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Figure 3 | Respiratory Research

Figure 3

From: JNK suppresses pulmonary fibroblast elastogenesis during alveolar development

Figure 3

JNK activation and elastogenesis are inversely correlated. (A) By JNK pull down assay, JNK activity (c-Jun phosphorylation) was increased during saccular (PND1%3) and alveolar (PND9%14) stages of lung development with activity at PND14 being highest. (B) Comparing the lung JNK activity of mice from different litters, PND14 lungs had 11-fold higher JNK activity than PN 8 week lungs. (C) JNK phosphorylation was assessed by Western blot of lung homogenates from a different set of PND14 and PN 8 week mice (three mice from two different litters). PND14 mice had increased phosphorylation of the p54 JNK isoform but not the p46 isoform. No age-dependent difference in JNK isoform abundance was observed. (D) Western blot densitometry demonstrated a 7-fold increase in pJNK to total JNK ratio in PND14 lung homogenate compared to PN 8 week. (E) Tropoelastin (black bars), lysyl oxidase (gray bars), emilin-1 (dark gray bars), fibrillin-1 (dashed white bars), and fibulin-5 (white bars) mRNAs are all decreased in PND14 and PN 8 week lung compared to time points during saccular and early alveolar lung development (PND0-PND9). RNA is from lungs of three mice from at least two different litters. The noted statistical comparisons are to PN 8 weeks only but analyzed by one-way ANOVA. (F) A line plot of these same data demonstrates that despite different ages of peak mRNA concentration (denoted by arrows) the mRNA concentration of all five elastogenic genes decreases significantly at PND14. * p < 0.05, **p < 0.01, ***p < 0.001 by one-way ANOVA (>2 groups) or by two tail Student t-test (2 groups).

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