| 1997 |
MKP-4/DUSP9 is a dual-specificity phosphatase that catalyzes vanadate-sensitive dephosphorylation of p-nitrophenyl phosphate and directly inactivates purified ERK2 in vitro. When expressed in COS-7 cells, it inactivates MAP kinases with selectivity ERK > p38 = JNK/SAPK. It contains two N-terminal CH2 domains homologous to Cdc25 and the extended active-site motif VXVHCXAGXSRSXTX3AYLM conserved in dual-specificity phosphatases. Immunocytochemical analysis showed MKP-4 to be predominantly cytosolic, with punctate nuclear staining co-localizing with promyelocytic protein in a subpopulation of cells. |
In vitro phosphatase assay with purified ERK2, COS-7 cell overexpression, immunocytochemistry, Northern analysis, chromosomal localization |
The Journal of biological chemistry |
High |
9030581
|
| 2005 |
MKP-4/DUSP9 and an MKP-4/p38 complex purified via baculovirus expression both exhibit phosphatase activity toward surrogate substrates; the MKP-4/p38 complex provides substantially higher phosphatase activity than MKP-4 alone, demonstrating that p38 binding activates DUSP9 catalysis, analogous to the activation of MKP-3 by ERK2. |
Baculovirus expression, affinity and gel-filtration purification, in vitro spectrophotometric and fluorescence phosphatase assays with kinetic parameter determination |
Bioorganic chemistry |
High |
15668181
|
| 2005 |
DUSP9 knockout (X-linked gene; paternal X inactivated in extraembryonic tissues) in mice causes embryonic lethality due to failure of placental labyrinth development. The lethal phenotype maps specifically to trophoblast giant cells and labyrinth where DUSP9 is normally expressed. When the placental defect was rescued, DUSP9-null male embryos developed normally and were fertile, indicating DUSP9 is essential for placental organogenesis but dispensable for embryonic development. |
Gene targeting (knockout mouse), histological analysis of embryos 8–10.5 dpc, placental rescue experiments |
Molecular and cellular biology |
High |
16135819
|
| 2008 |
Overexpression of MKP-4/DUSP9 in 3T3-L1 adipocytes inhibits ERK and JNK phosphorylation and, to a lesser extent, p38 phosphorylation, thereby preventing anisomycin-induced IRS-1 Ser307 phosphorylation. This restores insulin-stimulated IRS-1 tyrosine phosphorylation, IRS-1 docking with PI3K, and Akt phosphorylation, and reverses TNF-α-induced inhibition of insulin signaling and glucose uptake. Adenoviral overexpression in ob/ob mouse liver decreased ERK and JNK phosphorylation, reducing glycemia and improving glucose tolerance. |
Stable overexpression in 3T3-L1 cells, immunoblotting for phospho-ERK/JNK/p38/IRS-1/Akt, PI3K co-immunoprecipitation, glucose uptake assay, adenoviral hepatic overexpression in ob/ob mice |
Proceedings of the National Academy of Sciences of the United States of America |
High |
18296638
|
| 2010 |
Crystal structure of the DUSP9/MKP-4 catalytic domain (MKP-4C) resolved at 2.7 Å reveals significant deviations from canonical DUSP active conformations, with notable gaps between the catalytic core and surrounding loops. Virtual library screening identified inhibitor-binding sites near these gaps distinct from the active site, suggesting allosteric inhibition could prevent transition to the fully active conformation. |
X-ray crystallography at 2.7 Å resolution, virtual library screening |
Acta crystallographica. Section D, Biological crystallography |
High |
21206059
|
| 2017 |
DUSP9 is upregulated in female compared to male mouse ESCs due to its X-linked location (two active X chromosomes in female ESCs). Heterozygous loss of DUSP9 in female ESCs leads to male-like (hypermethylated) DNA methylation levels genome-wide. Cell fusion experiments showed that the ratio of X chromosomes to autosomes dictates methylation levels, placing DUSP9 as a mediator of X-dosage-dependent epigenetic regulation. |
Genome-wide methylation profiling, cell fusion experiments, CRISPR-mediated heterozygous DUSP9 deletion in female ESCs, RNA-seq |
Cell stem cell |
High |
28366588
|
| 2018 |
In triple-negative breast cancer, HIF-1 transcriptionally induces DUSP9 expression in response to chemotherapy, leading to ERK dephosphorylation/inhibition. This ERK inhibition causes decreased inactivating phosphorylation of FoxO3, driving transcriptional induction of pluripotency factor Nanog and promoting breast cancer stem cell specification. |
siRNA knockdown of HIF1/DUSP9 in TNBC cells, immunoblotting for phospho-ERK/FoxO3, Nanog reporter assays, mammosphere formation, ALDH flow cytometry |
Cancer research |
Medium |
29880481
|
| 2019 |
ERK1/2 were identified as direct binding partners of MKP-4/DUSP9 by immunoprecipitation-mass spectrometry. MKP-4 negatively regulates ERK1/2 phosphorylation and reduces downstream CyclinD1 and c-Myc expression in hepatocellular carcinoma cells. Knockdown of MKP-4 increases cell proliferation and cancer stem cell traits, while upregulation of MKP-4 or ERK1/2 inhibitor treatment reverses these effects. |
Immunoprecipitation-mass spectrometry (IP-MS), western blot, colony formation, EdU incorporation, sphere formation assays, xenograft tumor models |
Cancer cell international |
Medium |
30923463
|
| 2015 |
DUSP9/MKP-4 is constitutively expressed in mouse plasmacytoid dendritic cells (pDCs) but not conventional DCs, and its expression correlates with impaired ERK1/2 phosphorylation upon TLR9 stimulation. Enforced retroviral expression of Dusp9 in GM-CSF-induced cDCs increased TLR9-induced IL-12p40 and IFN-β but not IL-10. Conditional deletion of Dusp9 in pDCs did not restore ERK1/2 activation after TLR9 stimulation and only weakly affected IFN-β and IL-12p40 production, indicating Dusp9 is sufficient but not essential for high-level IFN-β production in pDCs. |
Transcriptome analysis, retroviral overexpression in cDCs, conditional knockout (Dusp9flox/flox; CD11c-Cre), ELISA for cytokines, flow cytometry for phospho-ERK |
Journal of immunology |
Medium |
26170386
|
| 2022 |
DUSP9 directly binds to apoptosis signal-regulating kinase 1 (ASK1) and inhibits ASK1 phosphorylation, thereby decreasing TRAF6 levels, K63-linked ubiquitination, and downstream p38/JNK1 (but not ERK1) phosphorylation in hepatic ischemia/reperfusion injury. This mechanism is distinct from canonical ERK-focused DUSP9 activity. |
Co-immunoprecipitation (DUSP9–ASK1 binding), western blot for phospho-ASK1/p38/JNK1/ERK1, TRAF6/ubiquitin immunoprecipitation, adenoviral overexpression and siRNA knockdown in vivo and in vitro |
Acta biochimica et biophysica Sinica |
Medium |
36789693
|
| 2024 |
HDAC9 represses DUSP9 expression by deacetylating histone H4K12 (H4K12ac) at the DUSP9 promoter, thereby activating downstream MAPK signaling and promoting particulate matter-induced airway inflammation. HDAC9 upregulation is mediated upstream by the METTL3/m6A/IGF2BP3 pathway acting on HDAC9 mRNA. |
ChIP for H4K12ac at DUSP9 promoter, siRNA knockdown of HDAC9/DUSP9, western blot for MAPK pathway, in vivo mouse airway inflammation model |
Journal of hazardous materials |
Medium |
39088948
|
| 2025 |
DUSP9 directly interacts with insulin receptor substrate 1 (IRS1) and inhibits IRS1 phosphorylation at Tyr632, impairing downstream IRS1/PI3K/AKT insulin signaling. This interaction was demonstrated by co-immunoprecipitation and pull-down assays in high-glucose-treated trophoblast cells, and DUSP9 knockdown in a GDM mouse model restored IRS1/PI3K/AKT pathway activation. |
Co-immunoprecipitation, pull-down assay, western blot for phospho-IRS1(Tyr632)/PI3K/AKT, lentivirus-mediated shRNA knockdown in GDM mouse model |
Human immunology |
Medium |
40020430
|
| 2025 |
DUSP9 dephosphorylates STAT3 to negatively regulate PD-L1 expression in tumor cells. Mechanistic experiments showed that DUSP9 overexpression reduced phospho-STAT3 levels, leading to decreased PD-L1 transcription, while DUSP9 knockdown increased PD-L1 expression. Combining DUSP9 targeting with anti-PD-1 antibody enhanced therapeutic sensitivity in syngeneic tumor models. |
DUSP9 overexpression/knockdown, immunoblotting for phospho-STAT3 and PD-L1, syngeneic tumor models with anti-PD-1 combination |
Advanced science |
Medium |
41405398
|
| 2025 |
FBXO3 E3 ubiquitin ligase directly interacts with DUSP9 and promotes its ubiquitination and degradation, thereby activating the MAPK pathway and maintaining leukemia stem cell activity in CML. DUSP9 knockdown partially reverses the LSC elimination caused by FBXO3 deficiency, placing DUSP9 downstream of FBXO3 in this pathway. |
Co-immunoprecipitation (FBXO3–DUSP9 interaction), ubiquitination assay, FBXO3 KO/DUSP9 KD in CML cell lines and primary LSCs, in vivo LSC models |
Cell reports. Medicine |
Medium |
41850237
|
| 2025 |
Caffeine directly targets DUSP9 (identified by surface plasmon resonance, CETSA, and DARTS assays) and restores hepatic DUSP9 expression reduced by high-fat/high-carbohydrate diet. DUSP9 knockdown in vivo counteracted the therapeutic effects of caffeine on MASH, including glycolipid metabolism disorders. The downstream mechanism involves DUSP9-mediated inactivation of the ASK1-p38/JNK signaling pathway. |
Surface plasmon resonance (SPR), CETSA, DARTS for direct target identification; DUSP9 knockdown in vivo; western blot for ASK1/p38/JNK; metabolic phenotyping in MASH mouse models |
Redox biology |
Medium |
39879738
|
| 2020 |
DUSP9 suppresses proliferation and migration of clear cell renal cell carcinoma cells and inhibits phosphorylation of mTOR and expression of downstream mTOR pathway proteins Sox2, c-Myc, and HIF-1α. This was confirmed by in vitro assays and xenograft tumor models. |
DUSP9 overexpression in ccRCC cell lines, western blot for p-mTOR/Sox2/c-Myc/HIF-1α, CCK-8 proliferation, wound-healing and transwell migration assays, nude mouse xenograft |
OncoTargets and therapy |
Low |
32103999
|