TY - JOUR
T1 - Substrate specificities of rat oatp1 and ntcp
T2 - Implications for hepatic organic anion uptake
AU - Hata, Soichiro
AU - Wang, Pijun
AU - Eftychiou, Nicole
AU - Ananthanarayanan, Meenakshisundaram
AU - Batta, Ashok
AU - Salen, Gerald
AU - Pang, K. Sandy
AU - Wolkoff, Allan W.
PY - 2003/11
Y1 - 2003/11
N2 - Transport of a series of 3H-radiolabeled C23, C 24, and C27 bile acid derivatives was compared and contrasted in HeLa cell lines stably transfected with rat Na +/taurocholate cotransporting polypeptide (ntcp) or organic anion transporting polypeptide 1 (oatp1) in which expression was under regulation of a zinc-inducible promoter. Similar uptake patterns were observed for both ntcp and oatp1, except that unconjugated hyodeoxycholate was a substrate of oatp1 but not ntcp. Conjugated bile acids were transported better than nonconjugated bile acids, and the configuration of the hydroxyl groups (α or β) had little influence on uptake. Although cholic and 23 norcholic acids were transported by ntcp and oatp1, other unconjugated bile acids (chenodeoxycholic, ursodeoxycholic) were not. In contrast to ntcp, oatp1-mediated uptake of the trihydroxy bile acids taurocholate and glycocholate was four- to eightfold below that of the corresponding dihydroxy conjugates. Ntcp mediated high affinity, sodium-dependent transport of [35S]sulfobromophthalein with a Km similar to that of oatp1-mediated transport of [ 35S] sulfobromophthalein (Km = 3.7 vs. 3.3 μM, respectively). In addition, for both transporters, uptake of sulfobromophthalein and taurocholic acid showed mutual competitive inhibition. These results indicate that the substrate specificity of ntcp is considerably broader than previously suspected and caution the extrapolation of transport data obtained in vitro to physiological function in vivo.
AB - Transport of a series of 3H-radiolabeled C23, C 24, and C27 bile acid derivatives was compared and contrasted in HeLa cell lines stably transfected with rat Na +/taurocholate cotransporting polypeptide (ntcp) or organic anion transporting polypeptide 1 (oatp1) in which expression was under regulation of a zinc-inducible promoter. Similar uptake patterns were observed for both ntcp and oatp1, except that unconjugated hyodeoxycholate was a substrate of oatp1 but not ntcp. Conjugated bile acids were transported better than nonconjugated bile acids, and the configuration of the hydroxyl groups (α or β) had little influence on uptake. Although cholic and 23 norcholic acids were transported by ntcp and oatp1, other unconjugated bile acids (chenodeoxycholic, ursodeoxycholic) were not. In contrast to ntcp, oatp1-mediated uptake of the trihydroxy bile acids taurocholate and glycocholate was four- to eightfold below that of the corresponding dihydroxy conjugates. Ntcp mediated high affinity, sodium-dependent transport of [35S]sulfobromophthalein with a Km similar to that of oatp1-mediated transport of [ 35S] sulfobromophthalein (Km = 3.7 vs. 3.3 μM, respectively). In addition, for both transporters, uptake of sulfobromophthalein and taurocholic acid showed mutual competitive inhibition. These results indicate that the substrate specificity of ntcp is considerably broader than previously suspected and caution the extrapolation of transport data obtained in vitro to physiological function in vivo.
KW - Cell transfection
KW - Hepatocyte
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U2 - 10.1152/ajpgi.00352.2002
DO - 10.1152/ajpgi.00352.2002
M3 - Article
C2 - 12842829
AN - SCOPUS:0142151027
SN - 0193-1857
VL - 285
SP - G829-G839
JO - American Journal of Physiology - Gastrointestinal and Liver Physiology
JF - American Journal of Physiology - Gastrointestinal and Liver Physiology
IS - 5 48-5
ER -