Effect of HDAC9 on the differentiation of chicken embryonic stem cells into male germ cells

Histone deacetylase 9 (HDAC9) is a histone deacetylase (HDAC) subtype IIa protein that deacetylates histone 3 (H3), histone 4 (H4), and nonhistone proteins in vivo to alter chromosomal shape and regulate gene transcription. There have been few studies on the regulatory influence of the HDAC9 gene on the differentiation of chicken embryonic stem cells (cESCs) into male germ cells, and the significance of HDAC9 is still unknown. Therefore, we explored the specific role of HDAC9 during differentiation of the cESCs of Jilin Luhua chickens through inhibition or overexpression. In medium supplemented with 10-5 mol/L retinoic acid (RA), cESCs were stimulated to develop into germ cells. HDAC9 and germline marker gene mRNA and protein levels were measured using qRT‒PCR and western blotting. During the differentiation of cESCs into male germ cells, overexpression of the HDAC9 gene greatly increased the mRNA and protein expression levels of the germline marker genes Stra8, Dazl, c-kit, and integrin ɑ6. The HDAC9 inhibitor TMP195 significantly decreased the mRNA and protein expression levels of the above markers. In summary, HDAC9 positively regulates the differentiation of cESCs.

The antiviral potential of the antiandrogen enzalutamide and the viral-androgen signaling interplay in seasonal coronaviruses

The sex disparity in COVID-19 outcomes with males generally faring worse than females has been associated with the androgen-regulated expression of the protease TMPRSS2 and the cell receptor ACE2 in the lung and fueled interest in antiandrogens as potential antivirals. In this study, we explored enzalutamide, an antiandrogen used commonly to treat prostate cancer, as a potential antiviral against the human coronaviruses which cause seasonal respiratory infections (HCoV-NL63, -229E, and -OC43). Using lentivirus-pseudotyped and authentic HCoV, we report that enzalutamide reduced 229E and NL63 entry and infection in both TMPRSS2- and nonexpressing immortalized cells, suggesting a TMPRSS2-independent mechanism. However, no effect was observed against OC43. To decipher this distinction, we performed RNA-sequencing analysis on 229E- and OC43-infected primary human airway cells. Our results show a significant induction of androgen-responsive genes by 229E compared to OC43 at 24 and 72 h postinfection. The virus-mediated effect on AR-signaling was further confirmed with a consensus androgen response element-driven luciferase assay in androgen-depleted MRC-5 cells. Specifically, 229E induced luciferase-reporter activity in the presence and absence of the synthetic androgen mibolerone, while OC43 inhibited induction. These findings highlight a complex interplay between viral infections and androgen-signaling, offering insights for disparities in viral outcomes and antiviral interventions.

Analysis of microRNA expression profiles during the differentiation of chicken embryonic stem cells into male germ cells

The differentiation of embryonic stem cells (ESCs) into germ cells in vitro could have very promising applications for infertility treatment and could provide an excellent model for uncovering the molecular mechanisms of germline generation. This study aimed to investigate the differentially expressed miRNAs (DEMs) during the differentiation of chicken ESCs (cESCs) into male germ cells and to establish a profile of the DEMs. Cells before and after induction were subjected to miRNA sequencing (miRNA-seq). A total of 113 DEMs were obtained, including 61 upregulated and 52 downregulated DEMs. GO and KEGG enrichment analyses showed that the target genes were enriched mainly in the MAPK signaling pathway, HTLV infection signaling pathway, cell adhesion molecule (CAM)-related pathways, viral myocarditis, Wnt signaling pathway, ABC transporters, TGF-β signaling pathways, Notch signaling pathways and insulin signaling pathway. The target genes of the miRNAs were related to cell binding, cell parts and biological regulatory processes. Six DEMs, let-7k-5p, miR-132c-5p, miR-193a-5p, miR-202-5p, miR-383-5p and miR-6553-3p, were assessed by qRT-PCR, and the results were consistent with the results of miRNA-seq. Based on qRT-PCR and western blot verification, miR-383-5p and its putative target gene STRN3 were selected to construct an STRN3 3'-UTR dual-luciferase gene reporter vector and its mutant vector. The double luciferase reporter activity of the cotransfected STRN3-WT + miR-383-5p mimics group was significantly lower (by approximately 46%) than that of the other five groups (p < 0.01). There was no significant difference in luciferase activity among the other 5 groups. This study establishes a DEM profile during the process of cESC differentiation into male germ cells; illustrates the mechanisms by which miRNAs regulate target genes; provides a theoretical basis for further research on the mechanisms of the formation and regulation of male germ cells; and provides an important strategy for gene editing, animal genetic resource protection and transgenic animal production.

Creating resistance to avian influenza infection through genome editing of the ANP32 gene family

Chickens genetically resistant to avian influenza could prevent future outbreaks. In chickens, influenza A virus (IAV) relies on host protein ANP32A. Here we use CRISPR/Cas9 to generate homozygous gene edited (GE) chickens containing two ANP32A amino acid substitutions that prevent viral polymerase interaction. After IAV challenge, 9/10 edited chickens remain uninfected. Challenge with a higher dose, however, led to breakthrough infections. Breakthrough IAV virus contained IAV polymerase gene mutations that conferred adaptation to the edited chicken ANP32A. Unexpectedly, this virus also replicated in chicken embryos edited to remove the entire ANP32A gene and instead co-opted alternative ANP32 protein family members, chicken ANP32B and ANP32E. Additional genome editing for removal of ANP32B and ANP32E eliminated all viral growth in chicken cells. Our data illustrate a first proof of concept step to generate IAV-resistant chickens and show that multiple genetic modifications will be required to curtail viral escape.

Small RNA deep sequencing revealed microRNAs' involvement in modulating cellular senescence and immortalization state

Unlike rodent cells, spontaneous immortalization of avian cells and human cells is a very rare event. According to patent publications and current literature, there are no more than 4 spontaneously immortalized chicken embryo fibroblast (CEF) cell lines established up to date. One of those cell lines is ADOL (Avian Disease and Oncology Laboratory) ZS-1 cell line, which was established by continuous passaging of the CEFs derived from the specific pathogen free (SPF) 0.TVB*S1 (commonly known as rapid feathering susceptible or RFS) genetic line of chickens. The RFS genetic line of chickens was developed and has been maintained on the SPF chicken farm of USDA-ARS facility, ADOL, in East Lansing, Michigan, which is known as one of a few lines of chickens that are free of any known avian endogenous virus genes. To explore potential roles that epigenetic factors may play in modulating cellular senescence processes and spontaneous immortalization state, total RNAs extracted from samples of the RFS primary CEFs, RFS CEFs reached the 21st passage, and the ZS-1 cells were subjected to small RNA sequencing. Collectively, a total of 531 miRNAs was identified in the 3 types of samples. In contrast to the primary CEF samples, 50 miRNAs were identified with significantly differential expression only in the 21st passage samples; a different subset of 63 differentially expressed miRNAs was identified only in the ZS-1 samples; the majority of differentially expressed miRNAs identified in both the 21st passage CEF and the ZS-1 samples were more or less directionally consistent. Gene Ontology analysis results suggested that the epigenetic factor, miRNAs, plays a role in modulating the cellular senescence and spontaneous immortalization processes through various bioprocesses and key pathways including ErbB and MAPK signaling pathways. These findings provided the experimental and bioinformatic evidence for a better understanding on the epigenetic factor of miRNAs in association with cellular senescence and spontaneous immortalization process in avian cells.

Construction of a peacock immortalized fibroblast cell line for avian virus production

The mammalian-derived MDCK cells are the most widely used for avian virus vaccine production at present. The use of heterologous cell systems for avian virus preparation may cause security risks. An avian cell line is available for avian virus vaccines urgently needed. In this study, a peacock immortalized fibroblast cell line that is suitable for avian virus vaccine production was generated. The primary peacock fibroblast cells were prepared, and the immortal cells PEF-1 were obtained by transferring hTERT into the primary cells and screening with G418. The PEF-1 has high cell viability and expresses exogenous TERT protein. More importantly, the virus replication ability was stronger in PEF-1 than in MDCK cells as evaluated by virus fluorescence and TCID₅₀, after being infected with NDV-GFP, VSV-GFP, and AIV. In conclusion, the peacock immortalized PEF cells are expected to be used for the production of peacock and other avian virus vaccines.

Ascorbic acid and all-trans retinoic acid promote proliferation of chicken blastoderm cells (cBCs) by mediating DNA demethylation

Chicken blastoderm cells (cBCs) obtained from stage X (EG&K) embryos are easily available materials for the study of cell development. However, cBCs are not widely used because they are hard to maintain in long-term culture in vitro. To solve this problem, ascorbic acid (AA; also known as vitamin C (VC)) and all-trans retinoic acid (ATRA) were added into basic culture medium to promote cell growth. Results suggested that cultured cBCs possessed strongly proliferative activity and maintained their pluripotency on the support of chicken embryonic fibroblast (CEF) feeder. Moreover, when VC or/and ATRA was added, the number and area of cBC colonies increased significantly compared with the control group. The expression of pluripotency genes (Sox2 and Nanog) and cell cycle-regulated genes (CCND1 and CDK6) was upregulated obviously. Furthermore, results showed that 5hmC levels in VC and RA groups increased significantly by DNA dot blot and immunofluorescence staining. These results provide strong evidence that VC and ATRA induced DNA demethylation and enhanced 5hmC level. The level of H3K27me3 was raised, while the level of H3K9me2 was reduced by addition of VC and ATRA. Finally, the expression of Tet1 and Dnmt3b was upregulated remarkably. Therefore, these results indicated that VC and ATRA enhanced DNA demethylation and then promoted cBC survival and proliferation in vitro.

Transcriptomic Analysis of Inbred Chicken Lines Reveals Infectious Bursal Disease Severity Is Associated with Greater Bursal Inflammation In Vivo and More Rapid Induction of Pro-Inflammatory Responses in Primary Bursal Cells Stimulated Ex Vivo

In order to better understand differences in the outcome of infectious bursal disease virus (IBDV) infection, we inoculated a very virulent (vv) strain into White Leghorn chickens of inbred line W that was previously reported to experience over 24% flock mortality, and three inbred lines (15I, C.B4 and 0) that were previously reported to display no mortality. Within each experimental group, some individuals experienced more severe disease than others but line 15I birds experienced milder disease based on average clinical scores, percentage of birds with gross pathology, average bursal lesion scores and average peak bursal virus titre. RNA-Seq analysis revealed that more severe disease in line W was associated with significant up-regulation of pathways involved in inflammation, cytoskeletal regulation by Rho GTPases, nicotinic acetylcholine receptor signaling, and Wnt signaling in the bursa compared to line 15I. Primary bursal cell populations isolated from uninfected line W birds contained a significantly greater percentage of KUL01+ macrophages than cells isolated from line 15I birds (p < 0.01) and, when stimulated ex vivo with LPS, showed more rapid up-regulation of pro-inflammatory gene expression than those from line 15I birds. We hypothesize that a more rapid induction of pro-inflammatory cytokine responses in bursal cells following IBDV infection leads to more severe disease in line W birds than in line 15I.

NF-κB as an Important Factor in Optimizing Poxvirus-Based Vaccines against Viral Infections

Poxviruses are large dsDNA viruses that are regarded as good candidates for vaccine vectors. Because the members of the Poxviridae family encode numerous immunomodulatory proteins in their genomes, it is necessary to carry out certain modifications in poxviral candidates for vaccine vectors to improve the vaccine. Currently, several poxvirus-based vaccines targeted at viral infections are under development. One of the important aspects of the influence of poxviruses on the immune system is that they encode a large array of inhibitors of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), which is the key element of both innate and adaptive immunity. Importantly, the NF-κB transcription factor induces the mechanisms associated with adaptive immunological memory involving the activation of effector and memory T cells upon vaccination. Since poxviruses encode various NF-κB inhibitor proteins, before the use of poxviral vaccine vectors, modifications that influence NF-κB activation and consequently affect the immunogenicity of the vaccine should be carried out. This review focuses on NF-κB as an essential factor in the optimization of poxviral vaccines against viral infections.

Advances in Isolation and Culture of Chicken Embryonic Stem Cells In Vitro

Chicken embryonic stem cells (cESCs) isolated from the egg at the stage X hold great promise for cell therapy, tissue engineering, pharmaceutical, and biotechnological applications. They are considered to be pluripotent cells with the capacity to self-renewal and differentiate into specialized cells. However, long-term maintenance of cESCs cannot be realized now, which impedes the establishment of cESC line and limits their applications. Therefore, the separation locations, isolation methods, and culture conditions especially the supplements and action mechanisms of cytokines, including leukemia inhibitory factor, fibroblast growth factor, transforming growth factor beta, bone morphogenic protein, and activin for cESCs in vitro, have been reviewed here. These defined strategies will contribute to identify the key mechanism on the self-renewal of cESCs, facilitate to optimize system that supports the derivation and longtime maintenance of cESCs, establish the cESC line, and develop the biobank of genetic resources in chicken.

Genomics of Avian Viral Infections

The poultry industry currently accounts for the production of around 118 million metric tons of meat and around 74 million metric tons of eggs annually. As the global population continues to increase, so does our reliance on poultry as a food source. It is therefore of vital importance that we safeguard this valuable resource and make the industry as economically competitive as possible. Avian viral infections, however, continue to cost the poultry industry billions of dollars annually. This can be in terms of vaccination costs, loss of birds and decreased production. With a view to improving the health and welfare of commercial birds and to minimizing associated economic losses, it is therefore of great importance that we try to understand the genetic mechanisms underlying host susceptibility and resilience to some of the major viral pathogens that threaten the poultry species. Some avian viruses, through their zoonotic potential, also pose a risk to human health. This Special Issue will present papers that describe our current knowledge on host responses to various viral pathogens, the genetics underlying those responses and how genomics can begin to provide a solution for resolving the threat posed by these infections.