Mapping of a potent transcriptional repression region of the human homeodomain protein EVX1

Abstract

The human homeodomain protein EVX1 is a transcriptional repressor in transfected mammalian cells and this function depends on a region carboxyl-terminal to the homeodomain. In this study, we transiently expressed several deletions of the EVX1 C-terminal region in mammalian cells and investigated their effect on the transcription of a reporter gene directed by different promoters. We show that the repressor activity maps to a region of 51 amino acids with a high abundance of alanine and proline residues. This region is able to transfer the repressor function to either the entire HOXC6 or CREB transcription factors, or to the GAL4 DNA binding domain.

Gtx, an oligodendrocyte‐specific homeodomain protein, has repressor activity

“…When tethered to DNA by way of the strong GAL4 DNA-binding domain, Gtx repressed transcription with a magnitude similar to that of other known repressors, including SMRT (Nagy et al, 1997) and Msx1 (Catron et al, 1995). Various truncations of the GAL4 -Gtx fusion identified a portable repressor domain within a relatively proline/alanine-rich region N-terminal to the Gtx homeodomain, which is similar to that found in another homeodomain protein, Evx1 (Briata et al, 1997). Cotransfection of a Gtx expression vector into a variety of cell lines, including oligodendrocytes, along with constructs containing portions of the PLP, MBP, or Gtx promoters fused to a reporter gene, however, did not alter transcription from any of these promoter constructs.…”

PRH Represses Transcription in Hematopoietic Cells by at Least Two Independent Mechanisms

“…Proline-rich transcription repression domains have been identified in a number of homeodomain proteins including Eve, Msx-1, and Evx-1 (35,46,47). The Eve proline-rich repression domain is involved in mediating protein-protein interactions that result in the cooperative binding of Eve to DNA (21).…”

Transcriptional Activity of the Paired-like Homeodomain Proteins CHX10 and VSX1

“…In one scenario, CHX10 repressed enhancer activity even when pRB did not. Studies with promoters lacking appropriate binding sites, and with CHX10 variants that do not bind DNA, showed that DNA binding was essential for repression, which distinguishes CHX10 from certain other HD repressors, including the pairedlike HD protein rHox (47)(48)(49)(50). We also found that CHX10 slightly enhanced transcription of specific activators in primary chick neuronal cultures.…”