The Oct4 homologue PouV and Nanog regulate pluripotency in chicken embryonic stem cells

Abstract

Embryonic stem cells (ESC) have been isolated from pregastrulation mammalian embryos. The maintenance of their pluripotency and ability to self-renew has been shown to be governed by the transcription factors Oct4 (Pou5f1) and Nanog. Oct4 appears to control cell-fate decisions of ESC in vitro and the choice between embryonic and trophectoderm cell fates in vivo. In nonmammalian vertebrates, the existence and functions of these factors are still under debate, although the identification of the zebrafish pou2 (spg; pou5f1) and Xenopus Pou91 (XlPou91) genes, which have important roles in maintaining uncommitted putative stem cell populations during early development, has suggested that these factors have common functions in all vertebrates. Using chicken ESC (cESC), which display similar properties of pluripotency and long-term self-renewal to mammalian ESC, we demonstrated the existence of an avian homologue of Oct4 that we call chicken PouV (cPouV). We established that cPouV and the chicken Nanog gene are required for the maintenance of pluripotency and self-renewal of cESC. These findings show that the mechanisms by which Oct4 and Nanog regulate pluripotency and self-renewal are not exclusive to mammals.

Pitx2 regulates gonad morphogenesis

“…To ascertain whether the transcriptional activity induced by Pitx2c might affect the interactions between somatic and primordial germ cells (PGCs) we assayed the spatiotemporal transcript distribution of vasa, a characteristic functional marker of PGCs in vertebrates and invertebrates (31)(32)(33)(34)(35)(36), oct4 (37), and nanog (38) transcripts. Avian PGCs originate in the epiblast and migrate into the germinal ridges via the bloodstream and through the gut and dorsal mesentery (39,40).…”

Identification of a pou2 ortholog in Chinese sturgeon, Acipenser sinensis and its expression patterns in tissues, immature individuals and during embryogenesis

“…X. laevis Oct91 transcripts were expressed in the brain. Additionally, class V POU family gene mRNAs of chicken, rabbit and human were also observed in the brain (Lavial et al 2007;Shi et al 2008;Takeda et al 1992). Gonadotropinreleasing hormone (GnRH), gonadotropic hormones (GtHs), and gonadal steroids are the key hormones of the brain-pituitary-gonadal axis that regulate vertebrate reproduction (Weltzien et al 2004).…”

“…Aspou2 mRNA was widespread in diverse tissues, with abundant transcripts in the pituitary, muscle and almost all subdivisions of the brain, lower expressions in the kidney, heart, ovary, spleen, intestine and fat, and unable to detect in the liver. To date, there is no species with the same expression pattern of Aspou2, including zebrafish (Takeda et al 1994), medaka (Sanchez-Sanchez et al 2010, cod (Holen et al 2010), frog (Hinkley et al 1992), axolotl (Bachvarova et al 2004), tammar (Frankenberg et al 2010), chicken (Lavial et al 2007), mouse (Pesce et al 1998;Palmieri et al 1994), cat (Yu et al 2009), rabbit (Shi et al 2008), bovine (van Eijk et al 1999) and human (Takeda et al 1992). Comparing the expression of the class V POU family genes in the liver, we found that among these species, only tammar Pou5f1 mRNAs were detected in the liver, except for medaka and mouse in which no one has detected the liver expression characteristics of class V POU family genes so far, suggesting that during the evolution, tammar Pou5f1 gene might get some additional function in the liver.…”

“…In axolotl, only a single class V POU gene, AxOct4, was identified, which was expressed in the epiblast, in the posterior mesoderm of late gastrulae, and in diplotente growing oocytes (Bachvarova et al 2004). In chicken, the class V POU gene, cPouV, was required for the maintenance of pluripotency and self-renewal of ESC (Lavial et al 2007). From the current point of view, a common ancestor of gnathostomes has a single POU V gene, syntenic to zebrafish pou5f1/pou2 (Niwa et al 2008;Frankenberg et al 2010).…”

Germline development in amniotes: A paradigm shift in primordial germ cell specification

“…In this respect, it is notable that the distribution of the pluripotency markers Nanog and PouV (a Pou2 ‐variant in birds; Pou5f1 in mouse 103) in chick is comparable to that observed in mouse. Both RNAs are ubiquitously expressed in the early epiblast and at late gastrulation stage they are expressed in the PGCs only 104, 105.…”