Directional differentiation of chicken primordial germ cells into adipocytes, neuron-like cells, and osteoblasts

piRNA-19128 regulates spermatogenesis by silencing of KIT in chicken

Spermatogenesis is a complex process. Some studies have shown that Piwi-interacting RNAs (piRNAs) play an important role in spermatogenesis. To verify the evaluate between piRNAs and PIWI proteins in chicken and its possible role in spermatogenesis and reproductive stem cell proliferation and differentiation, we performed immunoprecipitation and deep sequencing analyses and determined the expression profiles of small RNAs in primordial germ cells (PGCs), spermatogonial stem cells (SSCs), spermatogonia (Sa) cells, and spermatozoa. Length analysis showed that piRNAs bound to PIWIL1 mainly contained 23-30 nt. Base preference analysis showed "1U-10A"; moreover, base preference of piRNAs was obvious in all of germline cells. Here we reported the TE family of gallus gallus, and targeted by piRNA. Target gene of piRNA annotation enrichment analysis identified candidate genes KIT, SRC, WNT4, and HMGB2. Kyoto Encyclopedia of Genes and Genomes analysis showed that these genes were associated with steroid hormone biosynthesis, Notch signaling pathway, and melanogenesis. These results indicate that chicken piRNAs perform important regulatory roles during spermatogenesis similar to mice piRNAs. Chicken piRNAs interacted with PIWI proteins and regulated spermatogenesis and germ cell proliferation and differentiation. Further, we observed a negative correlation between piRNA-19128 and KIT expression. Results of dual-luciferase reporter assay confirmed that piRNA-19128 directly interacted with KIT, suggesting that it plays a key role in the regulation spermatogenesis by inhibiting KIT expression. Thus, the present study provides information on the length and base preference of chicken piRNAs and suggests that piRNA-19128 regulates spermatogenesis in chicken by silencing KIT.

Discovery of piRNAs Pathway Associated with Early-Stage Spermatogenesis in Chicken

Piwi-interacting RNAs (piRNAs) play a key role in spermatogenesis. Here, we describe the piRNAs profiling of primordial germ cells (PGCs), spermatogonial stem cells (SSCs), and the spermatogonium (Sp) during early-stage spermatogenesis in chicken. We obtained 31,361,989 reads from PGCs, 31,757,666 reads from SSCs, and 46,448,327 reads from Sp cells. The length distribution of piRNAs in the three samples showed peaks at 33 nt. The resulting genes were subsequently annotated against the Gene Ontology (GO) database. Five genes (RPL7A, HSPA8, Pum1, CPXM2, and PRKCA) were found to be involved in cellular processes. Interactive pathway analysis (IPA) further revealed three important pathways in early-stage spermatogenesis including the FGF, Wnt, and EGF receptor signaling pathways. The gene Pum1 was found to promote germline stem cell proliferation, but it also plays a role in spermatogenesis. In conclusion, we revealed characteristics of piRNAs during early spermatogonial development in chicken and provided the basis for future research.

Isolation and Culture of Pig Spermatogonial Stem Cells and Their in Vitro Differentiation into Neuron-Like Cells and Adipocytes

Spermatogonial stem cells (SSCs) renew themselves throughout the life of an organism and also differentiate into sperm in the adult. They are multipopent and therefore, can be induced to differentiate into many cells types in vitro. SSCs from pigs, considered an ideal animal model, are used in studies of male infertility, regenerative medicine, and preparation of transgenic animals. Here, we report on a culture system for porcine SSCs and the differentiation of these cells into neuron-like cells and adipocytes. SSCs and Sertoli cells were isolated from neonatal piglet testis by differential adhesion and SSCs were cultured on a feeder layer of Sertoli cells. Third-generation SSCs were induced to differentiate into neuron-like cells by addition of retinoic acid, β-mercaptoethanol, and 3-isobutyl-1-methylxanthine (IBMX) to the induction media and into adipocytes by the addition of hexadecadrol, insulin, and IBMX to the induction media. The differentiated cells were characterized by biochemical staining, qRT-PCR, and immunocytochemistry. The cells were positive for SSC markers, including alkaline phosphatase and SSC-specific genes, consistent with the cells being undifferentiated. The isolated SSCs survived on the Sertoli cells for 15 generations. Karyotyping confirmed that the chromosomal number of the SSCs were normal for pig (2n = 38, n = 19). Pig SSCs were successfully induced into neuron-like cells eight days after induction and into adipocytes 22 days after induction as determined by biochemical and immunocytochemical staining. qPCR results also support this conclusion. The nervous tissue markers genes, Nestin and β-tubulin, were expressed in the neuron-like cells and the adipocyte marker genes, PPARγ and C/EBPα, were expressed in the adipocytes.

Chick stem cells: current progress and future prospects

Chick embryonic stem cells (cESCs) can be derived from cells obtained from stage X embryos (blastoderm stage); these have the ability to contribute to all somatic lineages in chimaeras, but not to the germ line. However, lines of stem cells that are able to contribute to the germ line can be established from chick primordial germ cells (cPGCs) and embryonic germ cells (cEGCs). This review provides information on avian stem cells, emphasizing different sources of cells and current methods for derivation and culture of pluripotent cells from chick embryos. We also review technologies for isolation and derivation of chicken germ cells and the production of transgenic birds.

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Chick embryonic stem cells (cESCs) can be derived from a variety of sources.

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cESCs can contribute to all somatic cell types but not to the germ line.

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germ cells can be isolated from early embryos, embryonic blood and gonads.

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germ cells can establish self-renewing lines and contribute to the germline.

Xenogeneic transfer of adult quail (Coturnix coturnix) spermatogonial stem cells to embryonic chicken (Gallus gallus) hosts: a model for avian conservation

As advanced reproductive technologies have become routine for domesticated species, they have begun to be applied in the field of endangered species conservation. For avian conservation, the most promising technology is the transfer of germ stem cells of exotic species to domestic hosts for the production of gametes. In this study, adult quail (model for exotic species) spermatogonial stem cells were xenogeneically transferred to stages 14-17 chicken host embryos. Fluorescent cellular dyes, quail-specific antibodies, and quail-specific quantitative PCR confirmed donor cell migration to and colonization of the host gonadal ridge. Donor-derived cells were observed by fluorescent microscopy in the caudal area as early as 2 h after injection, in the gonadal ridge at 4 h after injection, as well as in the gonads of stages 35-38 host embryos. Four of eight donor-derived cell flow cytometry-positive host gonads were confirmed by quantitative PCR using quail-specific primers. There was no statistically significant effect of host stage of injection, host gonad isolation stage, or host sex on the number of hosts positive for donor cells or the percent of donor-derived cells per positive gonad. Donor-derived cells isolated from stages 35-38 host gonads costained with the germ stem cell marker SSEA-1, indicating that the donor-derived cells have maintained stem cell-ness. This is the first study to suggest that it is feasible to rescue adult germ stem cells of deceased birds to prolong the reproductive lifespan of critically endangered species or genetically valuable individuals by transferring them to an embryonic chicken host.