Fradin A, Jove R, Hemenway C, Keiser H D, Manley J L, Prives C
Cell. 1984 Jul;37(3):927-36. doi: 10.1016/0092-8674(84)90427-6.
To examine the role of small nuclear ribonucleoproteins (snRNPs) in mRNA splicing, we have injected SV40 DNA, in the presence or absence of anti-Sm or anti-(U1)RNP antibodies, into the nucleus of X. laevis oocytes, and analyzed the viral specific RNAs and proteins that were synthesized. In the absence of antibodies, the majority of the viral mRNAs were spliced, giving rise to transcripts and proteins analogous to those found in infected monkey cells. However, the relative efficiencies with which the various splice sites were utilized were different in the two cell types. When sera from systemic lupus erythematosus (SLE) patients containing anti-Sm or anti-(U1)RNP antibodies were coinjected with the viral DNA, splicing of L-strand-specific (late) mRNA was dramatically inhibited. Cleavage at both 5' and 3' splice sites was blocked, leading to an accumulation of unspliced primary transcripts. Neither the total amount of late RNA synthesized nor the formation of mature polyadenylated late mRNA 3' ends was affected. These results indicate that U1 snRNPs play a crucial role in mRNA splicing in vivo. Unexpectedly, the effects of the sera on E-strand-specific (early) viral mRNA splicing were different. All anti-Sm or -(U1)RNP sera tested had no detectable effect on the splicing of the mRNA coding for the small tumor antigen. A subset of these sera, however, inhibited large tumor antigen mRNA splicing. On the basis of these data it is suggested that different pre-mRNAs, or even different splice sites within the same pre-mRNA, have dissimilar interactions with snRNP particles in the splicing reaction.
为了研究小核核糖核蛋白（snRNP）在mRNA剪接中的作用，我们在有或没有抗Sm或抗（U1）RNP抗体存在的情况下，将SV40 DNA注射到非洲爪蟾卵母细胞核中，并分析合成的病毒特异性RNA和蛋白质。在没有抗体的情况下，大多数病毒mRNA被剪接，产生的转录本和蛋白质类似于在感染的猴细胞中发现的。然而，两种细胞类型中各种剪接位点的利用效率不同。当将含有抗Sm或抗（U1）RNP抗体的系统性红斑狼疮（SLE）患者血清与病毒DNA共同注射时，L链特异性（晚期）mRNA的剪接受到显著抑制。5'和3'剪接位点的切割均被阻断，导致未剪接的初级转录本积累。合成的晚期RNA总量和成熟的多聚腺苷酸化晚期mRNA 3'末端的形成均未受影响。这些结果表明U1 snRNP在体内mRNA剪接中起关键作用。出乎意料的是，血清对E链特异性（早期）病毒mRNA剪接的影响不同。所有测试的抗Sm或抗（U1）RNP血清对编码小肿瘤抗原的mRNA剪接均无可检测到的影响。然而，这些血清中的一部分抑制了大肿瘤抗原mRNA的剪接。基于这些数据，提示不同的前体mRNA，甚至同一前体mRNA内的不同剪接位点，在剪接反应中与snRNP颗粒有不同的相互作用。
