Biology subjects

Ross, H.

Publications and source records attributed to Ross, H..

3 recordsLinked to original sources

bioRxiv2022

Cardiac muscle-restricted partial loss of Nos1ap expression has limited impact on electro- and echo-cardiographic features

Genome-wide association studies (GWAS) of QT interval variation have identified common noncoding variants at the NOS1AP gene as the most common genetic regulators of trait variation in the general population. Invoking a cis-regulatory mechanistic hypothesis, we have reported identification of a functional enhancer variant underlying the GWAS signal that influenced human cardiac NOS1AP expression. Functional studies based on in vitro overexpression in murine cardiomyocytes and ex vivo knockdown in zebrafish embryonic hearts, by us and others, have demonstrated that NOS1AP expression levels can alter cellular electrophysiology. Here, to explore the role of NOS1AP in cardiac electrophysiology at an organismal level, we generated and characterized constitutive and heart muscle-restricted Nos1ap knockout mice to assess whether NOS1AP disruption alters the QT interval in vivo. Constitutive loss of Nos1ap led to genetic background-dependent variable lethality at or right before birth. Heart muscle-restricted Nos1ap knockouts generated using cardiac specific alpha-myosin heavy chain promoter-driven tamoxifen-inducible Cre resulted in tissue-level Nos1ap expression reduced by half. This partial loss of expression had no detectable effect on the QT interval, but led to a small yet significant reduction in the QRS interval. Given that challenges associated with defining the end of T wave on murine electrocardiogram can limit identification of subtle effects on QT interval, and that common noncoding NOS1AP variants are also associated with QRS interval, our findings support the role of NOS1AP in regulation of the cardiac electrical cycle.

genetics↗

bioRxiv2021

Ret loss-of-function decreases enteric neural crest progenitor proliferation and restricts developmental fate potential during enteric nervous system development

The receptor tyrosine kinase gene RET plays a critical role in the fate specification of enteric neural crest-derived cells (ENCDCs) during enteric nervous system (ENS) development. Pathogenic RET loss of function (LoF) alleles are associated with Hirschsprung disease (HSCR), which is marked by aganglionosis of the gastrointestinal (GI) tract. ENCDCs invade the developing GI tract, proliferate, migrate caudally, and differentiate into all of the major ENS cell types. Although the major phenotypic consequences and the underlying transcriptional changes from Ret LoF in the developing ENS have been described, its cell type and state-specific effects are unknown. Consequently, we performed single- cell RNA sequencing (scRNA-seq) on an enriched population of ENCDCs isolated from the developing GI tract of Ret null heterozygous and homozygous mouse embryos at embryonic day (E)12.5 and E14.5. We demonstrate four significant findings: (1) Ret-expressing ENCDCs are a heterogeneous population composed of ENS progenitors as well as glial and neuronal committed cells; (2) neurons committed to a predominantly inhibitory motor neuron developmental trajectory are not produced under Ret LoF, leaving behind a mostly excitatory motor neuron developmental program; (3) HSCR-associated and Ret gene regulatory network genes exhibit distinct expression patterns across Ret-expressing ENCDC with their expression impacted by Ret LoF; and (4) Ret deficiency leads to precocious differentiation and reduction in the number of proliferating ENS precursors. Our results support a model in which Ret contributes to multiple distinct cellular phenotypes associated with the proper development of the ENS, including the specification of inhibitory neuron subtypes, cell cycle dynamics of ENS progenitors, and the developmental timing of neuronal and glial commitment. Summary StatementRet LoF affects proper development of the mouse ENS through multiple distinct cellular phenotypes including restriction of neuronal fate potential, disruption of ENCDC migration, and modulation of progenitor proliferation rate.

developmental biology↗

bioRxiv2020

Multiple, independent, common variants overlapping known and putative gut enhancers at RET, SEMA3 and NRG1 underlie Hirschsprung disease risk in European ancestry subjects

PurposeHirschsprung disease (HSCR) is a developmental disorder of the enteric nervous system (ENS) characterized by congenital aganglionosis, and where individual cases harbor coding risk variants in ENS genes. Low-penetrance, common, noncoding variants at RET, SEMA3 and NRG1 loci have been associated in HSCR as well, implicating variable gene expression mediated by cis-regulatory element (CRE) variants as the causal mechanism. However, the extent and combinatorial effects of all putative CRE variants within and across these loci on HSCR is unknown. MethodsUsing 583 HSCR subjects, one of the largest samples of European ancestry studied, and genotyping 56 tag variants we evaluated association of all common variants overlapping putative gut CREs and fine-mapped variants at RET, SEMA3 and NRG1. ResultsWe demonstrate that 28 and 8 tag variants, several of which are independent, overlapping putative-enhancers at the RET and SEMA3 loci, respectively, and, 2 fine-mapped tag variants at NRG1 locus, are associated with HSCR. We demonstrate that risk increases with increasing risk allele dosage from multiple variants within and across these loci and varies >25- fold. ConclusionGene regulatory networks in HSCR-relevant cell types quantify the total burden of risk alleles through sensing reduced gene expression of multiple genes on disease.

genetics↗