Expression dynamics of pluripotency genes in chicken primordial germ cells before and after colonization of the genital ridges

Abstract

Mammalian species utilize an inductive mechanism of germ cell specification, diverting the fate of some of somatic cells toward pluripotency and germ-cell totipotency. It is not known if avian species utilize a similar mechanism nor if, analogous to mammalian primordial germ cells (PGCs), pluripotency genes are continuously upregulated in migrating and genital ridge-colonizing avian PGCs. Thus, this study was conducted to quantify and to analyze the expression profile of pluripotency genes at different stages of chicken PGCs development at Hamburger and Hamilton (HH) stage 14, when the majority of PGCs have entered into the bloodstream; at HH stage 18, when PGCs have resided for 8-12 hr in the bloodstream; and at HH stage 28, when the majority of PGCs are found in the genital ridge. The transcription for Oct4, Sox2, and Nanog continuously decreased from HH stage 14 to HH stage 28. In addition, equal amounts of total RNA could be isolated from chicken PGCs at each stage of development, indicating that the observed drop of transcription of pluripotency genes is not a consequence of transcriptional repression in general. Decreased expression for all three proteins was also observed at HH stage 28. Furthermore, in comparison to blood PGCs, those residing in the gonad have lost their full capacity for colony formation. Our results indicate that, in contrast to mammalian PGCs, chicken PGCs continuously downregulate the expression of pluripotency genes and show a progressive loss of pluripotency-associated features during different stages of germ-line migration.

Production of Transgenic Chimeric Chicken from Cryopreserved Primordial Germ Cells and its Validation by Developing shRNA Transgenic Chicken Chimera

“…We isolated the PGCs from the chicken embryos, which were characterized with several markers and cytochemistry, and the results are similar to the ndings of earlier studies [9][10][11][12][13][14][15][16][17] . The chromosomes revealed both macro and micro-chromosomes in PGCs, which was i n agreement with the earlier reports 18 .…”

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

“…LIN28A is essential for proper PGC development [96] , and LIN28A induces somatic cells to become PGCs [97] . Previous studies have attempted to distinguish the phenotypes of E2.5 PGCs from E6 PGCs [98] , [99] , however, the transcriptomic difference has not been clearly identified. We found that the expression profiles of migrating PGCs (at E2.5) resemble those of colonized PGCs (at E6 in males and at E6–E8 in females).…”

Long-term in vitro culture and preliminary establishment of chicken primordial germ cell lines

“…Within this culture period, we performed many experiments to verify that the cells proliferate quantitatively as well as maintain their cellular properties in both their genotype and phenotype. We examined the expression of several germline-associated markers such as cDAZL, c-kit, and Sox2 [ 24 – 26 ], and PGC-specific markers such as SSEA-1. These efficient gametogenesis genes were expressed without any significant differences throughout the long-term culture and cryopreservation.…”