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Neuroendocrine modulation sustains the C. elegans forward motor state

View Article: PubMed Central - PubMed

ABSTRACT

Neuromodulators shape neural circuit dynamics. Combining electron microscopy, genetics, transcriptome profiling, calcium imaging, and optogenetics, we discovered a peptidergic neuron that modulates C. elegans motor circuit dynamics. The Six/SO-family homeobox transcription factor UNC-39 governs lineage-specific neurogenesis to give rise to a neuron RID. RID bears the anatomic hallmarks of a specialized endocrine neuron: it harbors near-exclusive dense core vesicles that cluster periodically along the axon, and expresses multiple neuropeptides, including the FMRF-amide-related FLP-14. RID activity increases during forward movement. Ablating RID reduces the sustainability of forward movement, a phenotype partially recapitulated by removing FLP-14. Optogenetic depolarization of RID prolongs forward movement, an effect reduced in the absence of FLP-14. Together, these results establish the role of a neuroendocrine cell RID in sustaining a specific behavioral state in C. elegans.

Doi:: http://dx.doi.org/10.7554/eLife.19887.001

No MeSH data available.


Related in: MedlinePlus

Restricting chrimson expression in RID by repurposing an embryonic E3 ligase.(A) Top panel, Representative image of an integrated transgenic array with restricted expression of Chrimson::GFP::ZF1 in the RID and CAN neurons. Most animals in the transgenic strain exhibited expression of Chrimson in RID and CAN. Bottom panel, When Chrimson::GFP in the CAN neuron was targeted for degradation using an endogenous C. elegans embryonic ubiquitin-ligase system, 10% of the population had Chrimson expression restricted to the RID neuron. Scale bar, 20 μm. The bottom panel is a representative image of transgenic animals used for optogenetic experiments. (B) Raw speed (phasic velocity) traces of individual wild-type, flp-14, unc-39, and npr-4 npr-11 before (lights off) and after RID stimulation (lights on).DOI:http://dx.doi.org/10.7554/eLife.19887.020
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fig7s1: Restricting chrimson expression in RID by repurposing an embryonic E3 ligase.(A) Top panel, Representative image of an integrated transgenic array with restricted expression of Chrimson::GFP::ZF1 in the RID and CAN neurons. Most animals in the transgenic strain exhibited expression of Chrimson in RID and CAN. Bottom panel, When Chrimson::GFP in the CAN neuron was targeted for degradation using an endogenous C. elegans embryonic ubiquitin-ligase system, 10% of the population had Chrimson expression restricted to the RID neuron. Scale bar, 20 μm. The bottom panel is a representative image of transgenic animals used for optogenetic experiments. (B) Raw speed (phasic velocity) traces of individual wild-type, flp-14, unc-39, and npr-4 npr-11 before (lights off) and after RID stimulation (lights on).DOI:http://dx.doi.org/10.7554/eLife.19887.020

Mentions: We further examined whether the role of RID in sustaining the forward motor state involves FLP-14 by examining the effect of optogenetic activation of RID. Through repurposing an endogenous C. elegans embryonic ubiquitin-ligase system (Armenti et al., 2014), we restricted the expression of Chrimson, a light-activated cation channel (Klapoetke et al., 2014) to RID (Figure 7—figure supplement 1; Appendix 1). Briefly, we tagged Chrimson with ZF1, a degron recognized by an embryonic-specific E3 ligase ZIF-1, so that selective chrimson degradation in non-RID neurons could be induced by an exogenous expression of ZIF-1 (Details described in Appendix 1). Due to potential concerns on a delay or ineffectiveness in optogenetic stimulation of DCV exocytosis (Arrigoni and Saper, 2014), we used a robust stimulation protocol (a three-minute light ON/three minute light OFF cycle; Materials and methods; Appendix 1), where we compared the run length with or without stimulation (Figure 7A), as well as the change of mean velocity before and after stimulation during a forward run (Figure 7B,C).10.7554/eLife.19887.019Figure 7.Activation of RID promotes forward movements in part through FLP-14.


Neuroendocrine modulation sustains the C. elegans forward motor state
Restricting chrimson expression in RID by repurposing an embryonic E3 ligase.(A) Top panel, Representative image of an integrated transgenic array with restricted expression of Chrimson::GFP::ZF1 in the RID and CAN neurons. Most animals in the transgenic strain exhibited expression of Chrimson in RID and CAN. Bottom panel, When Chrimson::GFP in the CAN neuron was targeted for degradation using an endogenous C. elegans embryonic ubiquitin-ligase system, 10% of the population had Chrimson expression restricted to the RID neuron. Scale bar, 20 μm. The bottom panel is a representative image of transgenic animals used for optogenetic experiments. (B) Raw speed (phasic velocity) traces of individual wild-type, flp-14, unc-39, and npr-4 npr-11 before (lights off) and after RID stimulation (lights on).DOI:http://dx.doi.org/10.7554/eLife.19887.020
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5120884&req=5

fig7s1: Restricting chrimson expression in RID by repurposing an embryonic E3 ligase.(A) Top panel, Representative image of an integrated transgenic array with restricted expression of Chrimson::GFP::ZF1 in the RID and CAN neurons. Most animals in the transgenic strain exhibited expression of Chrimson in RID and CAN. Bottom panel, When Chrimson::GFP in the CAN neuron was targeted for degradation using an endogenous C. elegans embryonic ubiquitin-ligase system, 10% of the population had Chrimson expression restricted to the RID neuron. Scale bar, 20 μm. The bottom panel is a representative image of transgenic animals used for optogenetic experiments. (B) Raw speed (phasic velocity) traces of individual wild-type, flp-14, unc-39, and npr-4 npr-11 before (lights off) and after RID stimulation (lights on).DOI:http://dx.doi.org/10.7554/eLife.19887.020
Mentions: We further examined whether the role of RID in sustaining the forward motor state involves FLP-14 by examining the effect of optogenetic activation of RID. Through repurposing an endogenous C. elegans embryonic ubiquitin-ligase system (Armenti et al., 2014), we restricted the expression of Chrimson, a light-activated cation channel (Klapoetke et al., 2014) to RID (Figure 7—figure supplement 1; Appendix 1). Briefly, we tagged Chrimson with ZF1, a degron recognized by an embryonic-specific E3 ligase ZIF-1, so that selective chrimson degradation in non-RID neurons could be induced by an exogenous expression of ZIF-1 (Details described in Appendix 1). Due to potential concerns on a delay or ineffectiveness in optogenetic stimulation of DCV exocytosis (Arrigoni and Saper, 2014), we used a robust stimulation protocol (a three-minute light ON/three minute light OFF cycle; Materials and methods; Appendix 1), where we compared the run length with or without stimulation (Figure 7A), as well as the change of mean velocity before and after stimulation during a forward run (Figure 7B,C).10.7554/eLife.19887.019Figure 7.Activation of RID promotes forward movements in part through FLP-14.

View Article: PubMed Central - PubMed

ABSTRACT

Neuromodulators shape neural circuit dynamics. Combining electron microscopy, genetics, transcriptome profiling, calcium imaging, and optogenetics, we discovered a peptidergic neuron that modulates C. elegans motor circuit dynamics. The Six/SO-family homeobox transcription factor UNC-39 governs lineage-specific neurogenesis to give rise to a neuron RID. RID bears the anatomic hallmarks of a specialized endocrine neuron: it harbors near-exclusive dense core vesicles that cluster periodically along the axon, and expresses multiple neuropeptides, including the FMRF-amide-related FLP-14. RID activity increases during forward movement. Ablating RID reduces the sustainability of forward movement, a phenotype partially recapitulated by removing FLP-14. Optogenetic depolarization of RID prolongs forward movement, an effect reduced in the absence of FLP-14. Together, these results establish the role of a neuroendocrine cell RID in sustaining a specific behavioral state in C. elegans.

Doi:: http://dx.doi.org/10.7554/eLife.19887.001

No MeSH data available.


Related in: MedlinePlus