Multiple Roles of RNA Regulatory Factors in Neuronal Development and Function in C. elegans

Author(s):  
Matthew G. Andrusiak ◽  
Yishi Jin

Recent evidence has highlighted the dynamic nature of mRNA regulation, particularly in the nervous system, from complex pre-mRNA processing to long-range transport and long-term storage of mature mRNAs. In accordance with the importance for mRNA-mediated regulation of nervous system development and maintenance, various mutations in RNA-binding proteins are associated with a range of human disorders. C. elegans express many RNA-binding factors that have human orthologs and perform similar biochemical functions. This chapter focuses on the research using C. elegans to dissect molecular mechanisms involving mRNA-mediated pathways. It highlights the key approaches and findings that integrate genetic and genomic studies in the nervous system. The analyses of genetic mutants, primarily using forward genetics, offer functional insights for genes important for neuronal development, synaptic transmission, and neuronal repair. In combination with single-neuron cell biology and cell-type genomics, the knowledge learned from this model organism has continued to lead to ground-breaking discoveries.

2021 ◽  
Vol 14 ◽  
Author(s):  
María Landínez-Macías ◽  
Olivier Urwyler

Neuronal morphogenesis, integration into circuits, and remodeling of synaptic connections occur in temporally and spatially defined steps. Accordingly, the expression of proteins and specific protein isoforms that contribute to these processes must be controlled quantitatively in time and space. A wide variety of post-transcriptional regulatory mechanisms, which act on pre-mRNA and mRNA molecules contribute to this control. They are thereby critically involved in physiological and pathophysiological nervous system development, function, and maintenance. Here, we review recent findings on how mRNA metabolism contributes to neuronal development, from neural stem cell maintenance to synapse specification, with a particular focus on axon growth, guidance, branching, and synapse formation. We emphasize the role of RNA-binding proteins, and highlight their emerging roles in the poorly understood molecular processes of RNA editing, alternative polyadenylation, and temporal control of splicing, while also discussing alternative splicing, RNA localization, and local translation. We illustrate with the example of the evolutionary conserved Musashi protein family how individual RNA-binding proteins are, on the one hand, acting in different processes of RNA metabolism, and, on the other hand, impacting multiple steps in neuronal development and circuit formation. Finally, we provide links to diseases that have been associated with the malfunction of RNA-binding proteins and disrupted post-transcriptional regulation.


2015 ◽  
Vol 225 (6) ◽  
pp. 319-330 ◽  
Author(s):  
Logan T. Schachtner ◽  
Ismail E. Sola ◽  
Daniel Forand ◽  
Simona Antonacci ◽  
Adam J. Postovit ◽  
...  

1996 ◽  
Vol 85 (4) ◽  
pp. 901-912 ◽  
Author(s):  
Michael C. Crowder ◽  
Laynie D. Shebester ◽  
Tim Schedl

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.


2019 ◽  
Vol 4 (Spring 2019) ◽  
Author(s):  
Alexa Vandenburg

The Norris lab recently identified two RNA binding proteins required for proper neuron-specific splicing. The lab conducted touch- response behavioral assays to assess the function of these proteins in touch-sensing neurons. After isolating C. elegans worms with specific phenotypes, the lab used automated computer tracking and video analysis to record the worms’ behavior. The behavior of mutant worms differed from that of wild-type worms. The Norris lab also discovered two possible RNA binding protein sites in SAD-1, a neuronal gene implicated in the neuronal development of C. elegans1. These two binding sites may control the splicing of SAD-1. The lab transferred mutated DNA into the genome of wild-type worms by injecting a mutated plasmid. The newly transformed worms fluoresced green, indicating that the two binding sites control SAD-1 splicing.


2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Vânia Gonçalves ◽  
Peter Jordan

Over the past decade, alternative splicing has been progressively recognized as a major mechanism regulating gene expression patterns in different tissues and disease states through the generation of multiple mRNAs from the same gene transcript. This process requires the joining of selected exons or usage of different pairs of splice sites and is regulated by gene-specific combinations of RNA-binding proteins. One archetypical splicing regulator is SRSF1, for which we review the molecular mechanisms and posttranscriptional modifications involved in its life cycle. These include alternative splicing of SRSF1 itself, regulatory protein phosphorylation events, and the role of nuclear versus cytoplasmic SRSF1 localization. In addition, we resume current knowledge on deregulated SRSF1 expression in tumors and describe SRSF1-regulated alternative transcripts with functional consequences for cancer cell biology at different stages of tumor development.


2020 ◽  
Vol 10 (9) ◽  
pp. 3271-3278 ◽  
Author(s):  
Albert Zhang ◽  
Kentaro Noma ◽  
Dong Yan

Abstract The regulation of gliogenesis is a fundamental process for nervous system development, as the appropriate glial number and identity is required for a functional nervous system. To investigate the molecular mechanisms involved in gliogenesis, we used C. elegans as a model and identified the function of the proneural gene lin-32/Atoh1 in gliogenesis. We found that lin-32 functions during embryonic development to negatively regulate the number of AMsh glia. The ectopic AMsh cells at least partially arise from cells originally fated to become CEPsh glia, suggesting that lin-32 is involved in the specification of specific glial subtypes. Moreover, we show that lin-32 acts in parallel with cnd-1/ NeuroD1 and ngn-1/ Neurog1 in negatively regulating an AMsh glia fate. Furthermore, expression of murine Atoh1 fully rescues lin-32 mutant phenotypes, suggesting lin-32/Atoh1 may have a conserved role in glial specification.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rachel N. Arey ◽  
Rachel Kaletsky ◽  
Coleen T. Murphy

AbstractPresynaptic protein synthesis is important in the adult central nervous system; however, the nervous system-wide set of mRNAs localized to presynaptic areas has yet to be identified in any organism. Here we differentially labeled somatic and synaptic compartments in adult C. elegans with fluorescent proteins, and isolated synaptic and somatic regions from the same population of animals. We used this technique to determine the nervous system-wide presynaptic transcriptome by deep sequencing. Analysis of the synaptic transcriptome reveals that synaptic transcripts are predicted to have specialized functions in neurons. Differential expression analysis identified 542 genes enriched in synaptic regions relative to somatic regions, with synaptic functions conserved in higher organisms. We find that mRNAs for pumilio RNA-binding proteins are abundant in synaptic regions, which we confirmed through high-sensitivity in situ hybridization. Presynaptic PUMILIOs regulate associative memory. Our approach enables the identification of new mechanisms that regulate synaptic function and behavior.


2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Margaret D. Holdeman ◽  
Farida Daouda ◽  
Heather A. Hundley, Ph.D.

Background and Hypothesis: Recently, a study conducted by the Hundley lab revealed that mutation of a specific RNA editing protein, ADR2, in the model organism C. elegans increased receptor-mediated endocytosis of yolk protein vit-2 and oocyte maturation. Of interest to us was what additional RNA binding proteins were involved in the expression of vit-2. To this end, RNA interference (RNAi) was used to knock out relevant RNA binding proteins. We hypothesized we would find candidates that both enhanced and reduced the expression of vit-2. Project Methods: Previously, adr-2(-) C. elegans strain expressing a yolk protein (vit-2) fused to GFP and a library of E. coli strains expressing RNAi directed to specific RNA binding proteins were engineered. vit-2:GFP reporter worms were grown on each RNAi bacterial strain. The COPAS Biosort, a large particle sorter which detects fluorescent intensity, was used to visualize and quantify vit-2 endocytosis. Results: Our screen yielded ten candidate proteins. These proteins had various functions and were expressed in different tissues, most commonly the nervous and reproductive systems. Remarkably, proteins gld-1 and puf-8 are negative regulators of oocyte fate determination and spermatogenesis respectively. Unlike the rest of our candidates, mutation of these two proteins did not have an observed effect on developmental progression but still caused significant increase in vit-2 expression. Conclusion and Potential Impact: This screen successfully gave direction to future studies of ADR-2 involvement in yolk protein uptake, oocyte maturation, and embryonic development. Two of our identified targets seem to be involved in reproductive processes. The remainder may be affecting vit-2 expression by altering development or receptor-mediated endocytosis. Our goal in the immediate future will be to compare loss of these target proteins in wildtype worms to loss in adr-2(-) worms. This would add to what is known about ADARs and life span and possibly demonstrate a role for ADARs in germ cell maturation.  


2019 ◽  
Author(s):  
Rachel Arey ◽  
Rachel Kaletsky ◽  
Coleen T. Murphy

AbstractPresynaptic protein synthesis is important in the adult central nervous system; however, the set of mRNAs localized to presynaptic areas has yet to be identified in any organism. We differentially labeled somatic and synaptic compartments nervous system-wide in adult C. elegans and isolated synaptic regions for deep sequencing. Analysis of the synaptic transcriptome reveals that synaptic transcripts are predicted to have specialized functions in neurons. Differential expression analysis identified 543 genes enriched in synaptic regions relative to somatic regions, with synaptic functions conserved in higher organisms. We find that mRNAs for pumilio RNA-binding proteins are abundant in synaptic regions, which we confirmed through high-sensitivity in situ hybridization. We identified a new role for the PUM2 orthologs puf-7/8 as repressors of memory formation through regulation of the mitochondrial dynamics regulator, mff-1. Identification of presynaptic mRNAs provides insight into mechanisms that regulate synaptic function and behavior.


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