Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway
Albumin is a major serum protein and is frequently used as a cell culture supplement. It is crucially involved in the regulation of osmotic pressure and distribution of fluid between different compartments. Alveolar epithelial Na<sup>+</sup> transport drives alveolar fluid clearance (AFC...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-08-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/23/15/8823 |
| _version_ | 1797441713065689088 |
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| author | Mandy Laube Ulrich H. Thome |
| author_facet | Mandy Laube Ulrich H. Thome |
| author_sort | Mandy Laube |
| collection | DOAJ |
| description | Albumin is a major serum protein and is frequently used as a cell culture supplement. It is crucially involved in the regulation of osmotic pressure and distribution of fluid between different compartments. Alveolar epithelial Na<sup>+</sup> transport drives alveolar fluid clearance (AFC), enabling air breathing. Whether or not albumin affects AFC and Na<sup>+</sup> transport is yet unknown. We therefore determined the acute and chronic effects of albumin on Na<sup>+</sup> transport in fetal distal lung epithelial (FDLE) cells and the involved kinase pathways. Chronic BSA treatment strongly increased epithelial Na<sup>+</sup> transport and barrier integrity in Ussing chambers. BSA did not elevate mRNA expression of Na<sup>+</sup> transporters in FDLE cells after 24 h. Moreover, acute BSA treatment for 45 min mimicked the chronic effects. The elevated Na<sup>+</sup> transport was caused by an increased maximal ENaC activity, while Na,K-ATPase activity remained unchanged. Acute and chronic BSA treatment lowered membrane permeability, confirming the increased barrier integrity observed in Ussing chambers. Western blots demonstrated an increased phosphorylation of AKT and SGK1, and PI3K inhibition abolished the stimulating effect of BSA. BSA therefore enhanced epithelial Na<sup>+</sup> transport and barrier integrity by activating the PI3K/AKT/SGK1 pathway. |
| first_indexed | 2024-03-09T12:29:03Z |
| format | Article |
| id | doaj.art-c86f2c02d1a34fa2be2e4dcd6e5ad897 |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T12:29:03Z |
| publishDate | 2022-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-c86f2c02d1a34fa2be2e4dcd6e5ad8972023-11-30T22:31:29ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-08-012315882310.3390/ijms23158823Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 PathwayMandy Laube0Ulrich H. Thome1Center for Pediatric Research Leipzig, Division of Neonatology, Department of Pediatrics, University of Leipzig, 04103 Leipzig, GermanyCenter for Pediatric Research Leipzig, Division of Neonatology, Department of Pediatrics, University of Leipzig, 04103 Leipzig, GermanyAlbumin is a major serum protein and is frequently used as a cell culture supplement. It is crucially involved in the regulation of osmotic pressure and distribution of fluid between different compartments. Alveolar epithelial Na<sup>+</sup> transport drives alveolar fluid clearance (AFC), enabling air breathing. Whether or not albumin affects AFC and Na<sup>+</sup> transport is yet unknown. We therefore determined the acute and chronic effects of albumin on Na<sup>+</sup> transport in fetal distal lung epithelial (FDLE) cells and the involved kinase pathways. Chronic BSA treatment strongly increased epithelial Na<sup>+</sup> transport and barrier integrity in Ussing chambers. BSA did not elevate mRNA expression of Na<sup>+</sup> transporters in FDLE cells after 24 h. Moreover, acute BSA treatment for 45 min mimicked the chronic effects. The elevated Na<sup>+</sup> transport was caused by an increased maximal ENaC activity, while Na,K-ATPase activity remained unchanged. Acute and chronic BSA treatment lowered membrane permeability, confirming the increased barrier integrity observed in Ussing chambers. Western blots demonstrated an increased phosphorylation of AKT and SGK1, and PI3K inhibition abolished the stimulating effect of BSA. BSA therefore enhanced epithelial Na<sup>+</sup> transport and barrier integrity by activating the PI3K/AKT/SGK1 pathway.https://www.mdpi.com/1422-0067/23/15/8823lungNa<sup>+</sup> transportbarrier integrityENaCBSAprotein kinase B |
| spellingShingle | Mandy Laube Ulrich H. Thome Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway International Journal of Molecular Sciences lung Na<sup>+</sup> transport barrier integrity ENaC BSA protein kinase B |
| title | Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway |
| title_full | Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway |
| title_fullStr | Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway |
| title_full_unstemmed | Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway |
| title_short | Albumin Stimulates Epithelial Na<sup>+</sup> Transport and Barrier Integrity by Activating the PI3K/AKT/SGK1 Pathway |
| title_sort | albumin stimulates epithelial na sup sup transport and barrier integrity by activating the pi3k akt sgk1 pathway |
| topic | lung Na<sup>+</sup> transport barrier integrity ENaC BSA protein kinase B |
| url | https://www.mdpi.com/1422-0067/23/15/8823 |
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