Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA338

Poster Communications

Modulation of endothelial chromatin remodelling complexes by long non-coding RNAs

J. A. Oo1,2, I. Wittig2,4, J. Heidler2,4, S. Günther3, M. S. Leisegang1,2, R. Brandes1,2

1. Institute for Cardiovascular Physiology, Vascular Research Centre, Frankfurt am Main, Germany. 2. German Center of Cardiovascular Research (DZHK), Frankfurt am Main, Germany. 3. Max-Planck-Institute for Heart and Lung Research, ECCPS Bioinformatics and Sequencing Facility, Bad Nauheim, Germany. 4. Functional Proteomics, SFB 815 Core Unit, Faculty of Medicine, Frankfurt am Main, Germany.

Long non-coding RNAs modulate chromatin remodelling complexes and thereby regulate the epigenetic landscape and gene expression. Complexes are recruited to their genomic targets where they either covalently modify histones or alter nucleosomal structure by utilising ATP1. However, the mechanisms governing the modulation of chromatin remodelling complexes and their recruitment to gene-specific promoters are largely unknown. We hypothesise that complexes, through a particular cell-type- and condition-specific subunit composition, are modulated by an even more specific network of lncRNAs; as is the case for the notable Polycomb Repressive Complex 2 (PRC2), whose main functions require lncRNAs such as Xist, HOTAIR and Kcnq1ot12. We recently identified the lncRNA MANTIS as a crucial component of the endothelial SWI/SNF complex. MANTIS was found to stabilise the interaction between the core ATP-ase, BRG1, and BRG1-associated factor 155 (BAF155). The scaffolding role of MANTIS maintained the ATP-ase activity of the complex, its targetting to angiogenesis-associated genes and, ultimately, vascular function3. This highlights the importance of lncRNAs in the normal functioning of a chromatin remodelling complex. Subsequently, a spheroid outgrowth assay after siRNA against BRG1 clearly demonstrated a fundamental role for BRG1 in endothelial function. Additional protein subunits of endothelial SWI/SNF were identified by mass spectrometry and one of them, Double PHD Fingers 2 (DPF2), was also found to uphold endothelial function. RNA-IP-sequencing was employed in order to identify novel RNA interaction partners of different chromatin remodelling proteins such as EZH2, BRG1, BRM, SMARCA5 and BAF170. We identified lncRNAs including EPHA1-AS1, CACNA1G-AS1, MALAT1, NEAT1 and BARX1-AS1 that appear to have significant implications in the endothelium. Importantly, there was an overlap of lncRNA profile for the SWI/SNF complex members BAF170, BRM and BRG1, but not with the PRC2 member, EZH2. Since lncRNAs are already known to modulate chromatin remodelling complexes we will investigate this relationship further in the context of the vascular system to dissect specific endothelial gene programs under physiological and pathophysiological conditions.

Where applicable, experiments conform with Society ethical requirements