Rohilla A M, Anderson C, Wood W M, Berhanu P
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
Biochem Biophys Res Commun. 1991 Mar 15;175(2):520-6. doi: 10.1016/0006-291x(91)91595-4.
The effects of insulin on the steady-state level of human insulin receptor (hIR) mRNA were examined in the HepG2 human liver cell line using Northern blot analysis of either total cellular or poly(A)+ RNA. In control cells, up to six (4.5, 5.2, 7.4, 8.5, 9.4 and 10.8 kb) hybridizable species of hIR mRNA were identified, with the 8.5 and 10.8 kb species being most prominent. Incubation for 18 hrs with 1 microM insulin resulted in a similar decrease (to approximately 35% of control) of all the hIR mRNA species. The insulin effect was dose-dependent and was half-maximal by 2-3 hrs and maximal by 4-6 hrs of incubation at 37 degrees C. The hIR mRNA levels remained maximally insulin suppressed for up to 18 hrs but thereafter the effect became attenuated. These results indicate that insulin downregulates the level of hIR mRNA with a biphasic time-course and that this process is most likely part of the general mechanism by which insulin maintains the homeostatic control of its cellular receptor levels.
利用对总细胞RNA或聚腺苷酸加尾（poly(A)+）RNA的Northern印迹分析，在HepG2人肝细胞系中研究了胰岛素对人胰岛素受体（hIR）mRNA稳态水平的影响。在对照细胞中，鉴定出多达六种（4.5、5.2、7.4、8.5、9.4和10.8 kb）可杂交的hIR mRNA种类，其中8.5 kb和10.8 kb的种类最为突出。用1微摩尔胰岛素孵育18小时导致所有hIR mRNA种类均出现类似程度的减少（降至对照的约35%）。胰岛素的作用呈剂量依赖性，在37℃孵育2 - 3小时达到最大效应的一半，4 - 6小时达到最大效应。hIR mRNA水平在长达18小时内保持最大程度的胰岛素抑制，但此后效应逐渐减弱。这些结果表明，胰岛素以双相时间进程下调hIR mRNA水平，并且这一过程很可能是胰岛素维持其细胞受体水平稳态控制的一般机制的一部分。
