Mouse Oct-1 contains a composite homeodomain of human Oct-1 and Oct-2

Abstract

Members of the Oct family of transcription factors specifically interact with the octamer motif, ATGC-AAAT, a regulatory element important for tissue- and cell-specific transcription as well as for the expression of housekeeping genes. Except for Oct-1, all Oct factors are expressed in a temporally and spatially restricted mode during murine development and their number varies in a given cell type. Despite its ubiquitous expression pattern Oct-1 may play a role in murine development. As a first step towards elucidating the role of Oct-1 we report the complementary DNA cloning of the mouse Oct-1 gene. Two large transcripts of 5 and 14 kb are derived from a single gene. The expression patterns of three splicing products of Oct-1 are similar in a number of cells and tissues. In the POU region murine Oct-1 differs in four amino acids from the human homologue and these differences are restricted to helices 1 and 2. Interestingly, two of the four variant amino acids are identical to those in human and mouse Oct-2 and thus the murine Oct-1 homeodomain is intermediary in sequence between human Oct-1 and Oct-2. These two amino acids together with a third one have been shown to be relevant for the interaction between human Oct-1 and herpes simplex virus transactivator VP16. Nevertheless, VP16 interacts albeit weakly with murine Oct-1. We speculate that the differences in the human and mouse Oct-1 homeodomains reflect host-specific differences in protein-protein interactions.

Selected Elements of Herpes Simplex Virus Accessory Factor HCF Are Highly Conserved in Caenorhabditis elegans

“…In contrast to the high level of conservation of the HCF surface that directs association with VP16, the surface of Oct-1 that directs association with VP16 has not been highly conserved. Indeed, owing to differences on the VP16-interaction surface of the mouse Oct-1 homeodomain, VP16 fails to associate effectively with mouse Oct-1 (6,27). Thus, apparently the VP16-interaction surface of Oct-1 is less important for Oct-1 cellular function than the VP16-interaction surface of HCF is for HCF cellular function.…”

The POU Homeodomain Transcription Factor Oct-1 Is Essential for Activity of the Gonadotropin-Releasing Hormone Neuron-Specific Enhancer

“…Alternatively spliced products of the murine Oct-2 gene have been cloned and found to be expressed in different regions of the brain (50). Recently, spliced forms of Oct-1 have also been detected, but the spliced products are present in all cell lines tested (5,17,55).…”

Tumor necrosis factor-alpha eliminates binding of NF-Y and an octamer-binding protein to the lipoprotein lipase promoter in 3T3-L1 adipocytes.

“…The antibody is against human OCT-1, and although it is expected to cross-react with murine OCT-1, the affinity for murine OCT-1 could be much less. Alternatively, the octamer-binding protein could be one of the recently identified splice variants of OCT-1 (19) that the antibody fails to recognize.…”