Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis
Abstract Background While extraocular muscles are affected early in myasthenia gravis (MG), but respond to treatment, we observe a high incidence of treatment-resistant ophthalmoplegia (OP-MG) among MG subjects with African genetic ancestry. Previously, using whole exome sequencing, we reported pote...
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| Format: | Article |
| Language: | English |
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BMC
2019-01-01
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| Series: | Orphanet Journal of Rare Diseases |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13023-019-1003-y |
| _version_ | 1818360744185430016 |
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| author | Melissa Nel Sharon Prince Jeannine M. Heckmann |
| author_facet | Melissa Nel Sharon Prince Jeannine M. Heckmann |
| author_sort | Melissa Nel |
| collection | DOAJ |
| description | Abstract Background While extraocular muscles are affected early in myasthenia gravis (MG), but respond to treatment, we observe a high incidence of treatment-resistant ophthalmoplegia (OP-MG) among MG subjects with African genetic ancestry. Previously, using whole exome sequencing, we reported potentially functional variants which associated with OP-MG. The aim of this study was to profile the expression of genes harbouring the OP-MG associated variants using patient-derived subphenotype-specific ‘myocyte’ cultures. Methods From well-characterised MG patients we developed the ‘myocyte’ culture models by transdifferentiating dermal fibroblasts using an adenovirus expressing MyoD. These myocyte cultures were treated with homologous acetylcholine receptor antibody-positive myasthenic sera to induce muscle transcripts in response to an MG stimulus. Gene expression in myocytes derived from OP-MG (n = 10) and control MG subjects (MG without ophthalmoplegia; n = 6) was quantified using a custom qPCR array profiling 93 potentially relevant genes which included the putative OP-MG susceptibility genes and other previously reported genes of interest in MG and experimental autoimmune myasthenia gravis (EAMG). Results OP-MG myocytes compared to control MG myocytes showed altered expression of four OP-MG susceptibility genes (PPP6R2, CANX, FAM136A and FAM69A) as well as several MG and EAMG genes (p < 0.05). A correlation matrix of gene pair expression levels revealed that 15% of gene pairs were strongly correlated in OP-MG samples (r > 0.78, p < 0.01), but not in control MG samples. OP-MG susceptibility genes and MG-associated genes accounted for the top three significantly correlated gene pairs (r ≥ 0.98, p < 1 × 10− 6) reflecting crosstalk between OP-MG and myasthenia pathways, which was not evident in control MG cells. The genes with altered expression dynamics between the two subphenotypes included those with a known role in gangliosphingolipid biosynthesis, mitochondrial metabolism and the IGF1-signalling pathway. Conclusion Using a surrogate cell culture model our findings suggest that muscle gene expression and co-expression differ between OP-MG and control MG individuals. These findings implicate pathways not previously considered in extraocular muscle involvement in myasthenia gravis and will inform future studies. |
| first_indexed | 2024-12-13T21:05:39Z |
| format | Article |
| id | doaj.art-674885b6003e4adbb76745d40c83395b |
| institution | Directory Open Access Journal |
| issn | 1750-1172 |
| language | English |
| last_indexed | 2024-12-13T21:05:39Z |
| publishDate | 2019-01-01 |
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| spelling | doaj.art-674885b6003e4adbb76745d40c83395b2022-12-21T23:31:28ZengBMCOrphanet Journal of Rare Diseases1750-11722019-01-0114111110.1186/s13023-019-1003-yProfiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravisMelissa Nel0Sharon Prince1Jeannine M. Heckmann2Neurology Research Group, Division of Neurology, E8-30, New Groote Schuur Hospital, Department of Medicine, Faculty of Health Sciences, University of Cape TownDepartment of Human Biology, Faculty of Health Sciences, University of Cape TownNeurology Research Group, Division of Neurology, E8-30, New Groote Schuur Hospital, Department of Medicine, Faculty of Health Sciences, University of Cape TownAbstract Background While extraocular muscles are affected early in myasthenia gravis (MG), but respond to treatment, we observe a high incidence of treatment-resistant ophthalmoplegia (OP-MG) among MG subjects with African genetic ancestry. Previously, using whole exome sequencing, we reported potentially functional variants which associated with OP-MG. The aim of this study was to profile the expression of genes harbouring the OP-MG associated variants using patient-derived subphenotype-specific ‘myocyte’ cultures. Methods From well-characterised MG patients we developed the ‘myocyte’ culture models by transdifferentiating dermal fibroblasts using an adenovirus expressing MyoD. These myocyte cultures were treated with homologous acetylcholine receptor antibody-positive myasthenic sera to induce muscle transcripts in response to an MG stimulus. Gene expression in myocytes derived from OP-MG (n = 10) and control MG subjects (MG without ophthalmoplegia; n = 6) was quantified using a custom qPCR array profiling 93 potentially relevant genes which included the putative OP-MG susceptibility genes and other previously reported genes of interest in MG and experimental autoimmune myasthenia gravis (EAMG). Results OP-MG myocytes compared to control MG myocytes showed altered expression of four OP-MG susceptibility genes (PPP6R2, CANX, FAM136A and FAM69A) as well as several MG and EAMG genes (p < 0.05). A correlation matrix of gene pair expression levels revealed that 15% of gene pairs were strongly correlated in OP-MG samples (r > 0.78, p < 0.01), but not in control MG samples. OP-MG susceptibility genes and MG-associated genes accounted for the top three significantly correlated gene pairs (r ≥ 0.98, p < 1 × 10− 6) reflecting crosstalk between OP-MG and myasthenia pathways, which was not evident in control MG cells. The genes with altered expression dynamics between the two subphenotypes included those with a known role in gangliosphingolipid biosynthesis, mitochondrial metabolism and the IGF1-signalling pathway. Conclusion Using a surrogate cell culture model our findings suggest that muscle gene expression and co-expression differ between OP-MG and control MG individuals. These findings implicate pathways not previously considered in extraocular muscle involvement in myasthenia gravis and will inform future studies.http://link.springer.com/article/10.1186/s13023-019-1003-yMyasthenia gravisOphthalmoplegiaGene expressionTransdifferentiationSubphenotypeMyotranscriptome |
| spellingShingle | Melissa Nel Sharon Prince Jeannine M. Heckmann Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis Orphanet Journal of Rare Diseases Myasthenia gravis Ophthalmoplegia Gene expression Transdifferentiation Subphenotype Myotranscriptome |
| title | Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis |
| title_full | Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis |
| title_fullStr | Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis |
| title_full_unstemmed | Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis |
| title_short | Profiling of patient-specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis |
| title_sort | profiling of patient specific myocytes identifies altered gene expression in the ophthalmoplegic subphenotype of myasthenia gravis |
| topic | Myasthenia gravis Ophthalmoplegia Gene expression Transdifferentiation Subphenotype Myotranscriptome |
| url | http://link.springer.com/article/10.1186/s13023-019-1003-y |
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