Turpaev K T, Zakhariev V M, Sokolova I V, Narovlyansky A N, Amchenkova A M, Justesen J, Frolova L Y
Engelhardt Institute of Molecular Biology, Moscow, Russia.
Eur J Biochem. 1996 Sep 15;240(3):732-7. doi: 10.1111/j.1432-1033.1996.0732h.x.
We have analysed the structure of mRNA isoforms of the human gene encoding tryptophanyl-tRNA synthetase (Trp-tRNA synthetase) expressed in the epithelial CaOv cells and MT-4 lymphocytes. The Trp-tRNA synthetase gene is induced by interferon-gamma in both lines and, in MT-4 lymphocytes, also by interferon-alpha. Four Trp-tRNA synthetase mRNA isoforms have different combinations of the first exons IA, IB and II. Two transcription initiation sites (P1 and P2) were detected 90 bp from each other. Processing of the primary transcript initiated from the P1 start site generates the mRNA isoform where exon IA joins to exon II. The other three isoforms are produced by alternative splicing of the primary transcript produced from the P2 start site. Isoform 2 has a 3'-end fragment of exon IA joined to exon II. Isoform 3 contains exons IA and IB. Isoform 4 contains exon IA and exon III and lacks exon II encoding the N-terminus of the Trp-tRNA synthetase. Therefore, the two primary transcripts of the Trp-tRNA synthetase gene differ only in the 5' flank sequence between P1 and P2, and this fragment regulates their processing. Both interferon-alpha and interferon-gamma induce exon IA-containing and exon IB-containing isoforms of the Trp-tRNA synthetase mRNA.
我们分析了在人上皮性CaOv细胞和MT-4淋巴细胞中表达的编码色氨酰-tRNA合成酶（Trp-tRNA合成酶）的人类基因的mRNA异构体结构。Trp-tRNA合成酶基因在这两种细胞系中均受γ干扰素诱导，在MT-4淋巴细胞中还受α干扰素诱导。四种Trp-tRNA合成酶mRNA异构体具有不同的第一外显子IA、IB和II的组合。检测到两个彼此相距90 bp的转录起始位点（P1和P2）。从P1起始位点起始的初级转录本的加工产生外显子IA与外显子II相连的mRNA异构体。其他三种异构体是由从P2起始位点产生的初级转录本的可变剪接产生的。异构体2具有与外显子II相连的外显子IA的3'末端片段。异构体3包含外显子IA和IB。异构体4包含外显子IA和外显子III，并且缺少编码Trp-tRNA合成酶N末端的外显子II。因此，Trp-tRNA合成酶基因的两个初级转录本仅在P1和P2之间的5'侧翼序列上有所不同，并且该片段调节它们的加工。α干扰素和γ干扰素均诱导Trp-tRNA合成酶mRNA的含外显子IA和含外显子IB的异构体。
