甲状腺刺激抗体对甲状腺细胞TTF-1和PAX-8表达的影响

Effects of thyroid stimulating antibody on the expressions of TTF-1 and PAX-8 genes in cultured thyrocytes

目的探讨甲状腺刺激抗体(TSAb)对甲状腺细胞甲状腺转录因子1(TTF-1)和双链复合蛋白(PAX-8)基因表达影响及其作用机制。方法以RT-PCR检测甲状腺细胞中TTF-1和PAX-8基因表达情况,并应用信号转导激活和抑制剂观察TSAb作用的信号转导途径。结果TSAb作用24h可使PAX-8基因表达量升高到对照组的198.4%,此效应与蛋白激酶A(PKA)激活剂的作用相似(对照组的204.4%),且可被PKA抑制剂抑制;蛋白激酶C(PKC)激活剂佛波酯(TPA)和抑制剂则无上述效应,TPA抑制TSAb刺激的PAX-8基因的表达,此作用可被PKC抑制剂(Calphostin C)逆转。TSAb对TTF-1基因表达无明显影响。结论TSAb通过cAMP/PKA信号转导途径上调PAX-8基因表达可能是其刺激甲状腺细胞功能亢进的机制之一。

Objective To investigate the effects of thyroid stimulating antibody （TSAb） on the expressions of thyroid transcription factor-1 （ TTF-1 ） and paired box protein-8 （ PAX-8 ） genes and its mechanism in cultured thyrocytes. Methods The expressions of TTF-1 and PAX-8 genes in cultured thyrocytes were evaluated with RT-PCR, and inhibitors or activators of signal transduction were used to observe the effective pathways of TSAb-stimulated expressions of TTF-1 and PAX-8 genes. Results TSAb increased PAX-8 gene expression in cultured thyrocytes after 24 h incubation （198.4% of controls）, which was mimicked by the protein kinase （PK） A activator （204.4% of controls） ,and was inhibited by the PKA inhibitor, whereas the inhibitor and activator of PKC had no such effect as PKA. TPA （ 12-0-tetradecanoylphorbol 13-acetate）, a PKC activator, inhibited the expression of PAX-8 gene stimulated by TSAb, which was reversed by the PKC inhibitior （ Calphostin C） . TSAb had no effect on the expression of TTF-1 gene. Conclusion The upregulation of PAX-8 gene expression by the cAMP/PKA pathway seems to be one of the mechanisms underlying TSAb-induced hyperfunctions of human thyrocytes.