Identification and differential expression patterns of porcine OCT4 variants

Abstract

OCT4 encoded by POU5F1 has a crucial role of maintaining pluripotency in embryonic stem cells during early embryonic development and several OCT4 variants have been identified in mouse and human studies. The objective of this study was to identify different variants of OCT4 and analyze their expression patterns in preimplantation porcine embryos and various tissues. In this study, we showed that POU5F1 transcribes its three variants, namely OCT4A, OCT4B, and OCT4B1. The OCT4B transcript consists of exons identical to the major form of the OCT4 variant, OCT4A, with a differential N-terminal domain-coding exon. The structure of OCT4B1 mRNA was the same as that of OCT4B mRNA, but harbored a cryptic exon. Based on these findings, the transcription levels were investigated and found that OCT4B and OCT4B1 made up w20% among the variants in the embryonic stage and this indicates that OCT4A mRNA is dominantly expressed during preimplantation embryo development. In addition, OCT4B mRNA was detected in all tissues examined, while OCT4A and OCT4B1 were detected only in testis but not in other tissues examined. OCT4B1 showed inversely correlated expression with SOX2 and NANOG expression. OCT4A protein was specifically localized to the nuclei, whereas OCT4B was mainly localized to the cytoplasm of the porcine embryos at the blastocyst stage. The findings of this study reveal that the porcine OCT4 gene can potentially encode three variants (OCT4A, OCT4B, and OCT4B1), and they are differentially expressed and would have roles dissimilar between each other in preimplantation embryos and various adult tissues.

Characterization of novel alternative splicing variants of Oct4 gene expressed in mouse pluripotent stem cells

“…Previous reports showed that Oct4 retained several expressed pseudogenes and alternative splicing variants (Guo et al, ; Scarola et al, ). Though Oct4b1 was a lately discovered Oct4 splicing variant in human and other animal (Atlasi et al, ; Farashahi Yazd et al, ; Hwang et al, ), it was not reported in mouse yet. And the Oct4 splicing variants reported in mouse were inconsistent.…”

“…Though Oct4b1 was a lately discovered Oct4 splicing variant in human and other animal (Atlasi et al, 2008;Farashahi Yazd et al, 2011;Hwang et al, 2014), it was not reported in mouse yet. And the Oct4 splicing variants reported in mouse were inconsistent.…”

Overexpression of <i>OCT4A</i> ortholog elevates endogenous <i>XIST</i> in porcine parthenogenic blastocysts

“…Virus titration was performed by calculating the integrated copy numbers in HEK293-LTV cells inoculated with the prepared virus. To calculate copy numbers of integrated vectors and genomes, a linear-regression plot was prepared following our previous report [ 21 ]. Human genomic region ( hGAPDH ) and internal ribosome entry site (IRES) in lentiviral vector plasmids were assessed to calculate the number of integrated transgenes in the genome.…”

“…Therefore, in present study, we aimed to examine whether overexpression of OCT4A , which has been reported to be pluripotent gene and major variant of OCT4A gene in pigs [ 21 ], could affect expression of X-linked genes regulating XCI in female porcine preimplantation embryos.…”

SALL4 maintains self-renewal of porcine pluripotent stem cells through downregulation of OTX2

“…These variants can form protein-protein interactions that could lead to developmental state-specific regulatory networks, thereby increasing the biological complexity compare to a single locus. For instance, Oct4 has more than two splice variants, in which Oct4A is expressed in ESCs and iPSCs, while Oct4B is expressed in differentiated cells and somatic tissues [32][33][34] . In this study, we found that porcine SALL4B was globally expressed in somatic tissues and cells, however, SALL4A was only detected in piPSCs, but was undetectable in muscle and liver tissues.…”