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Structural determinants for transport across the intestinal bile acid transporter using C-24 bile acid conjugates.

ABSTRACT: The human apical sodium dependent bile acid transporter (hASBT) reabsorbs gram quantities of bile acid daily and is a potential prodrug target to increase oral drug absorption. In the absence of a high resolution hASBT crystal structure, 3D-QSAR modeling may prove beneficial in designing prodrug targets to hASBT. The objective was to derive a conformationally sampled pharmacophore 3D-QSAR (CSP-SAR) model for the uptake of bile acid conjugates by hASBT. A series of bile acid conjugates of glutamyl chenodeoxycholate were evaluated in terms of K(m) and normalized V(max) (normV(max)) using hASBT-MDCK cells. All monoanionic conjugates were potent substrates. Dianions, cations and zwitterions, which bound with a high affinity, were not substrates. CSP-SAR models were derived using structural and physicochemical descriptors, and evaluated via cross validation. The best CSP-SAR model for K(m) included two structural and two physiochemical descriptors, where substrate hydrophobicity enhanced affinity. A best CSP-SAR model for K(m)/normV(max) employed one structural and three physicochemical descriptors, also indicating hydrophobicity enhanced efficiency. Overall, the bile acid C-24 region accommodated a range of substituted anilines, provided a single negative charge was present near C-24. In comparing uptake findings to prior inhibition results, increased hydrophobicity enhanced activity, with dianions and zwitterions hindering activity.

SUBMITTER: Rais R

PROVIDER: S-EPMC2997912 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Structural determinants for transport across the intestinal bile acid transporter using C-24 bile acid conjugates.

Rais Rana R Acharya Chayan C Mackerell Alexander D AD Polli James E JE

Molecular pharmaceutics 20101101 6

The human apical sodium dependent bile acid transporter (hASBT) reabsorbs gram quantities of bile acid daily and is a potential prodrug target to increase oral drug absorption. In the absence of a high resolution hASBT crystal structure, 3D-QSAR modeling may prove beneficial in designing prodrug targets to hASBT. The objective was to derive a conformationally sampled pharmacophore 3D-QSAR (CSP-SAR) model for the uptake of bile acid conjugates by hASBT. A series of bile acid conjugates of glutamy ...[more]

PMID: 20939504

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Project description:Intrahepatic cholestasis of pregnancy (ICP) is estimated to impact between 0.4% and 5% of pregnancies worldwide. This disease is associated with elevated maternal bile acids and frequently untoward neonatal outcomes such as respiratory distress and asphyxia. Multiple candidate genes have been implicated, but none have provided insight into the mechanisms of neonatal respiratory distress and death. Herein our studies demonstrate that maternal cholestasis (due to Abcb11 deficiency) produces 100% neonatal death within 24h due to atelectasis producing pulmonary hypoxia, which recapitulates the respiratory distress and asphyxia of human ICP. We show that these neonates have elevated pulmonary bile acids that are associated with disrupted structure of pulmonary surfactant. Maternal absence of Nr1i2 superimposed upon Abcb11 deficiency strongly increased neonatal survival and is directly related to reduced maternal bile acid concentrations. The mechanism accounting for reduced serum bile acids in the mothers deficient in both Nr1i2 and Abcb11 appears related to disrupted reabsorption of intestinal bile acids due to changes in transporter expression. These findings provide novel insights into pulmonary failure by revealing bile acids capability to disrupt the structure of surfactant producing collapsed alveoli, pulmonary failure and ultimately death. These findings have important implications for neonatal health especially when maternal bile acids are elevated during pregnancy and highlight a potential pathway and targets amenable to therapeutic intervention to ameliorate this condition. We used microarrays to measure changes in gene expression profiles in lung tissues from Abcb11+/- lungs after interbreeding C57BL/6 wild-type female or C57BL/6 Abcb11-/- female mice against either C57BL/6 wild-type male mice or C57BL/6 Abcb11-/- male mice to create only heterozygote offspring. We also measured profiles in liver tissues from age-matched C57BL/6 wild-type and C57BL/6 Abcb11-/- mice. Lung tissues were collected from day E17.5, E18.5 and neonatal (N0) mice. Liver tissues were collected from 1.5-month-old C57BL/6 wildtype and Abcb11-/- mice.

Dataset Information

Structural determinants for transport across the intestinal bile acid transporter using C-24 bile acid conjugates.

Publications

Structural determinants for transport across the intestinal bile acid transporter using C-24 bile acid conjugates.

Similar Datasets

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