Lung tissue regeneration after induced injury in Runx3 KO mice.

Runx3 is essential for normal murine lung development, and Runx3 knockout (KO) mice, which die soon after birth, exhibit alveolar hyperplasia. Wound healing, tissue repair, and regeneration mechanisms are necessary in humans for proper early lung development. Previous studies have reported that various signaling molecules, such as pErk, Tgf-beta1, CCSP, pJnk, Smad3, and HSP70 are closely related to wound healing. In order to confirm the relationship between lung defects caused by the loss of function of Runx3 and wound healing, we have localized various wound-healing markers after laser irradiation in wild-type and in Runx3 KO mouse lungs at post-natal day 1. Our results indicate that pERK, Tgf-beta1, CCSP, pJnk, and HSP70 are dramatically down-regulated by loss of Runx3 during lung wound healing. However, Smad3 is up-regulated in the Runx3 KO laser-irradiated lung region. Therefore, the lung wound-healing mechanism is inhibited in the Runx3 KO mouse, which shows abnormal lung architecture, by reduced pErk, Tgf-beta1, CCSP, pJnk, and HSP70 and by induced Smad3.