Gene OCT4 plays pivotal roles in maintaining pluripotency of early mammalian embryonic development and embryonic stem cells. It is essential to establish a reporter system based on the OCT4 promoter region for the study of pluripotency. However, there is still a lack of sufficient information about the porcine OCT4 upstream reporter system. To improve our understanding of the porcine OCT4 regulatory region, first, we conducted an investigation to find conserved regions in the porcine OCT4 promoter upstream region by sequence-based comparative analysis using various mammalian genome sequences. A similarity of nucleotide sequences of the 5′ upstream region was low among mammalian species. However, the OCT4 promoter and 4 regulatory regions including distal and proximal enhancer elements have a high similarity. Next, a functional analysis of the porcine OCT4 promoter region was conducted. Luciferase reporter assay indicated that the porcine OCT4 distal enhancer and proximal enhancer are highly activated in mouse embryonic stem cells and embryonic carcinoma cells, respectively (n=3). Comparison analysis of naïve (Tbx3, Nr0b1, Rex1, Esrrb, Nanog, Klf2) or primed (Gata6, Mixl1, Fgf5, Otx2) state marker gene expression in a dual-reporter assay using pOCT4-DE-eGFP and pOCT4-PE-DsRed2 showed that expression of naïve and primed markers were up-regulated in cells with high green fluorescent protein and red fluorescent protein expression, respectively (n=3). Porcine OCT4-upstream region-based reporter constructs showed exclusive expression patterns depending on the state of pluripotency. This work could provide basic information for the porcine OCT4 upstream region and the various porcine OCT4-fluorescence reporter constructs, which can be applied to study species-specific pluripotency in early embryo development and for the establishment of embryonic stem cells in pigs.
This work was supported by the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (IPET) through the Development of High Value-Added Food Technology Program, funded by the Ministry of Agriculture, Food and Rural Affairs (MAFRA, 118042-03-1-HD020).
