title: Direct proteomic quantification of the secretome of activated immune cells.
abstract: Protein secretion allows communication of distant cells in an organism and controls a broad range of physiological functions. We describe a quantitative, high-resolution mass spectrometric workflow to detect and quantify proteins that are released from immune cells upon receptor ligation. We quantified the time-resolved release of 775 proteins, including 52 annotated cytokines from only 150,000 primary Toll-like receptor 4-activated macrophages per condition. Achieving low picogram sensitivity, we detected secreted proteins whose abundance increased by a factor of more than 10,000 upon stimulation. Secretome to transcriptome comparisons revealed the transcriptionally decoupled release of lysosomal proteins. From genetic models, we defined secretory profiles that depended on distinct intracellular signaling adaptors and showed that secretion of many proinflammatory proteins is safeguarded by redundant mechanisms, whereas signaling adaptor synergy promoted the release of anti-inflammatory proteins.
authors.affiliation: Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Meissner
authors.forename: Richard A
authors.initials: RA
authors.lastname: Scheltema
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Mollenkopf
authors.forename: Matthias
authors.initials: M
authors.lastname: Mann
mesh_terms: D000818:Animals; D008070:Lipopolysaccharides / Q000276:immunology; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology*; D013058:Mass Spectrometry / Q000379:methods*; D051379:Mice; D018345:Mice, Knockout; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics; D051197:Toll-Like Receptor 4 / Q000819:agonists*; D014158:Transcription, Genetic; D059467:Transcriptome
chemical_list: D008070:Lipopolysaccharides; D011506:Proteins; D020543:Proteome; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C018589:lysosomal proteins