Micheli M, Albi E, Leray C, Magni M V
Istituto di Patologia Generale Università degli Studi di Perugia, Policlinico Monteluce, Italy.
FEBS Lett. 1998 Jul 24;431(3):443-7. doi: 10.1016/s0014-5793(98)00810-2.
Chromatin phospholipidic fraction, as previously demonstrated, shows the same localization as RNA inside the nuclei. DNase and RNase treatment of nuclei removed almost totally the DNA, 63% of RNA and caused a 50% loss of phospholipids. The aim of the present investigation is to study the fraction of RNase undigested nuclear RNA and its relationship with the phospholipids still present in the nuclei. Isolated hepatocyte nuclei were treated with Triton X-100 and digested with RNase and DNase. The undigested nuclear material contained proteins (98%) and a small amount of RNA (1.7%), DNA (0.4%) and phospholipids (0.18%). The analysis of phospholipids showed the presence of two components only, namely phosphatidylcholine and sphingomyelin. In the same complex, the activity of sphingomyelin synthase, phosphatidylcholine-dependent phospholipase C and neutral sphingomyelinase has been detected. Treatment of isolated RNA with neutral sphingomyelinase modified the RNA in RNase sensitive RNA, thus suggesting that the SM may represent a bridge between two RNA strands possibly regulating transcription.
如先前所示，染色质磷脂部分在细胞核内的定位与RNA相同。用脱氧核糖核酸酶（DNase）和核糖核酸酶（RNase）处理细胞核几乎完全去除了DNA、63%的RNA，并导致50%的磷脂损失。本研究的目的是研究核糖核酸酶未消化的核RNA部分及其与细胞核中仍存在的磷脂的关系。分离的肝细胞核用曲拉通X-100处理，并用核糖核酸酶和脱氧核糖核酸酶消化。未消化的核物质含有蛋白质（98%）和少量RNA（1.7%）、DNA（0.4%）和磷脂（0.18%）。磷脂分析表明仅存在两种成分，即磷脂酰胆碱和鞘磷脂。在同一复合物中，已检测到鞘磷脂合酶、磷脂酰胆碱依赖性磷脂酶C和中性鞘磷脂酶的活性。用中性鞘磷脂酶处理分离的RNA会将RNA转变为对核糖核酸酶敏感的RNA，因此表明鞘磷脂可能代表两条RNA链之间的桥梁，可能调节转录。
