# Cyclin G: looking for the causes of developmental noise

Delphine Dardalhon-Cumenal, Valérie Ribeiro, Wissem Hamel, Marco da Costa, F. Peronnet

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## To cite this version:

Delphine Dardalhon-Cumenal, Valérie Ribeiro, Wissem Hamel, Marco da Costa, F. Peronnet. Cyclin G: looking for the causes of developmental noise. VIP and DIF 2022, Jun 2022, Paris, France. 8, 2022, 10.1186/s13072-015-0008-6. [hal-03808326](https://hal.science/hal-03808326)

HAL Id: hal-03808326

https://hal.science/hal-03808326

Submitted on 10 Oct 2022

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Drosophila melanogaster Cyclin G (dCycG) controls transcription and regulates the cell cycle. We previously determined that dCycG shares many transcriptional targets with the Polycomb PRC1 and PR-DUB complexes¹. Overexpression of a potentially more stable form of dCycG down-regulates genes involved in mitochondrial activity. Interestingly, it also induces a high developmental noise, as estimated by an increase of wing fluctuating asymmetry (FA) in adults². Overexpression of dCycG in background mutants for the Polycomb complexes PRC1 or PR-DUB leads to a previously unseen FA¹. We show here that dCycG directly interacts with dRing, the ubiquitine-ligase of PRC1 and Calypso, the deubiquitinase of PR-DUB. Our results suggest that dCycG undergoes a ubiquitination/deubiquitination cycle driven by these complexes and bookmarks its transcriptional targets during mitosis. We have produced a *dCycG* mutant by CRISPR/Cas9. This mutant displays a high FA. Although its amount of mitochondrial DNA does not vary, wing imaginal disc respiration unexpectedly increases. The next step will be to check the amount of Reactive Oxygen Species in these tissues and address whether an increase in ROS is causal to developmental noise.

## I - Developmental Stability and Fluctuating Asymmetry

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In bilaterians, developmental noise is assessed by Fluctuating Asymmetry (FA) in a population of isogenic flies raised in a standardized environment.

Measure of the centroid size of right (R) and left (L) wings using a set of 15 landmarks (geometric morphometrics)

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Distribution of (R-L) within a population

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Low noise:
Low (R-L) variance

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High noise:
High (R-L) variance

High developmental noise in flies expressing dCycG deleted of the PEST domain

ETP interacting domain 542
PEST domain 566

ETP interacting domain 542

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Overexpression of *CycG* in isogenic flies raised in a standardized environment induces very high FA. The ETP interacting domain limits *CycG*-induced fluctuating asymmetry

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A CRISPR/Cas9 mutant of *CycG*: HR2 raised in a standardized environment induces high FA

## II - Cyclin G interacts with PRC1 and PR-DUB

Mutations in the Polycomb complexes PRC1 and PR-DUB increase *dCycG*-induced FA

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*dCycG* physically interacts with ASX and the deubiquitinase Calypso, the two sub-units of PR-DUB

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IP Myc-ASX

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IP mock

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Co-IP Flag-Cyclin G

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Co-IP Flag-CALY

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Input IP mock

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*dCycG* physically interacts with dRing, the ubiquitine-ligase of PRC1

## III - Cyclin G interacts with mitochondrial genes

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Down-regulation of genes involved in mitochondrial activity in wing imaginal discs expressing dCycG deleted of the PEST domain (RNA-seq)

Many direct transcriptional targets of dCycG are shared with PRC1, PR-DUB and RNA pol II (ChIP-seq)

Mutants for most mitochondrial genes increase dCycG-induced FA, whereas a mutant for *larp* decreases it

Electron Transport Complexes and ATP synthase within the inner mitochondrial membrane

Pletcher et al., 2019

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<table><tr><td>UQCR-Q</td><td>mitochondrial respiratory chain complex III</td></tr><tr><td>COX6B</td><td>mitochondrial respiratory chain complex IV</td></tr><tr><td>Jafrac1<br>levy</td><td>proton transport</td></tr><tr><td>ATPSynF</td><td>translation at the mitochondrial membrane</td></tr><tr><td>larp</td><td></td></tr></table>

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F-tests, *** p-value<0.001

Higher respiration in flies expressing dCycG deleted of the PEST domain

Seahorse

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## Ongoing projects

* ✓ Is *dCycG* ubiquitinated/deubiquitinated during the cell cycle? and if so, are PRC1 and PR-DUB involved in this process?

* ✓ Binding of *dCycG* to mitochondrial gene promoters during the cell cycle (Cut&Run experiments on flow cytometry sorted cells): Is *dCycG* involved in mitosis bookmarking of these genes?

* ✓ Amount of reactive oxygen species in wing imaginal discs : are ROS a causal factor in developmental noise ?

## References

1- Dardalhon-Cuménal D et al. PLoS Genet. 2018;14(7):e1007498.

2- Debat V et al. PLoS Genet. 2011;7(10):e1002314.

3- Dupont CA et al. Epigenetics Chromatin. 2015 May 7;8:18. doi: 10.1186/s13072-015-0008-6.

4- Salvaing, J et al. PLoS One 3, e1658.