Dual Specificity Phosphatase 5, a Specific Negative Regulator of ERK Signaling, Is Induced by Serum Response Factor and EIk-1 Transcription Factor

Serum stimulation of mammalian cells induces, via the MAPK pathway, the nuclear protein DUSP5 (dual-specificity phosphatase 5), which specifically interacts with and inactivates the ERK1/2 MAP kinases. However, molecular mechanisms underlying DUSP5 induction are not well known. Here, we found that the DUSP5 mRNA induction depends on a transcriptional regulation by the MAPK pathway, without any modification of the mRNA stability. Two contiguous CArG boxes that bind serum response factor (SRF) were found in a 1 Kb promoter region, as well as several E twenty-six transcription factor family binding sites (EBS). These sites potentially bind EIk-1, a transcription factor activated by ERK1/2. Using wild type or mutated DUSP5 promoter reporters, we demonstrated that SRF plays a crucial role in serum induction of DUSP5 promoter activity, the proximal CArG box being important for SRF binding in vitro and in living cells. Moreover, in vitro and in vivo binding data of EIk-1 to the same promoter region further demonstrate a role for EIk-1 in the transcriptional regulation of DUSP5. SRF and EIk-1 form a ternary complex (EIk-1-SRF-DNA) on DUSP5 promoter, consequently providing a link to an important negative feedback tightly regulating phosphorylated ERK levels.