Endoplasmic reticulum stress induced by aqueous extracts of cigarette smoke in 3T3 cells activates the unfolded-protein-response-dependent PERK pathway of cell survival.
Cigarette smoke (CS) generally places severe stress on cells, as reflected by gene expression profiling and pathway analysis, which, among other effects, also suggested activation of the unfolded protein response pathway triggered by the stressed endoplasmic reticulum (ER stress). Here, we present data indicating that noncytotoxic concentrations of aqueous extracts of CS induce a distinct ER stress response in immortalized nontransformed Swiss 3T3 cells, primarily by activating the PERK pathway of global protein synthesis inhibition. Activation of PERK and PERK-dependent signaling by aqueous extracts of CS was demonstrated by (i) the inhibition of protein synthesis, (ii) the phosphorylation of PERK and its substrate eIF2alpha, (iii) the activation of ATF4, and (iv) the expression of ATF4-dependent target genes chop, gadd34, BiP, and atf3. Within the dose range tested, all effects appeared to be transient in nature, while the periods of recovery from ER stress were clearly concentration dependent. In contrast to these data and to the effects seen with thapsigargin (used as positive control), only minor effects were observed for the activation of xbp-1, a common target of the other two canonical sensors of ER stress, i.e., ATF6 and IRE1. In mechanistic terms, neither the disruption of energy levels nor a contribution of arylating quinones played a major role under the experimental conditions tested. Notably however, the effects of aqueous extracts of CS on the ER could be mimicked in the presence of acrolein at CS-relevant concentrations, indicating that CS interferes with proper ER function, presumably due mainly to changes in cellular redox homeostasis. Since ER stress has been linked to diseases that are also related to CS exposure, these data are relevant in the discussion of a general molecular mechanism of CS-induced disease.
Hengstermann
Arnd
A
Philip Morris Research Laboratories GmbH, Fuggerstr. 3, D-51149 Cologne, Germany.
Müller
Thomas
T
D016475:3T3 Cells; D051701:Activating Transcription Factor 4 / Q000187:drug effects / Q000378:metabolism; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000187:drug effects*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000187:drug effects / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; D019892:eIF-2 Kinase / Q000187:drug effects* / Q000378:metabolism
D051701:Activating Transcription Factor 4; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D014028:Tobacco Smoke Pollution; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; D019892:eIF-2 Kinase; C081452:Atf4 protein, mouse; C000605544:Xbp1 protein, mouse