title: MAPK superfamily activation in human airway smooth muscle: mitogenesis requires prolonged p42/p44 activation.
abstract: Asthma is frequently associated with abnormal airway smooth muscle (ASM) growth that may contribute to airway narrowing and hyperresponsiveness to contractile agents. Although numerous hormones and cytokines have been shown to induce human ASM (HASM) proliferation, the cellular and molecular mechanisms underlying HASM hyperplasia are largely unknown. Here we characterize the roles of the mitogen-activated protein kinase (MAPK) superfamily [p42/p44 MAPK, c-Jun amino-terminal kinase/stress-activated protein kinase (JNK/SAPK), and p38] in mediating hormone- and cytokine-induced HASM proliferation. Significant enhancement of [(3)H]thymidine incorporation in HASM cultures was observed only by treatment with agents (epidermal growth factor, platelet-derived growth factor, thrombin, and phorbol 12-myristate 13-acetate) that promoted a strong and sustained activation of p42/p44 MAPK. Significant activation of the JNK/SAPK and p38 pathways was only observed on stimulation with interleukin (IL)-1beta and tumor necrosis factor-alpha, agents that did not appreciably stimulate HASM proliferation. Two different inhibitors of MAPK/extracellular signal-regulated kinase kinase (MEK), PD-98059 and U-0126, inhibited mitogen-induced [3H]thymidine incorporation in a manner consistent with their ability to inhibit p42/p44 activation. Elk-1 and activator protein-1 reporter activation by mitogens was similarly inhibited by inhibition of MEK, suggesting a linkage between p42/p44 activation, transcription factor activation, and HASM proliferation. These findings establish a fundamental role for p42/p44 activation in regulating HASM proliferation and provide insight into species-specific differences observed among studies in ASM mitogenesis.
authors.affiliation: Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia 19107, Pennsylvania, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Orsini
authors.forename: V P
authors.initials: VP
authors.lastname: Krymskaya
authors.forename: A J
authors.initials: AJ
authors.lastname: Eszterhas
authors.forename: J L
authors.initials: JL
authors.lastname: Benovic
authors.forename: R A
authors.initials: RA
authors.lastname: Panettieri
authors.forename: R B
authors.initials: RB
authors.lastname: Penn
mesh_terms: D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008938:Mitosis / Q000502:physiology; D005810:Multigene Family / Q000235:genetics*; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins / Q000235:genetics; D014132:Trachea / Q000166:cytology / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000235:genetics; D014157:Transcription Factors; D014158:Transcription, Genetic; D050807:ets-Domain Protein Elk-1
chemical_list: D004268:DNA-Binding Proteins; C494112:ELK1 protein, human; D011518:Proto-Oncogene Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases