Activation of ERK and JNK1 MAP kinases in cultured lung tissue.
The biochemical mechanisms responsible for lung cell growth and proliferation are not well defined during tissue injury. We previously showed stimulation of DNA synthesis in intact lung tissue cultured in vitro after exposure to elevated fractions of O2. By use of this in vitro model, the current study examined the enzymatic activities of the extracellular-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) mitogen-activated protein (MAP) kinase pathways. ERK and JNK activities were transiently elevated in lung tissue cultured under serum-free conditions. Raf-1 kinase, the primary upstream activator of the ERK pathway, was also transiently activated, suggesting a receptor-mediated ERK activation. Phosphorylation of the guanine nucleotide exchange protein p170 son of sevenless further suggested a receptor-mediated activation of the ERK pathway. c-Fos and c-Jun expression, downstream targets of ERK and JNK, was dramatically increased in cultured tissue compared with uncultured tissue. After the initial transient activation, ERK and JNK could be reactivated with specific agonists, demonstrating that these signaling pathways were functional. These findings demonstrate activation of the ERK and JNK MAP kinase pathways in intact lung tissue and provide a model system to define signaling pathways involved in lung tissue remodeling injury.
Shapiro
P
P
Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309, USA.
Absher
P M
PM
Posada
J P
JP
Evans
J N
JN
D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D046508:Culture Techniques; D004789:Enzyme Activation; D048031:JNK Mitogen-Activated Protein Kinases; D008168:Lung / Q000201:enzymology*; D008565:Membrane Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D019908:Proto-Oncogene Proteins c-raf; D012333:RNA, Messenger / Q000378:metabolism; D020664:Son of Sevenless Proteins
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D020664:Son of Sevenless Proteins; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases