title: Physiological levels of TNFalpha stimulation induce stochastic dynamics of NF-kappaB responses in single living cells.
abstract: Nuclear factor kappa B (NF-kappaB) signalling is activated by cellular stress and inflammation and regulates cytokine expression. We applied single-cell imaging to investigate dynamic responses to different doses of tumour necrosis factor alpha (TNFalpha). Lower doses activated fewer cells and those responding showed an increasingly variable delay in the initial NF-kappaB nuclear translocation and associated IkappaBalpha degradation. Robust 100 minute nuclear:cytoplasmic NF-kappaB oscillations were observed over a wide range of TNFalpha concentrations. The result is supported by computational analyses, which identified a limit cycle in the system with a stable 100 minute period over a range of stimuli, and indicated no co-operativity in the pathway activation. These results suggest that a stochastic threshold controls functional all-or-nothing responses in individual cells. Deterministic and stochastic models simulated the experimentally observed activation threshold and gave rise to new predictions about the structure of the system and open the way for better mechanistic understanding of physiological TNFalpha activation of inflammatory responses in cells and tissues.
authors.affiliation: Centre for Cell Imaging, School of Biological Sciences, Bioscience Research Building, Liverpool, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Turner
authors.forename: Pawel
authors.initials: P
authors.lastname: Paszek
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Woodcock
authors.forename: David E
authors.initials: DE
authors.lastname: Nelson
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Horton
authors.forename: Yunjiao
authors.initials: Y
authors.lastname: Wang
authors.forename: David G
authors.initials: DG
authors.lastname: Spiller
authors.forename: David A
authors.initials: DA
authors.lastname: Rand
authors.forename: Michael R H
authors.initials: MR
authors.lastname: White
authors.forename: Claire V
authors.initials: CV
authors.lastname: Harper
mesh_terms: D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008954:Models, Biological; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013269:Stochastic Processes; D051996:Transcription Factor RelA / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C498143:RELA protein, human; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha