C-MYC controlled TIP110 protein expression regulates OCT4 mRNA splicing in human embryonic stem cells.

We reported previously that HIV-1 the Tat-interacting protein of 110 kDa (TIP110; P110(NRB)/SART3/p110) is important in regulation of hematopoiesis, and in maintaining pluripotent factor (NANOG, OCT4, and SOX2) expression in and pluripotency of human embryonic stem cells (hESCs). Here we show that TIP110 expression in hESCs line H9 and embryonal carcinoma cell line NT-2 is regulated by C-MYC expression in ESCs through an E box present in the TIP110 promoter region. Through up- and down- modulation of expression, TIP110 induces OCT4 exon 1a inclusion and exon 1b skipping in our OCT4 minigene model. Thus, TIP110 expression in ESCs regulates alternative splicing of OCT4, an event required for pluripotency of ESCs.