Chan S, McCabe C J, Visser T J, Franklyn J A, Kilby M D
Division of Reproductive and Child Health, University of Birmingham, Birmingham Women's Hospital, Edgbaston, Birmingham B15 2TG, UK.
J Endocrinol. 2003 Jul;178(1):159-67. doi: 10.1677/joe.0.1780159.
N-TERA-2 cl/D1 (NT2) cells, a human embryonal cell line with characteristics of central nervous system precursor cells, were utilised to study thyroid hormone action during early neuronal growth and differentiation. Undifferentiated NT2 cells expressed mRNAs encoding thyroid hormone receptors (TRs) alpha1, alpha2 and beta1, iodothyronine deiodinases types 2 (D2) and 3 (D3) (which act as the pre-receptor regulators), and the thyroid hormone-responsive genes myelin basic protein (MBP) and neuroendocrine specific protein A (NSP-A). When terminally differentiated into post-mitotic neurons (hNT), TRalpha1 and TRbeta1 mRNA expression was decreased by 74% (P=0.05) and 95% (P<0.0001) respectively, while NSP-A mRNA increased 7-fold (P<0.05). However, mRNAs encoding TRalpha2, D2, D3 and MBP did not alter significantly upon neuronal differentiation and neither did activities of D2 and D3. With increasing 3,5,3'-triiodothyronine (T(3)) concentrations, TRbeta1 mRNA expression in cultured NT2 cells increased 2-fold at 10 nM T(3) and 1.3-fold at 100 nM T(3) (P<0.05) compared with that in T(3)-free media but no change was seen with T(3) treatment of hNT cells. D3 mRNA expression in NT2 cells also increased 3-fold at 10 nM T(3) (P=0.01) and 2.4-fold at 100 nM T(3) (P<0.05) compared with control, but there was no change in D3 enzyme activity. In contrast there was a 20% reduction in D3 mRNA expression in hNT cells at 10 nM T(3) (P<0.05) compared with control, with accompanying reductions in D3 activity with increasing T(3) concentrations (P<0.05). There was no significant change in the expression of the TRalpha isoforms, D2, MBP and NSP-A with increasing T(3) concentrations in either NT2 or hNT cells. Undifferentiated NT2 and differentiated hNT cells show differing patterns of T(3)-responsiveness, suggesting that there are different regulatory factors operating within these cell types.
N-TERA-2 cl/D1（NT2）细胞是一种具有中枢神经系统前体细胞特征的人类胚胎细胞系，被用于研究甲状腺激素在早期神经元生长和分化过程中的作用。未分化的NT2细胞表达编码甲状腺激素受体（TRs）α1、α2和β1、2型（D2）和3型（D3）碘甲状腺原氨酸脱碘酶（其作为受体前调节因子）以及甲状腺激素反应性基因髓鞘碱性蛋白（MBP）和神经内分泌特异性蛋白A（NSP-A）的mRNA。当终末分化为有丝分裂后神经元（hNT）时，TRα1和TRβ1 mRNA表达分别下降74%（P=0.05）和95%（P<0.0001），而NSP-A mRNA增加7倍（P<0.05）。然而，编码TRα2、D2、D3和MBP的mRNA在神经元分化时没有显著改变，D2和D3的活性也没有改变。随着3,5,3'-三碘甲状腺原氨酸（T(3)）浓度增加，与无T(3)培养基相比，培养的NT2细胞中TRβ1 mRNA表达在10 nM T(3)时增加2倍，在100 nM T(3)时增加1.3倍（P<0.05），但T(3)处理hNT细胞时未见变化。与对照相比，NT2细胞中D3 mRNA表达在10 nM T(3)时也增加3倍（P=0.01），在100 nM T(3)时增加2.4倍（P<0.05），但D3酶活性没有变化。相比之下，与对照相比，10 nM T(3)时hNT细胞中D3 mRNA表达降低20%（P<0.05），随着T(3)浓度增加，D3活性随之降低（P<0.05）。在NT2或hNT细胞中，随着T(3)浓度增加，TRα亚型、D2、MBP和NSP-A的表达没有显著变化。未分化的NT2细胞和分化的hNT细胞显示出不同的T(3)反应模式，表明在这些细胞类型中有不同的调节因子在起作用。
