title: Establishment of extracellular signal-regulated kinase 1/2 bistability and sustained activation through Sprouty 2 and its relevance for epithelial function.
abstract: Our objective was to establish an experimental model of a self-sustained and bistable extracellular signal-regulated kinase 1/2 (ERK1/2) signaling process. A single stimulation of cells with cytokines causes rapid ERK1/2 activation, which returns to baseline in 4 h. Repeated stimulation leads to sustained activation of ERK1/2 but not Jun N-terminal protein kinase (JNK), p38, or STAT6. The ERK1/2 activation lasts for 3 to 7 days and depends upon a positive-feedback mechanism involving Sprouty 2. Overexpression of Sprouty 2 induces, and its genetic deletion abrogates, ERK1/2 bistability. Sprouty 2 directly activates Fyn kinase, which then induces ERK1/2 activation. A genome-wide microarray analysis shows that the bistable phospho-ERK1/2 (pERK1/2) does not induce a high level of gene transcription. This is due to its nuclear exclusion and compartmentalization to Rab5+ endosomes. Cells with sustained endosomal pERK1/2 manifest resistance against growth factor withdrawal-induced cell death. They are primed for heightened cytokine production. Epithelial cells from cases of human asthma and from a mouse model of chronic asthma manifest increased pERK1/2, which is associated with Rab5+ endosomes. The increase in pERK1/2 was associated with a simultaneous increase in Sprouty 2 expression in these tissues. Thus, we have developed a cellular model of sustained ERK1/2 activation, which may provide a mechanistic understanding of self-sustained biological processes in chronic illnesses such as asthma.
authors.affiliation: Division of Allergy and Immunology, Department of Medicine, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA.
authors.forename: Weimin
authors.initials: W
authors.lastname: Liu
authors.forename: Kavita
authors.initials: K
authors.lastname: Tundwal
authors.forename: Qiaoling
authors.initials: Q
authors.lastname: Liang
authors.forename: Nicholas
authors.initials: N
authors.lastname: Goplen
authors.forename: Sadee
authors.initials: S
authors.lastname: Rozario
authors.forename: Nayeem
authors.initials: N
authors.lastname: Quayum
authors.forename: Magdalena
authors.initials: M
authors.lastname: Gorska
authors.forename: Sally
authors.initials: S
authors.lastname: Wenzel
authors.forename: Silvana
authors.initials: S
authors.lastname: Balzar
authors.forename: Rafeul
authors.initials: R
authors.lastname: Alam
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001249:Asthma / Q000378:metabolism / Q000503:physiopathology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D011992:Endosomes / Q000378:metabolism; D004789:Enzyme Activation; D004795:Enzyme Stability; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology*; D020869:Gene Expression Profiling; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D046228:Microarray Analysis; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; C485561:SPRY2 protein, human; D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; C118389:Spry2 protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020691:rab GTP-Binding Proteins