Involvement of the transcriptional factor GATA-1 in regulation of expression of coproporphyrinogen oxidase in mouse erythroleukemia cells.

Coproporphyrinogen oxidase (CPO; EC 1.3.3.3), the sixth enzyme of heme biosynthesis, transcribed from a single promoter is markedly induced during erythroid differentiation. CPO is ubiquitously expressed in all cells. To determine cis-acting elements of the human CPO gene, the promoter region of the gene was isolated, and three potential GATA-1 motifs and four GC boxes were found within this fragment. In a functional analysis of various deletion mutants, we found that the GATA-1 binding site at -143 to -138 was essential for basic and inducible expressions of the CPO gene in mouse erythroleukemia (MEL) cells. Gel mobility shift assay revealed that GATA-1 bound to the region is required for the expression and this was confirmed by observations that the nuclear protein bound to the GATA-1 motif was supershifted with anti GATA-1 antibody, by gel mobility shift assay. Furthermore, co-expression of mouse GATA-1 in MEL cells led to an increase in the promoter activity, which was markedly increased by dimethyl sulfoxide-treatment. These results indicate that GATA-1 plays an important role in regulation of transcription of the CPO gene in erythroid cells.