, Up-Frameshift 1 (UPF1), UPF2, and UPF3X/B. However, the levels of some PTC-containing splice variants are less or not detectably affected by the knockdown of UPF2 and/or UPF3X, compared with the knockdown of UPF1. The intron sequences flanking the affected alternative exons are often highly conserved, suggesting important regulatory roles for these AS events. The corresponding genes represent diverse cellular functions, and surprisingly, many encode core spliceosomal proteins and assembly factors. We further show that conserved, PTC-introducing AS events are enriched in genes that encode core spliceosomal proteins. Where tested, altering the expression levels of these core spliceosomal components affects the regulation of PTC-containing splice variants from the corresponding genes. Together, our results show that AS-coupled NMD can have different UPF factor requirements and is likely to regulate many general components of the spliceosome. The results further implicate general spliceosomal components in AS regulation.

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P4-259: Transgenic expression of glutamate gehydrogenase 1 in neurons: An in vivo model of hyperglutamatergic nervous system and chronic neurodegeneration

Alzheimer s & Dementia ◽

10.1016/j.jalz.2008.05.2328 ◽

2008 ◽

Vol 4 ◽

pp. T747-T747

Author(s):

Elias K. Michaelis ◽

Xiaodong Bao ◽

Ranu Pal ◽

Kevin Hascup ◽

Todd McKerchar ◽

...

Keyword(s):

Nervous System ◽

In Vivo Model ◽

Transgenic Expression

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Heparan sulfate molecules mediate synapse formation and function of male mating neural circuits in C. elegans

10.1101/277137 ◽

2018 ◽

Author(s):

María I. Lázaro-Peña ◽

Carlos A. Díaz-Balzac ◽

Hannes E. Bülow ◽

Scott W. Emmons

Keyword(s):

Nervous System ◽

Cell Adhesion ◽

Neural Cell ◽

Male Mating ◽

Synaptic Connections ◽

Adhesion Protein ◽

C Elegans ◽

Neural Cell Adhesion ◽

Heparan Sulfates ◽

And Function

AbstractThe nervous system regulates complex behaviors through a network of neurons interconnected by synapses. How specific synaptic connections are genetically determined is still unclear. Male mating is the most complex behavior in C. elegans. It is composed of sequential steps that are governed by more than 3,000 chemical connections. Here we show that heparan sulfates (HS) play a role in the formation and function of the male neural network. Cell-autonomous and non-autonomous 3-O sulfation by the HS modification enzyme HST-3.1/HS 3-O-sulfotransferase, localized to the HSPG glypicans LON-2/glypican and GPN-1/glypican, was specifically required for response to hermaphrodite contact during mating. Loss of 3-O sulfation resulted in the presynaptic accumulation of RAB-3, a molecule that localizes to synaptic vesicles, disrupting the formation of synapses in a component of the mating circuits. We also show that neural cell adhesion protein neurexin promotes and neural cell adhesion protein neuroligin inhibits formation of the same set of synapses in a parallel pathway. Thus, neural cell adhesion proteins and extracellular matrix components act together in the formation of synaptic connections.Author SummaryThe formation of the nervous system requires the function of several genetically-encoded proteins to form complex networks. Enzymatically-generated modifications of these proteins play a crucial role during this process. These authors analyzed the role of heparan sulfates in the process of synaptogenesis in the male tail of C. elegans. A modification of heparan sulfate is required for the formation of specific synapses between neurons by acting cell-autonomously and non-autonomously. Could it be that heparan sulfates and their diverse modifications are a component of the specification factor that neurons use to make such large numbers of connections unique?

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