Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations]
Background Heterozygous de novo variants in the gene SAMD9 cause the complex multisystem disorder, MIRAGE syndrome. Patients are characterised by myelodysplasia, infections, growth restriction, adrenal insufficiency, gonadal dysfunction and enteropathies. Pathogenic variants in SAMD9 are gain-of-fun...
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| Format: | Article |
| Language: | English |
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F1000 Research Ltd
2024-02-01
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| Online Access: | https://f1000research.com/articles/12-155/v2 |
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| author | Federica Buonocore Monika Balys Glenn Anderson John C. Achermann |
| author_facet | Federica Buonocore Monika Balys Glenn Anderson John C. Achermann |
| author_sort | Federica Buonocore |
| collection | DOAJ |
| description | Background Heterozygous de novo variants in the gene SAMD9 cause the complex multisystem disorder, MIRAGE syndrome. Patients are characterised by myelodysplasia, infections, growth restriction, adrenal insufficiency, gonadal dysfunction and enteropathies. Pathogenic variants in SAMD9 are gain-of-function and enhance its role as a growth repressor, leading to growth restriction of many tissues. Two studies have reported changes in skin fibroblasts derived from MIRAGE patients, more specifically identifying enlarged endosomes. We have also previously shown subtle changes in endosome size in patients’ fibroblasts compared to controls. However, these variations in endosomes were not as marked as those described in the literature. Methods We have performed an observational study using transmission electron microscopy (TEM) in a larger number of cells derived from three patients’ fibroblasts to assess ultrastructure morphology compared to control images. Results Consistent changes were observed in cell organelles in all patient samples. In particular, increased endosomal activity was detected, characterised by augmented pinocytosis and vesicle budding, increased endosome number, as well as by large lysosomes and endosomes. Endoplasmic reticulum was also prominent. Mitochondria appeared enlarged in selected cells, possibly due to cellular stress. Cell nuclei did not display major differences compared to controls. Conclusions TEM is a powerful tool to investigate morphological features of tissues and cell organelles, although TEM data could be affected by sample preparation methodology, therefore potentially explaining the variability between independent studies, and its analysis can be dependent on the experience of the researcher. The increased endosomal activity we have observed in patients’ fibroblasts could indicate that SAMD9 regulates endocytosis of receptors, acting as an endosome fusion facilitator, or in lysosomal activation. However, the precise mechanism(s) by which SAMD9 regulates cell growth is still not fully understood, and further studies are needed to elucidate its pathogenic pathway and develop therapeutic approaches to support patients. |
| first_indexed | 2024-03-07T19:45:22Z |
| format | Article |
| id | doaj.art-54b718ef09c14cbc84c42a4b4d4c0c82 |
| institution | Directory Open Access Journal |
| issn | 2046-1402 |
| language | English |
| last_indexed | 2024-03-07T19:45:22Z |
| publishDate | 2024-02-01 |
| publisher | F1000 Research Ltd |
| record_format | Article |
| series | F1000Research |
| spelling | doaj.art-54b718ef09c14cbc84c42a4b4d4c0c822024-02-29T01:00:01ZengF1000 Research LtdF1000Research2046-14022024-02-0112162387Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations]Federica Buonocore0https://orcid.org/0000-0002-8274-7241Monika Balys1Glenn Anderson2John C. Achermann3Genetics and Genomic Medicine Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, University College London, London, UKHistopathology Department, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UKHistopathology Department, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UKGenetics and Genomic Medicine Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, University College London, London, UKBackground Heterozygous de novo variants in the gene SAMD9 cause the complex multisystem disorder, MIRAGE syndrome. Patients are characterised by myelodysplasia, infections, growth restriction, adrenal insufficiency, gonadal dysfunction and enteropathies. Pathogenic variants in SAMD9 are gain-of-function and enhance its role as a growth repressor, leading to growth restriction of many tissues. Two studies have reported changes in skin fibroblasts derived from MIRAGE patients, more specifically identifying enlarged endosomes. We have also previously shown subtle changes in endosome size in patients’ fibroblasts compared to controls. However, these variations in endosomes were not as marked as those described in the literature. Methods We have performed an observational study using transmission electron microscopy (TEM) in a larger number of cells derived from three patients’ fibroblasts to assess ultrastructure morphology compared to control images. Results Consistent changes were observed in cell organelles in all patient samples. In particular, increased endosomal activity was detected, characterised by augmented pinocytosis and vesicle budding, increased endosome number, as well as by large lysosomes and endosomes. Endoplasmic reticulum was also prominent. Mitochondria appeared enlarged in selected cells, possibly due to cellular stress. Cell nuclei did not display major differences compared to controls. Conclusions TEM is a powerful tool to investigate morphological features of tissues and cell organelles, although TEM data could be affected by sample preparation methodology, therefore potentially explaining the variability between independent studies, and its analysis can be dependent on the experience of the researcher. The increased endosomal activity we have observed in patients’ fibroblasts could indicate that SAMD9 regulates endocytosis of receptors, acting as an endosome fusion facilitator, or in lysosomal activation. However, the precise mechanism(s) by which SAMD9 regulates cell growth is still not fully understood, and further studies are needed to elucidate its pathogenic pathway and develop therapeutic approaches to support patients.https://f1000research.com/articles/12-155/v2SAMD9 endosomes MIRAGE syndrome transmission electron microscopy.eng |
| spellingShingle | Federica Buonocore Monika Balys Glenn Anderson John C. Achermann Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations] F1000Research SAMD9 endosomes MIRAGE syndrome transmission electron microscopy. eng |
| title | Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations] |
| title_full | Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations] |
| title_fullStr | Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations] |
| title_full_unstemmed | Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations] |
| title_short | Investigating ultrastructural morphology in MIRAGE syndrome-derived fibroblasts using transmission electron microscopy. [version 2; peer review: 1 approved, 2 approved with reservations] |
| title_sort | investigating ultrastructural morphology in mirage syndrome derived fibroblasts using transmission electron microscopy version 2 peer review 1 approved 2 approved with reservations |
| topic | SAMD9 endosomes MIRAGE syndrome transmission electron microscopy. eng |
| url | https://f1000research.com/articles/12-155/v2 |
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