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Respiratory distress and perinatal lethality in Nedd4-2-deficient mice.

Boase NA, Rychkov GY, Townley SL, Dinudom A, Candi E, Voss AK, Tsoutsman T, Semsarian C, Melino G, Koentgen F, Cook DI, Kumar S - Nat Commun (2011)

Bottom Line: This increased ENaC activity is the likely reason for premature fetal lung fluid clearance in Nedd4-2(-/-) animals, resulting in a failure to inflate lungs and perinatal lethality.A small percentage of Nedd4-2(-/-) animals survive up to 22 days, and these animals also show increased ENaC expression and develop lethal sterile inflammation of the lung.Thus, we provide critical in vivo evidence that Nedd4-2 is essential for correct regulation of ENaC expression, fetal and postnatal lung function and animal survival.

View Article: PubMed Central - PubMed

Affiliation: Department of Haematology, Centre for Cancer Biology, SA Pathology, PO Box 14, Rundle Mall, Adelaide, South Australia 5000, Australia.

ABSTRACT
The epithelial sodium channel (ENaC) is essential for sodium homoeostasis in many epithelia. ENaC activity is required for lung fluid clearance in newborn animals and for maintenance of blood volume and blood pressure in adults. In vitro studies show that the ubiquitin ligase Nedd4-2 ubiquitinates ENaC to regulate its cell surface expression. Here we show that knockout of Nedd4-2 in mice leads to increased ENaC expression and activity in embryonic lung. This increased ENaC activity is the likely reason for premature fetal lung fluid clearance in Nedd4-2(-/-) animals, resulting in a failure to inflate lungs and perinatal lethality. A small percentage of Nedd4-2(-/-) animals survive up to 22 days, and these animals also show increased ENaC expression and develop lethal sterile inflammation of the lung. Thus, we provide critical in vivo evidence that Nedd4-2 is essential for correct regulation of ENaC expression, fetal and postnatal lung function and animal survival.

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Surviving Nedd4-2−/− mice develop lung inflammation.Lung sections of Nedd4-2+/+ and Nedd4-2−/− mice. (a, b) Haematoxylin and eosin (HE) stained P10 lung. (c, d) βENaC expression in P21 lung sections. (e, f) HE stained P21 lung. (g) Enlarged view of a section in f. Arrowhead indicates a macrophage, arrows indicate neutrophils. (h, i) HE stained P21 lung at higher magnification. (j, k) Ly6G staining neutrophils in P14 lung. (l, m) Ly6G staining in P19 lung. Scale bars represent 100 μm except in g where it represents 20 μM.
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f5: Surviving Nedd4-2−/− mice develop lung inflammation.Lung sections of Nedd4-2+/+ and Nedd4-2−/− mice. (a, b) Haematoxylin and eosin (HE) stained P10 lung. (c, d) βENaC expression in P21 lung sections. (e, f) HE stained P21 lung. (g) Enlarged view of a section in f. Arrowhead indicates a macrophage, arrows indicate neutrophils. (h, i) HE stained P21 lung at higher magnification. (j, k) Ly6G staining neutrophils in P14 lung. (l, m) Ly6G staining in P19 lung. Scale bars represent 100 μm except in g where it represents 20 μM.

Mentions: As stated previously a small number (∼4.2%) of Nedd4-2−/− animals survive up to a maximum of 22 days of age. We analysed the possible cause of lethality in these mice. The lung architecture of surviving Nedd4-2−/− mice was the same as wild type at P10 (Fig. 5a,b); however, the increased level of βENaC expression in the lung compared with wild-type littermates persisted at P21 (Fig. 5c,d), indicating this phenotype is chronic from birth. Lung sections from a Nedd4-2−/− animal that died at P21 demonstrated extensive fibrosis in the alveolar spaces compared with wild-type littermates (Fig. 5e–i). We also observed significant cellular infiltrate in lung tissue and air spaces of Nedd4-2−/− survivors examined, and the amount of infiltrate varied between animals. At higher magnification different types of inflammatory cells such as macrophages and neutrophils were clearly visible in alveolar spaces (Fig. 5g).


Respiratory distress and perinatal lethality in Nedd4-2-deficient mice.

Boase NA, Rychkov GY, Townley SL, Dinudom A, Candi E, Voss AK, Tsoutsman T, Semsarian C, Melino G, Koentgen F, Cook DI, Kumar S - Nat Commun (2011)

Surviving Nedd4-2−/− mice develop lung inflammation.Lung sections of Nedd4-2+/+ and Nedd4-2−/− mice. (a, b) Haematoxylin and eosin (HE) stained P10 lung. (c, d) βENaC expression in P21 lung sections. (e, f) HE stained P21 lung. (g) Enlarged view of a section in f. Arrowhead indicates a macrophage, arrows indicate neutrophils. (h, i) HE stained P21 lung at higher magnification. (j, k) Ly6G staining neutrophils in P14 lung. (l, m) Ly6G staining in P19 lung. Scale bars represent 100 μm except in g where it represents 20 μM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3104547&req=5

f5: Surviving Nedd4-2−/− mice develop lung inflammation.Lung sections of Nedd4-2+/+ and Nedd4-2−/− mice. (a, b) Haematoxylin and eosin (HE) stained P10 lung. (c, d) βENaC expression in P21 lung sections. (e, f) HE stained P21 lung. (g) Enlarged view of a section in f. Arrowhead indicates a macrophage, arrows indicate neutrophils. (h, i) HE stained P21 lung at higher magnification. (j, k) Ly6G staining neutrophils in P14 lung. (l, m) Ly6G staining in P19 lung. Scale bars represent 100 μm except in g where it represents 20 μM.
Mentions: As stated previously a small number (∼4.2%) of Nedd4-2−/− animals survive up to a maximum of 22 days of age. We analysed the possible cause of lethality in these mice. The lung architecture of surviving Nedd4-2−/− mice was the same as wild type at P10 (Fig. 5a,b); however, the increased level of βENaC expression in the lung compared with wild-type littermates persisted at P21 (Fig. 5c,d), indicating this phenotype is chronic from birth. Lung sections from a Nedd4-2−/− animal that died at P21 demonstrated extensive fibrosis in the alveolar spaces compared with wild-type littermates (Fig. 5e–i). We also observed significant cellular infiltrate in lung tissue and air spaces of Nedd4-2−/− survivors examined, and the amount of infiltrate varied between animals. At higher magnification different types of inflammatory cells such as macrophages and neutrophils were clearly visible in alveolar spaces (Fig. 5g).

Bottom Line: This increased ENaC activity is the likely reason for premature fetal lung fluid clearance in Nedd4-2(-/-) animals, resulting in a failure to inflate lungs and perinatal lethality.A small percentage of Nedd4-2(-/-) animals survive up to 22 days, and these animals also show increased ENaC expression and develop lethal sterile inflammation of the lung.Thus, we provide critical in vivo evidence that Nedd4-2 is essential for correct regulation of ENaC expression, fetal and postnatal lung function and animal survival.

View Article: PubMed Central - PubMed

Affiliation: Department of Haematology, Centre for Cancer Biology, SA Pathology, PO Box 14, Rundle Mall, Adelaide, South Australia 5000, Australia.

ABSTRACT
The epithelial sodium channel (ENaC) is essential for sodium homoeostasis in many epithelia. ENaC activity is required for lung fluid clearance in newborn animals and for maintenance of blood volume and blood pressure in adults. In vitro studies show that the ubiquitin ligase Nedd4-2 ubiquitinates ENaC to regulate its cell surface expression. Here we show that knockout of Nedd4-2 in mice leads to increased ENaC expression and activity in embryonic lung. This increased ENaC activity is the likely reason for premature fetal lung fluid clearance in Nedd4-2(-/-) animals, resulting in a failure to inflate lungs and perinatal lethality. A small percentage of Nedd4-2(-/-) animals survive up to 22 days, and these animals also show increased ENaC expression and develop lethal sterile inflammation of the lung. Thus, we provide critical in vivo evidence that Nedd4-2 is essential for correct regulation of ENaC expression, fetal and postnatal lung function and animal survival.

Show MeSH
Related in: MedlinePlus