ABSTRACT
OBJECTIVE: Pseudoxanthoma elasticum is an inherited metabolic disorder resulting from ABCC6 gene mutations. It is characterized by progressive calcification and fragmentation of elastic fibers in the skin, retina, and the arterial wall. Despite calcium accumulation in the arteries of patients with pseudoxanthoma elasticum, functional consequences remain unknown. In the present study, we investigated arterial structure and function in Abcc6(-/-) mice, a model of the human disease. APPROACH AND RESULTS: Arterial calcium accumulation was evaluated using alizarin red stain and atomic absorption spectrometry. Expression of genes involved in osteochondrogenic differentiation was measured by polymerase chain reaction. Elastic arterial properties were evaluated by carotid echotracking. Vascular reactivity was evaluated using wire and pressure myography and remodeling using histomorphometry. Arterial calcium accumulation was 1.5- to 2-fold higher in Abcc6(-/-) than in wild-type mice. Calcium accumulated locally leading to punctuate pattern. Old Abcc6(-/-) arteries expressed markers of both osteogenic (Runx2, osteopontin) and chondrogenic lineage (Sox9, type II collagen). Abcc6(-/-) arteries displayed slight increase in arterial stiffness and vasoconstrictor tone in vitro tended to be higher in response to phenylephrine and thromboxane A2. Pressure-induced (myogenic) tone was significantly higher in Abcc6(-/-) arteries than in wild type. Arterial blood pressure was not significantly changed in Abcc6(-/-), despite higher variability. CONCLUSIONS: Scattered arterial calcium depositions are probably a result of osteochondrogenic transdifferentiation of vascular cells. Lower elasticity and increased myogenic tone without major changes in agonist-dependent contraction evidenced in aged Abcc6(-/-) mice suggest a reduced control of local blood flow, which in turn may alter vascular homeostasis in the long term.
Subject(s)
ATP-Binding Cassette Transporters/deficiency , Arteries/metabolism , Calcium/metabolism , Elastic Tissue/metabolism , Pseudoxanthoma Elasticum/metabolism , Vascular Calcification/metabolism , Vascular Stiffness , Vasoconstriction , ATP-Binding Cassette Transporters/genetics , Animals , Arterial Pressure , Arteries/pathology , Arteries/physiopathology , Biomarkers/metabolism , Cell Transdifferentiation , Chondrogenesis , Collagen Type II/genetics , Collagen Type II/metabolism , Core Binding Factor Alpha 1 Subunit/genetics , Core Binding Factor Alpha 1 Subunit/metabolism , Disease Models, Animal , Elastic Tissue/pathology , Elastic Tissue/physiopathology , Gene Expression Regulation , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Multidrug Resistance-Associated Proteins , Osteogenesis , Osteopontin/genetics , Osteopontin/metabolism , Pseudoxanthoma Elasticum/genetics , Pseudoxanthoma Elasticum/pathology , Pseudoxanthoma Elasticum/physiopathology , RNA, Messenger/metabolism , Regional Blood Flow , SOXB1 Transcription Factors/genetics , SOXB1 Transcription Factors/metabolism , Vascular Calcification/genetics , Vascular Calcification/pathology , Vascular Calcification/physiopathologyABSTRACT
In resistance arteries, a chronic increase in blood flow induces hypertrophic outward remodeling. This flow-mediated remodeling (FMR) is absent in male rats aged 10 mo and more. As FMR depends on estrogens in 3-mo-old female rats, we hypothesized that it might be preserved in 12-mo-old female rats. Blood flow was increased in vivo in mesenteric resistance arteries after ligation of the side arteries in 3- and 12-mo-old male and female rats. After 2 wk, high-flow (HF) and normal-flow (NF) arteries were isolated for in vitro analysis. Arterial diameter and cross-sectional area increased in HF arteries compared with NF arteries in 3-mo-old male and female rats. In 12-mo-old rats, diameter increased only in female rats. Endothelial nitric oxide synthase expression and endothelium-mediated relaxation were higher in HF arteries than in NF arteries in all groups. ERK1/2 phosphorylation, NADPH oxidase subunit expression levels, and arterial contractility to KCl and to phenylephrine were greater in HF vessels than in NF vessels in 12-mo-old male rats only. Ovariectomy in 12-mo-old female rats induced a similar pattern with an increased contractility without diameter increase in HF arteries. Treatment of 12-mo-old male rats and ovariectomized female rats with hydralazine, the antioxidant tempol, or the angiotensin II type 1 receptor blocker candesartan restored HF remodeling and normalized arterial contractility in HF vessels. Thus, we found that FMR of resistance arteries remains efficient in 12-mo-old female rats compared with age-matched male rats. A balance between estrogens and vascular contractility might preserve FMR in mature female rats.
Subject(s)
Estrogens/metabolism , Mesenteric Arteries/physiology , Vascular Remodeling , Vascular Resistance , Age Factors , Animals , Benzimidazoles/pharmacology , Biphenyl Compounds , Cyclic N-Oxides/pharmacology , Estrogens/pharmacology , Female , Hydralazine/pharmacology , Male , Mesenteric Arteries/drug effects , Mesenteric Arteries/growth & development , Mesenteric Arteries/metabolism , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/metabolism , NADPH Oxidases/metabolism , Nitric Oxide Synthase Type III/genetics , Nitric Oxide Synthase Type III/metabolism , Rats , Rats, Wistar , Spin Labels , Tetrazoles/pharmacology , Vasoconstriction , Vasoconstrictor Agents/pharmacology , Vasodilation , Vasodilator Agents/pharmacologyABSTRACT
OBJECTIVE: Flow- (shear stress-)mediated outward remodeling of resistance arteries is involved in collateral growth during postischemic revascularization. As this remodeling is especially important during pregnancy, we hypothesized that estrogens may be involved. A surgical model eliciting a local increase in blood flow in 1 mesenteric resistance artery was used in 3-month-old ovariectomized female rats either treated with 17-ß-estradiol (E2) or left untreated. METHODS AND RESULTS: After 14 days, arterial diameter was greater in high-flow arteries than in normal-flow vessels. An ovariectomy suppressed high-flow remodeling, while E2 restored it. High-flow remodeling was absent in mice lacking the estrogen receptor α but not estrogen receptor ß. The kinetics of inflammatory marker expression, macrophage infiltration, oxidative stress, and metaloproteinases expression were not altered by the absence of E2 after 2 and 4 days, that is, during remodeling. Nevertheless, E2 was required for the increase in endothelial nitric oxide synthase expression and activation at day 4 when diameter expansion occurs. Finally, the impact of E2 on the endothelium appeared crucial for high-flow remodeling, as this E2 action was abrogated in mice lacking endothelial NOS, as well as in Tie2-Cre(+) ERα(f/f) mice. CONCLUSIONS: We demonstrate the essential role of E2 and endothelial estrogen receptor α in flow-mediated remodeling of resistance arteries in vivo.
Subject(s)
Endothelial Cells/metabolism , Estradiol/administration & dosage , Estrogen Receptor alpha/agonists , Estrogen Replacement Therapy , Mesenteric Arteries/drug effects , Vascular Resistance/drug effects , Animals , Blood Pressure/drug effects , Caveolin 1/metabolism , Endothelial Cells/drug effects , Estrogen Receptor alpha/deficiency , Estrogen Receptor alpha/genetics , Estrogen Receptor beta/deficiency , Estrogen Receptor beta/genetics , Female , Mesenteric Arteries/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Nitric Oxide/metabolism , Nitric Oxide Synthase Type III/deficiency , Nitric Oxide Synthase Type III/genetics , Ovariectomy , Phosphorylation , Rats , Rats, Wistar , Regional Blood Flow/drug effects , Splanchnic Circulation/drug effects , Time Factors , Vasodilation/drug effectsABSTRACT
In lower and higher eukaryotes, a family of tightly related proteins designated eRF1 (for eukaryotic release factor 1) catalyses termination of protein synthesis at all three stop codons. The human genome contains four eRF1 homologous sequences localised on chromosomes 5, 6, 7 and X. We report here the cloning and the structural analysis of the human eRF1 gene family. It appears that the gene located on chromosome 5 alone is potentially functional, whereas the other three sequences resemble processed pseudogenes. This is the first description of the structural organisation of the human eRF1 gene, which has been remarkably conserved during evolution and which is essential in the translation termination process.
Subject(s)
Chromosomes, Human, Pair 5 , Peptide Termination Factors/chemistry , Peptide Termination Factors/genetics , Pseudogenes , Base Sequence , Chromosomes, Human, Pair 6 , Chromosomes, Human, Pair 7 , Cloning, Molecular , Cosmids , Exons , Gene Library , Humans , Introns , Models, Genetic , Molecular Sequence Data , Saccharomyces cerevisiae/genetics , X ChromosomeABSTRACT
Heparin (Hep) and sulfated polysaccharides (SPs) have been reported to inhibit HIV infection in vitro. In vivo, anticoagulant activity and reduced bioavailability were found to limit the antiviral effects of Hep. In this investigation, three nonanticoagulant N-acylated Hep conjugates [OI1:3Hep, Pal1:5Hep, and Pal1:5Hep(SO4)] were compared to Hep for their ability to interact with HIV replication in CD4-positive cell lines and PBMCs. Resulfated palmitoyl-Hep [Pal1:5Hep(SO4)] exhibited the strongest anti-HIV effects. For instance, no provirus HIV DNA was detected in the genome of HIV-1-LAI-infected PBMCs treated with this heparin derivative. Cell-to-cell fusion and RT activity were explored to explain these differences. Hep and Pal1:5Hep(SO4) derivative exerted identical effects on cell-to-cell fusion. On the other hand, Pal1:5Hep(SO4) displayed the strongest inhibitory effects in the acellular RT inhibition assay. This suggests that RT might be a second target for N-acylated Hep, even though SP uptake and the preferential effects of SPs on RT as opposed to DNA polymerase have not yet been demonstrated. Nevertheless, considering the anticoagulant, antiviral, and antiinflammatory effects of N-acylated Hep, the N-acylated Hep derivatives might be excellent candidates as new anti-HIV pharmacological tools.
Subject(s)
Antiviral Agents/pharmacology , CD4-Positive T-Lymphocytes/virology , HIV-1/drug effects , HIV-2/drug effects , Heparin/analogs & derivatives , Heparin/pharmacology , CD4-Positive T-Lymphocytes/cytology , Cell Fusion , Cell Line , Cells, Cultured , DNA, Viral/genetics , HIV-1/genetics , HIV-2/genetics , Humans , Leukocytes, Mononuclear/cytology , Leukocytes, Mononuclear/virology , Phytohemagglutinins/pharmacology , RNA-Directed DNA Polymerase/drug effects , RNA-Directed DNA Polymerase/metabolism , Virus IntegrationABSTRACT
The human genome contains four ETF1 (eukaryotic translation termination factor 1) homologous sequences, localized on chromosomes 5, 6, 7 and X, and corresponding to a functional gene on chromosome 5 and three processed pseudogenes on the other chromosomes. ETF1 genomic or cDNA probes were mapped by fluorescence in situ hybridization to 5q31, 6p21, 7q11 and Xp11.4-->p11.1. A microsatellite marker (D5S500) was identified in intron 7 of the functional ETF1 gene providing its exact position in the 5q31 band. Thus, the ETF1 gene is located in a 5q region which contains unidentified genes responsible for genetic or malignant disorders, and it might be considered as a candidate gene involved in the pathogenesis of these diseases.