Although 90% of children with acute lymphoblastic leukemia (ALL) are now cured1, the prognosis of infant-ALL (diagnosis within the first year of life) remains dismal2. Infant-ALL is usually caused by a single genetic hit that arises in utero: rearrangement of the MLL/KMT2A gene (MLL-r). This is sufficient to give rise to a uniquely aggressive and treatment-refractory leukemia compared to older children with the same MLL-r3–5. The reasons for disparate outcomes in patients of different ages with identical driver mutations are unknown. This paper addresses the hypothesis that fetal-specific gene expression programs co-operate with MLL-AF4 to initiate and maintain infant-ALL. Using direct comparison of fetal and adult HSC and progenitor transcriptomes we identify fetal-specific gene expression programs in primary human cells. We show that MLL-AF4-driven infant-ALL, but not MLL-AF4 childhood-ALL, displays expression of fetal-specific genes. In a direct test of this observation, we find that CRISPR-Cas9 gene editing of primary human fetal liver cells to produce a t(4;11)/MLL-AF4 translocation replicates the clinical features of infant-ALL and drives infant-ALL-specific and fetal-specific gene expression programs. These data strongly support the hypothesis that fetal-specific gene expression programs co-operate with MLL-AF4 to initiate and maintain the distinct biology of infant-ALL.
Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): British Heart Foundation and Propionic Acidemia Foundation Background In the heart, various metabolic pathways produce the three-carbon intermediate, propionate. This metabolite has been postulated to increase histone propionylation and acetylation (via deacetylase inhibition), and therefore affect transcription. Normally, propionate levels are kept low by propionyl-CoA carboxylase (PCC), but build-up has been reported in cardiometabolic diseases. The highest levels are attained in propionic acidaemia (PA; mutations in PCC), which also serves as a model for studying propionate biology [1]. Purpose To establish the effect of propionate on cardiac gene expression and physiology using a mouse model of elevated propionate/propionyl-CoA signalling. Methods Experiments were performed using either wild-type (WT) neonatal ventricular myocytes (NRVMs) treated with propionate in vitro, or the hypomorphic mouse model of PA (Pcca-/- A138T) [2]. IC-MS metabolomics was performed on methanol-extracted metabolites. RNA-sequencing was carried out on an Illumina HiSeq 4000. For chromatin immunoprecipitation (ChIP), chromatin was isolated from PFA-fixed ventricular tissue. cGMP levels were measured by the FRET-based sensor, cGi500. Ca2+ transients were imaged in isolated myocytes using FuraRed. Cine-MRI was performed in a 7 tesla MR scanner. Results PA mice had the metabolic signature of propionate accumulation in plasma and cardiac lysates (metabolomics). RNA-seq of ventricular lysates identified differentially expressed genes (DEGs), but the effect was more pronounced in females. Thus, subsequent experiments were performed in females. To determine which DEGs are likely a direct response to propionate, RNA-seq was performed on propionate-treated NRVMs. The most significant DEGs common to both datasets were upregulated Pde9a (cGMP-selective phosphodiesterase) and Mme (degrades natriuretic peptides). ChIP-qPCR for histone acylation in PA and WT hearts demonstrated increases in H3K27ac at Pde9a, and strikingly, increases in propionylation at Pde9a and Mme, indicating a mechanism for this transcriptional induction. Propionate-treated NRVMs show greater sensitivity of cGMP to pharmacological inhibition of PDE9A (measured by FRET), consistent with Pde9a induction. Such changes are expected to result in diastolic dysfunction [3]. Indeed, ventricular myocytes from PA mice had higher diastolic Ca2+. Cine-MRI confirmed contractile dysfunction in vivo, with PA mice manifesting increased end-systolic and end-diastolic volumes. Conclusions We demonstrate that cardiac elevations of the metabolic intermediate, propionate, increases histone modifications that drive transcriptional changes in the heart, including those involved in cyclic nucleotide signalling. We also present evidence for histone propionylation, which has not been described previously in the heart. Thus, using a mouse model of a rare metabolic disease, we show how propionate/propionyl-CoA signalling affects cardiac function through epigenetic changes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.