SRA

Somatic cells can be reprogrammed into pluripotent stem cells by the ectopic expression of OCT4, SOX2, KLF4, and c-MYC. Although SOX2, KLF4, and c-MYC (SKM) can be substituted by their respective family members, OCT4 is considered to not be interchangeable with any octamer-binding POU proteins. Through a screening with 102 candidate genes, here we have identified that the POU protein OCT6 (also known as SCIP, TST-1, and POU3F1), in conjunction with SKM, is capable of functionally replacing OCT4 and inducing pluripotency. OCT6-mediated reprogramming works with any human cell type, but not with mouse cells. The reprogramming process involving OCT6 is relatively inefficient and slow. This is mainly due to either inefficient formation of OCT6-SOX2 heterodimers onto canonical SOX-OCT sites or lower transactivation activity of OCT6. We demonstrate that modulating either the DNA-binding propensity or the transactivation activity of OCT6 enhances iPSC generation to the efficiency of OCT4. These results thus provide the first evidence that a POU factor other than OCT4 can induce human pluripotency. Overall design: The TRA1-60+ cells in the two induction system at day 2, 4, 6, 8, 10, 12, and 16, which were isolated by FACS using APC anti-human CD13 (BioLegend), PE anti-human TRA-1-60 (BioLegend). The sorted TRA1-60+ cells during reprogramming were washed several times in 0.5% BSA-PBS (Sigma) solution and subsequently picked and transferred into lysate buffer by a mouth pipette with 50 cell for each tube. At least 3 replicates were set for each time point.