1. Supplementary informations and figures from Mutant SPART causes defects in mitochondrial protein import and bioenergetics reversed by Coenzyme Q
- Author
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Diquigiovanni, Chiara, Rizzardi, Nicola, Kampmeier, Antje, Liparulo, Irene, Bianco, Francesca, De Nicolo, Bianca, Cataldi-Stagetti, Erica, Cuna, Elisabetta, Severi, Giulia, Seri, Marco, Bertrand, Miriam, Haack, Tobias B., Marina, Adela Della, Braun, Frederik, Fato, Romana, Kuechler, Alma, Bergamini, Christian, and Bonora, Elena
- Abstract
Pathogenic variants in SPART cause Troyer syndrome, characterized by lower extremity spasticity and weakness, short stature and cognitive impairment, and a severe mitochondrial impairment. Herein, we report the identification of a role of Spartin in nuclear-encoded mitochondrial proteins. SPART biallelic missense variants were detected in a 5-year-old boy with short stature, developmental delay, muscle weakness with impaired walking distance. Patient-derived fibroblasts showed an altered mitochondrial network, decreased mitochondrial respiration and increased mitochondrial reactive oxygen species and altered Ca2+ versus control cells. We investigated the mitochondrial import of nuclear-encoded proteins in these fibroblasts and in another cell model carrying a SPART loss-of-function mutation. In both cell, models the mitochondrial import was impaired, leading to a significant decrease in different proteins, including two key enzymes involved in CoQ10 (CoQ) synthesis, COQ7 and COQ9, with a severe reduction in CoQ content, versus control cells. CoQ supplementation restored cellular ATP levels to the same extent shown by the re-expression of wild-type SPART, suggesting CoQ treatment as a promising therapeutic approach for patients carrying mutations in SPART.
- Published
- 2023
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