The Human GATA1 Gene Retains a 5′ Insulator That Maintains Chromosomal Architecture and GATA1 Expression Levels in Splenic Erythroblasts

GATA1 is a key transcription factor for erythropoiesis.GATA1 gene expression is strictly regulated at the transcriptional level. While the regulatory mechanisms governing mouseGata1 (mGata1 ) gene expression have been studied extensively, how expression of the humanGATA1 (hGATA1 ) gene is regulated remains to be elucidated. To address this issue, we generatedhGATA1 bacterial artificial chromosome (BAC) transgenic mouse lines harboring a 183-kbhGATA1 locus covering thehGATA1 exons and distal flanking sequences. TransgenichGATA1 expression coincides with endogenousmGata1 expression and fully rescues hematopoietic deficiency inmGata1 knockdown mice. The transgene exhibited copy number-dependent and integration position-independent expression ofhGATA1 , indicating the presence of chromatin insulator activity within the transgene. We found a novel insulator element at 29 kb 5′ to thehGATA1 gene and refer to this element as the 5′ CCCTC-binding factor (CTCF) site. Substitution mutation of the 5′ CTCF site in thehGATA1 BAC disrupted the chromatin architecture and led to a reduction ofhGATA1 expression in splenic erythroblasts under conditions of stress erythropoiesis. Our results demonstrate that expression of thehGATA1 gene is regulated through the chromatin architecture organized by 5′ CTCF site-mediated intrachromosomal interactions in thehGATA1 locus.