Dataset Information

Regulation of intracellular heme by FLVCR2 modulates retinal angiogenesis

ABSTRACT: Fowler syndrome is an embryonic lethal disease with proliferative vasculopathy and hydranencephaly-hydrocephaly of the central nervous system due to mutations in Feline Leukemia Virus Subgroup C Receptor-Related Protein 2 (FLVCR2) characterized by large regions of hypovascularization along with glomeruloid formation of poorly organized vascular endothelial cell mass. Recent animal models have characterized reduced vascularization in brain in gene deletion models of Flvcr2. Here, we use conditional knockout of Flvcr2 in mice and knockdown in cell culture to explore retinal development and further understand the mechanism of angiogenic regulation by Flvcr2. Gene deletion of Flvcr2 or chemical inhibition of heme synthesis led to reduced retinal vascular expansion and reduced formation of deep capillary plexus with a partial penetrance of a severe phenotype with dramatic reduction in vascular expansion and glomeruloid and endothelial mass formation. Cell culture studies reveal reduced heme content in cells with Flvcr2 knockdown associated with increased stalk cell specification and hyperproliferation that could be reversed with addition of heme precursor. These effects could be recapitulated with chemical inhibition of heme synthesis and reversed with soluble hemin addition. Overexpression of Flvcr2 or addition of soluble hemin prevented VEGF induced proliferation without affecting receptor activation. Collectively, the data indicate a newly identified role for heme in the regulation of tip/stalk specification and vascular angiogenesis.

ORGANISM(S): Bos taurus

PROVIDER: GSE283153 | GEO | 2026/07/22

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Hemes are essential but potentially cytotoxic cofactors that participate in critical and diverse biological processes. Although the pathway and intermediates for heme biosynthesis have been well defined, the intracellular networks which mediate heme trafficking remain unknown. Caenorhabditis elegans and related helminths are natural heme auxotrophs requiring environmental heme for growth and development. We exploited this auxotrophy to identify HRG-1 and HRG-4 in C. elegans and show that they are essential for heme homeostasis and normal vertebrate development. We demonstrate that heme deficiency upregulates expression of hrg-4 and its evolutionarily conserved paralog hrg-1. Depletion of either HRG-1 or HRG-4 in worms results in disruption of organismal heme sensing and abnormal response to heme analogs. HRG-1 and HRG-4 are novel transmembrane proteins that bind heme and have evolutionarily conserved functions. Transient knockdown of hrg-1 in zebrafish leads to hydrocephalus, yolk tube malformations, and, most strikingly, profound defects in erythropoiesis - phenotypes that are fully rescued by worm HRG-1. These findings reveal unanticipated and conserved pathways for cellular heme trafficking in animals that defines the paradigm for eukaryotic heme transport. Uncovering the mechanisms of heme transport in C. elegans will provide novel insights into human disorders of heme metabolism and generate unique anthelmintics to combat worm infestations. Experiment Overall Design: As a first-step toward understanding heme homeostasis at the molecular level, we performed genome-wide microarrays to identify genes that are transcriptionally regulated by heme. For microarray analysis, synchronized F2 larvae were re-inoculated in mCeHR-2 medium supplemented with 4, 20 or 500 uM hemin and harvested at the late L4 stage for mRNA prep and probe hybridization to Affymetrix C. elegans Whole Genome Expression Arrays. Total RNA from three biological replicates were used at each hemin concentration. Data from worms grown in mCeHR-2 medium with 4 and 500 uM hemin were compared to data from worms grown in 20 uM hemin. Microarray data were verified with Microarray Suite 5.0 (Affymetrix) and Robust Multichip Average Method (RMA, R package). Results from MAS 5.0 and RMA analyses provided with 375 genes that showed 1.6 fold change in 4 and 500 uM hemin when compared to data from 20 uM hemin samples. Statistical analyses identified changes in 375 genes from worms grown in either 4 or 500 ÂµM heme (see Methods). The microarray results were validated by qRT-PCR (Supplementary Fig. 1) and the 375 heme-responsive genes were classified into eight categories based on their relative changes in gene expression (Table I). The data from the microarray study show that â?°1.9 % of genes in the worm genome are transcriptionally responsive to heme. Notably, of the 375 genes, 164 had some sequence identity in human genome databases at the amino acid level, and >90 % of the genes had no ascribed function in the C.

Project description:The response regulator HrrA belonging to the HrrSA two-component system (previously named CgtSR11) is known to be repressed by the global iron-dependent regulator DtxR in Corynebacterium glutamicum. Sequence analysis indicated an involvement of the HrrSA system in heme-dependent gene expression. Growth experiments revealed that the non-pathogenic soil bacterium C. glutamicum is able to use hemin or hemoglobin as sole iron source. In DNA microarray analyses a putative operon encoding the hemin-binding protein HtaA and the putative hemin ABC transporter HmuTUV showed a strong upregulation in heme-grown cells. Deletion of the hmu operon clearly affects heme utilization, but does not completely abolish growth on heme or hemoglobin. As a central part of this study, we investigated the regulon of the response regulator HrrA via comparative transcriptome analysis of a hrrA deletion mutant and C. glutamicum wild type in combination with DNA-protein interaction studies with purified HrrA protein. Our data provide evidence for a heme-dependent transcriptional activation of heme oxygenase (hmuO), an enzyme involved in the utilization of heme as iron source. Besides hmuO, HrrA was shown to activate the expression of heme-containing components of the respiratory chain, namely ctaD and the ctaE-qcrCAB operon encoding subunits I and III of cytochrome aa3 oxidase and three subunits of the cytochrome bc1 complex. Furthermore, HrrA represses almost all genes involved in heme biosynthesis, including glutamyl-tRNA reductase (hemA), uroporphyrinogen decarboxylase (hemE), and ferrochelatase (hemH). Thus, our data clearly emphasize a central role of the HrrSA system in the control of heme homeostasis in C. glutamicum. Three biological replicates of each experiment were performed. Experiment 1: Transcriptome comparison of wild type grown und FeSO4 or heme as iron source; Exp. 2: WT vs. hrrA deletion mutant grown on FeSO4; Exp. 3: WT vs. hrrA mutant grown on heme. For analysis via DNA microarraysose RNA was isolated from exponentially growing cells cultivated in CgXII medium containing glucose as carbon source and either 2.5 uM FeSO4 or 2.5 uM heme as iron source.

Dataset Information

Regulation of intracellular heme by FLVCR2 modulates retinal angiogenesis

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets