Limits...
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

Depletion of pll elicits caspases-dependent cell death in adult wing.(A-D) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. The loss-of-ACV phenotype in ptc>pll-IRV2889 flies (A) was significantly suppressed by the expression of DIAP1 (C) or DroncDN (D), but not that of LacZ (B), which served as a negative control. The lower panels are high magnification of the boxed areas in upper panels (A-D). (E) Quantification of the ACV phenotypes as shown in figures A-D. 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/UAS-pll-IRV2889 (B) ptc-Gal4/UAS-pll-IRV2889; UAS-LacZ/+ (C) ptc-Gal4/UAS-pll-IRV2889; UAS-DIAP1/+ (D) ptc-Gal4/UAS-pll-IRV2889; UAS-DroncDN/+.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4608839&req=5

pgen.1005589.g006: Depletion of pll elicits caspases-dependent cell death in adult wing.(A-D) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. The loss-of-ACV phenotype in ptc>pll-IRV2889 flies (A) was significantly suppressed by the expression of DIAP1 (C) or DroncDN (D), but not that of LacZ (B), which served as a negative control. The lower panels are high magnification of the boxed areas in upper panels (A-D). (E) Quantification of the ACV phenotypes as shown in figures A-D. 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/UAS-pll-IRV2889 (B) ptc-Gal4/UAS-pll-IRV2889; UAS-LacZ/+ (C) ptc-Gal4/UAS-pll-IRV2889; UAS-DIAP1/+ (D) ptc-Gal4/UAS-pll-IRV2889; UAS-DroncDN/+.

Mentions: Apoptosis in Drosophila is triggered by transcriptional up-regulation of three pro-apoptotic genes rpr, hid and grim, and is mediated by the cleavage and activation of caspases [40]. Consistent with its role in cell death, loss of pll in the wing pouch results in up-regulated transcription of hid and rpr as revealed by X-gal staining of a hid-LacZ and an rpr-LacZ reporters (Fig 4I, 4J, 4M and 4N; S4C–S4F Fig), which is suppressed by expressing Pll, but not GFP (Fig 4K, 4L, 4O and 4P). Furthermore, we found that a ubiquitous knock-down of pll (act>pll-IR) was able to activate the transcription of endogenous hid, rpr and grim, as compared to the act-Gal4 control, via executing a real-time qRT-PCR assay (S4M Fig). In addition, depletion of pll leads to enhanced antibody staining for the activated form of Caspase-3 (CC-3, Fig 5G and 5H), a read-out of the initiator caspase Dronc activity [43]. Moreover, we found that the loss-of-ACV phenotype induced by ptc>pll-IR was suppressed partially by the deficiency Df(3L)H99 that deletes rpr, hid and grim (S5A–S5C Fig), and significantly by expressing the inhibitor of apoptosis protein DIAP1 or a dominant-negative form of Dronc (DroncDN), but not LacZ (Fig 6). Accordingly, the phenotype of reduced distal-most area in Omb>pll-IR wing is considerably rescued by Df(3L)H99 (S5D–S5F Fig). Thus, we conclude from these data that depletion of pll is sufficient to activate caspase-mediated cell death.


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)

Depletion of pll elicits caspases-dependent cell death in adult wing.(A-D) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. The loss-of-ACV phenotype in ptc>pll-IRV2889 flies (A) was significantly suppressed by the expression of DIAP1 (C) or DroncDN (D), but not that of LacZ (B), which served as a negative control. The lower panels are high magnification of the boxed areas in upper panels (A-D). (E) Quantification of the ACV phenotypes as shown in figures A-D. 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/UAS-pll-IRV2889 (B) ptc-Gal4/UAS-pll-IRV2889; UAS-LacZ/+ (C) ptc-Gal4/UAS-pll-IRV2889; UAS-DIAP1/+ (D) ptc-Gal4/UAS-pll-IRV2889; UAS-DroncDN/+.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608839&req=5

pgen.1005589.g006: Depletion of pll elicits caspases-dependent cell death in adult wing.(A-D) Light micrographs showing Drosophila adult wings, anterior is to the left and distal up. The loss-of-ACV phenotype in ptc>pll-IRV2889 flies (A) was significantly suppressed by the expression of DIAP1 (C) or DroncDN (D), but not that of LacZ (B), which served as a negative control. The lower panels are high magnification of the boxed areas in upper panels (A-D). (E) Quantification of the ACV phenotypes as shown in figures A-D. 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/UAS-pll-IRV2889 (B) ptc-Gal4/UAS-pll-IRV2889; UAS-LacZ/+ (C) ptc-Gal4/UAS-pll-IRV2889; UAS-DIAP1/+ (D) ptc-Gal4/UAS-pll-IRV2889; UAS-DroncDN/+.
Mentions: Apoptosis in Drosophila is triggered by transcriptional up-regulation of three pro-apoptotic genes rpr, hid and grim, and is mediated by the cleavage and activation of caspases [40]. Consistent with its role in cell death, loss of pll in the wing pouch results in up-regulated transcription of hid and rpr as revealed by X-gal staining of a hid-LacZ and an rpr-LacZ reporters (Fig 4I, 4J, 4M and 4N; S4C–S4F Fig), which is suppressed by expressing Pll, but not GFP (Fig 4K, 4L, 4O and 4P). Furthermore, we found that a ubiquitous knock-down of pll (act>pll-IR) was able to activate the transcription of endogenous hid, rpr and grim, as compared to the act-Gal4 control, via executing a real-time qRT-PCR assay (S4M Fig). In addition, depletion of pll leads to enhanced antibody staining for the activated form of Caspase-3 (CC-3, Fig 5G and 5H), a read-out of the initiator caspase Dronc activity [43]. Moreover, we found that the loss-of-ACV phenotype induced by ptc>pll-IR was suppressed partially by the deficiency Df(3L)H99 that deletes rpr, hid and grim (S5A–S5C Fig), and significantly by expressing the inhibitor of apoptosis protein DIAP1 or a dominant-negative form of Dronc (DroncDN), but not LacZ (Fig 6). Accordingly, the phenotype of reduced distal-most area in Omb>pll-IR wing is considerably rescued by Df(3L)H99 (S5D–S5F Fig). Thus, we conclude from these data that depletion of pll is sufficient to activate caspase-mediated cell death.

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