Loss of Rearranged L-Myc Fusion (RLF) results in defects in heart development in the mouse

L M Bourke; G Del Monte-Nieto; J E Outhwaite; V Bharti; P M Pollock; D G Simmons; A Adam; S S J Hur; G J Maghzal; E Whitelaw; R Stocker; C M Suter; R P Harvey; S K Harten

doi:10.1016/j.diff.2016.11.004

Loss of Rearranged L-Myc Fusion (RLF) results in defects in heart development in the mouse

Differentiation. 2017 Mar-Apr:94:8-20. doi: 10.1016/j.diff.2016.11.004. Epub 2016 Dec 5.

Authors

L M Bourke¹, G Del Monte-Nieto², J E Outhwaite³, V Bharti⁴, P M Pollock⁵, D G Simmons³, A Adam⁶, S S J Hur⁶, G J Maghzal⁶, E Whitelaw⁷, R Stocker⁸, C M Suter², R P Harvey⁹, S K Harten¹⁰

Affiliations

¹ Epigenetics Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia; School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4006, Australia.
² The Victor Chang Cardiac Research Institute, Sydney, NSW 200, Australia; St. Vincent's Clinical School, University of New South Wales, Kensington 2052, Australia.
³ School of Biomedical Sciences, Faculty of Medicine and Biomedical Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia.
⁴ Epigenetics Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia.
⁵ School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4006, Australia.
⁶ The Victor Chang Cardiac Research Institute, Sydney, NSW 200, Australia.
⁷ Department of Genetics, La Trobe Institute for Molecular Science, Department of Genetics, La Trobe University, Bundoora, Victoria 3086, Australia.
⁸ The Victor Chang Cardiac Research Institute, Sydney, NSW 200, Australia; School of Medical Sciences, University of New South Wales, Kensington 2052, Australia.
⁹ The Victor Chang Cardiac Research Institute, Sydney, NSW 200, Australia; St. Vincent's Clinical School, University of New South Wales, Kensington 2052, Australia; School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington 2052, Australia. Electronic address: [email protected].
¹⁰ Epigenetics Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia. Electronic address: [email protected].

PMID: 27930960
DOI: 10.1016/j.diff.2016.11.004

Abstract

Recently we reported that Rearranged L-Myc Fusion, RLF, acts as an epigenetic modifier maintaining low levels of DNA methylation at CpG island shores and enhancers across the genome. Here we focus on the phenotype of Rlf null mutant mice generated via an ENU mutagenesis screen, to identify genes required for epigenetic regulation. RLF is expressed in a range of fetal mouse tissues, including the fetal heart. Comprehensive timed-mating studies are consistent with our previously reported findings that Rlf homozygous mutant mice rarely survive to adulthood, with the majority dying shortly after birth. Histological analysis of two independent Rlf ENU mutant lines at E11.5-E14.5 showed heart defects resembling those present in humans with Left Ventricular Non-Compaction (LVNC). In situ hybridisation analysis localized expression of Rlf to the endocardium and epicardium of embryonic and postnatal hearts, and transiently to cardiomyocytes during heart looping and early chamber formation stages. RNA-seq analysis of Rlf mutant hearts highlighted defective NOTCH pathway signalling, recently describe as one cause of LVNC. This study provides the first evidence that RLF is required for normal heart development in the mouse. The heart morphological defects present at high penetrance in Rlf mutants are consistent with features of LVNC in humans, and molecular analysis identified attenuated JAGGED 1 expression and NOTCH signalling as likely contributors to these defects. Our study highlights the importance of RLF-dependent epigenetic modifications to DNA for maintaining correct gene regulatory network and intercellular signalling interactions during heart chamber and septal development. Further investigations are needed to define the biochemical role of RLF in the developing heart, and whether RLF mutations are a cause of heart defects in humans.

Keywords: Cardiovascular development; Left ventricular non-compaction; NOTCH1 Signalling; RLF.

MeSH terms

Animals
Cell Differentiation / genetics*
DNA Methylation / genetics
Epigenesis, Genetic
Gene Regulatory Networks / genetics
Guanine Nucleotide Exchange Factors
Heart / growth & development*
Humans
Jagged-1 Protein / genetics
Mice
Mutation
Organogenesis / genetics*
Receptors, Notch / genetics
Transcription Factors / genetics*

Substances

Guanine Nucleotide Exchange Factors
Jagged-1 Protein
Receptors, Notch
Rgl2 protein, mouse
Transcription Factors