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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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Lung phenotype of surviving Nedd4-2−/− mice is not due to altered surfactants or mucous.(a, b) Surfactant Protein-C expression in P14 lung. (c, d) Mucin expression in P14 lung. (e, f) Alcian-blue/periodic acid-Schiff (AB-PAS) staining mucopolysaccharides in P21 lung. (g, h) TEM of P19 lung, with pyknotic nuclei (pn) and a macrophage (m) indicated. Scale bars represent 100 μm except in g, h where it represents 10 μM.
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f6: Lung phenotype of surviving Nedd4-2−/− mice is not due to altered surfactants or mucous.(a, b) Surfactant Protein-C expression in P14 lung. (c, d) Mucin expression in P14 lung. (e, f) Alcian-blue/periodic acid-Schiff (AB-PAS) staining mucopolysaccharides in P21 lung. (g, h) TEM of P19 lung, with pyknotic nuclei (pn) and a macrophage (m) indicated. Scale bars represent 100 μm except in g, h where it represents 10 μM.

Mentions: Nedd4-2 has been implicated in regulating the processing and levels of surfactant protein-C (SP-C), a pulmonary surfactant protein secreted by alveolar type II cells2627. However, we found that SP-C staining was similar in lung sections from both Nedd4-2−/− and Nedd4-2+/+ littermates (Fig. 6a,b). Furthermore, mucin levels in the lung of Nedd4-2−/− and Nedd4-2+/+ littermates were comparable (Fig. 6c,d) as were mucous levels (Fig. 6e,f). No bacterial infection was observed in either lung or spleen homogenates of Nedd4-2−/− survivors at P14, and there were a lack of CD4+ T cells in Nedd4-2+/+ and Nedd4-2−/− lungs, consistent with sterile inflammation. Indeed, ultrastructural examination of a P19 lung by transmission electron microscopy (TEM) commonly identified pyknotic nuclei in Nedd4-2−/− survivor lungs, indicating the occurrence of necrosis in the alveolar epithelium (Fig. 6g,h).


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)

Lung phenotype of surviving Nedd4-2−/− mice is not due to altered surfactants or mucous.(a, b) Surfactant Protein-C expression in P14 lung. (c, d) Mucin expression in P14 lung. (e, f) Alcian-blue/periodic acid-Schiff (AB-PAS) staining mucopolysaccharides in P21 lung. (g, h) TEM of P19 lung, with pyknotic nuclei (pn) and a macrophage (m) indicated. Scale bars represent 100 μm except in g, h where it represents 10 μM.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Lung phenotype of surviving Nedd4-2−/− mice is not due to altered surfactants or mucous.(a, b) Surfactant Protein-C expression in P14 lung. (c, d) Mucin expression in P14 lung. (e, f) Alcian-blue/periodic acid-Schiff (AB-PAS) staining mucopolysaccharides in P21 lung. (g, h) TEM of P19 lung, with pyknotic nuclei (pn) and a macrophage (m) indicated. Scale bars represent 100 μm except in g, h where it represents 10 μM.
Mentions: Nedd4-2 has been implicated in regulating the processing and levels of surfactant protein-C (SP-C), a pulmonary surfactant protein secreted by alveolar type II cells2627. However, we found that SP-C staining was similar in lung sections from both Nedd4-2−/− and Nedd4-2+/+ littermates (Fig. 6a,b). Furthermore, mucin levels in the lung of Nedd4-2−/− and Nedd4-2+/+ littermates were comparable (Fig. 6c,d) as were mucous levels (Fig. 6e,f). No bacterial infection was observed in either lung or spleen homogenates of Nedd4-2−/− survivors at P14, and there were a lack of CD4+ T cells in Nedd4-2+/+ and Nedd4-2−/− lungs, consistent with sterile inflammation. Indeed, ultrastructural examination of a P19 lung by transmission electron microscopy (TEM) commonly identified pyknotic nuclei in Nedd4-2−/− survivor lungs, indicating the occurrence of necrosis in the alveolar epithelium (Fig. 6g,h).

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