Schwann cell-specific Dp116 is expressed in glioblastoma cells, revealing two novel DMD gene splicing patterns

Abdul Qawee Mahyoob Rani; Kazuhiro Maeta; Tatsuya Kawaguchi; Hiroyuki Awano; Masashi Nagai; Hisahide Nishio; Masafumi Matsuo

doi:10.1016/j.bbrep.2019.100703

Schwann cell-specific Dp116 is expressed in glioblastoma cells, revealing two novel DMD gene splicing patterns

Biochem Biophys Rep. 2019 Nov 10:20:100703. doi: 10.1016/j.bbrep.2019.100703. eCollection 2019 Dec.

Authors

Abdul Qawee Mahyoob Rani^{1

2}, Kazuhiro Maeta^{1

2}, Tatsuya Kawaguchi³, Hiroyuki Awano⁴, Masashi Nagai⁴, Hisahide Nishio^{1

5}, Masafumi Matsuo^{1

2}

Affiliations

¹ Research Center for Locomotion Biology, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan.
² KNC Department of Nucleic Acid Drug Discovery, Faculty of Rehabilitation, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan.
³ Translational Research Department, Daiichi Sankyo RD Novare Co., Ltd., Edogawa, Tokyo, 134-8634, Japan.
⁴ Department of Pediatrics, Kobe University Graduate School of Medicine, Chuo, Kobe, 650-0017, Japan.
⁵ Department of Occupational Therapy, Faculty of Rehabilitation, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan.

Abstract

Background: The DMD gene is one of the largest human genes, being composed of 79 exons. Dystrophin Dp116 expressed from the promoter in intron 55 is a Schwann cell-specific isoform. The pathophysiological roles of Dp116 are largely unknown, because of its limited expression. This study assessed the expression of Dp116 in glioblastoma cells and evaluated the splicing patterns of the DMD gene in these cells.

Methods: Full-length Dp116 cDNA was PCR amplified from U-251 glioblastoma cells. Dp116 protein was analyzed by Western blotting.

Results: Full-length Dp116 cDNA, extending from exon S1 to exon 79, was PCR amplified to avoid confusion with other DMD isoforms. The full-length Dp116 transcript was amplified as nearly 3 kb in size. Western blotting of U-251 cell lysates revealed a signal at a position corresponding to vector-expressed Dp116 protein, indicating that Dp116 is expressed in glioblastoma cells. Sequencing of the amplified product revealed five splice variants, all skipping exon 78. The most abundant transcript lacked only exon 78 (Dp116b), whereas the second most abundant transcript lacked both exons 71 and 78 (Dp116ab). A third transcript lacking exons 71-74 and 78 was also identified (Dp116bc). Two novel splicing patterns were also observed, one with a deletion of exons 68 and 69 (Dp116bΔ68-69) and the other with a 100 bp deletion in the 5' terminal end of exon 75 (75s), which was produced by the activation of a cryptic splice acceptor site (Dp116b75s). However, the splicing patterns in glioblastoma cells of DMD exons in Dp116 and Dp71 showed no significant differences.

Conclusions: Dp116 is expressed in glioblastoma cells as five splicing variants, with Dp116b being the most abundant. Two novel splicing patterns of DMD exons were observed.

Keywords: DMD gene; Dp116; Dystrophin; Glioblastoma; Splice variants; Splicing.