title: USP18 Sensitivity of Peptide Transporters PEPT1 and PEPT2.
abstract: USP18 (Ubiquitin-like specific protease 18) is an enzyme cleaving ubiquitin from target proteins. USP18 plays a pivotal role in antiviral and antibacterial immune responses. On the other hand, ubiquitination participates in the regulation of several ion channels and transporters. USP18 sensitivity of transporters has, however, never been reported. The present study thus explored, whether USP18 modifies the activity of the peptide transporters PEPT1 and PEPT2, and whether the peptide transporters are sensitive to the ubiquitin ligase Nedd4-2. To this end, cRNA encoding PEPT1 or PEPT2 was injected into Xenopus laevis oocytes without or with additional injection of cRNA encoding USP18. Electrogenic peptide (glycine-glycine) transport was determined by dual electrode voltage clamp. As a result, in Xenopus laevis oocytes injected with cRNA encoding PEPT1 or PEPT2, but not in oocytes injected with water or with USP18 alone, application of the dipeptide gly-gly (2 mM) was followed by the appearance of an inward current (Igly-gly). Coexpression of USP18 significantly increased Igly-gly in both PEPT1 and PEPT2 expressing oocytes. Kinetic analysis revealed that coexpression of USP18 increased maximal Igly-gly. Conversely, overexpression of the ubiquitin ligase Nedd4-2 decreased Igly-gly. Coexpression of USP30 similarly increased Igly-gly in PEPT1 expressing oocytes. In conclusion, USP18 sensitive cellular functions include activity of the peptide transporters PEPT1 and PEPT2.
authors.affiliation: Department of Physiology I, University of Tuebingen, Tuebingen, Germany.
authors.forename: Jamshed
authors.initials: J
authors.lastname: Warsi
authors.affiliation: Department of Physiology I, University of Tuebingen, Tuebingen, Germany.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Hosseinzadeh
authors.affiliation: Department of Physiology I, University of Tuebingen, Tuebingen, Germany.
authors.forename: Bernat
authors.initials: B
authors.lastname: Elvira
authors.affiliation: Department of Physiology I, University of Tuebingen, Tuebingen, Germany.
authors.forename: Lisann
authors.initials: L
authors.lastname: Pelzl
authors.affiliation: Department of Physiology I, University of Tuebingen, Tuebingen, Germany.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.affiliation: Department of Pathology & Division of Biological Sciences, Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA, 92093, United States of America.
authors.forename: Dong-Er
authors.initials: DE
authors.lastname: Zhang
authors.affiliation: Institute of Immunology, Medical Faculty, University of Duisburg-Essen, Essen, Germany.
authors.forename: Karl S
authors.initials: KS
authors.lastname: Lang
authors.affiliation: Department of Molecular Medicine II, University of Duesseldorf, Duesseldorf, Germany.
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Lang
authors.affiliation: Department of Physiology I, University of Tuebingen, Tuebingen, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D001692:Biological Transport; D004151:Dipeptides / Q000378:metabolism* / Q000494:pharmacology; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism; D005260:Female; D006801:Humans; D007267:Injections; D051657:KCNQ1 Potassium Channel / Q000235:genetics / Q000378:metabolism; D008163:Luminescent Measurements / Q000379:methods; D008564:Membrane Potentials / Q000187:drug effects; D000075702:Nedd4 Ubiquitin Protein Ligases; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D000074011:Peptide Transporter 1; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics / Q000378:metabolism; D018075:RNA, Complementary / Q000008:administration & dosage / Q000235:genetics; D011817:Rabbits; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D043222:Ubiquitin Thiolesterase; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins; D014982:Xenopus laevis
chemical_list: D004151:Dipeptides; D056827:Endosomal Sorting Complexes Required for Transport; C489622:KCNE1 protein, human; D051657:KCNQ1 Potassium Channel; D000074011:Peptide Transporter 1; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; D027981:Symporters; D029867:Xenopus Proteins; C093694:hydrogen-coupled oligopeptide transporter PepT2; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618482:Nedd4 protein, Xenopus; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; C000618460:nedd4l protein, Xenopus; D044767:Ubiquitin-Protein Ligases; D010450:Endopeptidases; C485560:USP18 protein, human; D043222:Ubiquitin Thiolesterase