Janbandhu, V. | bioRxiv Science

bioRxiv2022

Quantitative trait and transcriptome analysis of genetic complexity underpinning cardiac interatrial septation in mice using an advanced intercross line

Unlike single-gene mutations leading to Mendelian conditions, common human diseases are likely emergent phenomena arising from multilayer, multiscale and highly interconnected interactions. Atrial and ventricular septal defects are the most common forms of cardiac congenital anomalies in humans. Atrial septal defects (ASD) show an open communication between left and right atria postnatally, potentially resulting in serious hemodynamic consequences if untreated. A milder form of atrial septal defect, patent foramen ovale (PFO), exists in about one quarter of the human population, strongly associated with ischaemic stroke and migraine. The anatomic liabilities and genetic and molecular basis of atrial septal defects remain unclear. Here, we advance our previous analysis of atrial septal variation through quantitative trait locus (QTL) mapping of an advanced intercross line (AIL) established between the inbred QSi5 and 129T2/SvEms mouse strains, that show extremes of septal phenotypes. Analysis resolved 37 unique septal QTL with high overlap between QTL for distinct septal traits. Whole genome sequencing of parental strains identified high confidence candidate deleterious variants, including in known human congenital heart disease genes, whereas transcriptome analysis of developing septa revealed networks involving ribosome, nucleosome, mitochondrial and extracellular matrix biosynthesis underlying septal variation. Analysis of variant architecture across different gene features, including enhancers and promoters, provided evidence for involvement of non-coding as well as protein coding variants. Our study provides the first high resolution picture of genetic complexity and network liability underlying common congenital heart disease, with relevance to human ASD and PFO.

genetics↗

bioRxiv2017

PDGFRα signaling in cardiac stem and stromal cells modulates quiescence, metabolism and self-renewal, and promotes anatomical and functional repair

The interstitial and perivascular spaces of the mammalian heart contain a highly interactive tissue community essential for cardiac homeostasis, repair and regeneration. Mesenchymal cells (fibroblasts) are one of the most abundant cell types, playing key roles as sentinels, tissue architects, paracrine signaling hubs and lineage precursors, and are linked to heart disease through their roles in inflammation and fibrosis. Platelet-derived growth factors (PDGFs) are secreted by several cell types involved in cardiac injury and repair, and are recognized mitogens for cardiac fibroblasts and mesenchymal stem cells. However, their roles are complex and investigations of their impact on heart repair have produced contrasting outcomes, leaving therapeutic potential uncertain. Here, we use new approaches and tools, including single cell RNA sequencing, to explore cardiac fibroblast heterogeneity and how PDGF receptor (PDGFR) signaling impacts fibroblasts during heart repair. Short-term systemic delivery of PDGF-AB to mice from the time of myocardial infarction (MI) led to enhanced anatomical and functional recovery. Underpinning these benefits was a priming effect, in which PDGF-AB accelerated exit of fibroblasts from quiescence and induced a higher translational biosynthetic capacity in both fibroblasts and macrophages without triggering fibrosis. Our study highlights the significant biosynthetic heterogeneity and plasticity in cardiac fibroblast populations, and suggests a rationale for a novel therapeutic approach to cardiac injury involving controlled stimulation of fibroblast activation.

cell biology↗