Chicken Embryonic-Stem Cells Are Permissive to Poxvirus Recombinant Vaccine Vectors.

The discovery of mammalian pluripotent embryonic stem cells (ESC) has revolutionised cell research and regenerative medicine. More recently discovered chicken ESC (cESC), though less intensively studied, are increasingly popular as vaccine substrates due to a dearth of avian cell lines. Information on the comparative performance of cESC with common vaccine viruses is limited. Using RNA-sequencing, we compared cESC transcriptional programmes elicited by stimulation with chicken type I interferon or infection with vaccine viruses routinely propagated in primary chicken embryo fibroblasts (CEF). We used poxviruses (fowlpox virus (FWPV) FP9, canarypox virus (CNPV), and modified vaccinia virus Ankara (MVA)) and a birnavirus (infectious bursal disease virus (IBDV) PBG98). Interferon-stimulated genes (ISGs) were induced in cESC to levels comparable to those in CEF and immortalised chicken fibroblast DF-1 cells. cESC are permissive (with distinct host transcriptional responses) to MVA, FP9, and CNPV but, surprisingly, not to PBG98. MVA, CNPV, and FP9 suppressed innate immune responses, while PBG98 induced a subset of ISGs. Dysregulation of signalling pathways (i.e., NFκB, TRAF) was observed, which might affect immune responses and viral replication. In conclusion, we show that cESC are an attractive alternative substrate to study and propagate poxvirus recombinant vaccine vectors

Long-term cultures of chicken embryonic primordial and gonadal germ cells.

National audiencePrimordial germ cells (PGCs) are the precursors of germ cell lineage. Located in the epiblast at stage X embryo (EG&K), the PGC translocate anteriorly to the germinal crescent and migrate through the blood vascular system to the germinal ridges within 48-56 hours of development, where they become the gonadal germ cells. We aim to compare the in vitro long-term cultured PGCs derived from the chicken blood of a 2 days old embryo (stages 14 to 17 HH) with the long-term cultured gonocytes taken from male gonads of a 5-6 days old embryo (stages 29 to 30 HH) and determined their basic characters. The results of immunostaining demonstrated that anti-SSEA-1, anti-EMA-1, anti-CVH, anti-integrin β1 and anti-CEACAM, together with PAS stain, bound specifically to chicken PGCs and GGCs. The reactivity of chicken embryonic germ cells obtained from the two different sources to the specific markers used in this study was not altered through the culture. In conclusion, the morphological analysis specific for chicken PGCs and GGCs presented in this study, will further contribute to quick and reliable characterization of these cell types in vitro

Epigenetic landscape of avian stem cells

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Deciphering the role of key epigenetic actors in chicken ESC and PGC physiology

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Marques épigénétiques des cellules pluripotentes de poulet

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Chicken embryonic stem cells and primordial germ cells display different heterochromatic histone marks than their mammalian counterparts

International audienceAbstractBackgroundChromatin epigenetics participate in control of gene expression during metazoan development. DNA methylation and post-translational modifications (PTMs) of histones have been extensively characterised in cell types present in, or derived from, mouse embryos. In embryonic stem cells (ESCs) derived from blastocysts, factors involved in deposition of epigenetic marks regulate properties related to self-renewal and pluripotency. In the germ lineage, changes in histone PTMs and DNA demethylation occur during formation of the primordial germ cells (PGCs) to reset the epigenome of the future gametes. Trimethylation of histone H3 on lysine 27 (H3K27me3) by Polycomb group proteins is involved in several epigenome-remodelling steps, but it remains unclear whether these epigenetic features are conserved in non-mammalian vertebrates. To investigate this question, we compared the abundance and nuclear distribution of the main histone PTMs, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in chicken ESCs, PGCs and blastodermal cells (BCs) with differentiated chicken ESCs and embryonic fibroblasts. In addition, we analysed the expression of chromatin modifier genes to better understand the establishment and dynamics of chromatin epigenetic profiles.ResultsThe nuclear distributions of most PTMs and 5hmC in chicken stem cells were similar to what has been described for mammalian cells. However, unlike mouse pericentric heterochromatin (PCH), chicken ESC PCH contained high levels of trimethylated histone H3 on lysine 27 (H3K27me3). In differentiated chicken cells, PCH was less enriched in H3K27me3 relative to chromatin overall. In PGCs, the H3K27me3 global level was greatly reduced, whereas the H3K9me3 level was elevated. Most chromatin modifier genes known in mammals were expressed in chicken ESCs, PGCs and BCs. Genes presumably involved in de novo DNA methylation were very highly expressed. DNMT3B and HELLS/SMARCA6 were highly expressed in chicken ESCs, PGCs and BCs compared to differentiated chicken ESCs and embryonic fibroblasts, and DNMT3A was strongly expressed in ESCs, differentiated ESCs and BCs.ConclusionsChicken ESCs and PGCs differ from their mammalian counterparts with respect to H3K27 methylation. High enrichment of H3K27me3 at PCH is specific to pluripotent cells in chicken. Our results demonstrate that the dynamics in chromatin constitution described during mouse development is not universal to all vertebrate species

Epigenetic marks in chicken pluripotent cells and embryo

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NANOG Is Required for the Long-Term Establishment of Avian Somatic Reprogrammed Cells

Summary: Somatic reprogramming, which was first identified in rodents, remains poorly described in non-mammalian species. Here, we generated avian reprogrammed cells by reprogramming of chicken and duck primary embryonic fibroblasts. The efficient generation of long-term proliferating cells depends on the method of delivery of reprogramming factors and the addition of NANOG and LIN28 to the canonical OCT4, SOX2, KLF4, and c-MYC gene combination. The reprogrammed cells were positive for several key pluripotency-associated markers including alkaline phosphatase activity, telomerase activity, SSEA1 expression, and specific cell cycle and epigenetic markers. Upregulated endogenous pluripotency-associated genes included POU5F3 (POUV) and KLF4, whereas cells failed to upregulate NANOG and LIN28A. However, cells showed a tumorigenic propensity when injected into recipient embryos. In conclusion, although the somatic reprogramming process is active in avian primary cells, it needs to be optimized to obtain fully reprogrammed cells with similar properties to those of chicken embryonic stem cells. : In this article, the authors show that the NANOG gene plays a crucial role in the long-term establishment of avian reprogrammed cells that have some of the specific markers of stem cells but that do not present all the developmental properties of induced pluripotent stem cells such as described in mammals. Keywords: avian species, somatic reprogramming, embryonic stem cells, NANOG, pluripotency, chicken, duck, embryos, blastoderm, phylogenic compariso

Transcriptomic analysis of MDV permissive chicken embryonic stem (ES)- derived cells

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