1.Screening and verifying potential NTCP inhibitors from herbal medicinal ingredients using the LLC-PK1 cell model stably expressing human NTCP.
Zhuo-Wei SHEN ; Meng-Yue LUO ; Hai-Hong HU ; Hui ZHOU ; Hui-Di JIANG ; Lu-Shan YU ; Su ZENG
Chinese Journal of Natural Medicines (English Ed.) 2016;14(7):549-560
NTCP is specifically expressed on the basolateral membrane of hepatocytes, participating in the enterohepatic circulation of bile salts, especially conjugated bile salts, to maintain bile salts homeostasis. In addition, recent studies have found that NTCP is a functional receptor of HBV and HDV. Therefore, it is important to study the interaction between drugs and NTCP and identify the inhibitors/substrates of NTCP. In the present study, a LLC-PK1 cell model stably expressing human NTCP was established, which was simple and suitable for high throughput screening, and utilized to screen and verify the potential inhibitors of NTCP from 102 herbal medicinal ingredients. The results showed that ginkgolic acid (GA) (13 : 0), GA (15 : 1), GA (17 : 1), erythrosine B, silibinin, and emodin have inhibitory effects on NTCP uptake of TCNa in a concentration-dependent manner. Among them, GA (13 : 0) and GA (15 : 1) exhibited the stronger inhibitory effects, with IC50 values being less than 8.3 and 13.5 μmol·L(-1), respectively, than the classical inhibitor, cyclosporin A (CsA) (IC50 = 20.33 μmol·L(-1)). Further research demonstrated that GA (13 : 0), GA (15 : 1), GA (17 : 1), silibinin, and emodin were not substrates of NTCP. These findings might contribute to a better understanding of the disposition of the herbal ingredients in vivo, especially in biliary excretion.
Animals
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Drug Evaluation, Preclinical
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Humans
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Kinetics
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LLC-PK1 Cells
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Models, Biological
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Organic Anion Transporters, Sodium-Dependent
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antagonists & inhibitors
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chemistry
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metabolism
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Plant Extracts
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chemistry
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pharmacology
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Plants, Medicinal
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chemistry
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Structure-Activity Relationship
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Swine
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Symporters
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antagonists & inhibitors
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chemistry
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metabolism
2.Effect of SC-435 on the gastrointestinal migrating myoelectric complex in guinea pigs.
Xue-mei ZHANG ; Lei DONG ; Li-na LIU ; Ya-mei LEI
Journal of Central South University(Medical Sciences) 2005;30(5):497-503
OBJECTIVE:
To determine whether SC-435, a new ileal apical sodium-codependent bile acid transporter (IBAT) inhibitor, can alter the gastrointestinal motility in guinea pigs.
METHODS:
Sixty guinea pigs received regular diet or IBAT inhibitor (SC-435) diet for 2, 4, and 8 weeks, respectively. At the end of the feeding period, the gallbladder motility was assessed and then four bipolar silver electrodes were implanted on the antrum, duodenum, jejunum, and ileum. Seven days later, migrating motor complex (MMC) was recorded and the total bile acid pool size was measured according to the isotope dilution principle in the meantime.
RESULTS:
After feeding SC435, the gallbladder motility was declined in the 4-week group and the 8-week group. The bile acid pool size decreased by 17.11% (P <0.05) in the 4-week group and 48.35% (P < 0.05) in the 8-week group. The places of origin of MMC were changed where antral origins (37%) and duodenal origins (46%) decreased whereas jejunal origins (17%) increased. The MMC cycle period was prolonged in the duodenum (1.16 times in the 4-week group, P < 0.05; 1.38 times in the 8-week group, P < 0.05) whereas MMC amplitude fell in the duodenum (10.58% in the 4-week group, P <0.05; 49.17% in the 8-week group, P <0.05). There were not significant differences in all parameters of MMC between the control group and the 2-week group in guinea pigs.
CONCLUSION
The IBAT inhibitor (SC-435) reduces the bile acid pool size and inhibits the MMC cycle activity. MMC is related to the enterohepatic circulation of bile acids, which is consistent with the changes of the bile acid pool size in guinea pigs.
Animals
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Bile Acids and Salts
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Cyclic N-Oxides
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pharmacology
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Female
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Gallbladder
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physiology
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Gastrointestinal Motility
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drug effects
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physiology
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Guinea Pigs
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Myoelectric Complex, Migrating
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drug effects
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Organic Anion Transporters, Sodium-Dependent
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antagonists & inhibitors
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Random Allocation
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Symporters
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antagonists & inhibitors
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Tropanes
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pharmacology
3.Increased Expression of Sodium Transporters in Rats Chronically Inhibited of Nitric Oxide Synthesis.
Joon Sik KIM ; Ki Chul CHOI ; Myung Ho JEONG ; Soo Wan KIM ; Yoon Wha OH ; Jong Un LEE
Journal of Korean Medical Science 2006;21(1):1-4
The present study was done to determine whether endogenous nitric oxide (NO) plays a role in the regulation of sodium transporters in the kidney. Male Sprague-Dawley rats were treated with NG-nitro-L-arginine methyl ester (L-NAME, 100 mg/L drinking water) for 4 weeks. Control rats were supplied with tap water without drugs. Expression of Na, K-ATPase, type 3 Na/H exchanger (NHE3), Na/K/2Cl cotransporter (BSC1), and thiazide-sensitive Na/Cl cotransporter (TSC) proteins was determined in the kidney by Western blot analysis. Catalytic activity of Na,K-ATPase was also determined. The treatment with L-NAME significantly and steadily increased the systemic blood pressure. Total and fractional excretion of urinary sodium decreased significantly, while creatinine clearance remained unaltered. Neither plasma renin activity nor aldosterone concentration was significantly altered. The alpha1 subunit expression and the catalytic activity of Na, K-ATPase were increased in the kidney. The expression of NHE3, BSC1 and TSC was also increased significantly. These results suggest that endogenously-derived NO exerts a tonic inhibitory effect on the expression of sodium transporters, including Na, K-ATPase, NHE3, BSC1, and TSC, in the kidney.
Animals
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Blotting, Western
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Carrier Proteins/*biosynthesis
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Enzyme Inhibitors/pharmacology
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Kidney/drug effects/metabolism
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Male
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NG-Nitroarginine Methyl Ester/*pharmacology
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Na(+)-K(+)-Exchanging ATPase/biosynthesis
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Nitric Oxide Synthase/*antagonists & inhibitors/metabolism
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Rats
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Rats, Sprague-Dawley
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Receptors, Drug/biosynthesis
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Sodium/*metabolism
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Sodium Chloride Symporters/biosynthesis
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Sodium-Hydrogen Antiporter/biosynthesis
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Sodium-Potassium-Chloride Symporters/biosynthesis
4.From DCPD to NTCP: The long journey towards identifying a functional hepatitis B virus receptor.
Clinical and Molecular Hepatology 2015;21(3):193-199
Hepatitis B virus (HBV) is the prototype of hepatotropic DNA viruses (hepadnaviruses) infecting a wide range of human and non-human hosts. Previous studies with duck hepatitis B virus (DHBV) identified duck carboxypeptidase D (dCPD) as a host specific binding partner for full-length large envelope protein, and p120 as a binding partner for several truncated versions of the large envelope protein. p120 is the P protein of duck glycine decarboxylase (dGLDC) with restricted expression in DHBV infectible tissues. Several lines of evidence suggest the importance of dCPD, and especially p120, in productive DHBV infection, although neither dCPD nor p120 cDNA could confer susceptibility to DHBV infection in any cell line. Recently, sodium taurocholate cotransporting polypeptide (NTCP) has been identified as a binding partner for the N-terminus of HBV large envelope protein. Importantly, knock down and reconstitution experiments unequivocally demonstrated that NTCP is both necessary and sufficient for in vitro infection by HBV and hepatitis delta virus (HDV), an RNA virus using HBV envelope proteins for its transmission. What remains unclear is whether NTCP is the major HBV receptor in vivo. The fact that some HBV patients are homozygous with an NTCP mutation known to abolish its receptor function suggests the existence of NTCP-independent pathways of HBV entry. Also, NTCP very likely mediates just one step of the HBV entry process, with additional co-factors for productive HBV infection still to be discovered. NTCP offers a novel therapeutic target for the control of chronic HBV infection.
Animals
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Carboxypeptidases/genetics/*metabolism
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Gene Products, pol/genetics/metabolism
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Heparan Sulfate Proteoglycans/metabolism
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Hepatitis B virus/*physiology
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Hepatocytes/metabolism/virology
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Organic Anion Transporters, Sodium-Dependent/antagonists & inhibitors/genetics/metabolism
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RNA Interference
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Symporters/antagonists & inhibitors/genetics/metabolism
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Viral Envelope Proteins/metabolism
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Virus Internalization