title: TIMAP-protein phosphatase 1-complex controls endothelin-1 production via ECE-1 dephosphorylation.
abstract: Endothelin induced signaling pathways can affect blood pressure and vascular tone, but the influence of endothelins on tumor cells is also significant. We have detected elevated endothelin-1 secretion from TIMAP (TGF-β inhibited membrane associated protein) depleted vascular endothelial cells. The autocrine signaling activated by the elevated endothelin-1 level through the ETB receptors evoked an angiogenic-like phenotype, the cells assumed an elongated morphology, and enhanced tube formation and wound healing abilities. The depleted protein, TIMAP, is a highly specific and abundant protein in the endothelial cells, and it is a regulatory/targeting subunit for the catalytic subunit of protein phosphatase 1 (PP1c). Protein-protein interaction between the TIMAP-PP1c complex and the endothelin converting enzyme-1 (ECE-1) was detected, the latter of which is a transmembrane protein that produces the biologically active 21-amino acid form of endothelin-1 from proendothelin. The results indicate that silencing of TIMAP induces a reduction in TIMAP-PP1c activity connected to ECE-1. This leads to an increase in the amount of ECE-1 protein in the plasma membrane and a consequent increase in endothelin-1 secretion. Similarly, activation of PKC, the kinase responsible for ECE-1 phosphorylation increased ECE-1 protein level in the membrane fraction of the endothelial cells. The elevated ECE-1 level was mitigated in time in normal cells, but was clearly preserved in TIMAP-depleted cells. Overall, our results indicate that PKC-phosphorylated ECE-1 is a TIMAP-PP1c substrate and this phosphatase complex has an important role in endothelin-1 production of EC through the regulation of ECE-1 activity.
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary.
authors.forename: Anita
authors.initials: A
authors.lastname: Boratkó
authors.affiliation: Stem Cells and Eye Research Laboratory, Department of Ophthalmology, Faculty of Medicine, University of Szeged, Korányi fasor 10-11, Szeged H-6720, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Veréb
authors.affiliation: Stem Cells and Eye Research Laboratory, Department of Ophthalmology, Faculty of Medicine, University of Szeged, Korányi fasor 10-11, Szeged H-6720, Hungary.
authors.forename: Goran
authors.initials: G
authors.lastname: Petrovski
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen H-4032, Hungary. Electronic address: csortos@med.unideb.hu.
authors.forename: Csilla
authors.initials: C
authors.lastname: Csortos
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D042783:Endothelial Cells / Q000378:metabolism*; D019332:Endothelin-1 / Q000235:genetics / Q000378:metabolism*; D000072396:Endothelin-Converting Enzymes / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D019332:Endothelin-1; D008565:Membrane Proteins; C459597:PPP1R16B protein, human; D034741:RNA, Small Interfering; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes
keywords: Endothelial cells; Endothelin converting enzyme-1; Endothelin-1; Protein phosphatase 1; TIMAP