scholarly journals γ-TuRCs are required for asymmetric microtubule nucleation from the somatic Golgi of Drosophila neurons

2021 ◽  
Author(s):  
Paul Thomas Conduit ◽  
Amrita Mukherjee
Keyword(s):  
Sensory Neurons ◽  
Dependent Manner ◽  
Microtubule Nucleation ◽  
Microtubule Polarity ◽  
Neuronal Soma ◽  
Ring Complexes ◽  
Microtubule Growth

Microtubules are polarised polymers nucleated by multi-protein γ-tubulin ring complexes (γ-TuRCs). Within neurons, microtubule polarity is plus-end-out in axons and mixed or minus-end-out in dendrites. Previously we showed that within the soma of Drosophila sensory neurons γ-tubulin localises asymmetrically to Golgi stacks, Golgi-derived microtubules grow asymmetrically towards the axon, and growing microtubule plus-ends are guided towards the axon and restricted from entering dendrite in a Kinesin-2-dependent manner (Mukerjee et al., 2020). Here we show that depleting γ-TuRCs perturbs the direction of microtubule growth from the Golgi stacks, consistent with a model for asymmetric microtubule nucleation involving γ-TuRCs and other nucleation-promoting factors. We also directly observe microtubule turning along microtubule bundles and show that depleting APC, proposed to link Kinesin-2 to plus ends, reduces microtubule turning and increases plus end growth into dendrites. These results support a model of asymmetric nucleation and guidance within the neuronal soma that helps establish and maintain overall microtubule polarity.

scholarly journals Alp7-Mto1 and Alp14 synergize to promote interphase microtubule regrowth from the nuclear envelope

2019 ◽  
Vol 11 (11) ◽  
pp. 944-955 ◽  
Author(s):  
Wenyue Liu ◽  
Fan Zheng ◽  
Yucai Wang ◽  
Chuanhai Fu
Keyword(s):  
Nuclear Envelope ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Microtubule Assembly ◽  
Dependent Manner ◽  
Microtubule Nucleation ◽  
Microtubule Organizing Centers ◽  
Evolutionarily Conserved ◽  
Microtubule Growth ◽  
In Cells

Abstract Microtubules grow not only from the centrosome but also from various noncentrosomal microtubule-organizing centers (MTOCs), including the nuclear envelope (NE) and pre-existing microtubules. The evolutionarily conserved proteins Mto1/CDK5RAP2 and Alp14/TOG/XMAP215 have been shown to be involved in promoting microtubule nucleation. However, it has remained elusive as to how the microtubule nucleation promoting factors are specified to various noncentrosomal MTOCs, particularly the NE, and how these proteins coordinate to organize microtubule assembly. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, efficient interphase microtubule growth from the NE requires Alp7/TACC, Alp14/TOG/XMAP215, and Mto1/CDK5RAP2. The absence of Alp7, Alp14, or Mto1 compromises microtubule regrowth on the NE in cells undergoing microtubule repolymerization. We further demonstrate that Alp7 and Mto1 interdependently localize to the NE in cells without microtubules and that Alp14 localizes to the NE in an Alp7 and Mto1-dependent manner. Tethering Mto1 to the NE in cells lacking Alp7 partially restores microtubule number and the efficiency of microtubule generation from the NE. Hence, our study delineates that Alp7, Alp14, and Mto1 work in concert to regulate interphase microtubule regrowth on the NE.

scholarly journals Golgi Outposts Locally Regulate Microtubule Orientation in Neurons but Are Not Required for the Overall Polarity of the Dendritic Cytoskeleton

Genetics ◽  
2020 ◽  
Vol 215 (2) ◽  
pp. 435-447 ◽  
Author(s):  
Sihui Z. Yang ◽  
Jill Wildonger
Keyword(s):  
Matrix Protein ◽  
Cell Function ◽  
Microtubule Nucleation ◽  
Microtubule Organization ◽  
Microtubule Orientation ◽  
Microtubule Polarity ◽  
Ring Complex ◽  
Microtubule Growth ◽  
Microtubule Networks ◽  
Golgi Matrix

Microtubule-organizing centers often play a central role in organizing the cellular microtubule networks that underlie cell function. In neurons, microtubules in axons and dendrites have distinct polarities. Dendrite-specific Golgi “outposts,” in particular multicompartment outposts, have emerged as regulators of acentrosomal microtubule growth, raising the question of whether outposts contribute to establishing or maintaining the overall polarity of the dendritic microtubule cytoskeleton. Using a combination of genetic approaches and live imaging in a Drosophila model, we found that dendritic microtubule polarity is unaffected by eliminating known regulators of Golgi-dependent microtubule organization including the cis-Golgi matrix protein GM130, the fly AKAP450 ortholog pericentrin-like protein, and centrosomin. This indicates that Golgi outposts are not essential for the formation or maintenance of a dendrite-specific cytoskeleton. However, the overexpression of GM130, which promotes the formation of ectopic multicompartment units, is sufficient to alter dendritic microtubule polarity. Axonal microtubule polarity is similarly disrupted by the presence of ectopic multicompartment Golgi outposts. Notably, multicompartment outposts alter microtubule polarity independently of microtubule nucleation mediated by the γ-tubulin ring complex. Thus, although Golgi outposts are not essential to dendritic microtubule polarity, altering their organization correlates with changes to microtubule polarity. Based on these data, we propose that the organization of Golgi outposts is carefully regulated to ensure proper dendritic microtubule polarity.

scholarly journals Microtubule organization: A complex solution

2016 ◽  
Vol 213 (6) ◽  
pp. 609-612 ◽  
Author(s):  
Paul T. Conduit
Keyword(s):  
Complex Solution ◽  
Microtubule Nucleation ◽  
Microtubule Organization ◽  
Microtubule Organizing Centers ◽  
Cell Biol ◽  
Ring Complexes ◽  
And Function

Microtubule nucleation within cells is catalyzed by γ-tubulin ring complexes localized at specific microtubule-organizing centers. In this issue, Muroyama et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201601099) reveal heterogeneity in the composition and function of these complexes, with wide implications for how cells organize their microtubule arrays.

scholarly journals Chromatids segregate without centrosomes during Caenorhabditis elegans mitosis in a Ran- and CLASP-dependent manner

2015 ◽  
Vol 26 (11) ◽  
pp. 2020-2029 ◽  
Author(s):  
Wallis Nahaboo ◽  
Melissa Zouak ◽  
Peter Askjaer ◽  
Marie Delattre
Keyword(s):  
Caenorhabditis Elegans ◽  
Dependent Manner ◽  
Microtubule Polymerization ◽  
Spindle Poles ◽  
Sister Chromatids ◽  
Chromatid Segregation ◽  
Nucleation Agents ◽  
Interesting Possibility ◽  
Spindle Midzone ◽  
Microtubule Growth

During mitosis, chromosomes are connected to a microtubule-based spindle. Current models propose that displacement of the spindle poles and/or the activity of kinetochore microtubules generate mechanical forces that segregate sister chromatids. Using laser destruction of the centrosomes during Caenorhabditis elegans mitosis, we show that neither of these mechanisms is necessary to achieve proper chromatid segregation. Our results strongly suggest that an outward force generated by the spindle midzone, independently of centrosomes, is sufficient to segregate chromosomes in mitotic cells. Using mutant and RNAi analysis, we show that the microtubule-bundling protein SPD-1/MAP-65 and BMK-1/kinesin-5 act as a brake opposing the force generated by the spindle midzone. Conversely, we identify a novel role for two microtubule-growth and nucleation agents, Ran and CLASP, in the establishment of the centrosome-independent force during anaphase. Their involvement raises the interesting possibility that microtubule polymerization of midzone microtubules is continuously required to sustain chromosome segregation during mitosis.

scholarly journals Sphingosine 1-phosphate receptor 2 antagonist JTE-013 increases the excitability of sensory neurons independently of the receptor

2012 ◽  
Vol 108 (5) ◽  
pp. 1473-1483 ◽  
Author(s):  
Chao Li ◽  
Xian Xuan Chi ◽  
Wenrui Xie ◽  
J. A. Strong ◽  
J.-M. Zhang ◽  
...  
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Neuronal Excitability ◽  
Small Diameter ◽  
G Protein Coupled Receptors ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Previously we demonstrated that sphingosine 1-phosphate receptor 1 (S1PR1) played a prominent, but not exclusive, role in enhancing the excitability of small-diameter sensory neurons, suggesting that other S1PRs can modulate neuronal excitability. To examine the potential role of S1PR2 in regulating neuronal excitability we used the established selective antagonist of S1PR2, JTE-013. Here we report that exposure to JTE-013 alone produced a significant increase in excitability in a time- and concentration-dependent manner in 70–80% of recorded neurons. Internal perfusion of sensory neurons with guanosine 5′- O-(2-thiodiphosphate) (GDP-β-S) via the recording pipette inhibited the sensitization produced by JTE-013 as well as prostaglandin E2. Pretreatment with pertussis toxin or the selective S1PR1 antagonist W146 blocked the sensitization produced by JTE-013. These results indicate that JTE-013 might act as an agonist at other G protein-coupled receptors. In neurons that were sensitized by JTE-013, single-cell RT-PCR studies demonstrated that these neurons did not express the mRNA for S1PR2. In behavioral studies, injection of JTE-013 into the rat's hindpaw produced a significant increase in the mechanical sensitivity in the ipsilateral, but not contralateral, paw. Injection of JTE-013 did not affect the withdrawal latency to thermal stimulation. Thus JTE-013 augments neuronal excitability independently of S1PR2 by unknown mechanisms that may involve activation of other G protein-coupled receptors such as S1PR1. Clearly, further studies are warranted to establish the causal nature of this increased sensitivity, and future studies of neuronal function using JTE-013 should be interpreted with caution.

scholarly journals Neuronal soma–satellite glial cell interactions in sensory ganglia and the participation of purinergic receptors

2010 ◽  
Vol 6 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Yanping Gu ◽  
Yong Chen ◽  
Xiaofei Zhang ◽  
Guang-Wen Li ◽  
Congying Wang ◽  
...  
Keyword(s):  
Purinergic Receptors ◽  
Dorsal Root Ganglion Neurons ◽  
Dependent Manner ◽  
Sensory Ganglia ◽  
Satellite Glial Cells ◽  
Neuronal Soma ◽  
Bidirectional Communication ◽  
Afferent Information ◽  
Glial Cell Interactions ◽  
Ganglion Neurons

It has been known for some time that the somata of neurons in sensory ganglia respond to electrical or chemical stimulation and release transmitters in a Ca2+-dependent manner. The function of the somatic release has not been well delineated. A unique characteristic of the ganglia is that each neuronal soma is tightly enwrapped by satellite glial cells (SGCs). The somatic membrane of a sensory neuron rarely makes synaptic contact with another neuron. As a result, the influence of somatic release on the activity of adjacent neurons is likely to be indirect and/or slow. Recent studies of neuron–SGC interactions have demonstrated that ATP released from the somata of dorsal root ganglion neurons activates SGCs. They in turn exert complex excitatory and inhibitory modulation of neuronal activity. Thus, SGCs are actively involved in the processing of afferent information. In this review, we summarize our understanding of bidirectional communication between neuronal somata and SGCs in sensory ganglia and its possible role in afferent signaling under normal and injurious conditions. The participation of purinergic receptors is emphasized because of their dominant roles in the communication.

scholarly journals Phospho-regulated auto-inhibition of Cnn controls microtubule nucleation during cell division

2020 ◽  
Author(s):  
Corinne A. Tovey ◽  
Chisato Tsuji ◽  
Alice Egerton ◽  
Fred Bernard ◽  
Antoine Guichet ◽  
...  
Keyword(s):  
Cell Division ◽  
Microtubule Nucleation ◽  
Dividing Cells ◽  
Ring Complexes

Abstractγ-tubulin-ring-complexes (γ-TuRCs) nucleate microtubules. They are recruited to centrosomes in dividing cells via binding to N-terminal CM1 domains within γ-TuRC-tethering proteins, including Drosophila Cnn. Binding promotes microtubule nucleation and is restricted to centrosomes, but the mechanism regulating binding remains unknown. Here we identify an extreme N-terminal “CM1 auto-inhibition” (CAI) domain within the centrosomal isoform of Cnn (Cnn-C) that inhibits γ-TuRC binding. Cnn-C is phosphorylated at centrosomes and we find that phospho-mimicking sites within the CAI domain helps relieve auto-inhibition. In contrast, the testes-specific mitochondrial Cnn-T isoform lacks the CAI domain and can bind strongly to cytosolic γ-TuRCs. Ubiquitously expressing a version of Cnn-C lacking the CAI domain leads to major cell division defects, which appears to be due to ectopic cytosolic microtubule nucleation. We propose that the CAI domain folds back to sterically inhibit the CM1 domain, and that this auto-inhibition is relieved by phosphorylation that occurs specifically at centrosomes.

scholarly journals Almost nontoxic tetrodotoxin analog, 5,6,11-trideoxytetrodotoxin, as an olfactory chemoattractant for the grass puffer

2021 ◽  
Author(s):  
Yasuhisa Noguchi ◽  
Takehisa Suzuki ◽  
Keigo Matsutani ◽  
Ryota Nakahigashi ◽  
Yoshiki Satake ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Olfactory Sensory Neurons ◽  
Dependent Manner ◽  
Behavioral Experiments ◽  
Extracellular Signal Regulated Kinase ◽  
Behavioral Studies ◽  
Defense Substance ◽  
Extracellular Signal ◽  
Dose Dependent ◽  
Fluorescent Dextran

Toxic puffers contain the potent neurotoxin, tetrodotoxin (TTX). Although TTX is considered to serve as a defense substance, previous behavioral studies have demonstrated that TTX (extracted from the ovary) acts as an attractive pheromone for some toxic puffers. To determine the putative pheromonal action of TTX, we examined whether grass puffers (Takifugu alboplumbeus) can detect TTX using electrophysiological, morphological, and behavioral experiments. Electroolfactogram results suggest that the olfactory epithelium of grass puffers responded in a dose-dependent manner to a type of TTX analog (5,6,11-trideoxyTTX), although it did not respond to TTX. We also examined the attractive action of 5,6,11-trideoxyTTX on grass puffers by recording their swimming behavior under dark conditions. Grass puffers preferred to stay on the side of the aquarium where 5,6,11-trideoxyTTX was administered, and their swimming speed decreased. Additionally, odorant-induced labeling of olfactory sensory neurons using a fluorescent dextran conjugate or immunohistochemistry against phosphorylated extracellular signal regulated kinase (pERK) revealed that labeled olfactory sensory neurons were localized in the region surrounding "islets" where there was abundant cilia on the olfactory lamella. 5,6,11-trideoxyTTX has been known to accumulate in grass puffers, but its toxicity is much lower (almost nontoxic) than TTX. Our results suggest that grass puffers can detect 5,6,11-trideoxyTTX using their nose and may positively use this functionally unknown TTX analog as an olfactory chemoattractant.

scholarly journals C-Jun N-terminal kinase post-translational regulation of pain-related Acid-Sensing Ion Channels 1b and 3

2021 ◽  
Author(s):  
Clement Verkest ◽  
Sylvie Diochot ◽  
Eric Lingueglia ◽  
Anne Baron
Keyword(s):  
Ion Channels ◽  
Sensory Neurons ◽  
Hek293 Cells ◽  
Peripheral Sensitization ◽  
Dependent Manner ◽  
Short Term ◽  
Nociceptive Neurons ◽  
Acid Sensing Ion Channels ◽  
Putative Phosphorylation Site ◽  
Jnk Activation

Neuronal proton-gated Acid-Sensing Ion Channels (ASICs) participate in the detection of tissue acidosis, a phenomenon often encountered in painful pathological diseases. Such conditions often involve in parallel the activation of various signaling pathways such as the Mitogen Activated Protein Kinases (MAPKs) that ultimately leads to phenotype modifications of sensory neurons. Here, we identify one member of the MAPKs, c-Jun N-terminal Kinase (JNK), as a new post-translational positive regulator of ASIC channels in rodent sensory neurons. Recombinant H+-induced ASIC currents in HEK293 cells are potently inhibited within minutes by the JNK inhibitor SP600125 in a subunit and species dependent manner, targeting both rat and human ASIC1b and ASIC3 subunits but only mouse ASIC1b subunit. The regulation by JNK of recombinant ASIC1b- and ASIC3-containing channels (homomers and heteromers) is lost upon mutation of a putative phosphorylation site within the intracellular N- and the C-terminal domain of the ASIC1b and ASIC3 subunit, respectively. Moreover, short-term JNK activation regulates the activity of native ASIC1b- and ASIC3-containing channels in rodent sensory neurons and is involved in the rapid potentiation of ASIC activity by the proinflammatory cytokine TNFα. Local JNK activation in vivo in mice induces a short-term potentiation of the acid-induced cutaneous pain in inflammatory conditions that is partially blocked by the ASIC1-specific inhibitor mambalgin-1. Collectively, our data identify pain-related channels as novel physiological JNK substrates in nociceptive neurons, and propose JNK-dependent phosphorylation as a fast post-translational mechanism of regulation of sensory neuron-expressed ASIC1b- and ASIC3-containing channels that may contribute to peripheral sensitization and pain hypersensitivity.

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