BACKGROUND: Genomic imprinting is an epigenetic phenomenon that allows a subset of genes to be expressed mono-allelically based on the parent of origin and is typically regulated by differential DNA methylation inherited from gametes. Imprinting is pervasive in murine extra-embryonic lineages, and uniquely, the imprinting of several genes has been found to be conferred non-canonically through maternally inherited repressive histone modification H3K27me3. However, the underlying regulatory mechanisms of non-canonical imprinting in post-implantation development remain unexplored. RESULTS: We identify imprinted regions in post-implantation epiblast and extra-embryonic ectoderm (ExE) by assaying allelic histone modifications (H3K4me3, H3K36me3, H3K27me3), gene expression, and DNA methylation in reciprocal C57BL/6 and CAST hybrid embryos. We distinguish loci with DNA methylation-dependent (canonical) and independent (non-canonical) imprinting by assaying hybrid embryos with ablated maternally inherited DNA methylation. We find that non-canonical imprints are localized to endogenous retrovirus-K (ERVK) long terminal repeats (LTRs), which act as imprinted promoters specifically in extra-embryonic lineages. Transcribed ERVK LTRs are CpG-rich and located in close proximity to gene promoters, and imprinting status is determined by their epigenetic patterning in the oocyte. Finally, we show that oocyte-derived H3K27me3 associated with non-canonical imprints is not maintained beyond pre-implantation development at these elements and is replaced by secondary imprinted DNA methylation on the maternal allele in post-implantation ExE, while being completely silenced by bi-allelic DNA methylation in the epiblast. CONCLUSIONS: This study reveals distinct epigenetic mechanisms regulating non-canonical imprinted gene expression between embryonic and extra-embryonic development and identifies an integral role for ERVK LTR repetitive elements.

• Klíčová slova
• Development, Embryo, Endogenous retroviruses (ERVs), Extra-embryonic, Genomic imprinting, H3K27me3, Histone modifications, Long terminal repeats (LTRs), Non-canonical imprinting, Placenta,
• MeSH
• genomový imprinting * MeSH
• histonový kód * MeSH
• koncové repetice MeSH
• maternální dědičnost * MeSH
• metylace DNA MeSH
• myši MeSH
• Retroviridae fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Paxillin (PXN) is a focal adhesion protein that has been implicated in signal transduction from the extracellular matrix. Recently, it has been shown to shuttle between the cytoplasm and the nucleus. When inside the nucleus, paxillin promotes cell proliferation. Here, we introduce paxillin as a transcriptional regulator of IGF2 and H19 genes. It does not affect the allelic expression of the two genes; rather, it regulates long-range chromosomal interactions between the IGF2 or H19 promoter and a shared distal enhancer on an active allele. Specifically, paxillin stimulates the interaction between the enhancer and the IGF2 promoter, thus activating IGF2 gene transcription, whereas it restrains the interaction between the enhancer and the H19 promoter, downregulating the H19 gene. We found that paxillin interacts with cohesin and the mediator complex, which have been shown to mediate long-range chromosomal looping. We propose that these interactions occur at the IGF2 and H19 gene cluster and are involved in the formation of loops between the IGF2 and H19 promoters and the enhancer, and thus the expression of the corresponding genes. These observations contribute to a mechanistic explanation of the role of paxillin in proliferation and fetal development.

• Klíčová slova
• Cohesin, Enhancer, H19, IGF2, Imprinting, Paxillin,
• MeSH
• buňky Hep G2 MeSH
• chromozomální proteiny, nehistonové genetika   MeSH
• extracelulární matrix genetika   MeSH
• fokální adheze genetika   MeSH
• genomový imprinting genetika   MeSH
• insulinu podobný růstový faktor II biosyntéza   genetika   MeSH
• koheziny MeSH
• lidé MeSH
• metylace DNA genetika   MeSH
• paxilin aplikace a dávkování   MeSH
• proliferace buněk účinky léků   genetika   MeSH
• promotorové oblasti (genetika) MeSH
• proteiny buněčného cyklu genetika   MeSH
• RNA dlouhá nekódující biosyntéza   genetika   MeSH
• signální transdukce účinky léků   MeSH
• vývoj plodu genetika   MeSH
• vývojová regulace genové exprese MeSH
• zesilovače transkripce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromozomální proteiny, nehistonové MeSH
• H19 long non-coding RNA MeSH Prohlížeč
• IGF2 protein, human MeSH Prohlížeč
• insulinu podobný růstový faktor II MeSH
• paxilin MeSH
• proteiny buněčného cyklu MeSH
• RNA dlouhá nekódující MeSH

Prague hypertriglyceridemic (HTG) rats represent a suitable model of metabolic syndrome. We have established the set of F(2) hybrids derived from HTG and Lewis progenitors to investigate the relationship between respective polymorphism(s) of Igf2 gene and blood pressure (BP) or other cardiovascular phenotypes. HTG rats had elevated systolic BP and plasma triglycerides but lower plasma cholesterol compared to Lewis rats of both genders. In males, there was higher mean arterial pressure, diastolic BP and relative heart weight in HTG than in Lewis rats. The results obtained in the total population of F(2) hybrids indicated strong segregation of Igf2 genotype with plasma triglycerides. There was no segregation of Igf2 genotype with any BP component except BP changes occurring after the blockade of either renin-angiotensin system (RAS) or NO synthase. When F(2) population was analyzed according to gender, male F(2) progeny homozygous for HTG Igf2 allele had significantly higher plasma triglycerides and greater BP changes after NO synthase blockade than those homozygous for Lewis allele. On the contrary, male F(2) progeny homozygous for HTG Igf2 allele had significantly lower plasma cholesterol and smaller BP changes after RAS blockade. PCR analysis of Igf2 gene by using of microsatelite D1Mgh22 has shown polymorphism between HTG and Lewis rats. Sequence analysis of cDNA revealed insertion of 14 nucleotides in HTG gene. In conclusion, polymorphism in Igf2 gene may be responsible for differences in lipid metabolism between HTG and Lewis rats. It remains to determine how these abnormalities could be involved in BP regulation by particular vasoactive systems.

• MeSH
• genetická vazba MeSH
• genotyp MeSH
• hypertriglyceridemie krev   genetika   patologie   patofyziologie   MeSH
• inbrední kmeny potkanů MeSH
• insulinu podobný růstový faktor II genetika   MeSH
• krevní tlak fyziologie   MeSH
• křížení genetické MeSH
• krysa rodu Rattus MeSH
• ledviny anatomie a histologie   MeSH
• lipidy krev   MeSH
• mikrosatelitní repetice MeSH
• mutační analýza DNA MeSH
• potkani inbrední LEW MeSH
• srdce anatomie a histologie   MeSH
• tělesná hmotnost genetika   MeSH
• velikost orgánu genetika   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• insulinu podobný růstový faktor II MeSH
• lipidy MeSH