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Pelle Modulates dFoxO-Mediated Cell Death in Drosophila.

Wu C, Chen Y, Wang F, Chen C, Zhang S, Li C, Li W, Wu S, Xue L - PLoS Genet. (2015)

Bottom Line: Interleukin-1 receptor-associated kinases (IRAKs) are crucial mediators of the IL-1R/TLR signaling pathways that regulate the immune and inflammation response in mammals.Finally, Pll physically interacts with dFoxO and phosphorylates dFoxO directly.This study not only identifies a previously unknown physiological function of pll in cell death, but also shed light on the mechanism of IRAKs in cell survival/death during tumorigenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China.

ABSTRACT
Interleukin-1 receptor-associated kinases (IRAKs) are crucial mediators of the IL-1R/TLR signaling pathways that regulate the immune and inflammation response in mammals. Recent studies also suggest a critical role of IRAKs in tumor development, though the underlying mechanism remains elusive. Pelle is the sole Drosophila IRAK homolog implicated in the conserved Toll pathway that regulates Dorsal/Ventral patterning, innate immune response, muscle development and axon guidance. Here we report a novel function of pll in modulating apoptotic cell death, which is independent of the Toll pathway. We found that loss of pll results in reduced size in wing tissue, which is caused by a reduction in cell number but not cell size. Depletion of pll up-regulates the transcription of pro-apoptotic genes, and triggers caspase activation and cell death. The transcription factor dFoxO is required for loss-of-pll induced cell death. Furthermore, loss of pll activates dFoxO, promotes its translocation from cytoplasm to nucleus, and up-regulates the transcription of its target gene Thor/4E-BP. Finally, Pll physically interacts with dFoxO and phosphorylates dFoxO directly. This study not only identifies a previously unknown physiological function of pll in cell death, but also shed light on the mechanism of IRAKs in cell survival/death during tumorigenesis.

No MeSH data available.


Related in: MedlinePlus

Loss of pll produces Toll/NF-κB pathway independent wing phenotype.(A-L) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. Compared with ptc-Gal4 control (A), expression of pll RNAi (pll-IRV2889) induced a loss-of-ACV phenotype (C) that was rescued by expression of Pll (D), while expression of Pll alone showed no obvious defects (E). Expression of RFP was included as a negative control (B). Down-regulation of Toll/NF-κB pathway by expressing RNAi of Toll (F), tube (G), dorsal (I) or Dif (J), or the negative regulator Cactus (H), had no effect on wing development. ptc>pll-IRV2889 was not rescued by co-expressing a cactus RNAi (K and L). The lower panels show high magnification view of the ACV area, boxed in panel A, in upper panels. (M) Quantification of the ACV phenotype as shown in figures A-L. One-way ANOVA with Bonferroni multiple comparison test was used to compute P-values, significance is indicated with asterisks (*** P<0.001). ns stands for not significant. Detailed genotypes: (A) ptc-Gal4/+ (B) ptc-Gal4/+; UAS-RFP/+ (C) ptc-Gal4/UAS-pll-IRV2889 (D) ptc-Gal4/UAS-pll-IRV2889; UAS-Pll; (E) ptc-Gal4/+; UAS-Pll/+ (F) ptc-Gal4/+; UAS-Toll-IR/+ (G) ptc-Gal4/+; UAS-tube-IR/+ (H) ptc-Gal4/UAS-Cactus (I) ptc-Gal4/+; UAS-dorsal-IR/+ (J) ptc-Gal4/+; UAS-Dif-IR/+ (K) ptc-Gal4/+; UAS-cactus-IR/+ (L) ptc-Gal4/UAS-pll-IRV2889; UAS-cactus-IR/+.
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pgen.1005589.g001: Loss of pll produces Toll/NF-κB pathway independent wing phenotype.(A-L) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. Compared with ptc-Gal4 control (A), expression of pll RNAi (pll-IRV2889) induced a loss-of-ACV phenotype (C) that was rescued by expression of Pll (D), while expression of Pll alone showed no obvious defects (E). Expression of RFP was included as a negative control (B). Down-regulation of Toll/NF-κB pathway by expressing RNAi of Toll (F), tube (G), dorsal (I) or Dif (J), or the negative regulator Cactus (H), had no effect on wing development. ptc>pll-IRV2889 was not rescued by co-expressing a cactus RNAi (K and L). The lower panels show high magnification view of the ACV area, boxed in panel A, in upper panels. (M) Quantification of the ACV phenotype as shown in figures A-L. One-way ANOVA with Bonferroni multiple comparison test was used to compute P-values, significance is indicated with asterisks (*** P<0.001). ns stands for not significant. Detailed genotypes: (A) ptc-Gal4/+ (B) ptc-Gal4/+; UAS-RFP/+ (C) ptc-Gal4/UAS-pll-IRV2889 (D) ptc-Gal4/UAS-pll-IRV2889; UAS-Pll; (E) ptc-Gal4/+; UAS-Pll/+ (F) ptc-Gal4/+; UAS-Toll-IR/+ (G) ptc-Gal4/+; UAS-tube-IR/+ (H) ptc-Gal4/UAS-Cactus (I) ptc-Gal4/+; UAS-dorsal-IR/+ (J) ptc-Gal4/+; UAS-Dif-IR/+ (K) ptc-Gal4/+; UAS-cactus-IR/+ (L) ptc-Gal4/UAS-pll-IRV2889; UAS-cactus-IR/+.

Mentions: As a crucial component of the Toll pathway, Pll is known to regulate the dorsal-ventral polarity in early embryos [35] and the immune response in fat body [10]. Despite its ubiquitous lower level expression throughout development [6], the post-embryonic functions of Pll remain poorly understood. To explore the physiological function of pll in late development, we employed the UAS/Gal4 binary system to knockdown pll in a specific temporal and spatial manner. We found that expression of a pll RNA interference (RNAi) driven by ptc-Gal4 (ptc>pll-IR) along the anterior/posterior (A/P) compartment boundary resulted in a consistent loss of anterior cross-vein (ACV) phenotype (Fig 1C and 1M), compared with ptc-Gal4 control (Fig 1A) or RFP expression (Fig 1B). To exclude the possibility that the phenotype is a result of RNAi’s off-target effect, we examined two additional pll RNAi that target distinct regions of the pll transcript, and observed the same loss-of-ACV phenotype (S1A, S1F and S1H Fig). In addition, this phenotype could be rescued by expression of Pll (Fig 1D and 1M; S1G and S1H Fig), which by itself has no effect on ACV development (Fig 1E and 1M). The knock-down efficiencies of three pll RNAi lines were verified by their abilities to suppress the GMR>Pll rough eye phenotype (S2A–S2E Fig) and by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay (S2L Fig). To further verify the physiological function of pll in ACV development, we examined two pll mutant alleles: pll2 and pll7. While the heterozygous mutants show no obvious ACV defect, they could significantly increase the percentage of loss-of-ACV phenotype in the ptc>pll-IRW background (S1A–S1E and S1H Fig). Together these data suggest that pll is physiologically required for ACV development in Drosophila wing.


Pelle Modulates dFoxO-Mediated Cell Death in Drosophila.

Wu C, Chen Y, Wang F, Chen C, Zhang S, Li C, Li W, Wu S, Xue L - PLoS Genet. (2015)

Loss of pll produces Toll/NF-κB pathway independent wing phenotype.(A-L) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. Compared with ptc-Gal4 control (A), expression of pll RNAi (pll-IRV2889) induced a loss-of-ACV phenotype (C) that was rescued by expression of Pll (D), while expression of Pll alone showed no obvious defects (E). Expression of RFP was included as a negative control (B). Down-regulation of Toll/NF-κB pathway by expressing RNAi of Toll (F), tube (G), dorsal (I) or Dif (J), or the negative regulator Cactus (H), had no effect on wing development. ptc>pll-IRV2889 was not rescued by co-expressing a cactus RNAi (K and L). The lower panels show high magnification view of the ACV area, boxed in panel A, in upper panels. (M) Quantification of the ACV phenotype as shown in figures A-L. One-way ANOVA with Bonferroni multiple comparison test was used to compute P-values, significance is indicated with asterisks (*** P<0.001). ns stands for not significant. Detailed genotypes: (A) ptc-Gal4/+ (B) ptc-Gal4/+; UAS-RFP/+ (C) ptc-Gal4/UAS-pll-IRV2889 (D) ptc-Gal4/UAS-pll-IRV2889; UAS-Pll; (E) ptc-Gal4/+; UAS-Pll/+ (F) ptc-Gal4/+; UAS-Toll-IR/+ (G) ptc-Gal4/+; UAS-tube-IR/+ (H) ptc-Gal4/UAS-Cactus (I) ptc-Gal4/+; UAS-dorsal-IR/+ (J) ptc-Gal4/+; UAS-Dif-IR/+ (K) ptc-Gal4/+; UAS-cactus-IR/+ (L) ptc-Gal4/UAS-pll-IRV2889; UAS-cactus-IR/+.
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pgen.1005589.g001: Loss of pll produces Toll/NF-κB pathway independent wing phenotype.(A-L) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. Compared with ptc-Gal4 control (A), expression of pll RNAi (pll-IRV2889) induced a loss-of-ACV phenotype (C) that was rescued by expression of Pll (D), while expression of Pll alone showed no obvious defects (E). Expression of RFP was included as a negative control (B). Down-regulation of Toll/NF-κB pathway by expressing RNAi of Toll (F), tube (G), dorsal (I) or Dif (J), or the negative regulator Cactus (H), had no effect on wing development. ptc>pll-IRV2889 was not rescued by co-expressing a cactus RNAi (K and L). The lower panels show high magnification view of the ACV area, boxed in panel A, in upper panels. (M) Quantification of the ACV phenotype as shown in figures A-L. One-way ANOVA with Bonferroni multiple comparison test was used to compute P-values, significance is indicated with asterisks (*** P<0.001). ns stands for not significant. Detailed genotypes: (A) ptc-Gal4/+ (B) ptc-Gal4/+; UAS-RFP/+ (C) ptc-Gal4/UAS-pll-IRV2889 (D) ptc-Gal4/UAS-pll-IRV2889; UAS-Pll; (E) ptc-Gal4/+; UAS-Pll/+ (F) ptc-Gal4/+; UAS-Toll-IR/+ (G) ptc-Gal4/+; UAS-tube-IR/+ (H) ptc-Gal4/UAS-Cactus (I) ptc-Gal4/+; UAS-dorsal-IR/+ (J) ptc-Gal4/+; UAS-Dif-IR/+ (K) ptc-Gal4/+; UAS-cactus-IR/+ (L) ptc-Gal4/UAS-pll-IRV2889; UAS-cactus-IR/+.
Mentions: As a crucial component of the Toll pathway, Pll is known to regulate the dorsal-ventral polarity in early embryos [35] and the immune response in fat body [10]. Despite its ubiquitous lower level expression throughout development [6], the post-embryonic functions of Pll remain poorly understood. To explore the physiological function of pll in late development, we employed the UAS/Gal4 binary system to knockdown pll in a specific temporal and spatial manner. We found that expression of a pll RNA interference (RNAi) driven by ptc-Gal4 (ptc>pll-IR) along the anterior/posterior (A/P) compartment boundary resulted in a consistent loss of anterior cross-vein (ACV) phenotype (Fig 1C and 1M), compared with ptc-Gal4 control (Fig 1A) or RFP expression (Fig 1B). To exclude the possibility that the phenotype is a result of RNAi’s off-target effect, we examined two additional pll RNAi that target distinct regions of the pll transcript, and observed the same loss-of-ACV phenotype (S1A, S1F and S1H Fig). In addition, this phenotype could be rescued by expression of Pll (Fig 1D and 1M; S1G and S1H Fig), which by itself has no effect on ACV development (Fig 1E and 1M). The knock-down efficiencies of three pll RNAi lines were verified by their abilities to suppress the GMR>Pll rough eye phenotype (S2A–S2E Fig) and by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay (S2L Fig). To further verify the physiological function of pll in ACV development, we examined two pll mutant alleles: pll2 and pll7. While the heterozygous mutants show no obvious ACV defect, they could significantly increase the percentage of loss-of-ACV phenotype in the ptc>pll-IRW background (S1A–S1E and S1H Fig). Together these data suggest that pll is physiologically required for ACV development in Drosophila wing.

Bottom Line: Interleukin-1 receptor-associated kinases (IRAKs) are crucial mediators of the IL-1R/TLR signaling pathways that regulate the immune and inflammation response in mammals.Finally, Pll physically interacts with dFoxO and phosphorylates dFoxO directly.This study not only identifies a previously unknown physiological function of pll in cell death, but also shed light on the mechanism of IRAKs in cell survival/death during tumorigenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Interventional Radiology, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China.

ABSTRACT
Interleukin-1 receptor-associated kinases (IRAKs) are crucial mediators of the IL-1R/TLR signaling pathways that regulate the immune and inflammation response in mammals. Recent studies also suggest a critical role of IRAKs in tumor development, though the underlying mechanism remains elusive. Pelle is the sole Drosophila IRAK homolog implicated in the conserved Toll pathway that regulates Dorsal/Ventral patterning, innate immune response, muscle development and axon guidance. Here we report a novel function of pll in modulating apoptotic cell death, which is independent of the Toll pathway. We found that loss of pll results in reduced size in wing tissue, which is caused by a reduction in cell number but not cell size. Depletion of pll up-regulates the transcription of pro-apoptotic genes, and triggers caspase activation and cell death. The transcription factor dFoxO is required for loss-of-pll induced cell death. Furthermore, loss of pll activates dFoxO, promotes its translocation from cytoplasm to nucleus, and up-regulates the transcription of its target gene Thor/4E-BP. Finally, Pll physically interacts with dFoxO and phosphorylates dFoxO directly. This study not only identifies a previously unknown physiological function of pll in cell death, but also shed light on the mechanism of IRAKs in cell survival/death during tumorigenesis.

No MeSH data available.


Related in: MedlinePlus