title: TRPM5-mediated calcium uptake regulates mucin secretion from human colon goblet cells.
abstract: Mucin 5AC (MUC5AC) is secreted by goblet cells of the respiratory tract and, surprisingly, also expressed de novo in mucus secreting cancer lines. siRNA-mediated knockdown of 7343 human gene products in a human colonic cancer goblet cell line (HT29-18N2) revealed new proteins, including a Ca(2+)-activated channel TRPM5, for MUC5AC secretion. TRPM5 was required for PMA and ATP-induced secretion of MUC5AC from the post-Golgi secretory granules. Stable knockdown of TRPM5 reduced a TRPM5-like current and ATP-mediated Ca(2+) signal. ATP-induced MUC5AC secretion depended strongly on Ca(2+) influx, which was markedly reduced in TRPM5 knockdown cells. The difference in ATP-induced Ca(2+) entry between control and TRPM5 knockdown cells was abrogated in the absence of extracellular Ca(2+) and by inhibition of the Na(+)/Ca(2+) exchanger (NCX). Accordingly, MUC5AC secretion was reduced by inhibition of NCX. Thus TRPM5 activation by ATP couples TRPM5-mediated Na(+) entry to promote Ca(2+) uptake via an NCX to trigger MUC5AC secretion. DOI:http://dx.doi.org/10.7554/eLife.00658.001.
authors.affiliation: Department of Cell and Developmental Biology , Centre for Genomic Regulation , Barcelona , Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Mitrovic
authors.forename: Cristina
authors.initials: C
authors.lastname: Nogueira
authors.forename: Gerard
authors.initials: G
authors.lastname: Cantero-Recasens
authors.forename: Kerstin
authors.initials: K
authors.lastname: Kiefer
authors.forename: José M
authors.initials: JM
authors.lastname: Fernández-Fernández
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Popoff
authors.forename: Laetitia
authors.initials: L
authors.lastname: Casano
authors.forename: Frederic A
authors.initials: FA
authors.lastname: Bard
authors.forename: Raul
authors.initials: R
authors.lastname: Gomez
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Valverde
authors.forename: Vivek
authors.initials: V
authors.lastname: Malhotra
mesh_terms: D002118:Calcium / Q000378:metabolism*; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D020397:Goblet Cells / Q000166:cytology / Q000378:metabolism*; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D009077:Mucins / Q000378:metabolism*; D050053:TRPM Cation Channels / Q000378:metabolism / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D009077:Mucins; D050053:TRPM Cation Channels; C404409:TRPM5 protein, human; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium
keywords: Human; Mucin5AC; Secretion; TRPM5