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Glucocorticoid regulation and glycosylation of mouse intestinal type IIb Na-P i cotransporter during ontogeny

2002; American Physiological Society; Volume: 283; Issue: 2 Linguagem: Inglês

10.1152/ajpgi.00319.2001

1522-1547

Kayo Arima, Eric R. Hines, Pawel R. Kiela, Jason B. Drees, James F. Collins, Fayez K. Ghishan,

Electrolyte and hormonal disorders

We sought to characterize expression of an apically expressed intestinal Na-P i cotransporter (Na-P i -IIb) during mouse ontogeny and to assess the effects of methylprednisolone (MP) treatment. In control mice, Na-P i uptake by intestinal brush-border membrane vesicles was highest at 14 days of age, lower at 21 days, and further reduced at 8 wk and 8–9 mo of age. Na-P i -IIb mRNA and immunoreactive protein levels in 14-day-old animals were markedly higher than in older groups. MP treatment significantly decreased Na-P i uptake and Na-P i -IIb mRNA and protein expression in 14-day-old mice. Additionally, the size of the protein was smaller in 14-day-old mice. Deglycosylation of protein from 14-day-old and 8-wk-old animals with peptide N-glycosidase reduced the molecular weight to the predicted size. We conclude that intestinal Na-P i uptake and Na-P i -IIb expression are highest at 14 days and decrease with age. Furthermore, MP treatment reduced intestinal Na-P i uptake approximately threefold in 14-day-old mice and this reduction correlates with reduced Na-P i -IIb mRNA and protein expression. We also demonstrate that Na-P i -IIb is an N-linked glycoprotein and that glycosylation is age dependent.