Ectopic expression of S28A-mutated Histone H3 modulates longevity, stress resistance and cardiac function in Drosophila

I Viktorinová,S Weber,G Heusch,E Koch,J P Joos,P Tomancak,J Backs,S Nattel,A R Saadatmand,T Brand,A El-Armouche,C Schnabel,M Kramer,D Dobrev,P Kleinbongard,K Lorenz

doi:10.1038/s41598-018-21372-3

Abstract

Histone H3 serine 28 (H3S28) phosphorylation and de-repression of polycomb repressive complex (PRC)-mediated gene regulation is linked to stress conditions in mitotic and post-mitotic cells. To better understand the role of H3S28 phosphorylation in vivo, we studied a Drosophila strain with ectopic expression of constitutively-activated H3S28A, which prevents PRC2 binding at H3S28, thus mimicking H3S28 phosphorylation. H3S28A mutants showed prolonged life span and improved resistance against starvation and paraquat-induced oxidative stress. Morphological and functional analysis of heart tubes revealed smaller luminal areas and thicker walls accompanied by moderately improved cardiac function after acute stress induction. Whole-exome deep gene-sequencing from isolated heart tubes revealed phenotype-corresponding changes in longevity-promoting and myotropic genes. We also found changes in genes controlling mitochondrial biogenesis and respiration. Analysis of mitochondrial respiration from whole flies revealed improved efficacy of ATP production with reduced electron transport-chain activity. Finally, we analyzed posttranslational modification of H3S28 in an experimental heart failure model and observed increased H3S28 phosphorylation levels in HF hearts. Our data establish a critical role of H3S28 phosphorylation in vivo for life span, stress resistance, cardiac and mitochondrial function in Drosophila. These findings may pave the way for H3S28 phosphorylation as a putative target to treat stress-related disorders such as heart failure.

Highlights

Phosphorylation of histone H3 (H3) is an important downstream signalling event that couples signal transduction pathways, gene regulation and biological processes[1,2]
To determine whether transgenic overexpression of H3S28A modulates life span and stress resistance, we first examined male flies, to avoid experimental confounding due e.g. nutrition influence that is elevated in Drosophila females to produce eggs
We found a nearly 70% increase in median life span of H3S28A mutants under basal conditions (Fig. 1a), an increased resistance against food withdrawal (Fig. 1b), and a greater resistance against oxidative stress conditions in the paraquat feeding model (Fig. 1c)

Summary

Introduction

Phosphorylation of histone H3 (H3) is an important downstream signalling event that couples signal transduction pathways, gene regulation and biological processes[1,2]. Gross phenotypic analysis showed homeotic transformations like antenna-to-leg transformations in adult tissues, underlining the importance of H3S28 in PRC-orchestrated transcriptional processes related to maintenance of cell identity These findings raise the possibility that a more moderate modulation of H3S28-mediated PRC axis de-repression might affect yet unexamined key biological processes like life span, organ integrity and stress resistance. Due to the complexity of genomic histone H3 coding sequences in vertebrate models, the best current state-of-the-art animal model to study the impact of aberrant H3S28 phosphorylation is a transgenic Drosophila melanogaster model with an H3S28A replacement This mutant reduces the ability of PRC2 to methylate H3K27 on nucleosomal substrates, mimicking increased H3S28 phosphorylation and subsequent H3K27 acetylation[19].

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Results

Conclusion