Harahap Nur Imma Fatimah, Niba Emma Tabe Eko, Ar Rochmah Mawaddah, Wijaya Yogik Onky Silvana, Saito Toshio, Saito Kayoko, Awano Hiroyuki, Morioka Ichiro, Iijima Kazumoto, Lai Poh San, Matsuo Masafumi, Nishio Hisahide, Shinohara Masakazu
Department of Community Medicine and Social Healthcare Science, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan; Department of Clinical Pathology, Faculty of Medicine, Universitas Gadjah Mada, Radiopoetro Building 5th Floor, Jl. Farmako, Sekip Utara, Yogyakarta 55281, Indonesia.
Department of Community Medicine and Social Healthcare Science, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
Brain Dev. 2018 Sep;40(8):670-677. doi: 10.1016/j.braindev.2018.03.001. Epub 2018 Mar 23.
The SMN genes, SMN1 and SMN2, are highly homologous genes which are related to the development or clinical severity of spinal muscular atrophy. Some alternative splicing patterns of the SMN genes have been well documented. In 2007, an SMN1 transcript with a full sequence of intron 3 was reported as the first intron-retained SMN transcript.
Intron-retained SMN transcripts in various cells and tissues were studied using reverse transcription (RT)-PCR. HeLa cells were used for subcellular localization of the transcripts and protein expression analysis with Western blotting.
Two intron-retained SMN transcripts were detected, which contain full sequences of intron 2b or intron 3. These transcripts were produced from SMN1 and SMN2, and ubiquitously expressed in human cells and tissues. Western blotting analysis showed no proteins derived from the intron-retained transcripts. Fractionation analysis showed that these intron-retained transcripts were localized mainly in the nucleus. Contrary to our expectation, the intron-retained transcript levels decreased during the treatment of cycloheximide, an inhibitor of nonsense-mediated decay (NMD), suggesting that they were not targets of NMD.
Intron 2b-retained SMN transcript and intron3-retained SMN transcript were ubiquitously expressed in human cells and tissues. The intron-retained transcripts were mainly localized in the nucleus and decreased through non-NMD pathway.
SMN基因，即SMN1和SMN2，是高度同源的基因，与脊髓性肌萎缩症的发展或临床严重程度相关。SMN基因的一些可变剪接模式已有充分记录。2007年，报道了一种具有完整内含子3序列的SMN1转录本，这是首个保留内含子的SMN转录本。
使用逆转录（RT）-PCR研究各种细胞和组织中保留内含子的SMN转录本。使用HeLa细胞进行转录本的亚细胞定位以及通过蛋白质印迹法进行蛋白质表达分析。
检测到两种保留内含子的SMN转录本，它们包含内含子2b或内含子3的完整序列。这些转录本由SMN1和SMN2产生，在人类细胞和组织中普遍表达。蛋白质印迹分析显示没有源自保留内含子转录本的蛋白质。分级分离分析表明，这些保留内含子的转录本主要定位于细胞核。与我们的预期相反，在使用无义介导衰变（NMD）抑制剂环己酰亚胺处理期间，保留内含子的转录本水平下降，这表明它们不是NMD的靶标。
保留内含子2b的SMN转录本和保留内含子3的SMN转录本在人类细胞和组织中普遍表达。保留内含子的转录本主要定位于细胞核，并通过非NMD途径减少。
