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The COP9 signalosome converts temporal hormone signaling to spatial restriction on neural competence.

Huang YC, Lu YN, Wu JT, Chien CT, Pi H - PLoS Genet. (2014)

Bottom Line: We found that the COP9 signalosome (CSN) suppresses the neural competence of non-innervated bristles at the PWM.Several CSN subunits physically associate with ecdysone receptors to represses br at the transcriptional level.We propose a model in which nuclear hormone receptors cooperate with the deneddylation machinery to temporally shutdown downstream target gene expression, conferring a spatial restriction on neural competence at the PWM.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Insitute of Molecular Biology, Academia Sinica, Taipei, Taiwan.

ABSTRACT
During development, neural competence is conferred and maintained by integrating spatial and temporal regulations. The Drosophila sensory bristles that detect mechanical and chemical stimulations are arranged in stereotypical positions. The anterior wing margin (AWM) is arrayed with neuron-innervated sensory bristles, while posterior wing margin (PWM) bristles are non-innervated. We found that the COP9 signalosome (CSN) suppresses the neural competence of non-innervated bristles at the PWM. In CSN mutants, PWM bristles are transformed into neuron-innervated, which is attributed to sustained expression of the neural-determining factor Senseless (Sens). The CSN suppresses Sens through repression of the ecdysone signaling target gene broad (br) that encodes the BR-Z1 transcription factor to activate sens expression. Strikingly, CSN suppression of BR-Z1 is initiated at the prepupa-to-pupa transition, leading to Sens downregulation, and termination of the neural competence of PWM bristles. The role of ecdysone signaling to repress br after the prepupa-to-pupa transition is distinct from its conventional role in activation, and requires CSN deneddylating activity and multiple cullins, the major substrates of deneddylation. Several CSN subunits physically associate with ecdysone receptors to represses br at the transcriptional level. We propose a model in which nuclear hormone receptors cooperate with the deneddylation machinery to temporally shutdown downstream target gene expression, conferring a spatial restriction on neural competence at the PWM.

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Transformation from non-innervated to innervated PWM bristles in CSN mutants.(A) AWM innervated bristles. Arrow and arrowhead indicate stout mechanosensory and chemosensory bristles, respectively. Also indicated are dome-shape sockets (asterisks) surrounding shafts. (B) PWM non-innervated bristles. (C–H) PWM bristles in CSN4 (C), CSN5 (D), en-GAL4 control (E), CSN2 RNAi (F), CSN3 RNAi (G) and CSN6 RNAi (H) driven by en-GAL4 driver. Arrowheads indicate single bristles with a thicker shaft and a socket. Arrows indicate single bristles with two shafts and one large socket. (I–L′) CSN4 clones, located at the PWM and marked by the absence of GFP, exhibited elevated Hnt expression 20–24 h APF (red in I, I′), and ectopic expression of Pros 24–28 h APF (red in J, J′), Elav 28–32 h APF (red in K, K′) and Futsch 28–32 h APF (red in L, L′). (I′, J′, K′, L′) Single-channel images. (M–P) Hnt (red) expressions 20–24 h APF at the PWM of en-GAL4 control (M), and CSN1b RNAi (N), CSN2 RNAi (O) and CSN7 RNAi (P) by en-GAL4.
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pgen-1004760-g001: Transformation from non-innervated to innervated PWM bristles in CSN mutants.(A) AWM innervated bristles. Arrow and arrowhead indicate stout mechanosensory and chemosensory bristles, respectively. Also indicated are dome-shape sockets (asterisks) surrounding shafts. (B) PWM non-innervated bristles. (C–H) PWM bristles in CSN4 (C), CSN5 (D), en-GAL4 control (E), CSN2 RNAi (F), CSN3 RNAi (G) and CSN6 RNAi (H) driven by en-GAL4 driver. Arrowheads indicate single bristles with a thicker shaft and a socket. Arrows indicate single bristles with two shafts and one large socket. (I–L′) CSN4 clones, located at the PWM and marked by the absence of GFP, exhibited elevated Hnt expression 20–24 h APF (red in I, I′), and ectopic expression of Pros 24–28 h APF (red in J, J′), Elav 28–32 h APF (red in K, K′) and Futsch 28–32 h APF (red in L, L′). (I′, J′, K′, L′) Single-channel images. (M–P) Hnt (red) expressions 20–24 h APF at the PWM of en-GAL4 control (M), and CSN1b RNAi (N), CSN2 RNAi (O) and CSN7 RNAi (P) by en-GAL4.

Mentions: Innervated sensory bristles, including stout and slender mechanosensory and spaced chemosensory bristles, are located along the AWM of wild-type wings. These sensory bristles grow dome-shaped sockets at the base (Figure 1A), and are innervated by neurons [39]. Non-innervated bristles along the PWM, however, display only thin hairs without sockets (Figure 1B). In CSN4 and CSN5 mutant clones, PWM bristles adopted morphological characteristics of innervated sensory bristles. Mutant bristles had thicker hairs surrounded by sockets (arrowheads in Figure 1C, 1D). Some bristles had double hairs emerging from one large socket (arrows), reminiscent of the double hair/double socket phenotype caused by fate transformation of SOP lineage cells [40], [41]. Similar morphological changes of PWM bristles were also observed in wings expressing interference RNA (RNAi) by en-GAL4 to knockdown CSN1b, CSN2, CSN3, CSN6 and CSN7 in the posterior compartment (Figure 1F–H, and Figure S1A, S1B), suggesting that these CSN subunits function together as a holoenzyme to suppress formation of innervated bristles at the PWM.


The COP9 signalosome converts temporal hormone signaling to spatial restriction on neural competence.

Huang YC, Lu YN, Wu JT, Chien CT, Pi H - PLoS Genet. (2014)

Transformation from non-innervated to innervated PWM bristles in CSN mutants.(A) AWM innervated bristles. Arrow and arrowhead indicate stout mechanosensory and chemosensory bristles, respectively. Also indicated are dome-shape sockets (asterisks) surrounding shafts. (B) PWM non-innervated bristles. (C–H) PWM bristles in CSN4 (C), CSN5 (D), en-GAL4 control (E), CSN2 RNAi (F), CSN3 RNAi (G) and CSN6 RNAi (H) driven by en-GAL4 driver. Arrowheads indicate single bristles with a thicker shaft and a socket. Arrows indicate single bristles with two shafts and one large socket. (I–L′) CSN4 clones, located at the PWM and marked by the absence of GFP, exhibited elevated Hnt expression 20–24 h APF (red in I, I′), and ectopic expression of Pros 24–28 h APF (red in J, J′), Elav 28–32 h APF (red in K, K′) and Futsch 28–32 h APF (red in L, L′). (I′, J′, K′, L′) Single-channel images. (M–P) Hnt (red) expressions 20–24 h APF at the PWM of en-GAL4 control (M), and CSN1b RNAi (N), CSN2 RNAi (O) and CSN7 RNAi (P) by en-GAL4.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4230841&req=5

pgen-1004760-g001: Transformation from non-innervated to innervated PWM bristles in CSN mutants.(A) AWM innervated bristles. Arrow and arrowhead indicate stout mechanosensory and chemosensory bristles, respectively. Also indicated are dome-shape sockets (asterisks) surrounding shafts. (B) PWM non-innervated bristles. (C–H) PWM bristles in CSN4 (C), CSN5 (D), en-GAL4 control (E), CSN2 RNAi (F), CSN3 RNAi (G) and CSN6 RNAi (H) driven by en-GAL4 driver. Arrowheads indicate single bristles with a thicker shaft and a socket. Arrows indicate single bristles with two shafts and one large socket. (I–L′) CSN4 clones, located at the PWM and marked by the absence of GFP, exhibited elevated Hnt expression 20–24 h APF (red in I, I′), and ectopic expression of Pros 24–28 h APF (red in J, J′), Elav 28–32 h APF (red in K, K′) and Futsch 28–32 h APF (red in L, L′). (I′, J′, K′, L′) Single-channel images. (M–P) Hnt (red) expressions 20–24 h APF at the PWM of en-GAL4 control (M), and CSN1b RNAi (N), CSN2 RNAi (O) and CSN7 RNAi (P) by en-GAL4.
Mentions: Innervated sensory bristles, including stout and slender mechanosensory and spaced chemosensory bristles, are located along the AWM of wild-type wings. These sensory bristles grow dome-shaped sockets at the base (Figure 1A), and are innervated by neurons [39]. Non-innervated bristles along the PWM, however, display only thin hairs without sockets (Figure 1B). In CSN4 and CSN5 mutant clones, PWM bristles adopted morphological characteristics of innervated sensory bristles. Mutant bristles had thicker hairs surrounded by sockets (arrowheads in Figure 1C, 1D). Some bristles had double hairs emerging from one large socket (arrows), reminiscent of the double hair/double socket phenotype caused by fate transformation of SOP lineage cells [40], [41]. Similar morphological changes of PWM bristles were also observed in wings expressing interference RNA (RNAi) by en-GAL4 to knockdown CSN1b, CSN2, CSN3, CSN6 and CSN7 in the posterior compartment (Figure 1F–H, and Figure S1A, S1B), suggesting that these CSN subunits function together as a holoenzyme to suppress formation of innervated bristles at the PWM.

Bottom Line: We found that the COP9 signalosome (CSN) suppresses the neural competence of non-innervated bristles at the PWM.Several CSN subunits physically associate with ecdysone receptors to represses br at the transcriptional level.We propose a model in which nuclear hormone receptors cooperate with the deneddylation machinery to temporally shutdown downstream target gene expression, conferring a spatial restriction on neural competence at the PWM.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Insitute of Molecular Biology, Academia Sinica, Taipei, Taiwan.

ABSTRACT
During development, neural competence is conferred and maintained by integrating spatial and temporal regulations. The Drosophila sensory bristles that detect mechanical and chemical stimulations are arranged in stereotypical positions. The anterior wing margin (AWM) is arrayed with neuron-innervated sensory bristles, while posterior wing margin (PWM) bristles are non-innervated. We found that the COP9 signalosome (CSN) suppresses the neural competence of non-innervated bristles at the PWM. In CSN mutants, PWM bristles are transformed into neuron-innervated, which is attributed to sustained expression of the neural-determining factor Senseless (Sens). The CSN suppresses Sens through repression of the ecdysone signaling target gene broad (br) that encodes the BR-Z1 transcription factor to activate sens expression. Strikingly, CSN suppression of BR-Z1 is initiated at the prepupa-to-pupa transition, leading to Sens downregulation, and termination of the neural competence of PWM bristles. The role of ecdysone signaling to repress br after the prepupa-to-pupa transition is distinct from its conventional role in activation, and requires CSN deneddylating activity and multiple cullins, the major substrates of deneddylation. Several CSN subunits physically associate with ecdysone receptors to represses br at the transcriptional level. We propose a model in which nuclear hormone receptors cooperate with the deneddylation machinery to temporally shutdown downstream target gene expression, conferring a spatial restriction on neural competence at the PWM.

Show MeSH
Related in: MedlinePlus