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Chromatin Modulatory Proteins and Olfactory Receptor Signaling in the Refinement and Maintenance of Fruitless Expression in Olfactory Receptor Neurons.

Hueston CE, Olsen D, Li Q, Okuwa S, Peng B, Wu J, Volkan PC - PLoS Biol. (2016)

Bottom Line: This regulation requires the chromatin modulatory protein Alhambra (Alh).Our results highlight two feed-forward regulatory mechanisms with both developmentally hardwired and olfactory receptor activity-dependent components that establish and maintain fru expression in ORNs.Such a dual mechanism of fru regulation in ORNs might be a trait of neurons driving plastic aspects of sex-specific behaviors.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
During development, sensory neurons must choose identities that allow them to detect specific signals and connect with appropriate target neurons. Ultimately, these sensory neurons will successfully integrate into appropriate neural circuits to generate defined motor outputs, or behavior. This integration requires a developmental coordination between the identity of the neuron and the identity of the circuit. The mechanisms that underlie this coordination are currently unknown. Here, we describe two modes of regulation that coordinate the sensory identities of Drosophila melanogaster olfactory receptor neurons (ORNs) involved in sex-specific behaviors with the sex-specific behavioral circuit identity marker fruitless (fru). The first mode involves a developmental program that coordinately restricts to appropriate ORNs the expression of fru and two olfactory receptors (Or47b and Ir84a) involved in sex-specific behaviors. This regulation requires the chromatin modulatory protein Alhambra (Alh). The second mode relies on the signaling from the olfactory receptors through CamK and histone acetyl transferase p300/CBP to maintain ORN-specific fru expression. Our results highlight two feed-forward regulatory mechanisms with both developmentally hardwired and olfactory receptor activity-dependent components that establish and maintain fru expression in ORNs. Such a dual mechanism of fru regulation in ORNs might be a trait of neurons driving plastic aspects of sex-specific behaviors.

Show MeSH
Alh represses Or47b and fru in developmentally related ORNs in the same sensillum during development.(A) Asymmetric divisions of neuronal precursors give rise to ORNs in at4 sensilla. From the mutant phenotype, we predict that Alh represses Or47b and fru expression in Or88a and Or65a ORNs. (B)AlhGAL4-driven UAS-CD8GFP expression in developing pupal antennae. (C) Double labeling of Or47b (magenta) and alh (green) around 60–70 h APF (left panel) and 80 h APF. Or47b expression is excluded from alh expressing cells (arrows) but clusters with them (circled in white). (D) High magnification of a sensillum double labeled with Or47b-CD2 (magenta) and alh (green). Arrow points to the dendrite of Or47b ORN innervating the sensory hair together with alh-positive fibers. (E) Enlarged portions of wild-type (left panels) and alh mutant (right panels) antennae at 60–70 h APF, expressing Or47b-Gal4 UASCD8GFP (top panels), or fru-gal4 UASCD8GFP (bottom panels). (F) Wild-type (top panels) and alh mutant (bottom panels) antennal lobes expressing Or47bGal4UASCD8GFP (green) and stained for ncadherin (magenta).GENOTYPES:(B) 50hrs: AlhGal4NP7010/UAS-CD8GFP; 60hrs-adult: AlhGal4NP7441/UAS-CD8GFP(C) Or47b-lexA lexOp-tomato:nls AlhGal4NP6628/UAS-CD8GFP(D) Or47B-CD2/+; AlhGal4NP6628/UAS-CD8GFP(E) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82/FRT82Gal80E2FeyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353 /FRT82Gal80E2For eyFLP/+; UAS-CD8GFP/+; FRT82 fruGAL4/FRT82Gal80E2FeyFLP/+; UAS-CD8GFP/+; FRT82 alh1353 fruGAL4/FRT82Gal80E2F(F) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 /FRT82Gal80E2For eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353/FRT82Gal80E2F
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pbio.1002443.g004: Alh represses Or47b and fru in developmentally related ORNs in the same sensillum during development.(A) Asymmetric divisions of neuronal precursors give rise to ORNs in at4 sensilla. From the mutant phenotype, we predict that Alh represses Or47b and fru expression in Or88a and Or65a ORNs. (B)AlhGAL4-driven UAS-CD8GFP expression in developing pupal antennae. (C) Double labeling of Or47b (magenta) and alh (green) around 60–70 h APF (left panel) and 80 h APF. Or47b expression is excluded from alh expressing cells (arrows) but clusters with them (circled in white). (D) High magnification of a sensillum double labeled with Or47b-CD2 (magenta) and alh (green). Arrow points to the dendrite of Or47b ORN innervating the sensory hair together with alh-positive fibers. (E) Enlarged portions of wild-type (left panels) and alh mutant (right panels) antennae at 60–70 h APF, expressing Or47b-Gal4 UASCD8GFP (top panels), or fru-gal4 UASCD8GFP (bottom panels). (F) Wild-type (top panels) and alh mutant (bottom panels) antennal lobes expressing Or47bGal4UASCD8GFP (green) and stained for ncadherin (magenta).GENOTYPES:(B) 50hrs: AlhGal4NP7010/UAS-CD8GFP; 60hrs-adult: AlhGal4NP7441/UAS-CD8GFP(C) Or47b-lexA lexOp-tomato:nls AlhGal4NP6628/UAS-CD8GFP(D) Or47B-CD2/+; AlhGal4NP6628/UAS-CD8GFP(E) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82/FRT82Gal80E2FeyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353 /FRT82Gal80E2For eyFLP/+; UAS-CD8GFP/+; FRT82 fruGAL4/FRT82Gal80E2FeyFLP/+; UAS-CD8GFP/+; FRT82 alh1353 fruGAL4/FRT82Gal80E2F(F) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 /FRT82Gal80E2For eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353/FRT82Gal80E2F

Mentions: We hypothesized that in wild-type flies Alh, either directly or indirectly, coordinates repression of fru and Or expression in fru-negative ORNs (Fig 4A). If this is the case, then alh should be expressed in fru-negative at4 ORNs and excluded from their fru-positive sibling ORNs at the onset of or expression. To test this, we used three GAL4 enhancer trap lines. Two of the lines have P-element insertions upstream of the first exon of short alh transcripts. The third line has an insertion within the first intron of the short isoform at a similar site to that of alhj8c8 (S3 Fig). All insertions are located within the fifth intron of the long isoforms (S3 Fig).


Chromatin Modulatory Proteins and Olfactory Receptor Signaling in the Refinement and Maintenance of Fruitless Expression in Olfactory Receptor Neurons.

Hueston CE, Olsen D, Li Q, Okuwa S, Peng B, Wu J, Volkan PC - PLoS Biol. (2016)

Alh represses Or47b and fru in developmentally related ORNs in the same sensillum during development.(A) Asymmetric divisions of neuronal precursors give rise to ORNs in at4 sensilla. From the mutant phenotype, we predict that Alh represses Or47b and fru expression in Or88a and Or65a ORNs. (B)AlhGAL4-driven UAS-CD8GFP expression in developing pupal antennae. (C) Double labeling of Or47b (magenta) and alh (green) around 60–70 h APF (left panel) and 80 h APF. Or47b expression is excluded from alh expressing cells (arrows) but clusters with them (circled in white). (D) High magnification of a sensillum double labeled with Or47b-CD2 (magenta) and alh (green). Arrow points to the dendrite of Or47b ORN innervating the sensory hair together with alh-positive fibers. (E) Enlarged portions of wild-type (left panels) and alh mutant (right panels) antennae at 60–70 h APF, expressing Or47b-Gal4 UASCD8GFP (top panels), or fru-gal4 UASCD8GFP (bottom panels). (F) Wild-type (top panels) and alh mutant (bottom panels) antennal lobes expressing Or47bGal4UASCD8GFP (green) and stained for ncadherin (magenta).GENOTYPES:(B) 50hrs: AlhGal4NP7010/UAS-CD8GFP; 60hrs-adult: AlhGal4NP7441/UAS-CD8GFP(C) Or47b-lexA lexOp-tomato:nls AlhGal4NP6628/UAS-CD8GFP(D) Or47B-CD2/+; AlhGal4NP6628/UAS-CD8GFP(E) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82/FRT82Gal80E2FeyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353 /FRT82Gal80E2For eyFLP/+; UAS-CD8GFP/+; FRT82 fruGAL4/FRT82Gal80E2FeyFLP/+; UAS-CD8GFP/+; FRT82 alh1353 fruGAL4/FRT82Gal80E2F(F) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 /FRT82Gal80E2For eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353/FRT82Gal80E2F
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Related In: Results  -  Collection

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pbio.1002443.g004: Alh represses Or47b and fru in developmentally related ORNs in the same sensillum during development.(A) Asymmetric divisions of neuronal precursors give rise to ORNs in at4 sensilla. From the mutant phenotype, we predict that Alh represses Or47b and fru expression in Or88a and Or65a ORNs. (B)AlhGAL4-driven UAS-CD8GFP expression in developing pupal antennae. (C) Double labeling of Or47b (magenta) and alh (green) around 60–70 h APF (left panel) and 80 h APF. Or47b expression is excluded from alh expressing cells (arrows) but clusters with them (circled in white). (D) High magnification of a sensillum double labeled with Or47b-CD2 (magenta) and alh (green). Arrow points to the dendrite of Or47b ORN innervating the sensory hair together with alh-positive fibers. (E) Enlarged portions of wild-type (left panels) and alh mutant (right panels) antennae at 60–70 h APF, expressing Or47b-Gal4 UASCD8GFP (top panels), or fru-gal4 UASCD8GFP (bottom panels). (F) Wild-type (top panels) and alh mutant (bottom panels) antennal lobes expressing Or47bGal4UASCD8GFP (green) and stained for ncadherin (magenta).GENOTYPES:(B) 50hrs: AlhGal4NP7010/UAS-CD8GFP; 60hrs-adult: AlhGal4NP7441/UAS-CD8GFP(C) Or47b-lexA lexOp-tomato:nls AlhGal4NP6628/UAS-CD8GFP(D) Or47B-CD2/+; AlhGal4NP6628/UAS-CD8GFP(E) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82/FRT82Gal80E2FeyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353 /FRT82Gal80E2For eyFLP/+; UAS-CD8GFP/+; FRT82 fruGAL4/FRT82Gal80E2FeyFLP/+; UAS-CD8GFP/+; FRT82 alh1353 fruGAL4/FRT82Gal80E2F(F) eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 /FRT82Gal80E2For eyFLP/+; Or47b-GAL4 UAS-CD8GFP/+; FRT82 alh1353/FRT82Gal80E2F
Mentions: We hypothesized that in wild-type flies Alh, either directly or indirectly, coordinates repression of fru and Or expression in fru-negative ORNs (Fig 4A). If this is the case, then alh should be expressed in fru-negative at4 ORNs and excluded from their fru-positive sibling ORNs at the onset of or expression. To test this, we used three GAL4 enhancer trap lines. Two of the lines have P-element insertions upstream of the first exon of short alh transcripts. The third line has an insertion within the first intron of the short isoform at a similar site to that of alhj8c8 (S3 Fig). All insertions are located within the fifth intron of the long isoforms (S3 Fig).

Bottom Line: This regulation requires the chromatin modulatory protein Alhambra (Alh).Our results highlight two feed-forward regulatory mechanisms with both developmentally hardwired and olfactory receptor activity-dependent components that establish and maintain fru expression in ORNs.Such a dual mechanism of fru regulation in ORNs might be a trait of neurons driving plastic aspects of sex-specific behaviors.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
During development, sensory neurons must choose identities that allow them to detect specific signals and connect with appropriate target neurons. Ultimately, these sensory neurons will successfully integrate into appropriate neural circuits to generate defined motor outputs, or behavior. This integration requires a developmental coordination between the identity of the neuron and the identity of the circuit. The mechanisms that underlie this coordination are currently unknown. Here, we describe two modes of regulation that coordinate the sensory identities of Drosophila melanogaster olfactory receptor neurons (ORNs) involved in sex-specific behaviors with the sex-specific behavioral circuit identity marker fruitless (fru). The first mode involves a developmental program that coordinately restricts to appropriate ORNs the expression of fru and two olfactory receptors (Or47b and Ir84a) involved in sex-specific behaviors. This regulation requires the chromatin modulatory protein Alhambra (Alh). The second mode relies on the signaling from the olfactory receptors through CamK and histone acetyl transferase p300/CBP to maintain ORN-specific fru expression. Our results highlight two feed-forward regulatory mechanisms with both developmentally hardwired and olfactory receptor activity-dependent components that establish and maintain fru expression in ORNs. Such a dual mechanism of fru regulation in ORNs might be a trait of neurons driving plastic aspects of sex-specific behaviors.

Show MeSH