title: Syntaxin-4 is implicated in the secretion of antibodies by human plasma cells.
abstract: PCs are responsible for the production and secretion of antibodies, the effector molecules of the humoral immune response. The molecular mechanisms responsible for vesicle docking and secretion implicated in the antibody-secretion process are not well-known, as they have not been studied, but it is known that SNARE proteins are responsible for many membrane-fusion processes in the cell. We show here that freshly isolated human colon LP-PCs and T-PCs from MM-PC patients and the U266 cell line, as a model for PC secretion, contain a set of these proteins. SNAP23, STX3, and STX4 were localized mainly in the plasma membrane of PCs, and interactions of SNAP23 with STX3 and with STX4 were proven by IP. Interaction between SNAP23 and STX4 was also confirmed in situ. With the use of siRNA, as well as shRNA, the functional role of SNAP23, STX3, and STX4 in antibody secretion was also examined. The findings demonstrate that in addition to SNAP23, STX4 is implicated in the antibody secretion by a myeloma cell line and by normal human colon LP-PCs.
authors.affiliation: 2.9 planta, Hospital Universitario "Puerta del Mar", Avda. Ana de Viya, 21, 11009-Cádiz, Spain. antonio.campos.exts@juntadeandalucia.es.
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez-Jaramillo
authors.forename: Luis
authors.initials: L
authors.lastname: Delgado-Pérez
authors.forename: Elena
authors.initials: E
authors.lastname: Reales
authors.forename: Francisco
authors.initials: F
authors.lastname: Mora-López
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Mateos
authors.forename: Antonio
authors.initials: A
authors.lastname: García-Poley
authors.forename: José A
authors.initials: JA
authors.lastname: Brieva
authors.forename: Antonio
authors.initials: A
authors.lastname: Campos-Caro
mesh_terms: D000906:Antibodies / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002469:Cell Separation; D004318:Doxycycline / Q000494:pharmacology; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis; D007073:Immunoglobulin E / Q000378:metabolism; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology; D010950:Plasma Cells / Q000187:drug effects / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D050765:Qa-SNARE Proteins / Q000378:metabolism*; D050766:Qb-SNARE Proteins / Q000378:metabolism; D050767:Qc-SNARE Proteins / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D000906:Antibodies; D007070:Immunoglobulin A; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D034741:RNA, Small Interfering; C100493:SNAP23 protein, human; C587292:syntaxin 4, human; D007073:Immunoglobulin E; D004318:Doxycycline
keywords: RNAi protein knockdown; SNARE; immunoglobulin exocytosis