H008 Le blocage des récepteurs AT1 de L′angiotensine II inhibe L′hypertrophie ventriculaire gauche et L′activation de FHL1 chez la souris hétérozygote déficiente en cMyBP-C

Les mutations de la protéine C cardiaque (cMyBP-C) sont une cause de cardiomyopathies hypertrophiques (CMH). Les souris transgéniques hétérozygotes défi cientes en cMyBP-C (HET) présentent une CMH d′apparition tardive à fonction systolique conservée. Le système rénine angiotensine (SRA) cardiaque joue un rôle important dans l′hypertrophie, mais son rôle dans le développement d′une CMH génétiquement déterminée a été peu étudié.Cette étude évaluait le rôle du SRA dans l′induction de la CMH chez la souris HET. Des souris HET et sauvages (WT), âgées de 5 mois, ont été traitées par irbésartan (50mg/kg/jour) ou placebo pendant 8 semaines. L′expression dans le ventricule gauche (VG) des gènes de l′enzyme de conversion de l′angiotensine I (ACE), du récepteur AT1 de l′angiotensine II (AGTR1), de la calcineurine A (PPP3CB) de la calcipressin 1 (RCAN1), et de FHL1 (four and a half LIM domains 1, une protéine associée à cMyBP-C au sein du sarcomère) a été analysée par RT-qPCR.Après 8 semaines de traitement, la pression artérielle est normale dans tous les groupes. Le poids du VG/poids du corps des souris HET est augmenté par rapport aux WT (3,9±0,3 vs. 3,3±0,4mg/g; p<0.01) dans le groupe placebo. Dans les groupes traités par irbésartan, ce rapport est comparable pour les souris HET (3,4±0,5mg/g) et WT (3,2±0,4mg/g; p=ns). L′expression des gènes de l′ACE, PPP3CB et RCAN1 est comparable entre les souris HET et WT et n′est pas affectée par le traitement par irbésartan. L′expression d′AGTR1 est similaire chez les souris HET et WT traitées par placebo mais augmente après traitement par irbésartan uniquement chez les souris HET. A l′inverse, l′expression de FHL1 est activée chez les souris HET par rapport aux souris WT mais cette augmentation est prévenue par le traitement par irbésartan.En conclusion, chez la souris cMyBP-C, le développement de l′hypertrophie est accompagné par une augmentation de l′expression du gène FHL1 dans le VG. Le traitement par irbésartan inhibe l′hypertrophie et l′activation de l′expression de FHL1 don′t le mécanisme reste à déterminer

Nanostructural and Transcriptomic Analyses of Human Saliva Derived Exosomes

Exosomes, derived from endocytic membrane vesicles are thought to participate in cell-cell communication and protein and RNA delivery. They are ubiquitous in most body fluids (breast milk, saliva, blood, urine, malignant ascites, amniotic, bronchoalveolar lavage, and synovial fluids). In particular, exosomes secreted in human saliva contain proteins and nucleic acids that could be exploited for diagnostic purposes. To investigate this potential use, we isolated exosomes from human saliva and characterized their structural and transcriptome contents.Exosomes were purified by differential ultracentrifugation and identified by immunoelectron microscopy (EM), flow cytometry, and Western blot with CD63 and Alix antibodies. We then described the morphology, shape, size distribution, and density using atomic force microscopy (AFM). Microarray analysis revealed that 509 mRNA core transcripts are relatively stable and present in the exosomes. Exosomal mRNA stability was determined by detergent lysis with RNase A treatment. In vitro, fluorescently labeled saliva exosomes could communicate with human keratinocytes, transferring their genetic information to human oral keratinocytes to alter gene expression at a new location.Our findings are consistent with the hypothesis that exosomes shuttle RNA between cells and that the RNAs present in the exosomes may be a possible resource for disease diagnostics

Construction of 3D models of the CYP11B family as a tool to predict ligand binding characteristics

Aldosterone is synthesised by aldosterone synthase (CYP11B2). CYP11B2 has a highly homologous isoform, steroid 11β-hydroxylase (CYP11B1), which is responsible for the biosynthesis of aldosterone precursors and glucocorticoids. To investigate aldosterone biosynthesis and facilitate the search for selective CYP11B2 inhibitors, we constructed three-dimensional models for CYP11B1 and CYP11B2 for both human and rat. The models were constructed based on the crystal structure of Pseudomonas Putida CYP101 and Oryctolagus Cuniculus CYP2C5. Small steric active site differences between the isoforms were found to be the most important determinants for the regioselective steroid synthesis. A possible explanation for these steric differences for the selective synthesis of aldosterone by CYP11B2 is presented. The activities of the known CYP11B inhibitors metyrapone, R-etomidate, R-fadrazole and S-fadrazole were determined using assays of V79MZ cells that express human CYP11B1 and CYP11B2, respectively. By investigating the inhibitors in the human CYP11B models using molecular docking and molecular dynamics simulations we were able to predict a similar trend in potency for the inhibitors as found in the in vitro assays. Importantly, based on the docking and dynamics simulations it is possible to understand the enantioselectivity of the human enzymes for the inhibitor fadrazole, the R-enantiomer being selective for CYP11B2 and the S-enantiomer being selective for CYP11B1

A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15-1.73 GHz

We conducted a search for narrowband radio signals over four observing sessions in 2020-2023 with the L-band receiver (1.15-1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of ~11,680 stars and planetary systems in the ~9 arcminute beam of the telescope. All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. In this work, we also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable frequency range of the receiver and 98.7% of the injections when regions of dense RFI are excluded. In another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ~15 times smaller at ~6%. The pipeline efficiency affects calculations of transmitter prevalence and SETI search volume. Accordingly, we developed an improved Drake Figure of Merit and a formalism to place upper limits on transmitter prevalence that take the pipeline efficiency and transmitter duty cycle into account. Based on our observations, we can state at the 95% confidence level that fewer than 6.6% of stars within 100 pc host a transmitter that is detectable in our search (EIRP > 1e13 W). For stars within 20,000 ly, the fraction of stars with detectable transmitters (EIRP > 5e16 W) is at most 3e-4. Finally, we showed that the UCLA SETI pipeline natively detects the signals detected with AI techniques by Ma et al. (2023).Comment: 22 pages, 9 figures, submitted to AJ, revise