Stoeckle M Y, Guan L
Division of Infectious Diseases, Cornell University Medical College, New York, NY 10021.
Nucleic Acids Res. 1993 Apr 11;21(7):1613-7. doi: 10.1093/nar/21.7.1613.
We have previously shown that destabilization of gro alpha mRNA is associated with poly(A) shortening. In this study, we used high-resolution Northern blots to determine the rate and extent of gro alpha mRNA poly(A) shortening. gro alpha mRNA was found to undergo complete deadenylation within 2 h following withdrawal of IL-1. However, the process was not uniform: at 1 h following IL-1 withdrawal, gro alpha mRNA poly(A) lengths ranged from 0 to 180 nucleotides. There was an accumulation of deadenylated gro alpha mRNA which suggested that there may be another step before the mRNA is destroyed. Cycloheximide was found to block gro alpha mRNA degradation at the level of poly(A) shortening. Northern blots revealed a previously unrecognized periodic distribution of poly(A) lengths that was consistent with endonucleolytic cleavage between complexes of poly(A)-binding protein. The findings indicate that the degradation pathway of gro alpha mRNA is a slower version of the c-fos mRNA model, with the important additional feature that deadenylation and degradation are subject to physiologic regulation. This study provides a detailed picture of gro alpha mRNA poly(A) shortening and establishes a basis for further investigation of the mechanism by which IL-1 stabilizes specific mRNAs.
我们之前已经表明，groα mRNA的去稳定化与多聚腺苷酸（poly(A)）缩短有关。在本研究中，我们使用高分辨率Northern印迹法来确定groα mRNA多聚腺苷酸缩短的速率和程度。发现groα mRNA在白细胞介素-1（IL-1）撤除后2小时内经历完全去腺苷酸化。然而，这个过程并不均匀：在IL-1撤除后1小时，groα mRNA的多聚腺苷酸长度范围为0至180个核苷酸。存在去腺苷酸化的groα mRNA的积累，这表明在mRNA被破坏之前可能还有另一个步骤。发现放线菌酮在多聚腺苷酸缩短水平上阻断groα mRNA的降解。Northern印迹揭示了一种以前未被识别的多聚腺苷酸长度的周期性分布，这与多聚腺苷酸结合蛋白复合物之间的内切核酸酶切割一致。这些发现表明，groα mRNA的降解途径是c-fos mRNA模型的一个较慢版本，具有重要的额外特征，即去腺苷酸化和降解受生理调节。本研究提供了groα mRNA多聚腺苷酸缩短的详细情况，并为进一步研究IL-1稳定特定mRNA的机制奠定了基础。
