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PPM1H phosphatase reverses Parkinson's disease-associated, Leucine Rich Repeat Kinase 2-mediated Rab GTPase phosphorylation. We show here that PPM1H relies on an N-terminal amphipathic helix for Golgi localization. The amphipathic helix enables PPM1H to bind to liposomes in vitro, and small, highly curved liposomes stimulate PPM1H activity. We artificially anchored PPM1H to the Golgi, mitochondria, or mother centriole. Our data show that regulation of Rab10 GTPase phosphorylation requires PPM1H access to Rab10 at or near the mother centriole. Moreover, poor colocalization of Rab12 explains in part why it is a poor substrate for PPM1H in cells but not in vitro. These data support a model in which localization drives PPM1H substrate selection and centriolar PPM1H is critical for regulation of Rab GTPase-regulated ciliogenesis. Moreover, Golgi localized PPM1H may maintain active Rab GTPases on the Golgi to carry out their nonciliogenesis-related functions in membrane trafficking.
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http://dx.doi.org/10.1073/pnas.2315171120 | DOI Listing |
J Biol Chem
September 2025
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, San Francisco, CA, United States. Electronic address:
PPM1H phosphatase reverses Parkinson's disease-associated, Leucine Rich Repeat Kinase 2-mediated, Rab GTPase phosphorylation. We showed previously that PPM1H relies on an N-terminal amphipathic helix for Golgi membrane localization and this helix enables PPM1H to associate with liposomes in vitro; binding to highly curved liposomes activates PPM1H's phosphatase activity. We show here that PPM1H also contains an allosteric binding site for its non-phosphorylated reaction products, Rab8A and Rab10.
View Article and Find Full Text PDFBiochem J
September 2025
Institute of Pharmaceutical Chemistry, Goethe University, Frankfurt , 60438, Germany.
The Rab GTPase switch-2 region is a hotspot for post-translational modifications. Its phosphorylation can determine whether individuals develop Parkinson's disease or not. Other modifications of the same region are catalyzed by enzymes from bacterial pathogens when they infect human cells.
View Article and Find Full Text PDFbioRxiv
August 2025
School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland.
Inherited mutations in VPS35 and the kinase LRRK2 lead to hyperphosphorylation of Rab GTPases and promote the formation of phospho-Rab signalling complexes. A subset of RH2 domain-containing proteins from the RILP-homology family, including RILP, RILPL1, RILPL2, JIP3, and JIP4 are Rab effectors that recognize the LRRK2-phosphorylated switch 2 threonine of phospho-Rab8A and phospho-Rab10. More recently, phospho-Rabs have been found on lysosomal membranes within multi-protein assemblies involving TMEM55B and RILPL1.
View Article and Find Full Text PDFbioRxiv
August 2025
Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE.
Altered lipid metabolism and lipid droplet (LD) dynamics are hallmark features of hepatocellular carcinoma (HCC) subtypes, but the molecular mechanisms governing LD trafficking and catabolism in HCC cells remain unclear. The small GTPase Rab5, a key regulator of early endosomal dynamics, has been observed to localize to the surface of LDs, suggesting it may play a role in LD turnover. However, the regulation of Rab5-LD interactions and its functional consequences in HCC cell metabolism and proliferation have not been elucidated.
View Article and Find Full Text PDFSci Signal
September 2025
Center for Neuroscience and Pain Research, Department of Anesthesiology and Perioperative Medicine, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Opioids relieve pain by activating μ-opioid receptors (MORs), which inhibit communication between pain-sensing neurons (nociceptors) and the spinal cord. However, prolonged opioid use can paradoxically lead to increased pain sensitivity (hyperalgesia) and reduced analgesic efficacy (tolerance), partly because of the activation of NMDA-type glutamate receptors (NMDARs) at the central terminals of primary sensory neurons in the spinal cord. Here, we identified a critical role for the G protein Gα in this paradox.
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