Supplemental figures from: Role of the thyroid gland in expression of the thyroid phenotype of SBP2 deficient mice

Selenocysteine insertion sequence binding protein 2, SBP2 (SECISBP2), is required for selenoprotein synthesis. Partial SBP2 deficiency syndrome manifests characteristic thyroid function tests. The Sbp2 deficiency mouse model, Sbp2 iCKO, replicates this thyroid phenotype and was used for pathophysiologic investigations. As selenoproteins have antioxidative role in thyroid gland function, their deficiencies have potential to affect thyroid hormone (TH) synthesis. Sbp2 iCKO mice had larger thyroids relative to body weight and increased thyroidal T4 and T3 content while 5’ deiodinases enzymatic activities were decreased. Possible mechanisms for the discrepancy between the increased thyroidal T3 and normal circulating T3 were investigated in dynamic experiments. Treatment with bovine TSH resulted in increased delta T4 in Sbp2 iCKO mice, indicating increased availability of preformed thyroidal TH. Next, the recovery of TH levels was evaluated after withdrawal of chemical suppression. At one d...硒半胱氨酸插入序列结合蛋白2（SBP2，SECISBP2）是硒蛋白合成所必需的。部分SBP2缺乏综合征可表现出特征性甲状腺功能检测异常。SBP2缺陷小鼠模型Sbp2 iCKO可复现该甲状腺表型，并被用于病理生理学研究。鉴于硒蛋白在甲状腺功能中发挥抗氧化作用，其缺失可能影响甲状腺激素（TH）的合成。Sbp2 iCKO小鼠的甲状腺相对体重更大，甲状腺内T4和T3含量升高，而5’-脱碘酶的酶活性降低。研究人员通过动态实验探究了甲状腺内T3升高与循环T3正常之间这一差异的潜在机制。给予牛促甲状腺激素（TSH）处理后，Sbp2 iCKO小鼠的ΔT4水平升高，提示预形成的甲状腺内甲状腺激素可用性提升。随后，研究人员评估了化学抑制撤除后甲状腺激素水平的恢复情况。在第1天……