Malek Kammoun1, Jerome Piquereau2, Lydie Nadal-Desbarats3, Sandra Même4, Maud Beuvin5, Gisèle Bonne5, Vladimir Veksler2, Yann Le Fur6, Philippe Pouletaut1, William Même4, Frederic Szeremeta4, Jean-Marc Constans7, Elizabeth S Bruinsma8, Molly H Nelson Holte8, Zeynab Najafova9, Steven A Johnsen9, Malayannan Subramaniam8, John R Hawse8, Sabine F Bensamoun1. 1. Biomechanics and Bioengineering Laboratory, Alliance Sorbonne Universités, Université de Technologie de Compiègne, UMR CNRS 7338, Compiègne, France. 2. Signalling and Cardiovascular Pathophysiology - UMR-S 1180, Université Paris-Sud, INSERM, Université Paris-Saclay, Châtenay-Malabry, France. 3. UMR 1253, iBrain, Université de Tours, Inserm, Tours, France. 4. CNRS UPR4301, Centre de Biophysique Moléculaire, Orléans, France. 5. Inserm U974, Centre de Recherche en Myologie, Sorbonne Université, Paris, France. 6. Aix-Marseille University, CNRS, CRMBM, Marseille, France. 7. Institut Faire Faces, EA Chimère, Imagerie et Radiologie Médicale, CHU Amiens, Amiens, France. 8. Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA. 9. Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany.
Abstract
AIM: Tieg1 is involved in multiple signalling pathways, human diseases, and is highly expressed in muscle where its functions are poorly understood. METHODS: We have utilized Tieg1 knockout (KO) mice to identify novel and important roles for this transcription factor in regulating muscle ultrastructure, metabolism and mitochondrial functions in the soleus and extensor digitorum longus (EDL) muscles. RNA sequencing, immunoblotting, transmission electron microscopy, MRI, NMR, histochemical and mitochondrial function assays were performed. RESULTS: Loss of Tieg1 expression resulted in altered sarcomere organization and a significant decrease in mitochondrial number. Histochemical analyses demonstrated an absence of succinate dehydrogenase staining and a decrease in cytochrome c oxidase (COX) enzyme activity in KO soleus with similar, but diminished, effects in the EDL. Decreased complex I, COX and citrate synthase (CS) activities were detected in the soleus muscle of KO mice indicating altered mitochondrial function. Complex I activity was also diminished in KO EDL. Significant decreases in CS and respiratory chain complex activities were identified in KO soleus. 1 H-NMR spectra revealed no significant metabolic difference between wild-type and KO muscles. However, 31 P spectra revealed a significant decrease in phosphocreatine and ATPγ. Altered expression of 279 genes, many of which play roles in mitochondrial and muscle function, were identified in KO soleus muscle. Ultimately, all of these changes resulted in an exercise intolerance phenotype in Tieg1 KO mice. CONCLUSION: Our findings have implicated novel roles for Tieg1 in muscle including regulation of gene expression, metabolic activity and organization of tissue ultrastructure. This muscle phenotype resembles diseases associated with exercise intolerance and myopathies of unknown consequence.
AIM: Tieg1 is involved in multiple signalling pathways, human diseases, and is highly expressed in muscle where its functions are poorly understood. METHODS: We have utilized Tieg1 knockout (KO) mice to identify novel and important roles for this transcription factor in regulating muscle ultrastructure, metabolism and mitochondrial functions in the soleus and extensor digitorum longus (EDL) muscles. RNA sequencing, immunoblotting, transmission electron microscopy, MRI, NMR, histochemical and mitochondrial function assays were performed. RESULTS: Loss of Tieg1 expression resulted in altered sarcomere organization and a significant decrease in mitochondrial number. Histochemical analyses demonstrated an absence of succinate dehydrogenase staining and a decrease in cytochrome c oxidase (COX) enzyme activity in KO soleus with similar, but diminished, effects in the EDL. Decreased complex I, COX and citrate synthase (CS) activities were detected in the soleus muscle of KO mice indicating altered mitochondrial function. Complex I activity was also diminished in KO EDL. Significant decreases in CS and respiratory chain complex activities were identified in KO soleus. 1 H-NMR spectra revealed no significant metabolic difference between wild-type and KO muscles. However, 31 P spectra revealed a significant decrease in phosphocreatine and ATPγ. Altered expression of 279 genes, many of which play roles in mitochondrial and muscle function, were identified in KO soleus muscle. Ultimately, all of these changes resulted in an exercise intolerance phenotype in Tieg1 KO mice. CONCLUSION: Our findings have implicated novel roles for Tieg1 in muscle including regulation of gene expression, metabolic activity and organization of tissue ultrastructure. This muscle phenotype resembles diseases associated with exercise intolerance and myopathies of unknown consequence.
Authors: Nadine Baroukh; Nathan Canteleux; Antoine Lefèvre; Camille Dupuy; Cécile Martias; Antoine Presset; Malayannan Subramaniam; John R Hawse; Patrick Emond; Philippe Pouletaut; Sandrine Morandat; Sabine F Bensamoun; Lydie Nadal-Desbarats Journal: Metabolites Date: 2022-06-17