Characterization of the POU5F1 Homologue in Nile Tilapia: From Expression Pattern to Biological Activity

Abstract

POU5F1 (OCT4) is a crucial transcription factor for induction and maintenance of cellular pluripotency, as well as survival of germ cells in mammals. However, the homologues of POU5F1 in teleost fish, including zebrafish and medaka, now named Pou5f3, exhibit considerable differences in expression pattern and pluripotency-maintaining activity. To what extent the POU5F1 homologues are conserved in vertebrates has been unclear. In this study, we report that the POU5F1 homologue from the Nile tilapia (Oreochromis niloticus), OnPou5f3, displays an expression pattern and biological activity somewhat different from those in zebrafish or medaka. The expression of Onpou5f3 at both mRNA and protein levels was abundant in early development embryos until blastula stages, barely detectable as proceeding, and then displayed a transiently strong expression domain in the brain region during neurula stages similar to zebrafish but not medaka. Afterward, OnPou5f3 appeared as germline-restricted (including primordial germ cells and female and male gonad germ cells) expression just like medaka. Notably, OnPou5f3 depletion through morpholino oligos caused blastula blockage or lethality and failure of survival and proliferation of blastula cell-derived cells. These findings indicate that equivalent POU5F1-like expression and activity of Pou5f3 might be conserved accompanying with species-specific expression pattern during evolution. Our study provides insight into the evolutionary conservation of the POU5F1 homologues across vertebrates.

The cycling gonad: retinoic‐acid synthesis and degradation patterns during adult zebrafish Danio rerio oogenesis

“…A role in germ cell survival and apoptosis was proposed: in agreement with the apoptosis‐induced sexual differentiation in the developing gonad (Rodriguez‐Mari et al, ). Yet, in adult teleosts, such as the Japanese flounder Paralichthys olivaceus (Temminck & Schlegel 1846), Medaka Oryzias latipes (Temminck & Schlegel 1846) and Nile tilapia Oreochromis niloticus (L. 1758), oct4 – pou5f3 was restricted to the gonad and, in P. olivaceus its expression was continuous throughout oogenesis, in agreement with the present results (Sanchez‐Sanchez et al, ; Xiaohuan et al, ; Gao et al, ). Similarly, the pluripotency and proliferation–differentiation modulator nanog , yielded no significant results.…”

“…In addition to RA metabolism, the expression patterns of the egg yolk precursor vitellogenin vtg1 and of the pluripotency markers oct4 – pou5f3 and nanog were also determined. Oct4 – pou5f3 and nanog are homeodomain transcription factors which modulate pluripotency: while the former stimulates and maintains pluripotency and promotes survival of germ cells (Frankenberg & Renfree, ; Xiaohuan et al, ; Gao et al, ), the latter is linked to the acquisition of pluripotency, favouring proliferation instead of cellular differentiation (Camp et al, ; Theunissen et al, ; Schuff et al, ).…”

Evolutionary Conservation of pou5f3 Genomic Organization and Its Dynamic Distribution during Embryogenesis and in Adult Gonads in Japanese Flounder Paralichthys olivaceus

“…Pou5f1 is an important marker gene of stem cells. In the past 20 years, the homologues of Pou5f1 in mammals as well as in other vertebrates, including human [ 34 ], bovine [ 35 ], brushtail possum [ 36 , 37 ], rhesus monkey [ 38 ], platypus [ 39 ], vole [ 40 ], chicken [ 41 ], xenopus [ 42 ], zebrafish [ 21 , 43 ], medaka [ 17 , 44 ], Chinese sturgeon [ 45 ], goldfish [ 18 ], and Nile tilapia [ 19 ], have been identified. Several research studies have revealed their critical roles during early embryonic development and their importance in the maintenance of stem cell pluripotency.…”

“…A specific expression of Oct4 among mouse adult tissues is observed in the germ stem cells [ 13 , 14 ]. In contrast to the ICM localization of Oct4 in mammals, the homologue of Oct4 in lower teleosts, which was recently renamed pou5f3 , is spatially expressed throughout the blastomere from fertilized egg to gastrulae [ 15 , 16 , 17 , 18 , 19 ]. In addition to pluripotency regulation, zebrafish pou5f3 (originally named pou2/spg) also has some new roles as well as partial function loss when compared with other species.…”

Sex change in aquarium systems establishes the New Zealand spotty wrasse (Notolabrus celidotus) as a temperate model species for the investigation of sequential hermaphroditism

“…Stem cell maintenance and pluripotency may be important for sex change in wrasses, where no male germ cells are identifiable prior to sex change (Todd et al, 2019). Vertebrate pluripotency factor pou5f3 (POU domain, class 5, transcription factor 1) is critical for the maintenance and regulation of stem cell pluripotency in teleosts (Gao et al, 2017;Lacerda et al, 2019;Xiaohuan et al, 2016).…”