TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy
A de novo missense variant in Rag GTPase protein C (RagC<sup>S75Y</sup>) was recently identified in a syndromic dilated cardiomyopathy (DCM) patient. However, its pathogenicity and the related therapeutic strategy remain unclear. We generated a zebrafish Rragc<sup>S56Y</sup>...
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MDPI AG
2021-05-01
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| Series: | International Journal of Molecular Sciences |
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| author | Maengjo Kim Linghui Lu Alexey V. Dvornikov Xiao Ma Yonghe Ding Ping Zhu Timothy M. Olson Xueying Lin Xiaolei Xu |
| author_facet | Maengjo Kim Linghui Lu Alexey V. Dvornikov Xiao Ma Yonghe Ding Ping Zhu Timothy M. Olson Xueying Lin Xiaolei Xu |
| author_sort | Maengjo Kim |
| collection | DOAJ |
| description | A de novo missense variant in Rag GTPase protein C (RagC<sup>S75Y</sup>) was recently identified in a syndromic dilated cardiomyopathy (DCM) patient. However, its pathogenicity and the related therapeutic strategy remain unclear. We generated a zebrafish Rragc<sup>S56Y</sup> (corresponding to human RagC<sup>S75Y</sup>) knock-in (KI) line via TALEN technology. The KI fish manifested cardiomyopathy-like phenotypes and poor survival. Overexpression of RagC<sup>S75Y</sup> via adenovirus infection also led to increased cell size and fetal gene reprogramming in neonatal rat ventricle cardiomyocytes (NRVCMs), indicating a conserved mechanism. Further characterization identified aberrant mammalian target of rapamycin complex 1 (mTORC1) and transcription factor EB (TFEB) signaling, as well as metabolic abnormalities including dysregulated autophagy. However, mTOR inhibition failed to ameliorate cardiac phenotypes in the RagC<sup>S75Y</sup> cardiomyopathy models, concomitant with a failure to promote TFEB nuclear translocation. This observation was at least partially explained by increased and mTOR-independent physical interaction between RagC<sup>S75Y</sup> and TFEB in the cytosol. Importantly, TFEB overexpression resulted in more nuclear TFEB and rescued cardiomyopathy phenotypes. These findings suggest that S75Y is a pathogenic gain-of-function mutation in RagC that leads to cardiomyopathy. A primary pathological step of RagC<sup>S75Y</sup> cardiomyopathy is defective mTOR–TFEB signaling, which can be corrected by TFEB overexpression, but not mTOR inhibition. |
| first_indexed | 2024-03-10T11:08:16Z |
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| language | English |
| last_indexed | 2024-03-10T11:08:16Z |
| publishDate | 2021-05-01 |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-552f61c315bd48e4b10d95161fbbbb082023-11-21T21:00:28ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672021-05-012211549410.3390/ijms22115494TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> CardiomyopathyMaengjo Kim0Linghui Lu1Alexey V. Dvornikov2Xiao Ma3Yonghe Ding4Ping Zhu5Timothy M. Olson6Xueying Lin7Xiaolei Xu8Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USADepartment of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55901, USAA de novo missense variant in Rag GTPase protein C (RagC<sup>S75Y</sup>) was recently identified in a syndromic dilated cardiomyopathy (DCM) patient. However, its pathogenicity and the related therapeutic strategy remain unclear. We generated a zebrafish Rragc<sup>S56Y</sup> (corresponding to human RagC<sup>S75Y</sup>) knock-in (KI) line via TALEN technology. The KI fish manifested cardiomyopathy-like phenotypes and poor survival. Overexpression of RagC<sup>S75Y</sup> via adenovirus infection also led to increased cell size and fetal gene reprogramming in neonatal rat ventricle cardiomyocytes (NRVCMs), indicating a conserved mechanism. Further characterization identified aberrant mammalian target of rapamycin complex 1 (mTORC1) and transcription factor EB (TFEB) signaling, as well as metabolic abnormalities including dysregulated autophagy. However, mTOR inhibition failed to ameliorate cardiac phenotypes in the RagC<sup>S75Y</sup> cardiomyopathy models, concomitant with a failure to promote TFEB nuclear translocation. This observation was at least partially explained by increased and mTOR-independent physical interaction between RagC<sup>S75Y</sup> and TFEB in the cytosol. Importantly, TFEB overexpression resulted in more nuclear TFEB and rescued cardiomyopathy phenotypes. These findings suggest that S75Y is a pathogenic gain-of-function mutation in RagC that leads to cardiomyopathy. A primary pathological step of RagC<sup>S75Y</sup> cardiomyopathy is defective mTOR–TFEB signaling, which can be corrected by TFEB overexpression, but not mTOR inhibition.https://www.mdpi.com/1422-0067/22/11/5494RagC<sup>S75Y</sup>cardiomyopathyRagsmTORTFEB |
| spellingShingle | Maengjo Kim Linghui Lu Alexey V. Dvornikov Xiao Ma Yonghe Ding Ping Zhu Timothy M. Olson Xueying Lin Xiaolei Xu TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy International Journal of Molecular Sciences RagC<sup>S75Y</sup> cardiomyopathy Rags mTOR TFEB |
| title | TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy |
| title_full | TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy |
| title_fullStr | TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy |
| title_full_unstemmed | TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy |
| title_short | TFEB Overexpression, Not mTOR Inhibition, Ameliorates RagC<sup>S75Y</sup> Cardiomyopathy |
| title_sort | tfeb overexpression not mtor inhibition ameliorates ragc sup s75y sup cardiomyopathy |
| topic | RagC<sup>S75Y</sup> cardiomyopathy Rags mTOR TFEB |
| url | https://www.mdpi.com/1422-0067/22/11/5494 |
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