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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

pll regulates cell number but not cell size in development.(A and B) Fluorescence micrographs of third instar larval wing discs with clones (marked by GFP) expressing no (A) or pll RNAi (B). Clones were induced by heat shock at 37°C for 1 hour and recovered at 25°C for 42 hours. Nuclei were labeled with DAPI (blue). (C) Quantification of clone size shown in A and B. Unpaired t test was used to calculate statistical significance, indicated with asterisks (*** P<0.001, n = 10 in each group). (D and E) Clones (marked by y-, yellow) expressing no (D) or pll RNAi (E) in adult wing margin bristles, 7 days after induction. (F) Quantification of bristle size as shown in D and E. The ratio of bristle size within clones (Y)/bristle size of internal control (I) remained unchanged when pll was knocked down in the clone. (G and H) Fluorescence micrographs of clones (marked by GFP) expressing pll RNAi in third instar larval fat body (FB, G) and salivary gland (SG, H) 42 hours after induction. Nuclei were labelled with DAPI (blue), cell membranes were stained by anti-Dlg antibody (red). (I and J) Fluorescence micrographs of wing discs are shown. The P compartment was labelled by GFP, while cell proliferation was detected by anti-pH3 staining (red) (I’ and J’), nuclei were labelled with DAPI (blue). (K) Quantification of pH3 positive cells shown in I and J. The P/A ratio of pH3 positive cells remained unchanged when pll was knocked down in the P compartment. ns stands for not significant. For all wing discs, anterior is to the left and dorsal up. Detailed genotypes: (A and D) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/+ (B, E, G, H) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/UAS-pll-IRV2889 (I) en-Gal4 UAS-GFP/+ (J) en-Gal4 UAS-GFP/UAS-pll-IRV2889.
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pgen.1005589.g003: pll regulates cell number but not cell size in development.(A and B) Fluorescence micrographs of third instar larval wing discs with clones (marked by GFP) expressing no (A) or pll RNAi (B). Clones were induced by heat shock at 37°C for 1 hour and recovered at 25°C for 42 hours. Nuclei were labeled with DAPI (blue). (C) Quantification of clone size shown in A and B. Unpaired t test was used to calculate statistical significance, indicated with asterisks (*** P<0.001, n = 10 in each group). (D and E) Clones (marked by y-, yellow) expressing no (D) or pll RNAi (E) in adult wing margin bristles, 7 days after induction. (F) Quantification of bristle size as shown in D and E. The ratio of bristle size within clones (Y)/bristle size of internal control (I) remained unchanged when pll was knocked down in the clone. (G and H) Fluorescence micrographs of clones (marked by GFP) expressing pll RNAi in third instar larval fat body (FB, G) and salivary gland (SG, H) 42 hours after induction. Nuclei were labelled with DAPI (blue), cell membranes were stained by anti-Dlg antibody (red). (I and J) Fluorescence micrographs of wing discs are shown. The P compartment was labelled by GFP, while cell proliferation was detected by anti-pH3 staining (red) (I’ and J’), nuclei were labelled with DAPI (blue). (K) Quantification of pH3 positive cells shown in I and J. The P/A ratio of pH3 positive cells remained unchanged when pll was knocked down in the P compartment. ns stands for not significant. For all wing discs, anterior is to the left and dorsal up. Detailed genotypes: (A and D) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/+ (B, E, G, H) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/UAS-pll-IRV2889 (I) en-Gal4 UAS-GFP/+ (J) en-Gal4 UAS-GFP/UAS-pll-IRV2889.

Mentions: To investigate the underlying mechanism by which loss of pll results in reduced wing tissue, we compared the cell number and cell size in the posterior (P) compartment with that in the anterior (A) compartment of the adult wing. We found that when pll was specifically knock-down in the P compartment by en-Gal4 (Fig 2L), the P/A ratio of cell size remained unaffected (Fig 2O), whereas the P/A ratio of cell number and total size decreased significantly (Fig 2P and 2Q), suggesting that pll regulates cell number, but not cell size, in wing development. To further verify this conclusion, we generated pll loss-of-function clones in larvae and found that the size of clones, labeled by GFP expression, was significantly smaller than that of wild-type (WT) controls in wing discs (Fig 3A–3C), confirming the role of pll in regulating tissue growth. However, the sizes of cells inside the clones (marked by GFP expression) were similar to that of wild-type controls in fat body (FB) and salivary gland (SG) (Fig 3G and 3H). Furthermore, wing margin bristles in pll knock-down clones, marked by loss of the yellow (y) gene, are not statistically different in size from their wild-type neighbors (Fig 3D–3F). Together, these data indicate that pll modulates tissue growth via regulating cell number but not cell size.


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)

pll regulates cell number but not cell size in development.(A and B) Fluorescence micrographs of third instar larval wing discs with clones (marked by GFP) expressing no (A) or pll RNAi (B). Clones were induced by heat shock at 37°C for 1 hour and recovered at 25°C for 42 hours. Nuclei were labeled with DAPI (blue). (C) Quantification of clone size shown in A and B. Unpaired t test was used to calculate statistical significance, indicated with asterisks (*** P<0.001, n = 10 in each group). (D and E) Clones (marked by y-, yellow) expressing no (D) or pll RNAi (E) in adult wing margin bristles, 7 days after induction. (F) Quantification of bristle size as shown in D and E. The ratio of bristle size within clones (Y)/bristle size of internal control (I) remained unchanged when pll was knocked down in the clone. (G and H) Fluorescence micrographs of clones (marked by GFP) expressing pll RNAi in third instar larval fat body (FB, G) and salivary gland (SG, H) 42 hours after induction. Nuclei were labelled with DAPI (blue), cell membranes were stained by anti-Dlg antibody (red). (I and J) Fluorescence micrographs of wing discs are shown. The P compartment was labelled by GFP, while cell proliferation was detected by anti-pH3 staining (red) (I’ and J’), nuclei were labelled with DAPI (blue). (K) Quantification of pH3 positive cells shown in I and J. The P/A ratio of pH3 positive cells remained unchanged when pll was knocked down in the P compartment. ns stands for not significant. For all wing discs, anterior is to the left and dorsal up. Detailed genotypes: (A and D) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/+ (B, E, G, H) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/UAS-pll-IRV2889 (I) en-Gal4 UAS-GFP/+ (J) en-Gal4 UAS-GFP/UAS-pll-IRV2889.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4608839&req=5

pgen.1005589.g003: pll regulates cell number but not cell size in development.(A and B) Fluorescence micrographs of third instar larval wing discs with clones (marked by GFP) expressing no (A) or pll RNAi (B). Clones were induced by heat shock at 37°C for 1 hour and recovered at 25°C for 42 hours. Nuclei were labeled with DAPI (blue). (C) Quantification of clone size shown in A and B. Unpaired t test was used to calculate statistical significance, indicated with asterisks (*** P<0.001, n = 10 in each group). (D and E) Clones (marked by y-, yellow) expressing no (D) or pll RNAi (E) in adult wing margin bristles, 7 days after induction. (F) Quantification of bristle size as shown in D and E. The ratio of bristle size within clones (Y)/bristle size of internal control (I) remained unchanged when pll was knocked down in the clone. (G and H) Fluorescence micrographs of clones (marked by GFP) expressing pll RNAi in third instar larval fat body (FB, G) and salivary gland (SG, H) 42 hours after induction. Nuclei were labelled with DAPI (blue), cell membranes were stained by anti-Dlg antibody (red). (I and J) Fluorescence micrographs of wing discs are shown. The P compartment was labelled by GFP, while cell proliferation was detected by anti-pH3 staining (red) (I’ and J’), nuclei were labelled with DAPI (blue). (K) Quantification of pH3 positive cells shown in I and J. The P/A ratio of pH3 positive cells remained unchanged when pll was knocked down in the P compartment. ns stands for not significant. For all wing discs, anterior is to the left and dorsal up. Detailed genotypes: (A and D) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/+ (B, E, G, H) y w hs-Flp/+; act>y+>Gal4 UAS-GFP/UAS-pll-IRV2889 (I) en-Gal4 UAS-GFP/+ (J) en-Gal4 UAS-GFP/UAS-pll-IRV2889.
Mentions: To investigate the underlying mechanism by which loss of pll results in reduced wing tissue, we compared the cell number and cell size in the posterior (P) compartment with that in the anterior (A) compartment of the adult wing. We found that when pll was specifically knock-down in the P compartment by en-Gal4 (Fig 2L), the P/A ratio of cell size remained unaffected (Fig 2O), whereas the P/A ratio of cell number and total size decreased significantly (Fig 2P and 2Q), suggesting that pll regulates cell number, but not cell size, in wing development. To further verify this conclusion, we generated pll loss-of-function clones in larvae and found that the size of clones, labeled by GFP expression, was significantly smaller than that of wild-type (WT) controls in wing discs (Fig 3A–3C), confirming the role of pll in regulating tissue growth. However, the sizes of cells inside the clones (marked by GFP expression) were similar to that of wild-type controls in fat body (FB) and salivary gland (SG) (Fig 3G and 3H). Furthermore, wing margin bristles in pll knock-down clones, marked by loss of the yellow (y) gene, are not statistically different in size from their wild-type neighbors (Fig 3D–3F). Together, these data indicate that pll modulates tissue growth via regulating cell number but not cell size.

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