Mannan-binding lectin serine protease-2 (MASP-2) in human kidney and its relevance for proteolytic activation of the epithelial sodium channel
Open Access
- 24 September 2022
- journal article
- research article
- Published by Springer Science and Business Media LLC in Scientific Reports
- Vol. 12 (1), 1-13
- https://doi.org/10.1038/s41598-022-20213-8
Abstract
Proteolytic activation of the renal epithelial sodium channel (ENaC) is increased by aldosterone. The aldosterone-sensitive protease remains unidentified. In humans, elevated circulating aldosterone is associated with increased urinary extracellular vesicle (uEVs) excretion of mannan-binding lectin associated serine protease-2 (MASP-2). We hypothesized that MASP-2 is a physiologically relevant ENaC-activating protease. It was confirmed that MASP2 mRNA is abundantly present in liver but not in human and mouse kidneys. Aldosterone-stimulation of murine cortical colleting duct (mCCD) cells did not induce MASP-2 mRNA. In human kidney collecting duct, MASP-2 protein was detected in AQP2-negative/ATP6VB1-positive intercalated cells suggestive of MASP2 protein uptake. Plasma concentration of full-length MASP-2 and the short splice variant MAp19 were not changed in a cross-over intervention study in healthy humans with low (70 mmol/day) versus high (250 mmol/day) Na+ intake despite changes in aldosterone. The ratio of MAp19/MASP-2 in plasma was significantly increased with a high Na+ diet and the ratio correlated with changes in aldosterone and fractional Na+ excretion. MASP-2 was not detected in crude urine or in uEVs. MASP2 activated an amiloride-sensitive current when co-expressed with ENaC in Xenopus oocytes, but not when added to the bath solution. In monolayers of collecting duct M1 cells, MASP2 expression did not increase amiloride-sensitive current and in HEK293 cells, MASP-2 did not affect γENaC cleavage. MASP-2 is neither expressed nor co-localized and co-regulated with ENaC in the human kidney or in urine after low Na+ intake. MASP-2 does not mediate physiological ENaC cleavage in low salt/high aldosterone settings.Funding Information
- Danish Diabetes Academy (OL 8201,ID phd0115)
- Syddansk Universitet (10-102-00000)
- Odense Universitetshospital (815 (A))
- Beckett-Fonden (49091)
- Bagermester August Jensen and wife grants (95-102-71226)
- Grosserer L. F. Foghts Fond (21.265)
- Fru Ruth I.E. Konig-Petersen Reasearch Foundation (71623)
- Dansk Nefrologisk Selskab (71406)
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (31003A_182478/1)
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