Chicken blastoderms and primordial germ cells possess a higher expression of DNA repair genes and lower expression of apoptosis genes to preserve their genome stability

Abstract

DNA is susceptible to damage by various sources. When the DNA is damaged, the cell repairs the damage through an appropriate DNA repair pathway. When the cell fails to repair DNA damage, apoptosis is initiated. Although several genes are involved in five major DNA repair pathways and two major apoptosis pathways, a comprehensive understanding of those gene expression is not well-understood in chicken tissues. We performed whole-transcriptome sequencing (WTS) analysis in the chicken embryonic fibroblasts (CEFs), stage X blastoderms, and primordial germ cells (PGCs) to uncover this deficiency. Stage X blastoderms mostly consist of undifferentiated progenitor (pluripotent) cells that have the potency to differentiate into all cell types. PGCs are also undifferentiated progenitor cells that later differentiate into male and female germ cells. CEFs are differentiated and abundant somatic cells. Through WTS analysis, we identified that the DNA repair pathway genes were expressed more highly in blastoderms and high in PGCs than CEFs. Besides, the apoptosis pathway genes were expressed low in blastoderms and PGCs than CEFs. We have also examined the WTS-based expression profiling of candidate pluripotency regulating genes due to the conserved properties of blastoderms and PGCs. In the results, a limited number of pluripotency genes, especially the core transcriptional network, were detected higher in both blastoderms and PGCs than CEFs. Next, we treated the CEFs, blastoderm cells, and PGCs with hydrogen peroxide (H2O2) for 1 h to induce DNA damage. Then, the H2O2 treated cells were incubated in fresh media for 3–12 h to observe DNA repair. Subsequent analyses in treated cells found that blastoderm cells and PGCs were more likely to undergo apoptosis along with the loss of pluripotency and less likely to undergo DNA repair, contrasting with CEFs. These properties of blastoderms and PGCs should be necessary to preserve genome stability during the development of early embryos and germ cells, respectively.

Dissecting chicken germ cell dynamics by combining a germ cell tracing transgenic chicken model with single-cell RNA sequencing

“…Among the examined genes, POUV , NANOG , PRDM14 , DDX4 , and PIWIL1 are the DAZL interacting genes [31] . Also, the expression of FADD and H2AFX reinforces the previous report that the chicken PGCs express lower levels of apoptosis genes and higher levels of DNA repair genes [32] . These results indicate that the DAZL::GFP PGCs are a valuable resource to produce transgenic chickens by germline transmission.…”

The Effect of Inhibiting the Wingless/Integrated (WNT) Signaling Pathway on the Early Embryonic Disc Cell Culture in Chickens

“…Interestingly, prior to culture, these genes were also highly expressed in BCs. To validate the expression of primed state-related genes in BCs, transcriptome data [27] were analyzed, and the findings confirmed that these genes were indeed highly expressed in EGK.X cells. However, the expression levels of primed state-related genes were significantly lower compared to EGK.X cells.…”

“…To determine whether the PSC-like cells derived from the FIX system have a primed state, we performed RT-PCR experiments and found that both isolated chicken BCs and PSC-like cells derived from the FIX system expressed genes AXIN1, AXIN2, OTX2, and FGF5 [13,23,29] (Figure 4A). To validate this result, transcriptome data [27] analysis revealed that compared to primordial germ cells (PGCs) and chicken embryonic fibroblasts (CEF), EGK.X stage cells indeed expressed higher levels of AXIN1, AXIN2, FGF5, and OTX2 genes (Figure 4B), further demonstrating the presence of cells in blastoderm at the EGK.X stage expressing primed state-related genes, which were maintained during culturing in the FIX system. The qRT-PCR analysis also showed that compared to the BC group, the PSC-like cells derived from the FIX system expressed lower levels of AXIN1, AXIN2, FGF5, and OTX2 genes (Figure 4C-F).…”

“…The transcriptomic data of primed-state genes was derived from publicly available data in the NCBI GEO database (GSE174603) [27]. All experiments were performed in triplicate, and data are presented as mean ± standard error of the mean (SEM).…”

Fate Decisions of Chicken Primordial Germ Cells (PGCs): Development, Integrity, Sex Determination, and Self-Renewal Mechanisms

“…In chicken PGCs, POU5F3 is expressed along with NANOG and SOX2 and may form a transcriptional network [ 84 , 96 ]. A recent study demonstrated that POU5F3 regulates globally active chromatin modification [ 97 ].…”