Cloning and molecular characterization of the ontogeny of a rat ileal sodium-dependent bile acid transporter.

Abstract

Sodium-dependent bile acid transport in the rat ileum is abruptly expressed at weaning. Degenerate oligonucleotides, based on amino acid sequence identities between the rat liver and hamster ileal transporters, were used to amplify a rat ileal probe. A 1.2-kb cDNA clone, which contains the full coding region (348 amino acids, 38 kD), was isolated by hybridization screening. In vitro translation yielded a 38-kD protein which glycosylated to 48 kD. Sodium-dependent uptake of taurocholate was observed in oocytes injected with cRNA. Northern blot analysis revealed a 5.0-kb mRNA in ileum, kidney, and cecum. A 48-kD protein was detected in ileal brush border membranes and localized to the apical border of villus ileal enterocytes. mRNA and protein expression, which were negligible before weaning, increased dramatically at weaning. Nuclear transcription rates for the transporter increased 15-fold between postnatal days 7 and 28. The apparent molecular weight of the transporter also increased between days 19 and 28. In summary, the developmental regulation of the rat ileal sodium-dependent bile acid cotransporter is characterized by transcriptionally regulated increases in mRNA and protein levels at the time of weaning with changes in apparent molecular weight of the protein after weaning. (J. Clin. Invest. 1995. 95:745-754.)

Age‐dependent glycosylation of the sodium taurocholate cotransporter polypeptide: From fetal to adult human livers

“…Our study suggests that NTCP protein N‐glycosylation is age dependent and is not completed until approximately 1 year after birth. In contrast, Ntcp glycosylation in rats was shown to be completed within 4 weeks after birth, illustrating significant species differences in transporter expression, as described 28, 29. Additionally, by using immunofluorescence, our study revealed that the adult NTCP membrane pattern was reached only after 1 year of age and was strongly correlated with the net increase of the NTCP 55‐kDa complex glycosylated band previously detected by immunoblotting analysis in hepatocytes older than 1 year.…”

Bile Acid Signaling Is Involved in the Neurological Decline in a Murine Model of Acute Liver Failure

“…The antibody against ASBT was a kind gift from Dr. Paul Dawson (Wake Forest University Health Sciences, Winston Salem, NC). 15 The primers for FXR (catalog number PPM24915A), ASBT (catalog number PPM24983A), Shp (catalog number PPM41772A), and glyceraldehyde-3-phosphate dehydrogenase (catalog number PPM02946E) were purchased from Qiagen, SABiosciences (Frederick, MD). Vivo-morpholino sequences were purchased from Gene Tools (Philomath, OR).…”

The solute carrier family SLC10: more than a family of bile acid transporters regarding function and phylogenetic relationships

“…Asbt was originally cloned from a hamster intestinal cDNA library by expression cloning (Wong et al 1994). Subsequently, human ASBT , rat Asbt (Shneider et al 1995), rabbit Asbt , and mouse Asbt (Saeki et al 1999) were cloned from the ileum. The ASBT/Asbt proteins of all mentioned species consist of 348 amino acids and show an overall amino acid identity of >80%.…”

“…This transport is electrogenic and shows a 2:1 Na + /bile acid coupling stoichiometry (Weinman et al 1998). In contrast to the basolateral localisation of Ntcp, Asbt is highly expressed in the apical brush border membrane of enterocytes of the terminal ileum (Shneider et al 1995). Here, Asbt is associated with the 14 kilodalton cytoplasmic ileal lipid-binding protein ILBP, which is the Amino acid identity values were determined after pairwise optimal GLOBAL alignment with the BioEdit program version 7.0.5.2 (Hall 1999).…”