Limits...
Activated Akt protects the lung from oxidant-induced injury and delays death of mice.

Lu Y, Parkyn L, Otterbein LE, Kureishi Y, Walsh K, Ray A, Ray P - J. Exp. Med. (2001)

Bottom Line: The serine-threonine kinase Akt has been implicated in inhibiting cell death induced by different stimuli including growth factor withdrawal, cell cycle discordance, DNA damage, and loss of cell adhesion in different cell types.However, the in vivo relevance of this prosurvival pathway has not been explored.This is the first demonstration of the in vivo protective function of Akt in the context of oxidant-induced lung injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Pulmonary and Critical Care Section, Yale University School of Medicine, New Haven, Connecticut 06520, USA.

ABSTRACT
Oxidant-induced injury to the lung causes extensive damage to lung epithelial cells. Impaired protection and repair of the lung epithelium can result in death. The serine-threonine kinase Akt has been implicated in inhibiting cell death induced by different stimuli including growth factor withdrawal, cell cycle discordance, DNA damage, and loss of cell adhesion in different cell types. However, the in vivo relevance of this prosurvival pathway has not been explored. Here we show that a constitutively active form of Akt introduced intratracheally into the lungs of mice by adenovirus gene transfer techniques protects mice from hyperoxic pulmonary damage and delays death of mice. This is the first demonstration of the in vivo protective function of Akt in the context of oxidant-induced lung injury.

Show MeSH

Related in: MedlinePlus

Inhibition of cell death in the airway epithelium by expression of constitutively active Akt (Ad-myr-Akt). (A) Lung sections from mice infected with control adenovirus or Ad-myr-Akt were subjected to TUNEL assay for detection of DNA fragmentation/cell death in lung tissue. Lung sections were deparaffinized. Sections were then subjected to TUNEL assay (Dead End; Promega) following instructions of the manufacturer. Brown staining of the cells represent apoptotic nuclei. (B) A quantitative estimate of apoptotic nuclei (brown stain) per unit area. At 72, 96, and 120 h after hyperoxic treatment, there was a significant suppression of airway epithelial cell death in mice expressing myr-Akt compared with mice infected with control virus at 72 h after hyperoxia (*P < 0.001, **P < 0.0134, and ***P < 0.035).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2195901&req=5

Figure 4: Inhibition of cell death in the airway epithelium by expression of constitutively active Akt (Ad-myr-Akt). (A) Lung sections from mice infected with control adenovirus or Ad-myr-Akt were subjected to TUNEL assay for detection of DNA fragmentation/cell death in lung tissue. Lung sections were deparaffinized. Sections were then subjected to TUNEL assay (Dead End; Promega) following instructions of the manufacturer. Brown staining of the cells represent apoptotic nuclei. (B) A quantitative estimate of apoptotic nuclei (brown stain) per unit area. At 72, 96, and 120 h after hyperoxic treatment, there was a significant suppression of airway epithelial cell death in mice expressing myr-Akt compared with mice infected with control virus at 72 h after hyperoxia (*P < 0.001, **P < 0.0134, and ***P < 0.035).

Mentions: We next examined whether expression of constitutively active Akt is sufficient to suppress cell death induced by hyperoxia. In these experiments, lung sections from mice infected with control adenovirus or adenovirus expressing constitutively active Akt were subjected to TUNEL assay for nuclear DNA fragmentation, an indicator of cell death. As shown in Fig. 4 A, mice infected with control virus and subjected to hyperoxia displayed extensive TUNEL+ nuclei in the airway epithelium as well as in alveolar epithelial cells at 72 h after hyperoxia. In contrast, at this time point, cell death in the airway epithelium was almost completely blocked and alveolar epithelial cell death was partially blocked when mice were infected with Ad-myr-Akt. The better protection of the airway epithelium was probably due to the fact that the airway epithelium is more accessible to adenovirus mediated gene transfer than the alveolar epithelium. At 120 h after exposure to hyperoxia, when hemorrhage, inflammation, and edema were evident in the lungs of the Ad-myr-Akt–infected mice (Fig. 4 A), correspondingly, cell death was apparent in both airway and alveolar epithelial cells. Thus, the increased survival of Ad-myr-Akt–expressing animals at 72 h after hyperoxia correlated with decreased hemorrhage, inflammation, and edema in the lung and a dramatic suppression of airway cell death. These results suggest that a better means of activating Akt in alveolar epithelial cells will provide a better survival advantage to the animals.


Activated Akt protects the lung from oxidant-induced injury and delays death of mice.

Lu Y, Parkyn L, Otterbein LE, Kureishi Y, Walsh K, Ray A, Ray P - J. Exp. Med. (2001)

Inhibition of cell death in the airway epithelium by expression of constitutively active Akt (Ad-myr-Akt). (A) Lung sections from mice infected with control adenovirus or Ad-myr-Akt were subjected to TUNEL assay for detection of DNA fragmentation/cell death in lung tissue. Lung sections were deparaffinized. Sections were then subjected to TUNEL assay (Dead End; Promega) following instructions of the manufacturer. Brown staining of the cells represent apoptotic nuclei. (B) A quantitative estimate of apoptotic nuclei (brown stain) per unit area. At 72, 96, and 120 h after hyperoxic treatment, there was a significant suppression of airway epithelial cell death in mice expressing myr-Akt compared with mice infected with control virus at 72 h after hyperoxia (*P < 0.001, **P < 0.0134, and ***P < 0.035).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195901&req=5

Figure 4: Inhibition of cell death in the airway epithelium by expression of constitutively active Akt (Ad-myr-Akt). (A) Lung sections from mice infected with control adenovirus or Ad-myr-Akt were subjected to TUNEL assay for detection of DNA fragmentation/cell death in lung tissue. Lung sections were deparaffinized. Sections were then subjected to TUNEL assay (Dead End; Promega) following instructions of the manufacturer. Brown staining of the cells represent apoptotic nuclei. (B) A quantitative estimate of apoptotic nuclei (brown stain) per unit area. At 72, 96, and 120 h after hyperoxic treatment, there was a significant suppression of airway epithelial cell death in mice expressing myr-Akt compared with mice infected with control virus at 72 h after hyperoxia (*P < 0.001, **P < 0.0134, and ***P < 0.035).
Mentions: We next examined whether expression of constitutively active Akt is sufficient to suppress cell death induced by hyperoxia. In these experiments, lung sections from mice infected with control adenovirus or adenovirus expressing constitutively active Akt were subjected to TUNEL assay for nuclear DNA fragmentation, an indicator of cell death. As shown in Fig. 4 A, mice infected with control virus and subjected to hyperoxia displayed extensive TUNEL+ nuclei in the airway epithelium as well as in alveolar epithelial cells at 72 h after hyperoxia. In contrast, at this time point, cell death in the airway epithelium was almost completely blocked and alveolar epithelial cell death was partially blocked when mice were infected with Ad-myr-Akt. The better protection of the airway epithelium was probably due to the fact that the airway epithelium is more accessible to adenovirus mediated gene transfer than the alveolar epithelium. At 120 h after exposure to hyperoxia, when hemorrhage, inflammation, and edema were evident in the lungs of the Ad-myr-Akt–infected mice (Fig. 4 A), correspondingly, cell death was apparent in both airway and alveolar epithelial cells. Thus, the increased survival of Ad-myr-Akt–expressing animals at 72 h after hyperoxia correlated with decreased hemorrhage, inflammation, and edema in the lung and a dramatic suppression of airway cell death. These results suggest that a better means of activating Akt in alveolar epithelial cells will provide a better survival advantage to the animals.

Bottom Line: The serine-threonine kinase Akt has been implicated in inhibiting cell death induced by different stimuli including growth factor withdrawal, cell cycle discordance, DNA damage, and loss of cell adhesion in different cell types.However, the in vivo relevance of this prosurvival pathway has not been explored.This is the first demonstration of the in vivo protective function of Akt in the context of oxidant-induced lung injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Pulmonary and Critical Care Section, Yale University School of Medicine, New Haven, Connecticut 06520, USA.

ABSTRACT
Oxidant-induced injury to the lung causes extensive damage to lung epithelial cells. Impaired protection and repair of the lung epithelium can result in death. The serine-threonine kinase Akt has been implicated in inhibiting cell death induced by different stimuli including growth factor withdrawal, cell cycle discordance, DNA damage, and loss of cell adhesion in different cell types. However, the in vivo relevance of this prosurvival pathway has not been explored. Here we show that a constitutively active form of Akt introduced intratracheally into the lungs of mice by adenovirus gene transfer techniques protects mice from hyperoxic pulmonary damage and delays death of mice. This is the first demonstration of the in vivo protective function of Akt in the context of oxidant-induced lung injury.

Show MeSH
Related in: MedlinePlus