The noncatalytic amino terminus of mitogen-activated protein kinase phosphatase 1 directs nuclear targeting and serum response element transcriptional regulation.
The mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) is an immediate-early gene comprised of a dual-specificity phosphatase domain and a noncatalytic NH(2) terminus. Here, we show that the NH(2) terminus of MKP-1, containing the cdc25 homology domains A (CH2A) and B (CH2B), mediates MKP-1 nuclear targeting and modulates MAPK-mediated gene expression. An LXXLL motif which is known to mediate protein-protein interactions with nuclear-targeted hormone receptors was identified proximal to the CH2A domain of MKP-1. The NH(2) terminus alone of MKP-1 containing this LXXLL motif was sufficient to direct nuclear targeting, and mutating this motif to LXXAA resulted in the exclusion of MKP-1 from the nucleus. We found that the LXXLL motif proximal to the CH2A domain was present in other nuclear-localized MKPs but was absent in MKPs that localized to the cytoplasm. These data suggest that this LXXLL motif confers nuclear targeting properties to the MKPs. The NH(2) terminus of MKP-1 was also found to inhibit the activation of the serum response element (SRE) by preventing MAPK-mediated phosphorylation of the regulatory serine 383 residue on Elk-1. Moreover, we show that MKP-1 plays a major role in the attenuation of serum-induced SRE activity, since MKP-1 null fibroblasts exhibited enhanced SRE activity in response to serum compared with wild-type fibroblasts. The NH(2) terminus of MKP-1, when reconstituted into MKP-1 null fibroblasts to levels similar to endogenous MKP-1 following serum stimulation, reduced serum-mediated SRE activity. Collectively, these data reveal novel roles for the NH(2) terminus of MKP-1 in nuclear targeting and transcriptional regulation.
Wu
J Julie
JJ
Yale University School of Medicine, Department of Pharmacology, SHM B226D, 333 Cedar Street, New Haven, CT 06520-8066, USA.
Zhang
Lei
L
Bennett
Anton M
AM
D021581:Active Transport, Cell Nucleus; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D054638:Dual Specificity Phosphatase 1; D005786:Gene Expression Regulation; D017874:Immediate-Early Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054645:Protein Phosphatase 1; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D027602:Serum Response Element / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D050807:ets-Domain Protein Elk-1
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C494113:Elk1 protein, mouse; D017874:Immediate-Early Proteins; D019913:Nuclear Localization Signals; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse; D017027:Protein Tyrosine Phosphatases