Center for Molecular Recognition, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
J Biol Chem. 2011 Jan 7;286(1):131-7. doi: 10.1074/jbc.M110.167197. Epub 2010 Oct 27.
Iodide (I(-)) is an essential constituent of the thyroid hormones triiodothyronine and thyroxine, which are required for the development of the central nervous system in the fetus and newborn. I(-) uptake in the thyroid is mediated by the Na(+)/I(-) symporter (NIS). NIS has gained particular medical interest due to its sensitivity to the environmental pollutant perchlorate (ClO(4)(-)) and its implication in radioiodide cancer treatment. Recently, others have shown that I(-) absorption in the intestine is mediated by NIS (Nicola, J. P., Basquin, C., Portulano, C., Reyna-Neyra, A., Paroder, M., and Carrasco, N. (2009) Am. J. Physiol. Cell Physiol. 296, C654-662). However, their data suggest the participation of other systems in the homeostasis of I(-), in particular because in vivo uptake studies revealed a ClO(4)(-)-insensitive transport component. Here, we describe Na(+)-coupled I(-) uptake by the human Na(+)/multivitamin transporter (hSMVT), a related protein isolated from the placenta, where it was suggested to supply the fetus with the water-soluble vitamins biotin and pantothenic acid, and α-lipoic acid. hSMVT-mediated Na(+)/I(-) symport is inhibited by the other three organic hSMVT substrates but not by NIS substrates; notably, hSMVT is insensitive to ClO(4)(-). Because hSMVT is found in the intestine and in many other tissues, we propose that hSMVT may play an important role in the homeostasis of I(-) in the body.
碘化物（I(-)）是甲状腺激素三碘甲状腺原氨酸和甲状腺素的必需组成部分，这两种激素对于胎儿和新生儿中枢神经系统的发育至关重要。甲状腺中的碘化物摄取是由钠离子/碘化物同向转运体（NIS）介导的。由于 NIS 对环境污染物高氯酸盐（ClO4(-)）敏感，并且与放射性碘癌症治疗有关，因此它引起了医学界的特别关注。最近，其他人已经表明，肠道中的碘化物吸收是由 NIS 介导的（Nicola, J. P., Basquin, C., Portulano, C., Reyna-Neyra, A., Paroder, M., and Carrasco, N. (2009) Am. J. Physiol. Cell Physiol. 296, C654-662）。然而，他们的数据表明，其他系统也参与了碘化物的动态平衡，特别是因为体内摄取研究表明存在一种对高氯酸盐不敏感的转运成分。在这里，我们描述了人 Na(+)/多种维生素转运蛋白（hSMVT）介导的 Na(+)-偶联碘化物摄取，hSMVT 是从胎盘分离出来的一种相关蛋白，据推测它为胎儿提供水溶性维生素生物素和泛酸，以及α-硫辛酸。hSMVT 介导的 Na(+)/I(-)同向转运被其他三种有机 hSMVT 底物抑制，但不受 NIS 底物抑制；值得注意的是，hSMVT 对高氯酸盐不敏感。由于 hSMVT 存在于肠道和许多其他组织中，我们提出 hSMVT 可能在体内碘化物的动态平衡中发挥重要作用。
