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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-RNAi induces AiA in late larval stages.(A-D'') Strong caspase activity, either visualized with anti-Caspase 3act (red in A-A', B-B') or anti-Dcp-1act (red in C-C', D-D'), can be detected non-autonomously in late larval wing disc in the anterior compartment (arrowheads in A-D'). Preventing cell death execution with p35 amplifies the overgrowth effect (asterisks in B'') but still induces AiA in the anterior half of the disc (B-B'', D-D'', arrowheads). Genotypes: (A-A'') and (C-C'') en-Gal4 UAS-GFP UAS-pzg-RNAi/+. (B-B'') and (D-D'') UAS-p35; en-Gal4 UAS-GFP UAS-pzg-RNAi/+. The A/P compartment boundary is marked with a dotted line. Scale bars: 100 μm.
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pone.0124652.g005: pzg-RNAi induces AiA in late larval stages.(A-D'') Strong caspase activity, either visualized with anti-Caspase 3act (red in A-A', B-B') or anti-Dcp-1act (red in C-C', D-D'), can be detected non-autonomously in late larval wing disc in the anterior compartment (arrowheads in A-D'). Preventing cell death execution with p35 amplifies the overgrowth effect (asterisks in B'') but still induces AiA in the anterior half of the disc (B-B'', D-D'', arrowheads). Genotypes: (A-A'') and (C-C'') en-Gal4 UAS-GFP UAS-pzg-RNAi/+. (B-B'') and (D-D'') UAS-p35; en-Gal4 UAS-GFP UAS-pzg-RNAi/+. The A/P compartment boundary is marked with a dotted line. Scale bars: 100 μm.

Mentions: Interestingly, cells doomed to die not only trigger AiP but also induce non-autonomous secondary apoptosis, abbreviated AiA (Apoptosis induced Apoptosis) [34]. To examine if such an effect is also observed in pzg-RNAi mutant cells we followed the activation of Caspase3 and Dcp1 in late third instar larval wing discs. Under these conditions, a strong caspase activity was observed in the anterior half of the disc, either visualized by staining for cleaved Caspase-3 or Dcp-1 (Fig 5A-A'' and 5C-C''). The co-expression of the baculovirus caspase inhibitor p35 in the pzg-RNAi mutant cells strongly enhanced this effect and triggered tumorous overgrowth of the wing discs and non autonomous AiA (Fig 5B-B'' and 5D-D''). This can be explained by the induction of the apoptotic machinery but the prevention of execution through inhibition of effector caspases by p35, resulting in so-called 'undead' cells [18,19,26,71]. Altogether, these data indicate that loss of pzg activity results in apoptosis followed by AiP and AiA.


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-RNAi induces AiA in late larval stages.(A-D'') Strong caspase activity, either visualized with anti-Caspase 3act (red in A-A', B-B') or anti-Dcp-1act (red in C-C', D-D'), can be detected non-autonomously in late larval wing disc in the anterior compartment (arrowheads in A-D'). Preventing cell death execution with p35 amplifies the overgrowth effect (asterisks in B'') but still induces AiA in the anterior half of the disc (B-B'', D-D'', arrowheads). Genotypes: (A-A'') and (C-C'') en-Gal4 UAS-GFP UAS-pzg-RNAi/+. (B-B'') and (D-D'') UAS-p35; en-Gal4 UAS-GFP UAS-pzg-RNAi/+. The A/P compartment boundary is marked with a dotted line. Scale bars: 100 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403878&req=5

pone.0124652.g005: pzg-RNAi induces AiA in late larval stages.(A-D'') Strong caspase activity, either visualized with anti-Caspase 3act (red in A-A', B-B') or anti-Dcp-1act (red in C-C', D-D'), can be detected non-autonomously in late larval wing disc in the anterior compartment (arrowheads in A-D'). Preventing cell death execution with p35 amplifies the overgrowth effect (asterisks in B'') but still induces AiA in the anterior half of the disc (B-B'', D-D'', arrowheads). Genotypes: (A-A'') and (C-C'') en-Gal4 UAS-GFP UAS-pzg-RNAi/+. (B-B'') and (D-D'') UAS-p35; en-Gal4 UAS-GFP UAS-pzg-RNAi/+. The A/P compartment boundary is marked with a dotted line. Scale bars: 100 μm.
Mentions: Interestingly, cells doomed to die not only trigger AiP but also induce non-autonomous secondary apoptosis, abbreviated AiA (Apoptosis induced Apoptosis) [34]. To examine if such an effect is also observed in pzg-RNAi mutant cells we followed the activation of Caspase3 and Dcp1 in late third instar larval wing discs. Under these conditions, a strong caspase activity was observed in the anterior half of the disc, either visualized by staining for cleaved Caspase-3 or Dcp-1 (Fig 5A-A'' and 5C-C''). The co-expression of the baculovirus caspase inhibitor p35 in the pzg-RNAi mutant cells strongly enhanced this effect and triggered tumorous overgrowth of the wing discs and non autonomous AiA (Fig 5B-B'' and 5D-D''). This can be explained by the induction of the apoptotic machinery but the prevention of execution through inhibition of effector caspases by p35, resulting in so-called 'undead' cells [18,19,26,71]. Altogether, these data indicate that loss of pzg activity results in apoptosis followed by AiP and AiA.

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