Tomosyn Negatively Regulates CAPS-Dependent Peptide Release at<i>Caenorhabditis elegans</i>Synapses

Gracheva, Elena O.; Burdina, Anna O.; Touroutine, Denis; Berthelot-Grosjean, Martine; Parekh, Hetal; Richmond, Janet E.

doi:10.1523/jneurosci.2339-07.2007

Cited by 58 publications

(78 citation statements)

References 46 publications

(96 reference statements)

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“…Second, neuronal HID-1-GFP is expressed in both neuronal cell bodies and synaptic rich regions, appears in a punctate distribution in the synaptic rich ventral and dorsal nerve cords, and its localization is dependent on UNC-104. This pattern is similar to that seen for other components of DCVs such as UNC-31, FMRFamide (Phe-Met-Arg-Phe-NH2)-related peptides, EGL-3, EGL-21, and IDA-1 (Kass et al 2001;Zahn et al 2001Zahn et al , 2004Jacob and Kaplan 2003;Gracheva et al 2007;Hammarlund et al 2008). Third, neuronal HID-1-GFP accumulates in the dorsal nerve cord when secretion from nerve terminals is disrupted in unc-13 and unc-31 mutants.…”

Section: Discussionsupporting

confidence: 78%

“…Furthermore, blocking of peptidergic release using unc-31 does not restore the level of fluorescently labeled peptide at release sites in the DNC in the hid-1 unc-31 double mutant. Since unc-31 mutants accumulate DCVs at synapses (Gracheva et al 2007;Hammarlund et al 2008), the data suggest that HID-1 acts prior to DCVs docking. Furthermore, the fact that in hid-1 mutants the absence of EGL-3 does not restore axonal ANF-GFP to wild-type levels, suggests that HID-1 either acts before the peptide processing that takes place during DCVs maturation or disrupts an aspect of cargo recognition, sorting, or trafficking that reduces the flux peptidergic granules down the axon.…”

Section: Discussionmentioning

confidence: 89%

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HID-1, a New Component of the Peptidergic Signaling Pathway

et al. 2011

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hid-1 was originally identified as a Caenorhabditis elegans gene encoding a novel conserved protein that regulates the decision to enter into the enduring dauer larval stage. We isolated a novel allele of hid-1 in a forward genetic screen for mutants mislocalizing RBF-1 rabphilin, a RAB-27 effector. Here we demonstrate that HID-1 functions in the nervous system to regulate neuromuscular signaling and in the intestine to regulate the defecation motor program. We further show that a conserved N-terminal myristoylated motif of both invertebrate and vertebrate HID-1 is essential for its association with intracellular membranes in nematodes and PC12 cells. C. elegans neuronal HID-1 resides on intracellular membranes in neuronal cell somas; however, the kinesin UNC-104 also transports HID-1 to synaptic regions. HID-1 accumulates in the axons of unc-13 and unc-31 mutants, suggesting it is associated with neurosecretory vesicles. Consistent with this, genetic studies place HID-1 in a peptidergic signaling pathway. Finally, a hid-1 null mutation reduces the levels of endogenous neuropeptides and alters the secretion of fluorescent-tagged cargos derived from neuronal and intestinal dense core vesicles (DCVs). Taken together, our findings indicate that HID-1 is a novel component of a DCV-based neurosecretory pathway and that it regulates one or more aspects of the biogenesis, maturation, or trafficking of DCVs.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionmentioning

confidence: 89%

HID-1, a New Component of the Peptidergic Signaling Pathway

et al. 2011

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“…UNC-31 is the C. elegans homolog of mammalian CAPS, a component of the DCV release machinery required for hormone and neuropeptide release from neuroendocrine cells (Walent et al 1992;Rupnik et al 2000). Although CAPS and its paralog CAPS-2 may have additional functions, including synaptic vesicle priming and catecholamine uptake into DCVs, the role of the only C. elegans CAPS homolog, UNC-31, specifically involves DCV docking in the process of exocytosis from neurons (Speidel et al 2005;Gracheva et al 2007;Jockusch et al 2007;Speese et al 2007;Zhou et al 2007;Hammarlund et al 2008). Drosophila CAPS function at the neuromuscular junction is also restricted to DCV exocytosis with additional cell nonautonomous effects on synaptic vesicle release believed to result from the lack of neuromodulators released from DCVs (Renden et al 2001).…”

Section: Discussionmentioning

confidence: 99%

UNC-73/Trio RhoGEF-2 Activity Modulates Caenorhabditis elegans Motility Through Changes in Neurotransmitter Signaling Upstream of the GSA-1/Gαs Pathway

Pawson

Steven

2011

Genetics

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Rho-family GTPases play regulatory roles in many fundamental cellular processes. Caenorhabditis elegans UNC-73 RhoGEF isoforms function in axon guidance, cell migration, muscle arm extension, phagocytosis, and neurotransmission by activating either Rac or Rho GTPase subfamilies. Multiple differentially expressed UNC-73 isoforms contain a Rac-specific RhoGEF-1 domain, a Rho-specific RhoGEF-2 domain, or both domains. The UNC-73E RhoGEF-2 isoform is activated by the G-protein subunit Ga q and is required for normal rates of locomotion; however, mechanisms of UNC-73 and Rho pathway regulation of locomotion are not clear. To better define UNC-73 function in the regulation of motility we used cell-specific and inducible promoters to examine the temporal and spatial requirements of UNC-73 RhoGEF-2 isoform function in mutant rescue experiments. We found that UNC-73E acts within peptidergic neurons of mature animals to regulate locomotion rate. Although unc-73 RhoGEF-2 mutants have grossly normal synaptic morphology and weak resistance to the acetylcholinesterase inhibitor aldicarb, they are significantly hypersensitive to the acetylcholine receptor agonist levamisole, indicating alterations in acetylcholine neurotransmitter signaling. Consistent with peptidergic neuron function, unc-73 RhoGEF-2 mutants exhibit a decreased level of neuropeptide release from motor neuron dense core vesicles (DCVs). The unc-73 locomotory phenotype is similar to those of rab-2 and unc-31, genes with distinct roles in the DCV-mediated secretory pathway. We observed that constitutively active Ga s pathway mutations, which compensate for DCV-mediated signaling defects, rescue unc-73 RhoGEF-2 and rab-2 lethargic movement phenotypes. Together, these data suggest UNC-73 RhoGEF-2 isoforms are required for proper neurotransmitter signaling and may function in the DCV-mediated neuromodulatory regulation of locomotion rate.

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“…To further test whether the neuropeptide secretion in unc-43 mutants is regulated or constitutive, we used the coelomocyte uptake assay to test whether the neuropeptide secretion in unc-43 lf mutants requires UNC-31 (CAPS), a protein that docks/primes dense core vesicles for regulated exocytosis (Grishanin et al 2004;Gracheva et al 2007;Hammarlund et al 2008). For this experiment we used a new integrated The data are means and standard errors of the total background-adjusted dorsal cord fluorescence per mm of cord length from 13 animals.…”

Section: Loss Of Neuropeptide From Unc-43 Mutant Neurons Requires Regmentioning

confidence: 99%

A Novel CaM Kinase II Pathway Controls the Location of Neuropeptide Release fromCaenorhabditis elegansMotor Neurons

Hoover

Edwards

et al. 2014

Genetics

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Neurons release neuropeptides via the regulated exocytosis of dense core vesicles (DCVs) to evoke or modulate behaviors. We found that Caenorhabditis elegans motor neurons send most of their DCVs to axons, leaving very few in the cell somas. How neurons maintain this skewed distribution and the extent to which it can be altered to control DCV numbers in axons or to drive release from somas for different behavioral impacts is unknown. Using a forward genetic screen, we identified loss-of-function mutations in UNC-43 (CaM kinase II) that reduce axonal DCV levels by 90% and cell soma/dendrite DCV levels by 80%, leaving small synaptic vesicles largely unaffected. Blocking regulated secretion in unc-43 mutants restored near wild-type axonal levels of DCVs. Time-lapse video microscopy showed no role for CaM kinase II in the transport of DCVs from cell somas to axons. In vivo secretion assays revealed that much of the missing neuropeptide in unc-43 mutants is secreted via a regulated secretory pathway requiring UNC-31 (CAPS) and . DCV cargo levels in unc-43 mutants are similarly low in cell somas and the axon initial segment, indicating that the secretion occurs prior to axonal transport. Genetic pathway analysis suggests that abnormal neuropeptide function contributes to the sluggish basal locomotion rate of unc-43 mutants. These results reveal a novel pathway controlling the location of DCV exocytosis and describe a major new function for CaM kinase II. BOTH neurons and neuroendocrine cells rely on the controlled release of neuropeptides via dense core vesicle (DCV) exocytosis to evoke or modulate behaviors (Scheller and Axel 1984;Kupfermann 1991;T. Liu et al. 2007;Li and Kim 2008). The DCVs in neuroendocrine and PC12 cells are much more abundant and accessible to biochemical and physiological experiments than those in neurons. For example, in chromaffin and pancreatic b-cells (both neuroendocrine cells), DCVs can number in the tens of thousands per cell and can occupy 31 and 12% of the cell volume, respectively (Dean 1973;Plattner et al. 1997). Exploiting these advantages, studies in PC12 and neuroendocrine cells have revealed that DCVs arise from a regulated secretory pathway. The pathway begins in the trans Golgi, where various sorting mechanisms cause regulated secretory proteins, such as neuropeptides and their processing enzymes, to coalesce into vesicles that bud from the trans Golgi to form immature DCVs. Additional sorting of non-DCV cargos away from DCV cargos occurs as DCVs mature through this pathway (Arvan and Castle 1998;Tooze et al. 2001;Borgonovo et al. 2006).DCVs must selectively retain and protect several distinct cargos that have different physical states as they mature. These include the neuropeptide core, which is thought to be in an aggregated state, the neuropeptide-processing enzymes PC-2 convertase and carboxypeptidase E, possibly soluble cargos, and transmembrane cargos.While neurons and neuroendocrine cells share this core pathway for DCV production, neurons have evolved additional...

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Tomosyn Negatively Regulates CAPS-Dependent Peptide Release atCaenorhabditis elegansSynapses

Cited by 58 publications

References 46 publications

HID-1, a New Component of the Peptidergic Signaling Pathway

HID-1, a New Component of the Peptidergic Signaling Pathway

UNC-73/Trio RhoGEF-2 Activity Modulates Caenorhabditis elegans Motility Through Changes in Neurotransmitter Signaling Upstream of the GSA-1/Gαs Pathway

A Novel CaM Kinase II Pathway Controls the Location of Neuropeptide Release fromCaenorhabditis elegansMotor Neurons

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