Biology subjects

Lupu, F.

Publications and source records attributed to Lupu, F..

4 recordsLinked to original sources

bioRxiv2024

S1PR1 Regulates Lymphatic Valve Development And Prevents Ileitis-Independent Tertiary Lymphoid Organ Formation

Lymphatic vessels function throughout the body to drain interstitial fluids. Efficient lymph flow is ensured by lymphatic valves (LVs). However, the mechanisms that regulate LV development are incompletely understood. Here, we show that the deletion of the GPCR sphingosine 1-phosphate receptor-1 (S1PR1) from lymphatic endothelial cells (LECs) results in fewer LVs. Interestingly, LVs that remained in the terminal-ileum draining lymphatic vessels were specifically dysfunctional, and tertiary lymphoid organs (TLOs) formed in this location. TLOs in the terminal ileum are associated with ileitis in humans and mice. However, mice lacking S1PR1 did not develop obvious characteristics of ileitis. Sphingosine kinases 1 and 2 (SPHK1/2) are required for the synthesis of S1P, the ligand of S1PR1. Mice that lack Sphk1/2 in LECs recapitulate the LV and TLO phenotypes of mice that lack S1PR1. Mechanistically, S1PR1 regulates shear stress signaling and the expression of the valve-regulatory molecules FOXC2 and connexin-37. Importantly, Foxc2+/- mice, a model for lymphedema-distichiasis syndrome, also develop TLOs in the terminal ileum. Thus, we have discovered S1PR1 as a previously unknown regulator of LV and TLO development. We also suggest that TLOs are a sign of subclinical inflammation that can form due to lymphatic disorders in the absence of ileitis.

developmental biology↗

bioRxiv2023

Tissue-specific sex difference in the metabolism of fatty acid esters of hydroxy fatty acids

Fatty acid esters of hydroxy fatty acids (FAHFAs) are endogenous bioactive lipids known for their anti-inflammatory and anti-diabetic properties. Despite their therapeutic potential, little is known about the sex-specific variations in FAHFA metabolism. This study investigated the role of Androgen Dependent TFPI Regulating Protein (ADTRP), a FAHFA hydrolase. Additionally, tissue-specific differences in FAHFA levels, focusing on the perigonadal white adipose tissue (pgWAT), subcutaneous white adipose tissue (scWAT), brown adipose tissue (BAT), plasma, and liver, were evaluated using metabolomics and lipidomics. We found that female mice exhibited higher FAHFA levels in pgWAT, scWAT, and BAT compared to males. FAHFA levels were inversely related to Adtrp mRNA, which showed significantly lower expression in females compared with males in pgWAT and scWAT. However, no significant differences between the sexes were observed in plasma and liver FAHFA levels. Adtrp deletion had minimal impact on both sexes metabolome and lipidome of pgWAT. However, we discovered higher endogenous levels of triacylglycerol estolides containing FAHFAs, a FAHFA metabolic reservoir, in the pgWAT of female mice. These findings suggest that sex-dependent differences in FAHFA levels occur primarily in specific WAT depots and may modulate local insulin sensitivity in adipocytes. However, further investigations are warranted to fully comprehend the underlying mechanisms and implications of sex effects on FAHFA metabolism in humans.

biochemistry↗

bioRxiv2023

Epigenetic Regulation of Endothelial Extracellular Matrix Components is Critical for Murine Lung Development

BackgroundThe chromatin remodeling enzymes BRG1 (brahma-related gene 1) and CHD4 (chromodomain helicase DNA binding protein 4) independently regulate transcription of genes critical for vascular development, but their coordinated impact on vessels in late- stage embryos has not been explored. MethodsIn this study we genetically deleted endothelial Brg1 and Chd4 in mixed background mice (Brg1fl/fl;Chd4fl/fl;VE-Cadherin-Cre+), and littermates that were negative for Cre recombinase were used as controls. Perinatal lung tissue was analyzed by immunostaining, immunoblots, and flow cytometry. Quantitative reverse transcription PCR was used to determine gene expression, and chromatin immunoprecipitation revealed gene targets of BRG1 and CHD4 in cultured endothelial cells (ECs). ResultsWe found that Brg1/Chd4 double mutants died soon after birth with small and compact lungs. Despite having normal cellular composition, distal air sacs of the mutant lungs displayed diminished ECM (extracellular matrix) components and TGF{beta} (transforming growth factor beta) signaling, which typically promotes matrix synthesis. Transcripts for collagen- and elastin-related genes and the TGF{beta} ligand Tgfb1 were decreased in mutant lung ECs, but genetic deletion of endothelial Tgfb1 failed to recapitulate the small lungs and ECM defects seen in Brg1/Chd4 mutants. We instead found several ECM genes to be direct targets of BRG1 and CHD4 in cultured ECs. ConclusionsCollectively, our data highlight essential roles for ECs in promoting ECM deposition at late stages of embryonic lung development. Moreover, this endothelial ECM production is epigenetically regulated. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/552718v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@210be1org.highwire.dtl.DTLVardef@192ee2dorg.highwire.dtl.DTLVardef@1530595org.highwire.dtl.DTLVardef@1938529_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIGenetic deletion of the chromatin remodeling enzymes BRG1 and CHD4 in endothelial cells of late-stage mouse embryos (Brg1/Chd4-ECdko) results in small and compact lungs at birth. C_LIO_LIMutant embryos display reduced collagen IV deposition, dysregulated elastin fibers, and diminished TGF{beta}1 in the distal air sacs. C_LIO_LIOur combined in vitro and in vivo analyses indicate that BRG1 and CHD4 epigenetically regulate collagen IV- and elastin-related gene expression in embryonic ECs to promote proper lung development. C_LI

developmental biology↗

bioRxiv2023

PROX1 inhibits PDGF-B expression to prevent myxomatous degeneration of heart valves

BackgroundCardiac valve disease (CVD) is observed in 2.5% of the general population and 10% of the elderly people. Effective pharmacological treatments are currently not available, and patients with severe CVD require surgery. PROX1 and FOXC2 are transcription factors that are required for the development of lymphatic and venous valves. We found that PROX1 and FOXC2 are expressed in a subset of valvular endothelial cells (VECs) that are located on the downstream (fibrosa) side of cardiac valves. Whether PROX1 and FOXC2 regulate cardiac valve development and disease is not known. MethodsWe used histology, electron microscopy and echocardiography to investigate the structure and functioning of heart valves from Prox1{Delta}VEC mice in which Prox1 was conditionally deleted from VECs. Isolated valve endothelial cells and valve interstitial cells were used to identify the molecular mechanisms in vitro, which were tested in vivo by RNAScope, additional mouse models and pharmacological approaches. The significance of our findings was tested by evaluation of human samples of mitral valve prolapse (MVP) and aortic valve insufficiency. ResultsHistological analysis revealed that the aortic and mitral valves of Prox1{Delta}VEC mice become progressively thick and myxomatous. Echocardiography revealed that the aortic valves of Prox1{Delta}VEC mice are stenotic. FOXC2 was downregulated and platelet-derived growth factor-B (PDGF-B) was upregulated in the VECs of Prox1{Delta}VEC mice. Conditional knockdown of FOXC2 and conditional overexpression of PDGF-B in VECs recapitulated the phenotype of Prox1{Delta}VEC mice. PDGF-B was also increased in mice lacking FOXC2 and in human MVP and insufficient aortic valve samples. Pharmacological inhibition of PDGF-B signaling with imatinib partially ameliorated the valve defects of Prox1{Delta}VEC mice. ConclusionPROX1 antagonizes PDGF-B signaling partially via FOXC2 to maintain the extracellular matrix composition and prevent myxomatous degeneration of cardiac valves. Novelty and SignificanceWhat Is Known? O_LIThe transcription factors PROX1 and FOXC2 are critical regulators of lymphatic and venous valve development. C_LIO_LIPROX1 and FOXC2 are expressed in the downstream valvular endothelial cells of heart valves. C_LI What Is New? O_LIDeletion of Prox1 from the valvular endothelial cells of mice results in enlarged and myxomatous aortic and mitral valves. Aortic valves of the mutant (Prox1{Delta}VEC) mice were stenotic. C_LIO_LIFOXC2 is partially responsible for the phenotype of Prox1{Delta}VEC mice. C_LIO_LIPROX1 and FOXC2 inhibit the expression of the cytokine PDGF-B in heart valves. C_LIO_LIHyperactivation of PDGF-B signaling results in aortic and mitral valve thickening. C_LIO_LIInhibition of PDGF-B signaling ameliorates aortic valve stenosis in Prox1{Delta}VEC mice. C_LIO_LIPDGFB is overexpressed and PROX1 is downregulated in human mitral valve prolapse (MVP) samples. C_LI Our findings suggest that PROX1 is an inhibitor of myxomatous valve disease that afflicts ~10% of the elderly population. We have also identified PDGF-B as a potential target for treating myxomatous valve disease.

developmental biology↗