DUSP8

DUSP8 is a dual-specificity MAPK phosphatase that dephosphorylates and inactivates mitogen-activated protein kinases, with its catalytic region directly hydrolyzing phosphosubstrate and inactivating MAPK in vitro (PMID:7561881). It engages JNK isoform-selectively, preferentially binding and acting on JNK1β/JNK2α over JNK1α1 and JNK3, and is partitioned among JIP scaffolds—constitutively bound to JIP1/JIP2 and inducibly recruited to JIP3 under oxidative stress (PMID:23159405). The specific MAPK branch DUSP8 controls is tissue-dependent: in cardiac myocytes it selectively restrains ERK1/2, where its loss elevates ERK1/2 phosphorylation and its overexpression drives ventricular remodeling and heart failure, with p38 and JNK largely unaffected (PMID:27225478), whereas in the hypothalamus it acts as a gatekeeper of JNK signaling, controlling HPA-axis feedback and glucose homeostasis in a sex-specific manner that is rescued by Jnk1 ablation or hypothalamic Dusp8 re-expression (PMID:32780722). Beyond canonical MAPK substrates, DUSP8 dephosphorylates the transcriptional repressor Pur-α upon TGF-β signaling, driving Pur-α nuclear export, IL-9 transcription, and Th9 differentiation in allergic inflammation (PMID:37909329). In microglia it binds TAK1 and suppresses downstream p38/JNK/NF-κB neuroinflammatory signaling (PMID:36279673).

1. 1995 High

   Established that DUSP8 is an enzymatically active phosphatase capable of inactivating MAPK, defining its core biochemical identity.

   Evidence In vitro enzymatic assay with recombinant catalytic fusion protein, p-nitrophenylphosphate hydrolysis and MAPK inactivation

   PMID:7561881

   Open questions at the time

   • Did not resolve which physiological MAPK substrates are targeted in cells
   • No isoform or tissue specificity addressed
2. 2012 High

   Resolved that DUSP8 acts on JNK with isoform selectivity and is targeted to substrate via JIP scaffolds, revealing how its activity is spatially organized and stress-regulated.

   Evidence Co-immunoprecipitation, in vitro phosphatase assays toward JNK isoforms, and arsenite-induced interaction remodeling in cells

   PMID:23159405

   Open questions at the time

   • Functional consequence of stress-induced scaffold switching not established in vivo
   • Structural basis of isoform preference unknown
3. 2016 High

   Showed that in the heart DUSP8 selectively controls ERK1/2 rather than JNK/p38, demonstrating tissue-specific substrate channeling with physiological consequences.

   Evidence Complementary Dusp8 KO and cardiac-specific transgenic overexpression mice with phospho-MAPK readouts and cardiac phenotyping

   PMID:27225478

   Open questions at the time

   • Mechanism dictating ERK selectivity in cardiomyocytes vs JNK preference elsewhere unexplained
   • Whether scaffold composition drives this tissue bias not tested
4. 2019 Medium

   Linked DUSP8-dependent ERK dephosphorylation to brain morphology, extending its ERK-regulatory role to the hippocampus.

   Evidence Dusp8 KO vs WT phospho-ERK/p38/JNK western blotting and brain morphometry

   PMID:31862894

   Open questions at the time

   • Causal link between ERK elevation and reduced hippocampal size not directly tested
   • Single method per endpoint
5. 2020 High

   Placed DUSP8 epistatically upstream of hypothalamic JNK1 in HPA-axis and glucose control, defining a CNS metabolic function distinct from its cardiac role.

   Evidence Global and CRH-neuron-specific Dusp8 KO, AAV re-expression, Jnk1 KO epistasis, and pharmacological adrenalectomy rescue in mice

   PMID:32780722

   Open questions at the time

   • Molecular basis of the sex-specific phenotype unresolved
   • Direct dephosphorylation of hypothalamic JNK not biochemically shown
6. 2022 Medium

   Identified TAK1 as a DUSP8 binding partner in microglia, extending DUSP8 control to upstream MAP3K/NF-κB neuroinflammatory signaling.

   Evidence Co-immunoprecipitation, AAV overexpression in SNL rat model, siRNA knockdown, and TAK1 inhibitor epistasis

   PMID:36279673

   Open questions at the time

   • Whether DUSP8 dephosphorylates TAK1 directly or acts via a different mechanism not established
   • Reciprocal co-IP and enzymatic validation limited
7. 2023 High

   Discovered a non-MAPK substrate, Pur-α, showing DUSP8 controls transcription factor localization and IL-9-driven Th9 differentiation.

   Evidence T cell-specific Dusp8 cKO, mass spectrometry, ChIP-Seq, co-IP, fractionation, Pur-α KO epistasis, and allergic asthma model

   PMID:37909329

   Open questions at the time

   • Direct phosphosite on Pur-α not mapped
   • Whether other DUSP8 substrates exist beyond MAPKs and Pur-α unknown
8. 2024 Medium

   Extended DUSP8 ERK-suppressive function to steroidogenic granulosa cells, linking it to lipid metabolism and progesterone synthesis.

   Evidence Overexpression and siRNA knockdown in primary chicken granulosa cells with phospho-ERK and metabolic/hormonal readouts

   PMID:38820772

   Open questions at the time

   • Avian system; conservation of mechanism in mammals not shown
   • Direct dephosphorylation not demonstrated
9. 2025 Low

   Implicated DUSP8 loss-of-function in hereditary gingival fibromatosis through a glycolysis/lactylation axis, suggesting a disease-relevant downstream pathway.

   Evidence Whole-exome sequencing identifying p.R450C, siRNA knockdown in human gingival fibroblasts, glycolysis and lactylation assays

   PMID:39887402

   Open questions at the time

   • Single KD approach with limited mechanistic depth
   • Connection between phosphatase activity and lactylation unestablished

• How DUSP8 substrate selectivity (ERK vs JNK vs p38 vs Pur-α) is determined across tissues, and the structural/scaffold basis for this context-dependent specificity, remains unresolved.
• No structural model linking scaffold engagement to substrate choice
• Mechanism of tissue-specific MAPK branch selection not defined