title: Neurotensin-induced proinflammatory signaling in human colonocytes is regulated by β-arrestins and endothelin-converting enzyme-1-dependent endocytosis and resensitization of neurotensin receptor 1.
abstract: The neuropeptide/hormone neurotensin (NT) mediates intestinal inflammation and cell proliferation by binding of its high affinity receptor, neurotensin receptor-1 (NTR1). NT stimulates IL-8 expression in NCM460 human colonic epithelial cells by both MAP kinase- and NF-κB-dependent pathways. Although the mechanism of NTR1 endocytosis has been studied, the relationship between NTR1 intracellular trafficking and inflammatory signaling remains to be elucidated. In the present study, we show that in NCM460 cells exposed to NT, β-arrestin-1 (βARR1), and β-arrestin-2 (βARR2) translocate to early endosomes together with NTR1. Endothelin-converting enzyme-1 (ECE-1) degrades NT in acidic conditions, and its activity is crucial for NTR1 recycling. Pretreatment of NCM460 cells with the ECE-1 inhibitor SM19712 or gene silencing of βARR1 or βARR2 inhibits NT-stimulated ERK1/2 and JNK phosphorylation, NF-κB p65 nuclear translocation and phosphorylation, and IL-8 secretion. Furthermore, NT-induced cell proliferation, but not IL-8 transcription, is attenuated by the JNK inhibitor, JNK(AII). Thus, NTR1 internalization and recycling in human colonic epithelial cells involves βARRs and ECE-1, respectively. Our results also indicate that βARRs and ECE-1-dependent recycling regulate MAP kinase and NF-κB signaling as well as cell proliferation in human colonocytes in response to NT.
authors.affiliation: Inflammatory Bowel Disease Center, Division of Digestive Diseases, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095-7019, USA.
authors.forename: Ivy Ka Man
authors.initials: IK
authors.lastname: Law
authors.forename: Jane E
authors.initials: JE
authors.lastname: Murphy
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Bakirtzi
authors.forename: Nigel W
authors.initials: NW
authors.lastname: Bunnett
authors.forename: Charalabos
authors.initials: C
authors.lastname: Pothoulakis
mesh_terms: D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003106:Colon / Q000166:cytology / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D000072396:Endothelin-Converting Enzymes; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D009496:Neurotensin / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D018028:Receptors, Neurotensin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D013453:Sulfonylurea Compounds / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins
chemical_list: C000605253:ARRB1 protein, human; C000605254:ARRB2 protein, human; D019390:Arrestins; C508606:CXCL8 protein, human; D016209:Interleukin-8; C498143:RELA protein, human; D018028:Receptors, Neurotensin; C419789:SM 19712; D013449:Sulfonamides; D013453:Sulfonylurea Compounds; D051996:Transcription Factor RelA; D000071559:beta-Arrestin 1; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; C114036:neurotensin type 1 receptor; D009496:Neurotensin; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048670:MAP Kinase Kinase 4; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes