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Loss of putzig Activity Results in Apoptosis during Wing Imaginal Development in Drosophila.

Zimmermann M, Kugler SJ, Schulz A, Nagel AC - PLoS ONE (2015)

Bottom Line: We present evidence that downregulation of Notch activates Dcp1 caspase and JNK signaling, however, neither induces ectopic wg nor dpp expression.In contrast, the consequences of Dref-RNAi were largely indistinguishable from pzg-RNAi with regard to apoptosis induction.Moreover, overexpression of Dref ameliorated the downregulation of pzg compatible with the notion that the two are required together to maintain cell and tissue homeostasis in Drosophila.

View Article: PubMed Central - PubMed

Affiliation: Institute of Genetics, University of Hohenheim, 70599 Stuttgart, Germany.

ABSTRACT
The Drosophila gene putzig (pzg) encodes a nuclear protein that is an integral component of the Trf2/Dref complex involved in the transcription of proliferation-related genes. Moreover, Pzg is found in a complex together with the nucleosome remodeling factor NURF, where it promotes Notch target gene activation. Here we show that downregulation of pzg activity in the developing wing imaginal discs induces an apoptotic response, accompanied by the induction of the pro-apoptotic gene reaper, repression of Drosophila inhibitor of apoptosis protein accumulation and the activation of the caspases Drice, Caspase3 and Dcp1. As a further consequence 'Apoptosis induced Proliferation' (AiP) and 'Apoptosis induced Apoptosis' (AiA) are triggered. As expected, the activity of the stress kinase Jun N-terminal kinase (JNK), proposed to mediate both processes, is ectopically induced in response to pzg loss. In addition, the expression of the mitogen wingless (wg) but not of decapentaplegic (dpp) is observed. We present evidence that downregulation of Notch activates Dcp1 caspase and JNK signaling, however, neither induces ectopic wg nor dpp expression. In contrast, the consequences of Dref-RNAi were largely indistinguishable from pzg-RNAi with regard to apoptosis induction. Moreover, overexpression of Dref ameliorated the downregulation of pzg compatible with the notion that the two are required together to maintain cell and tissue homeostasis in Drosophila.

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pzg genetically interacts with pro-apoptotic genes.(A-C) Control eyes after overexpression of lacZ and pzg, as well as pzg-RNAi induction. (D-F) Overexpression of hid, rpr and grim during eye development causes small and rough eyes in the adults. (G-I) Overexpression of pzg ameliorates the small eye size resulting from ectopically expressed pro-apoptotic genes, whereas depletion of pzg activity by RNAi enhances the phenotypes (J-L). Genotypes analyzed: Gmr-Gal4/+; UAS-lacZ/+. Gmr-Gal4/+; EP-pzg/+. Gmr-Gal4/+; UAS-pzg-RNAi/+. Gmr-hid/Gmr-Gal4; UAS-lacZ/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-lacZ. Gmr-hid/Gmr-Gal4; EP-pzg/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/EP-pzg. Gmr-hid/Gmr-Gal4; UAS-pzg-RNAi/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-pzg-RNAi.
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pone.0124652.g001: pzg genetically interacts with pro-apoptotic genes.(A-C) Control eyes after overexpression of lacZ and pzg, as well as pzg-RNAi induction. (D-F) Overexpression of hid, rpr and grim during eye development causes small and rough eyes in the adults. (G-I) Overexpression of pzg ameliorates the small eye size resulting from ectopically expressed pro-apoptotic genes, whereas depletion of pzg activity by RNAi enhances the phenotypes (J-L). Genotypes analyzed: Gmr-Gal4/+; UAS-lacZ/+. Gmr-Gal4/+; EP-pzg/+. Gmr-Gal4/+; UAS-pzg-RNAi/+. Gmr-hid/Gmr-Gal4; UAS-lacZ/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-lacZ. Gmr-hid/Gmr-Gal4; EP-pzg/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/EP-pzg. Gmr-hid/Gmr-Gal4; UAS-pzg-RNAi/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-pzg-RNAi.

Mentions: Knock down of pzg gene activity by pzg-RNAi induction during larval development results in tissue size reduction (Fig 1A–1C). Previously, we have shown that pzg-RNAi effects are negatively correlated with cell cycle progression, thereby influencing cell proliferation and cell growth [40]. In order to test whether tissue loss and size reduction might also be a consequence of the induction of programmed cell death, we performed genetic interaction assays with the well defined apoptosis-inducing factors hid, rpr and grim, whose transcriptional activation is an essential step in the execution of most apoptotic events in the development of Drosophila [54–57] (reviewed in [58]). It is well established that ectopic expression of pro-apoptotic genes in the developing eye imaginal disc using the Gmr promoter causes cell killing and therefore conspicuously small eyes in the adults (Fig 1D–1F). Eye size reduction was considerably suppressed by additional expression of Pzg (Fig 1G–1I and S1 Fig), whereas it was enhanced by pzg-RNAi induction within the affected tissue (Fig 1J–1L and S1 Fig).


Loss of putzig Activity Results in Apoptosis during Wing Imaginal Development in Drosophila.

Zimmermann M, Kugler SJ, Schulz A, Nagel AC - PLoS ONE (2015)

pzg genetically interacts with pro-apoptotic genes.(A-C) Control eyes after overexpression of lacZ and pzg, as well as pzg-RNAi induction. (D-F) Overexpression of hid, rpr and grim during eye development causes small and rough eyes in the adults. (G-I) Overexpression of pzg ameliorates the small eye size resulting from ectopically expressed pro-apoptotic genes, whereas depletion of pzg activity by RNAi enhances the phenotypes (J-L). Genotypes analyzed: Gmr-Gal4/+; UAS-lacZ/+. Gmr-Gal4/+; EP-pzg/+. Gmr-Gal4/+; UAS-pzg-RNAi/+. Gmr-hid/Gmr-Gal4; UAS-lacZ/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-lacZ. Gmr-hid/Gmr-Gal4; EP-pzg/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/EP-pzg. Gmr-hid/Gmr-Gal4; UAS-pzg-RNAi/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-pzg-RNAi.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4403878&req=5

pone.0124652.g001: pzg genetically interacts with pro-apoptotic genes.(A-C) Control eyes after overexpression of lacZ and pzg, as well as pzg-RNAi induction. (D-F) Overexpression of hid, rpr and grim during eye development causes small and rough eyes in the adults. (G-I) Overexpression of pzg ameliorates the small eye size resulting from ectopically expressed pro-apoptotic genes, whereas depletion of pzg activity by RNAi enhances the phenotypes (J-L). Genotypes analyzed: Gmr-Gal4/+; UAS-lacZ/+. Gmr-Gal4/+; EP-pzg/+. Gmr-Gal4/+; UAS-pzg-RNAi/+. Gmr-hid/Gmr-Gal4; UAS-lacZ/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-lacZ. Gmr-hid/Gmr-Gal4; EP-pzg/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/EP-pzg. Gmr-hid/Gmr-Gal4; UAS-pzg-RNAi/+. Gmr-Gal4/+; Gmr-rpr or Gmr-grim/ UAS-pzg-RNAi.
Mentions: Knock down of pzg gene activity by pzg-RNAi induction during larval development results in tissue size reduction (Fig 1A–1C). Previously, we have shown that pzg-RNAi effects are negatively correlated with cell cycle progression, thereby influencing cell proliferation and cell growth [40]. In order to test whether tissue loss and size reduction might also be a consequence of the induction of programmed cell death, we performed genetic interaction assays with the well defined apoptosis-inducing factors hid, rpr and grim, whose transcriptional activation is an essential step in the execution of most apoptotic events in the development of Drosophila [54–57] (reviewed in [58]). It is well established that ectopic expression of pro-apoptotic genes in the developing eye imaginal disc using the Gmr promoter causes cell killing and therefore conspicuously small eyes in the adults (Fig 1D–1F). Eye size reduction was considerably suppressed by additional expression of Pzg (Fig 1G–1I and S1 Fig), whereas it was enhanced by pzg-RNAi induction within the affected tissue (Fig 1J–1L and S1 Fig).

Bottom Line: We present evidence that downregulation of Notch activates Dcp1 caspase and JNK signaling, however, neither induces ectopic wg nor dpp expression.In contrast, the consequences of Dref-RNAi were largely indistinguishable from pzg-RNAi with regard to apoptosis induction.Moreover, overexpression of Dref ameliorated the downregulation of pzg compatible with the notion that the two are required together to maintain cell and tissue homeostasis in Drosophila.

View Article: PubMed Central - PubMed

Affiliation: Institute of Genetics, University of Hohenheim, 70599 Stuttgart, Germany.

ABSTRACT
The Drosophila gene putzig (pzg) encodes a nuclear protein that is an integral component of the Trf2/Dref complex involved in the transcription of proliferation-related genes. Moreover, Pzg is found in a complex together with the nucleosome remodeling factor NURF, where it promotes Notch target gene activation. Here we show that downregulation of pzg activity in the developing wing imaginal discs induces an apoptotic response, accompanied by the induction of the pro-apoptotic gene reaper, repression of Drosophila inhibitor of apoptosis protein accumulation and the activation of the caspases Drice, Caspase3 and Dcp1. As a further consequence 'Apoptosis induced Proliferation' (AiP) and 'Apoptosis induced Apoptosis' (AiA) are triggered. As expected, the activity of the stress kinase Jun N-terminal kinase (JNK), proposed to mediate both processes, is ectopically induced in response to pzg loss. In addition, the expression of the mitogen wingless (wg) but not of decapentaplegic (dpp) is observed. We present evidence that downregulation of Notch activates Dcp1 caspase and JNK signaling, however, neither induces ectopic wg nor dpp expression. In contrast, the consequences of Dref-RNAi were largely indistinguishable from pzg-RNAi with regard to apoptosis induction. Moreover, overexpression of Dref ameliorated the downregulation of pzg compatible with the notion that the two are required together to maintain cell and tissue homeostasis in Drosophila.

Show MeSH
Related in: MedlinePlus