Thyroid hormone transport by 4F2hc-IU12 heterodimers expressed in Xenopus oocytes

Ritchie, James W.A.; Peter, George J.; Shi, Yun‐Bo; Taylor, Peter M.

doi:10.1677/joe.0.163r005

Cited by 64 publications

(40 citation statements)

References 26 publications

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“…The fact that the T 3 -uptake system in tadpole RBCs was sensitive to taurocholate and bromosulfophthalein but was insensitive to choline suggests the possibility that some of Na + -independent organic anion transporters (Abe et al 1998, Fujiwara et al 2001 are involved in the tadpole T 3 -uptake system. The K m values obtained from our studies were within the same range of those values obtained for the System T-linked T 3 -uptake system , Zhou et al 1990, McLeese & Eales 1996b, but one order of magnitude lower than those values obtained for System L (Blondeau et al 1993, Ritchie et al 1999, Ritchie & Taylor 2001) and the organic anion transporters (rat oatp2 and oatp3, human LST-1 and OATP-E; Abe et al 1998, Fujiwara et al 2001. Therefore, the T 3 -uptake system that is responsible for a major part of saturable T 3 uptake into tadpole RBCs may be the System T-linked uptake system and may be a common feature for rat, bullfrog and rainbow trout RBCs.…”

Section: Discussionsupporting

confidence: 88%

Characteristics of 3,5,3′-triiodothyronine (T3)-uptake system of tadpole red blood cells: effect of endocrine-disrupting chemicals on cellular T3 response

Shimada¹,

Yamauchi²

2004

Journal of Endocrinology

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We characterized the 3,5,3 --triiodothyronine (T 3 )-uptake system on the plasma membrane of Rana catesbeiana tadpole red blood cells (RBCs) 125 I]T 3 uptake by 2-fold at 3·2 µM. When RBCs were cultured with 10 nM T 3 at 25 C for 2 days in the presence of monodansylcadaverine, ethinylestradiol, ioxynil or dicofol at the defined concentrations, these compounds inhibited significantly the induction of the thyroid hormone receptor gene by T 3 . However, not all chemicals competed with T 3 binding to the receptor at the same concentrations. Our results raise the possibility that the T 3 -uptake system on the plasma membrane of the tadpole RBCs could be a candidate target site for some EDCs and can modulate cellular T 3 response.

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Section: Discussionsupporting

confidence: 88%

Characteristics of 3,5,3′-triiodothyronine (T3)-uptake system of tadpole red blood cells: effect of endocrine-disrupting chemicals on cellular T3 response

Shimada¹,

Yamauchi²

2004

Journal of Endocrinology

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“…7A) (6 -8, 40, 41). It was previously reported that IU12 / ASUR4, a Xenopus homolog of LAT1, accepts thyroid hormones as substrates (42); based on the double-reciprocal-plot analysis (data not shown), these modified AAs with bulky side chains are determined to be competitive inhibitors of hLAT1-mediated transport. Therefore, hLAT1's binding site may accommodate bulky side chains such as those of the thyroid hormones and melphalan.…”

Section: Discussionmentioning

confidence: 86%

Establishment and Characterization of Mammalian Cell Lines Stably Expressing Human L-Type Amino Acid Transporters

et al. 2008

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Abstract. System L (SL), a basolateral amino acid transporter, transports large neutral amino acids (LNAAs) in a Na + -independent manner. Previously, we identified two isoforms of transporters: L-type amino acid transporter 1 (LAT1) and 2 (LAT2) and revealed their distinct substrate selectivity and transport properties. In this study, to establish more stable human LAT1 (hLAT1) and LAT2 (hLAT2) in vitro assay systems, we established mouse cell lines stably expressing hLAT1 (S2-LAT1) and hLAT2 (S2-LAT2). Real-time quantitative RT-PCR analysis revealed that S2-LAT1 and S2-LAT2 cells express hLAT1 and hLAT2 mRNAs at 20 -1000-fold higher levels than those of endogenous mouse Lat1 and Lat2. S2-LAT1 and S2-LAT2 mediated [14 C]L-leucine transport properties were measured and corresponded to results observed via Xenopus oocytes. Using these cells, the data demonstrate that hLAT1 and hLAT2 exhibit different characters in the acceptance of α-methyl amino acids and amino acid-related compounds with bulky side chains such as thyroid hormones and melphalan. S2-LAT1 and S2-LAT2 cells are expected to facilitate hLAT1 and hLAT2 substrate recognition research and contribute to drug development by providing an efficient assay system to screen for chemical compounds that interact with hLAT1 and hLAT2.

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“…It has been shown that the aromatic amino acids Tyr and Trp, which can be transported by both systems L and T, inhibit the uptake of T 3 in neonatal cardiomyocytes and transfected Xenopus oocytes (Everts et al 1996b, Ritchie et al 1999. Only system L is sensitive to the synthetic amino acid analogue BCH (Broer et al 1998, Ritchie et al 1999. Our results show that uptake of T 3 was not sensitive to BCH, from which we conclude that system L does not participate in uptake of T 3 in neonatal rat cardiomyocytes.…”

Section: Discussionmentioning

confidence: 44%

“…Other likely candidates for a putative accessory transport system could be members of amino acid transport systems T or L. Both system T and L are Na + independent, and both systems transport aromatic amino acids (Kragie 1994, Palacín et al 1998. It has been shown that the aromatic amino acids Tyr and Trp, which can be transported by both systems L and T, inhibit the uptake of T 3 in neonatal cardiomyocytes and transfected Xenopus oocytes (Everts et al 1996b, Ritchie et al 1999. Only system L is sensitive to the synthetic amino acid analogue BCH (Broer et al 1998, Ritchie et al 1999.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, a growing number of studies demonstrate that uptake systems for aromatic amino acids, e.g. system L and system T, are involved in the transport of thyroid hormones (Everts et al 1994, Mitchell et al 1999, Ritchie et al 1999. In our previous report, we investigated the effect of tyrosine and tryptophan on T 3 uptake and suggested that part of the T 3 uptake may occur through these systems (Everts et al 1996b).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterization of uptake and compartmentalization of 3,5,3'-tri-iodothyronine in cultured neonatal rat cardiomyocytes

Putten

Joosten²,

Klaren³

et al. 2001

Journal of Endocrinology

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The uptake of tri-iodothyronine (T 3 ) in cultured neonatal rat cardiomyocytes was investigated and compared with the uptake of reverse T 3 (rT 3 ) and thyroxine (T 4 ). Cellular compartmentalization of T 3 was studied by distinguishing T 3 activity associated with the plasma membrane from that in the cytosol or incorporated in the cell nucleus. T 3 and T 4 uptake displayed similar temperature dependencies which, in magnitude, differed from that of rT 3 uptake. T 3 uptake was Na + independent, and sensitive to oligomycin and monodansylcadaverine (42-49% and 25% inhibition of 15-min cellular uptake respectively). Furthermore, T 3 uptake could be inhibited by tryptophan (20%) and tyrosine (12%), while 2-aminobicyclo[2,2,1]heptanecarboxylic acid had no effect. Co-incubation with tryptophan and oligomycin resulted in an additive inhibition of T 3 uptake (77%). We therefore conclude that (i) T 3 uptake is energy dependent, (ii) receptor-mediated endocytosis may be involved and (iii) the aromatic amino acid transport system T may play a role, while system L is not involved in T 3 transport in cardiomyocytes. Co-incubation with unlabeled iodothyronines showed that 3,3 -di-iodothyronine and T 3 itself were the most effective inhibitors of T 3 uptake (30% and 36% inhibition of 15-min cellular uptake respectively). At 15-min incubation time, 38% of the total cell-associated T 3 was present in the cytosol and nucleus, and 62% remained associated to the plasma membrane. Unidirectional uptake rates did not saturate over a free T 3 concentration range up to 3·9 µM. We have concluded that T 3 uptake in neonatal rat cardiomyocytes occurs by an energy-and temperaturedependent mechanism that may include endocytosis and amino acid transport system T, and is not sensitive to the Na + gradient. Elucidation of the molecular basis for the T 3 transporter is the subject of current investigation.

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Thyroid hormone transport by 4F2hc-IU12 heterodimers expressed in Xenopus oocytes

Cited by 64 publications

References 26 publications

Characteristics of 3,5,3′-triiodothyronine (T3)-uptake system of tadpole red blood cells: effect of endocrine-disrupting chemicals on cellular T3 response

Characteristics of 3,5,3′-triiodothyronine (T3)-uptake system of tadpole red blood cells: effect of endocrine-disrupting chemicals on cellular T3 response

Establishment and Characterization of Mammalian Cell Lines Stably Expressing Human L-Type Amino Acid Transporters

Characterization of uptake and compartmentalization of 3,5,3'-tri-iodothyronine in cultured neonatal rat cardiomyocytes

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