Sequences Sufficient for Programming Imprinted Germline DNA Methylation Defined

Epigenetic marks are fundamental to normal development, but little is known about signals that dictate their placement. Insights have been provided by studies of imprinted loci in mammals, where monoallelic expression is epigenetically controlled. Imprinted expression is regulated by DNA methylation programmed during gametogenesis in a sex-specific manner and maintained after fertilization. At Rasgrf1 in mouse, paternal-specific DNA methylation on a differential methylation domain (DMD) requires downstream tandem repeats. The DMD and repeats constitute a binary switch regulating paternal-specific expression. Here, we define sequences sufficient for imprinted methylation using two transgenic mouse lines: One carries the entire Rasgrf1 cluster (RC); the second carries only the DMD and repeats (DR) from Rasgrf1. The RC transgene recapitulated all aspects of imprinting seen at the endogenous locus. DR underwent proper DNA methylation establishment in sperm and erasure in oocytes, indicating the DMD and repeats are sufficient to program imprinted DNA methylation in germlines. Both transgenes produce a DMD-spanning pit-RNA, previously shown to be necessary for imprinted DNA methylation at the endogenous locus. We show that when pit-RNA expression is controlled by the repeats, it regulates DNA methylation in cis only and not in trans. Interestingly, pedigree history dictated whether established DR methylation patterns were maintained after fertilization. When DR was paternally transmitted followed by maternal transmission, the unmethylated state that was properly established in the female germlines could not be maintained. This provides a model for transgenerational epigenetic inheritance in mice

Syndrome de Gougerot-Sjögren et/ou Sarcoïdose. Pathologies associées (discussion autour d'un cas)

PARIS7-Villemin (751102101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

[Human embryonic stem cells to rescue fulminant hepatic failure]

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Serious game versus online course for pretraining medical students before a simulation-based mastery learning course on cardiopulmonary resuscitation

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La prison du Pied-du-Courant

Background & Aims: We have specified the features of progressive familial intrahepatic cholestasis type 3 and investigated in 31 patients whether a defect of the multidrug resistance 3 gene (MDR3) underlies this phenotype. Methods: MDR3 sequencing liver MDR3 immunohistochemistry, and biliary phospholipid dosage were performed, Results: Liver histology showed a pattern of biliary cirrhosis with patency of the biliary tree. Age at presentation ranged from the neonatal period to early adulthood. Sequence analysis revealed 16 different mutations in 17 patients. Mutations were identified on both alleles in 12 patients and only on 1 allele in 5, Four mutations lead to a frame shift, 2 are nonsense, and 10 are missense, An additional missense mutation probably representing a polymorphism was found in 5 patients, MDR3 mutations were associated with abnormal MDRB canalicular staining and a low proportion of biliary phospholipids, Gallstones or episodes of cholestasis of pregnancy were found in patients or parents. Children with missense mutations had a less severe disease and more often a beneficial effect of ursodeoxycholic acid therapy. Conclusions: At least one third of the patients with a progressive familial intrahepatic cholestasis type 3 phenotype have a proven defect of MDR3, This gene defect should also be considered in adult liver diseases