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Feeding state, insulin and NPR-1 modulate chemoreceptor gene expression via integration of sensory and circuit inputs.

Gruner M, Nelson D, Winbush A, Hintz R, Ryu L, Chung SH, Kim K, Gabel CV, van der Linden AM - PLoS Genet. (2014)

Bottom Line: Using physical and genetic manipulation of ADL neurons, we show that sensory inputs from food presence and ADL neural output regulate srh-234 expression.While KIN-29 and DAF-2 act primarily via the MEF-2 (MEF2) and DAF-16 (FOXO) transcription factors to regulate srh-234 expression in ADL neurons, OCR-2 and NPR-1 likely act via a calcium-dependent but MEF-2- and DAF-16-independent pathway.Together, our results suggest that sensory- and circuit-mediated regulation of chemoreceptor genes via multiple pathways may allow animals to precisely regulate and fine-tune their chemosensory responses as a function of internal and external conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Nevada, Reno, Nevada, United States of America.

ABSTRACT
Feeding state and food availability can dramatically alter an animals' sensory response to chemicals in its environment. Dynamic changes in the expression of chemoreceptor genes may underlie some of these food and state-dependent changes in chemosensory behavior, but the mechanisms underlying these expression changes are unknown. Here, we identified a KIN-29 (SIK)-dependent chemoreceptor, srh-234, in C. elegans whose expression in the ADL sensory neuron type is regulated by integration of sensory and internal feeding state signals. We show that in addition to KIN-29, signaling is mediated by the DAF-2 insulin-like receptor, OCR-2 TRPV channel, and NPR-1 neuropeptide receptor. Cell-specific rescue experiments suggest that DAF-2 and OCR-2 act in ADL, while NPR-1 acts in the RMG interneurons. NPR-1-mediated regulation of srh-234 is dependent on gap-junctions, implying that circuit inputs regulate the expression of chemoreceptor genes in sensory neurons. Using physical and genetic manipulation of ADL neurons, we show that sensory inputs from food presence and ADL neural output regulate srh-234 expression. While KIN-29 and DAF-2 act primarily via the MEF-2 (MEF2) and DAF-16 (FOXO) transcription factors to regulate srh-234 expression in ADL neurons, OCR-2 and NPR-1 likely act via a calcium-dependent but MEF-2- and DAF-16-independent pathway. Together, our results suggest that sensory- and circuit-mediated regulation of chemoreceptor genes via multiple pathways may allow animals to precisely regulate and fine-tune their chemosensory responses as a function of internal and external conditions.

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Reducing npr-1 activity in RMG promotes srh-234 expression levels.A) Percentage of npr-1 mutant animals expressing srh-234p::gfp at wild-type levels. For strains carrying the npr-1::npr-1 genomic and ADL::npr-1 extrachromosomal arrays (see Material and Methods), data shown is the average of at least two independent transgenic lines. Animals (n>150) were examined at 150× magnification for each genotype. B) Relative expression of srh-234p::gfp in npr-1 mutants compared to wild-type. For strains carrying RMG::npr-1 extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 20–23) were examined at 400× magnification for each genotype. C) Percentage of animals of the indicated genotypes expressing srh-234p::gfp at wild-type levels. Animals (n>150) were examined at 150× magnification for each genotype. D) Relative expression of srh-234p::gfp in unc-7 npr-1 double mutants compared to wild-type. For strains carrying ADL::unc-7L cDNA, flp-21::unc-7L cDNA and pan-neural::unc-7L cDNA extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 15–22) were examined at 400× magnification for each genotype. In all experiments, * indicates values that is different from that of wild-type animals at P<0.001, and # indicates the values that are different between the genotypes compared by brackets at P<0.001 using either a χ2 test of independence or using a two-sample t-test. n.s. indicates the values between brackets that are not significantly different. Error bars denote the SEM or SEP.
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pgen-1004707-g004: Reducing npr-1 activity in RMG promotes srh-234 expression levels.A) Percentage of npr-1 mutant animals expressing srh-234p::gfp at wild-type levels. For strains carrying the npr-1::npr-1 genomic and ADL::npr-1 extrachromosomal arrays (see Material and Methods), data shown is the average of at least two independent transgenic lines. Animals (n>150) were examined at 150× magnification for each genotype. B) Relative expression of srh-234p::gfp in npr-1 mutants compared to wild-type. For strains carrying RMG::npr-1 extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 20–23) were examined at 400× magnification for each genotype. C) Percentage of animals of the indicated genotypes expressing srh-234p::gfp at wild-type levels. Animals (n>150) were examined at 150× magnification for each genotype. D) Relative expression of srh-234p::gfp in unc-7 npr-1 double mutants compared to wild-type. For strains carrying ADL::unc-7L cDNA, flp-21::unc-7L cDNA and pan-neural::unc-7L cDNA extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 15–22) were examined at 400× magnification for each genotype. In all experiments, * indicates values that is different from that of wild-type animals at P<0.001, and # indicates the values that are different between the genotypes compared by brackets at P<0.001 using either a χ2 test of independence or using a two-sample t-test. n.s. indicates the values between brackets that are not significantly different. Error bars denote the SEM or SEP.

Mentions: The neuropeptide receptor, NPR-1, in C. elegans regulates a range of food-related behaviors. For example, mutants lacking npr-1 move rapidly, avoid high oxygen concentrations and aggregate in groups in a food-dependent manner [33]–[35]. We therefore examined whether loss of NPR-1 activity alters the expression levels of srh-234 in ADL. Indeed, we found a strong reduction in srh-234 expression in ADL in lf mutants of npr-1 (alleles ad609, ky13 and ok1447), and in a reduction-of-function npr-1 allele, g320, in fed conditions, with the g320 allele having the weakest effect (Figure 4A; Table S2). lf mutations in flp-18 and flp-21 encoding NPR-1 ligands as well as double mutants inactivating both ligands did not alter srh-234 expression (Table S2), suggesting that neuropeptides other than FLP-18/FLP-21 may act on NPR-1 to regulate srh-234 expression. Expression of npr-1 under control of its own promoter fully restored the reduced srh-234 expression phenotype of npr-1(ad609) mutants back to wild-type levels (Figure 4A). However, ADL-specific expression of npr-1 using the sre-1 promoter did not restore the reduced srh-234 expression phenotype of npr-1(ad609) mutants (Figure 4A), suggesting that npr-1 activity is required in neurons other than ADL to regulate srh-234 expression.


Feeding state, insulin and NPR-1 modulate chemoreceptor gene expression via integration of sensory and circuit inputs.

Gruner M, Nelson D, Winbush A, Hintz R, Ryu L, Chung SH, Kim K, Gabel CV, van der Linden AM - PLoS Genet. (2014)

Reducing npr-1 activity in RMG promotes srh-234 expression levels.A) Percentage of npr-1 mutant animals expressing srh-234p::gfp at wild-type levels. For strains carrying the npr-1::npr-1 genomic and ADL::npr-1 extrachromosomal arrays (see Material and Methods), data shown is the average of at least two independent transgenic lines. Animals (n>150) were examined at 150× magnification for each genotype. B) Relative expression of srh-234p::gfp in npr-1 mutants compared to wild-type. For strains carrying RMG::npr-1 extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 20–23) were examined at 400× magnification for each genotype. C) Percentage of animals of the indicated genotypes expressing srh-234p::gfp at wild-type levels. Animals (n>150) were examined at 150× magnification for each genotype. D) Relative expression of srh-234p::gfp in unc-7 npr-1 double mutants compared to wild-type. For strains carrying ADL::unc-7L cDNA, flp-21::unc-7L cDNA and pan-neural::unc-7L cDNA extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 15–22) were examined at 400× magnification for each genotype. In all experiments, * indicates values that is different from that of wild-type animals at P<0.001, and # indicates the values that are different between the genotypes compared by brackets at P<0.001 using either a χ2 test of independence or using a two-sample t-test. n.s. indicates the values between brackets that are not significantly different. Error bars denote the SEM or SEP.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4214617&req=5

pgen-1004707-g004: Reducing npr-1 activity in RMG promotes srh-234 expression levels.A) Percentage of npr-1 mutant animals expressing srh-234p::gfp at wild-type levels. For strains carrying the npr-1::npr-1 genomic and ADL::npr-1 extrachromosomal arrays (see Material and Methods), data shown is the average of at least two independent transgenic lines. Animals (n>150) were examined at 150× magnification for each genotype. B) Relative expression of srh-234p::gfp in npr-1 mutants compared to wild-type. For strains carrying RMG::npr-1 extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 20–23) were examined at 400× magnification for each genotype. C) Percentage of animals of the indicated genotypes expressing srh-234p::gfp at wild-type levels. Animals (n>150) were examined at 150× magnification for each genotype. D) Relative expression of srh-234p::gfp in unc-7 npr-1 double mutants compared to wild-type. For strains carrying ADL::unc-7L cDNA, flp-21::unc-7L cDNA and pan-neural::unc-7L cDNA extrachromosomal arrays (see Material and Methods), data shown is for at least two independent transgenic lines. Animals (n = 15–22) were examined at 400× magnification for each genotype. In all experiments, * indicates values that is different from that of wild-type animals at P<0.001, and # indicates the values that are different between the genotypes compared by brackets at P<0.001 using either a χ2 test of independence or using a two-sample t-test. n.s. indicates the values between brackets that are not significantly different. Error bars denote the SEM or SEP.
Mentions: The neuropeptide receptor, NPR-1, in C. elegans regulates a range of food-related behaviors. For example, mutants lacking npr-1 move rapidly, avoid high oxygen concentrations and aggregate in groups in a food-dependent manner [33]–[35]. We therefore examined whether loss of NPR-1 activity alters the expression levels of srh-234 in ADL. Indeed, we found a strong reduction in srh-234 expression in ADL in lf mutants of npr-1 (alleles ad609, ky13 and ok1447), and in a reduction-of-function npr-1 allele, g320, in fed conditions, with the g320 allele having the weakest effect (Figure 4A; Table S2). lf mutations in flp-18 and flp-21 encoding NPR-1 ligands as well as double mutants inactivating both ligands did not alter srh-234 expression (Table S2), suggesting that neuropeptides other than FLP-18/FLP-21 may act on NPR-1 to regulate srh-234 expression. Expression of npr-1 under control of its own promoter fully restored the reduced srh-234 expression phenotype of npr-1(ad609) mutants back to wild-type levels (Figure 4A). However, ADL-specific expression of npr-1 using the sre-1 promoter did not restore the reduced srh-234 expression phenotype of npr-1(ad609) mutants (Figure 4A), suggesting that npr-1 activity is required in neurons other than ADL to regulate srh-234 expression.

Bottom Line: Using physical and genetic manipulation of ADL neurons, we show that sensory inputs from food presence and ADL neural output regulate srh-234 expression.While KIN-29 and DAF-2 act primarily via the MEF-2 (MEF2) and DAF-16 (FOXO) transcription factors to regulate srh-234 expression in ADL neurons, OCR-2 and NPR-1 likely act via a calcium-dependent but MEF-2- and DAF-16-independent pathway.Together, our results suggest that sensory- and circuit-mediated regulation of chemoreceptor genes via multiple pathways may allow animals to precisely regulate and fine-tune their chemosensory responses as a function of internal and external conditions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Nevada, Reno, Nevada, United States of America.

ABSTRACT
Feeding state and food availability can dramatically alter an animals' sensory response to chemicals in its environment. Dynamic changes in the expression of chemoreceptor genes may underlie some of these food and state-dependent changes in chemosensory behavior, but the mechanisms underlying these expression changes are unknown. Here, we identified a KIN-29 (SIK)-dependent chemoreceptor, srh-234, in C. elegans whose expression in the ADL sensory neuron type is regulated by integration of sensory and internal feeding state signals. We show that in addition to KIN-29, signaling is mediated by the DAF-2 insulin-like receptor, OCR-2 TRPV channel, and NPR-1 neuropeptide receptor. Cell-specific rescue experiments suggest that DAF-2 and OCR-2 act in ADL, while NPR-1 acts in the RMG interneurons. NPR-1-mediated regulation of srh-234 is dependent on gap-junctions, implying that circuit inputs regulate the expression of chemoreceptor genes in sensory neurons. Using physical and genetic manipulation of ADL neurons, we show that sensory inputs from food presence and ADL neural output regulate srh-234 expression. While KIN-29 and DAF-2 act primarily via the MEF-2 (MEF2) and DAF-16 (FOXO) transcription factors to regulate srh-234 expression in ADL neurons, OCR-2 and NPR-1 likely act via a calcium-dependent but MEF-2- and DAF-16-independent pathway. Together, our results suggest that sensory- and circuit-mediated regulation of chemoreceptor genes via multiple pathways may allow animals to precisely regulate and fine-tune their chemosensory responses as a function of internal and external conditions.

Show MeSH