Leitersdorf E, Banai Y, Friedman G, Kaempfer R
Department of Internal Medicine B, Hadassah University Hospital, Jerusalem, Israel.
Biochem Biophys Res Commun. 1989 Dec 15;165(2):574-80. doi: 10.1016/s0006-291x(89)80005-1.
Expression of human LDL receptor mRNA and protein is induced in human glioblastoma-astrocytoma cells upon transfer into lipoprotein-deficient medium, a mode of induction likely to be physiological. The presence of cycloheximide (CHX) leads to up to 7.5-fold superinduction of LDL receptor mRNA within 4 hr and, upon removal of this inhibitor, to superinduction of LDL receptor protein as well. The extent of superinduction of LDL receptor mRNA reaches over 40-fold beyond the level expressed in medium containing regular serum. Despite its extensive superinduction, LDL receptor mRNA decays rapidly in the presence of CHX. Stabilization of LDL receptor mRNA is thus unlikely to account for the observed superinduction. These results show that normally the LDL receptor gene is expressed to only a small fraction of its full potential.
将人胶质母细胞瘤-星形细胞瘤细胞转移至脂蛋白缺乏培养基后，人低密度脂蛋白（LDL）受体mRNA和蛋白的表达被诱导，这种诱导方式可能具有生理学意义。放线菌酮（CHX）的存在会在4小时内导致LDL受体mRNA超诱导达7.5倍，并且在去除该抑制剂后，LDL受体蛋白也会出现超诱导。LDL受体mRNA的超诱导程度超过含正常血清培养基中表达水平的40倍以上。尽管有广泛的超诱导，但在CHX存在下LDL受体mRNA迅速降解。因此，LDL受体mRNA的稳定化不太可能解释观察到的超诱导现象。这些结果表明，正常情况下LDL受体基因仅以其全部潜力的一小部分表达。
