title: Receptor-type PTP-NP inhibition of Dynamin-1 GTPase activity is associated with neuronal depolarization.
abstract: Dynamin-1 is a GTP-hydrolyzing protein and a key element in the clathrin-mediated endocytosis of secretory granules and neurovesicles at the plasma membrane. The unique receptor-like protein tyrosine phosphatase, PTP-NP/Phogrin/IAR/IA-2, is associated with neuroendocrine secretory granules and is highly expressed in the brain. Here, we show by confocal microscopy and biochemical studies that PTP-NP rapidly associates with Dynamin-1 in a depolarization-dependent manner and regulates Dynamin-1 GTPase activity upon KCl depolarization of rat primary hippocampal neurons. Depolarization of primary neurons induced direct association of PTP-NP with Dynamin-1 within 30 s. This association resulted in significant inhibition of Dynamin-1 GTPase activity (approximately 75% inhibition). Mutation within the phosphatase domain of PTP-NP (PTP-NP(D947A)) abolished the direct interaction of PTP-NP with Dynamin-1 and failed to inhibit Dynamin-1 GTPase activity. To further confirm the endogenous interaction of Dynamin-1 with wild-type PTP-NP, Dynamin-1 was purified biochemically from rat brain and its interaction with purified PTP-NP was analyzed. Highly purified Dynamin-1 specifically associated with wild-type PTP-NP and not with mutated PTP-NP, resulting in significant inhibition (approximately 70%) of Dynamin-1 GTPase activity. This is the first report to suggest a novel function of this unique receptor-type tyrosine phosphatase as a potential regulator of Dynamin-1 GTPase activity upon neuronal depolarization.
authors.affiliation: Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, 4 Blackfan Circle, Boston, MA 02115, USA.
authors.forename: Shuxian
authors.initials: S
authors.lastname: Jiang
authors.forename: Hava Karsenty
authors.initials: HK
authors.lastname: Avraham
authors.forename: Tae-Aug
authors.initials: TA
authors.lastname: Kim
authors.forename: Rick A
authors.initials: RA
authors.lastname: Rogers
authors.forename: Shalom
authors.initials: S
authors.lastname: Avraham
mesh_terms: D000409:Alanine / Q000378:metabolism; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D034284:Dynamin I / Q000037:antagonists & inhibitors / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology; D006624:Hippocampus / Q000166:cytology; D008564:Membrane Potentials / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8
chemical_list: D001324:Autoantigens; D008565:Membrane Proteins; D017027:Protein Tyrosine Phosphatases; C516864:Ptprn protein, rat; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D034284:Dynamin I; D000409:Alanine