| 2019 |
PPM1H directly dephosphorylates LRRK2-phosphorylated Rab GTPases (e.g., Rab8A at its Switch-II motif phosphorylation site). siRNA screen identified PPM1H as the phosphatase counteracting LRRK2 signaling; PPM1H knockout increased endogenous Rab phosphorylation; overexpression suppressed LRRK2-mediated Rab phosphorylation; a substrate-trapping mutant (Asp288Ala) bound with high affinity to LRRK2-phosphorylated Rab proteins, blocking dephosphorylation. |
siRNA screen of all human phosphatases, PPM1H knockout in A549 cells, overexpression assays, in vitro biochemical dephosphorylation of Rab8A, substrate-trapping mutagenesis (D288A) |
eLife |
High |
31663853
|
| 2019 |
PPM1H is localized to the Golgi, and its knockdown suppresses primary cilia formation, phenocopying pathogenic LRRK2. |
Immunofluorescence localization, siRNA knockdown with ciliogenesis readout |
eLife |
Medium |
31663853
|
| 2011 |
PPM1H dephosphorylates p27 at threonine 187, removing a signal for proteasomal degradation and stabilizing p27 protein levels. Knockdown of PPM1H reduces p27 protein levels and confers trastuzumab resistance. |
RNA interference screening, site-specific phosphorylation analysis (pThr187 of p27), western blotting |
Cancer discovery |
Medium |
22586611
|
| 2014 |
PPM1H directly interacts with Smad1/5/8 through its Smad-binding domain and dephosphorylates phospho-Smad1/5/8 in the cytoplasm, preventing nuclear translocation and attenuating BMP signaling. Loss of PPM1H enhances BMP-dependent gene regulation and mesenchymal differentiation. |
Co-immunoprecipitation, domain mapping, in vitro dephosphorylation assay, ectopic expression and loss-of-function studies, BMP reporter assays, mesenchymal differentiation assays |
Cell research |
High |
24732009
|
| 2021 |
Crystal structure of PPM1H reveals a conserved phosphatase fold with a unique 110-residue flap domain adjacent to the active site that encodes the docking motif for phosphorylated Rab GTPases. The flap domain distantly resembles tudor domains. A PPM1J chimera carrying the PPM1H flap domain gains ability to dephosphorylate pThr72 of Rab8a both in vitro and in cellular assays, confirming the flap domain as the determinant of Rab specificity. |
X-ray crystallography, domain-swap chimera (PPM1J + PPM1H flap), in vitro dephosphorylation assay, cellular dephosphorylation assay, crosslinking, 3D modelling |
EMBO reports |
High |
34580980
|
| 2023 |
PPM1H relies on an N-terminal amphipathic helix for Golgi localization. The amphipathic helix enables PPM1H to bind liposomes in vitro, and small, highly curved liposomes stimulate PPM1H activity. Localization drives substrate selection: PPM1H at the mother centriole is required for Rab10 dephosphorylation and ciliogenesis regulation, while poor colocalization of Rab12 explains why it is a poor PPM1H substrate in cells but not in vitro. |
Artificial targeting to Golgi, mitochondria, or mother centriole, liposome-binding assay, in vitro phosphatase activity assay with liposomes of varying curvature, live-cell imaging, Rab phosphorylation readouts |
Proceedings of the National Academy of Sciences of the United States of America |
High |
37889931
|
| 2023 |
LRRK2-hyperphosphorylated RABs disrupt axonal autophagosome transport by perturbing coordinated regulation of dynein and kinesin. PPM1H knockout phenocopies hyperactive LRRK2 in iPSC-derived neurons, causing frequent directional reversals and pauses in autophagosome transport. Overexpression of ARF6 (a GTPase switch for dynein/kinesin) attenuates transport defects in both LRRK2-p.R1441H knockin and PPM1H KO neurons, placing PPM1H upstream of ARF6 in this pathway. |
iPSC-derived human neurons, LRRK2 knockin (R1441H), PPM1H knockout, live imaging of autophagosome transport, ARF6 overexpression rescue experiments |
Cell reports |
High |
37133994
|
| 2009 |
PPM1H possesses phosphatase activity toward pNPP, casein, and phosphopeptides and shows substrate-dependent metal preference: Mn²⁺ is preferred with pNPP or phosphopeptide substrates, while Mg²⁺ is preferred with casein. When both cations are added, Mn²⁺ dominates due to greater affinity for PPM1H. |
In vitro phosphatase activity assays with pNPP, casein, and phosphopeptides; metal ion substitution experiments |
Biometals |
Medium |
19262998
|
| 2020 |
PPM1H is phosphorylated by PKA at Ser-123 and by CaMKI at Ser-210. A hierarchical phosphorylation occurs in neuronal cells whereby initial Ser-123 phosphorylation promotes subsequent Ser-210 phosphorylation. The S123A/S210A double mutant of PPM1H fails to dephosphorylate Smad1 in cell-based assays, establishing that dual phosphorylation at these sites is required for PPM1H activity toward Smad1. |
In vitro kinase assays, in silico site prediction, phospho-mimetic and non-phosphorylatable PPM1H mutants, cell-based Smad1 dephosphorylation assay in Neuro2a cells, kinase activator/inhibitor treatments |
Biochemical and biophysical research communications |
Medium |
32600616
|
| 2023 |
PPM1H directly dephosphorylates p-RPS6KB1 (ribosomal protein S6 kinase B1, a component of the BMP/TGF-β pathway). ATF6 transcriptionally downregulates PPM1H expression in hepatoma cells. |
Homology modeling/Rosetta substrate docking screen, in vitro dephosphorylation assay, hepatoma cell-based assays, Atf6 knockdown in mice, western blotting |
Molecular therapy. Nucleic acids |
Medium |
37456776
|
| 2025 |
PPM1H contains an allosteric binding site for its non-phosphorylated reaction products Rab8A and Rab10. Microscale thermophoresis showed that thiophosphorylated Rab8A binds the active site with KD ~1 µM, while non-phosphorylated Rab8A and Rab10 bind an alternative (allosteric) site at similar affinity; this interaction is not observed for Rab12. Non-phosphorylated Rab8A or Rab10 inhibit PPM1H phosphatase activity (product/end-product inhibition). Rab binding to the allosteric site also requires PPM1H's N-terminal amphipathic helix; removing it decreases affinity ~6-fold. Sucrose gradient co-flotation of non-phosphorylated Rabs with liposome-bound PPM1H provided independent confirmation. |
Microscale thermophoresis (binding affinity measurement), in vitro phosphatase activity inhibition assays, L66R mutagenesis, sucrose gradient co-flotation with liposomes |
The Journal of biological chemistry |
High |
40912655
|
| 2026 |
PPM1H knockout in primary neurons causes gene-dose-dependent disruption of axonal autophagosome transport, impaired degradation of axonal alpha-synuclein, and increased alpha-synuclein aggregation upon exposure to preformed fibrils. The aggregation phenotype is dependent on LRRK2 kinase activity, mechanistically linking PPM1H-controlled RAB dephosphorylation to autophagosomal cargo clearance. |
PPM1H knockout primary neurons, live imaging of autophagosome transport, preformed fibril seeding assay, LRRK2 kinase inhibitor rescue experiments, alpha-synuclein aggregation quantification |
Cell reports |
High |
42166327
|