Rnf11-like is a novel component of NF-κB signaling, governing the posterior patterning in the zebrafish embryos

What makes a bad egg? Egg transcriptome reveals dysregulation of translational machinery and novel fertility genes important for fertilization

BACKGROUND

Egg quality can be defined as the egg ability to be fertilized and subsequently develop into a normal embryo. Previous research has shed light on factors that can influence egg quality. Large gaps however remain including a comprehensive view of what makes a bad egg. Initial development of the embryo relies on maternally-inherited molecules, such as transcripts, deposited in the egg during its formation. Bad egg quality is therefore susceptible to be associated with alteration or dysregulation of maternally-inherited transcripts. We performed transcriptome analysis on a large number (N = 136) of zebrafish egg clutches, each clutch being split to monitor developmental success and perform transcriptome analysis in parallel. We aimed at drawing a molecular portrait of the egg in order to characterize the relation between egg transcriptome and developmental success and to subsequently identify new candidate genes involved in fertility.

RESULTS

We identified 66 transcript that were differentially abundant in eggs of contrasted phenotype (low or high developmental success). Statistical modeling using partial least squares regression and genetics algorithm demonstrated that gene signatures from transcriptomic data can be used to predict developmental success. The identity and function of differentially expressed genes indicate a major dysregulation of genes of the translational machinery in poor quality eggs. Two genes, otulina and slc29a1a, predominantly expressed in the ovary and dysregulated in poor quality eggs were further investigated using CRISPR/Cas9 mediated genome editing. Mutants of each gene revealed remarkable subfertility whereby the majority of their eggs were unfertilizable. The Wnt pathway appeared to be dysregulated in the otulina mutant-derived eggs.

CONCLUSIONS

Here we show that egg transcriptome contains molecular signatures, which can be used to predict developmental success. Our results also indicate that poor egg quality in zebrafish is associated with a dysregulation of (i) the translational machinery genes and (ii) novel fertility genes, otulina and slc29a1a, playing an important role for fertilization. Together, our observations highlight the diversity of the possible causes of egg quality defects and reveal mechanisms of maternal origin behind the lack of fertilization and early embryonic failures that can occur under normal reproduction conditions.

RNF11 negatively regulates antiviral signaling and incites inflammatory response in chicken embryo fibroblast

RNF11 (RING finger protein 11) has been indicated to be related to numerous immunological diseases. As a neo-regulator in innate immunity, RNF11 was proved to inhibit antiviral signaling and interferon-β (IFN-β) production in human cell line. Chicken antiviral signaling pathway is different with other species. However, there is little study about the role of RNF11 in chicken antiviral signaling pathway and inflammatory response. This study was designed to identify the function of RNF11 in chicken antiviral signaling pathway and inflammatory response. We overexpressed and interfered RNF11 in chicken embryo fibroblasts (CEFs) and then used quantitative reverse transcription polymerase chain reaction (qRT-PCR) to investigate the poly (I:C)-induced production of IFN-β and inflammatory response factors IL2 and IL10. The results indicated that RNF11 extremely significantly decreased the production of IFN-β and highly significantly increased the messenger RNA (mRNA) levels of IL2 and IL10, but depletion of RNF11 obtained inverse results. Thus, we concluded that RNF11 not only can inhibit antiviral signaling but also plays an important role in inflammatory response in chicken.