👤 Berit Jungnickel

Atherosclerosis is the leading cause of heart attack and stroke worldwide. The key characteristic of atherosclerosis is accumulation of LDL cholesterol in artery walls, the subsequent infiltration by monocytes/macrophages, and the development of inflammation. Recently, we reported that plasma protein complement factor H-related 1 (FHR1) binds to the necrotic surfaces of cardiovascular plaques and induces inflammation. Moreover, the concentration of FHR1 is higher, whereas Show less

Hepcidin, a liver-derived hormone, is the central regulator of systemic iron homeostasis. Elevated hepcidin levels contribute to iron-refractory iron deficiency anemia (IRIDA) and anemia of inflammation, both characterized by restricted iron availability. Current treatments, such as parenteral iron infusions, are often ineffective and pose risks of adverse reactions, underscoring the need for alternative therapeutic strategies targeting hepcidin. We previously identified a novel hepcidin regulatory pathway involving liver heparan sulfate (HS) proteoglycans (HSPGs), which modulate receptor-ligand interactions through their sulfated HS chains. Recently, we found that halofuginone impairs HS biosynthesis and considered whether it could be used as a hepcidin modulator. Here, we demonstrate that in human hepatoma (Hep3B) cells, halofuginone inhibits both basal and BMP6-induced hepcidin expression and p-SMAD1 signaling in a dose- and time-dependent manner. Consistently, Hep3B cells lacking HS (EXT1-/-) show no hepcidin suppression in response to halofuginone. In vivo administration of halofuginone reduces hepcidin expression in an iron-overload mouse model (8.3 g/kg carbonyl iron). This effect was absent in mice with impaired liver HS sulfation (Ndst1f/fAlbCre+), confirming that halofuginone suppresses hepcidin via HSPG-mediated mechanisms. Additionally, halofuginone decreased hepcidin expression in mice subjected to acute inflammation. These findings establish halofuginone as a potential therapeutic for mitigating hepcidin-driven iron restriction in anemic disorders. Show less

Genome-wide association studies (GWAS) aim at identifying genomic regions involved in phenotype expression, but identifying causative variants is difficult. Pig Combined Annotation Dependent Depletion (pCADD) scores provide a measure of the predicted consequences of genetic variants. Incorporating pCADD into the GWAS pipeline may help their identification. Our objective was to identify genomic regions associated with loin depth and muscle pH, and identify regions of interest for fine-mapping and further experimental work. Genotypes for ~ 40,000 single nucleotide morphisms (SNPs) were used to perform GWAS for these two traits, using de-regressed breeding values (dEBV) for 329,964 pigs from four commercial lines. Imputed sequence data was used to identify SNPs in strong ([Formula: see text] 0.80) linkage disequilibrium with lead GWAS SNPs with the highest pCADD scores. Fifteen distinct regions were associated with loin depth and one with loin pH at genome-wide significance. Regions on chromosomes 1, 2, 5, 7, and 16, explained between 0.06 and 3.55% of the additive genetic variance and were strongly associated with loin depth. Only a small part of the additive genetic variance in muscle pH was attributed to SNPs. The results of our pCADD analysis suggests that high-scoring pCADD variants are enriched for missense mutations. Two close but distinct regions on SSC1 were associated with loin depth, and pCADD identified the previously identified missense variant within the MC4R gene for one of the lines. For loin pH, pCADD identified a synonymous variant in the RNF25 gene (SSC15) as the most likely candidate for the muscle pH association. The missense mutation in the PRKAG3 gene known to affect glycogen content was not prioritised by pCADD for loin pH. For loin depth, we identified several strong candidate regions for further statistical fine-mapping that are supported in the literature, and two novel regions. For loin muscle pH, we identified one previously identified associated region. We found mixed evidence for the utility of pCADD as an extension of heuristic fine-mapping. The next step is to perform more sophisticated fine-mapping and expression quantitative trait loci (eQTL) analysis, and then interrogate candidate variants in vitro by perturbation-CRISPR assays. Show less

This paper reviews the localization of published potential causative variants in contemporary pig and cattle reference genomes, and the evidence for their causality. In spite of the difficulties inherent to the identification of causative variants from genetic mapping and genome-wide association studies, researchers in animal genetics have proposed putative causative variants for several traits relevant to livestock breeding. For this review, we read the literature that supports potential causative variants in 13 genes (ABCG2, DGAT1, GHR, IGF2, MC4R, MSTN, NR6A1, PHGK1, PRKAG3, PLRL, RYR1, SYNGR2 and VRTN) in cattle and pigs, and localized them in contemporary reference genomes. We review the evidence for their causality, by aiming to separate the evidence for the locus, the proposed causative gene and the proposed causative variant, and report the bioinformatic searches and tactics needed to localize the sequence variants in the cattle or pig genome. Taken together, there is usually good evidence for the association at the locus level, some evidence for a specific causative gene at eight of the loci, and some experimental evidence for a specific causative variant at six of the loci. We recommend that researchers who report new potential causative variants use referenced coordinate systems, show local sequence context, and submit variants to repositories. Show less