oa Identification of Two Novel Splice variants of SOX2OT which are Co-expressed with Pluripotency Genes during Neural Differentiation of Stem Cells

Our objectives were: Long non-coding RNAs (lncRNAs) are emerging as new regulators of stem cell pluripotency and neurogenesis. Recent studies revealed that the expression of several lncRNAs correlates with the expression of pluripotency regulators such as OCT4 and Nanog. Surprisingly, the SOX2 gene, another master regulator of pluripotency, is embedded within an intron of an lncRNA, known as SOX2OT. SOX2OT and has been suspected to participate in regulation of the SOX2 expression and related processes; nevertheless, its function has still remained untested. In this study, we investigated a potential correlation between the expression pattern of SOX2OT, also its newly discovered splice variants (SOX2OT-S1 and SOX2OT-S2) and master regulators of stem cell pluripotency (SOX2 and OCT4) in mesenchymal stem cells, as well as during the course of neural differentiation of the human EC cell line, NTERA2 (NT2).

We treated the NT2 cells with all-trans retinoic acid (ATRA) for four weeks to differentiate into neural phenotype. By designing specific primers for real-time PCR, we evaluated the expression pattern of SOX2OT, SOX2OT-S1, SOX2OT-S2, SOX2 and OCT4 in mesenchymal stem cells and also during the induction of neural differential of NT2 cells.

Our results showed that by using a different set of primers, we discovered two novel variants of SOX2OT, named SOX2OT-S1 (lacking exon4) and SOX2OT-S2 (lacking exons3 and 4). The expression pattern of SOX2OT variants was positively correlated with the expression of SOX2 and OCT4 in NT2 cells. Surprisingly, SOX2OT variants showed a distinct expression pattern during the course of neural differentiation of NT2 cells. The expression pattern of SOX2OT variants was similar to that of OCT4 and SOX2 during early differentiation of NT2 cells. However, in contrast to OCT4 and SOX2, a low expression of SOX2OT variants persist in later time points of neural differentiation of NT2 cells.

We found that close correlation between the expression pattern of SOX2OT variants and master regulators of pluripotency (OCT4 and SOX2) suggests that they may be involved in similar regulatory pathways including: self-renewal, pluripotency, and differentiation.