McDonald R A, Gelehrter T D
J Cell Biol. 1981 Mar;88(3):536-42. doi: 10.1083/jcb.88.3.536.
The transport of alpha-aminoisobutyric acid (AIB) by rat hepatoma tissue culture (HTC) cells is rapidly and reversibly inhibited by dexamethasone and other glucocorticoids. To investigate the role of the nucleus in the regulation of transport and to determine whether steroid hormones or steroid-receptor complexes may have direct effects on cytoplasmic or membrane functions, we have examined the regulation of transport by dexamethasone in anucleate HTC cells. Cytoplasts prepared from suspension cultures of HTC cells fully retain active transport of AIB with the same kinetic properties as intact cells. However, the uptake of AIB is not inhibited by dexamethasone or other corticosteroids. Neither is the inhibited rate of transport, manifested by cytoplasts prepared from dexamethasone-treated cells, restored to normal upon removal of the hormone. Anucleate cells exhibit specific, saturable binding of [3H]dexamethasone; however, the binding is reduced compared with that of intact cells. The nucleus is thus required for the glucocorticoid regulation of amino acid transport in HTC cells.
大鼠肝癌组织培养（HTC）细胞对α-氨基异丁酸（AIB）的转运可被地塞米松和其他糖皮质激素迅速且可逆地抑制。为了研究细胞核在转运调节中的作用，并确定类固醇激素或类固醇-受体复合物是否可能对细胞质或膜功能有直接影响，我们检测了地塞米松对无核HTC细胞转运的调节作用。从HTC细胞悬浮培养物制备的胞质体完全保留了AIB的主动转运能力，其动力学特性与完整细胞相同。然而，AIB的摄取不受地塞米松或其他皮质类固醇的抑制。由地塞米松处理的细胞制备的胞质体所表现出的转运抑制率，在去除激素后也不会恢复正常。无核细胞表现出对[3H]地塞米松的特异性、可饱和结合；然而，与完整细胞相比，这种结合减少了。因此，细胞核是HTC细胞中糖皮质激素调节氨基酸转运所必需的。
