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Toosaranont J, Ruschadaariyachat S, Mujchariyakul W, Arora JK, Charoensawan V, Suktitipat B, Palmer TN, Fletcher S, Wilton SD, Mitrpant C. Antisense Oligonucleotide Induction of the hnRNPA1b Isoform Affects Pre-mRNA Splicing of SMN2 in SMA Type I Fibroblasts. Int J Mol Sci 2022; 23:ijms23073937. [PMID: 35409296 PMCID: PMC8999010 DOI: 10.3390/ijms23073937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a severe, debilitating neuromuscular condition characterised by loss of motor neurons and progressive muscle wasting. SMA is caused by a loss of expression of SMN1 that encodes the survival motor neuron (SMN) protein necessary for the survival of motor neurons. Restoration of SMN expression through increased inclusion of SMN2 exon 7 is known to ameliorate symptoms in SMA patients. As a consequence, regulation of pre-mRNA splicing of SMN2 could provide a potential molecular therapy for SMA. In this study, we explored if splice switching antisense oligonucleotides could redirect the splicing repressor hnRNPA1 to the hnRNPA1b isoform and restore SMN expression in fibroblasts from a type I SMA patient. Antisense oligonucleotides (AOs) were designed to promote exon 7b retention in the mature mRNA and induce the hnRNPA1b isoform. RT-PCR and western blot analysis were used to assess and monitor the efficiency of different AO combinations. A combination of AOs targeting multiple silencing motifs in hnRNPA1 pre-mRNA led to robust hnRNPA1b induction, which, in turn, significantly increased expression of full-length SMN (FL-SMN) protein. A combination of PMOs targeting the same motifs also strongly induced hnRNPA1b isoform, but surprisingly SMN2 exon 5 skipping was detected, and the PMO cocktail did not lead to a significant increase in expression of FL-SMN protein. We further performed RNA sequencing to assess the genome-wide effects of hnRNPA1b induction. Some 3244 genes were differentially expressed between the hnRNPA1b-induced and untreated SMA fibroblasts, which are functionally enriched in cell cycle and chromosome segregation processes. RT-PCR analysis demonstrated that expression of the master regulator of these enrichment pathways, MYBL2 and FOXM1B, were reduced in response to PMO treatment. These findings suggested that induction of hnRNPA1b can promote SMN protein expression, but not at sufficient levels to be clinically relevant.
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Affiliation(s)
- Jarichad Toosaranont
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
| | - Sukanya Ruschadaariyachat
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
| | - Warasinee Mujchariyakul
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10700, Thailand; (W.M.); (J.K.A.); (V.C.)
| | - Jantarika Kumar Arora
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10700, Thailand; (W.M.); (J.K.A.); (V.C.)
| | - Varodom Charoensawan
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10700, Thailand; (W.M.); (J.K.A.); (V.C.)
- Integrative Computational BioScience (ICBS) Center, Mahidol University, Nakhon Pathom 73170, Thailand
- Systems Biology of Diseases Research Unit, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Bhoom Suktitipat
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
- Integrative Computational BioScience (ICBS) Center, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Thomas N. Palmer
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
| | - Sue Fletcher
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA 6150, Australia
| | - Steve D. Wilton
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA 6150, Australia
| | - Chalermchai Mitrpant
- Department of Biochemistry, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; (J.T.); (S.R.); (B.S.)
- Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA 6009, Australia; (T.N.P.); (S.F.); (S.D.W.)
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA 6150, Australia
- Correspondence:
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