Intron-retained transcripts of the spinal muscular atrophy genes, SMN1 and SMN2

Publication date: Available online 23 March 2018
Source:Brain and Development
Author(s): Nur Imma Fatimah Harahap, Emma Tabe Eko Niba, Mawaddah Ar Rochmah, Yogik Onky Silvana Wijaya, Toshio Saito, Kayoko Saito, Hiroyuki Awano, Ichiro Morioka, Kazumoto Iijima, Poh San Lai, Masafumi Matsuo, Hisahide Nishio, Masakazu Shinohara
BackgroundThe 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.MethodsIntron-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.ResultsTwo 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.ConclusionIntron 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.



https://ift.tt/2IPTgjN