TEFM variants impair mitochondrial transcription elongation causing childhood-onset neurological disease
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE185245 | GEO | 2022/11/08
REPOSITORIES: GEO
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Project description:Mutations in either the mitochondrial or nuclear genomes are associated with a diverse group of human disorders characterized by impaired mitochondrial respiration. Within this group, an increasing number of mutations have been identified in nuclear genes involved in mitochondrial RNA biology. The TEFM gene codes for the mitochondrial transcription elongation factor responsible for enhancing the processivity of mitochondrial RNA polymerase, POLRMT. Here, we report for the first time that TEFM variants are associated with mitochondrial respiratory chain deficiency and a wide range of clinical presentations including neonatal lactic acidosis, epileptic encephalopathy, developmental delay, intellectual disability or mitochondrial myopathy with a treatable neuromuscular transmission defect. Mechanistically, we show that muscle samples and primary fibroblasts from the affected individuals have reduced levels of promoter distal mitochondrial RNA transcripts, consistent with decreased processivity of POLRMT when TEFM is dysfunctional. We provide further evidence for the pathogenicity of these variants by investigating mitochondrial transcription and proteomic changes in patient cells and muscle and by studying TEFM activity in an in vitro system. Finally, tefm knock-down in zebrafish embryos resulted in neuromuscular junction abnormalities and abnormal mitochondrial function, strengthening the genotype-phenotype correlation. In conclusion, our study highlights that TEFM regulates mitochondrial transcription elongation in human tissues and its defect results in variable, tissue specific neurological and neuromuscular symptoms.
2022-11-07 | PXD030427 | Pride
Project description:TEFM variants impair mitochondrial transcription elongation causing childhood-onset neurological disease
| PRJNA768394 | ENA
Project description:Mutations in the mitochondrial or nuclear genomes are associated with a diverse group of human disorders characterized by impaired mitochondrial respiration. Within this group, an increasing number of mutations have been identified in nuclear genes involved in mitochondrial RNA biology. The TEFM gene encodes the mitochondrial transcription elongation factor responsible for enhancing the processivity of mitochondrial RNA polymerase, POLRMT. We report for the first time that TEFM variants are associated with mitochondrial respiratory chain deficiency and a wide range of clinical presentations including mitochondrial myopathy with a treatable neuromuscular transmission defect. Mechanistically, we show muscle and primary fibroblasts from the affected individuals have reduced levels of promoter distal mitochondrial RNA transcripts. Finally, tefm knockdown in zebrafish embryos resulted in neuromuscular junction abnormalities and abnormal mitochondrial function, strengthening the genotype-phenotype correlation. Our study highlights that TEFM regulates mitochondrial transcription elongation and its defect results in variable, tissue-specific neurological and neuromuscular symptoms.
| S-EPMC9950373 | biostudies-literature
Project description:Regulation of replication and expression of mitochondrial DNA (mtDNA) is essential for cellular energy conversion via oxidative phosphorylation. The mitochondrial transcription elongation factor (TEFM) has been proposed to regulate the switch between transcription termination for replication primer formation and processive, near-genome length transcription for mtDNA gene expression. Here, we report that Tefm is essential for mouse embryogenesis and that levels of promoter-distal mitochondrial transcripts are drastically reduced in conditional Tefm-knockout hearts. In contrast, the promoter-proximal transcripts are much increased in Tefm knockouts, but they mostly terminate before the region where the switch from transcription to replication occurs, and consequently de novo mtDNA replication is profoundly reduced. Unexpectedly, deep sequencing of RNA from Tefm knockouts revealed accumulation of unprocessed transcripts in addition to defective transcription elongation. Furthermore, a proximity labelling (BioID) assay showed that TEFM interacts with multiple RNA processing factors. Our data demonstrate that TEFM acts as a general transcription elongation factor, necessary for both gene transcription and replication primer formation, and loss of TEFM affects RNA processing in mammalian mitochondria.
2019-04-25 | PXD013398 | Pride
Project description:Background: Mitochondrial transcription elongation factor (TEFM) is a recently discovered factor involved in mitochondrial DNA replication and transcription. Previous study has reported that abnormal expression of TEFM can disrupt the assembly of mitochondrial respiratory chain and thus mitochondrial function. However, the role of TEFM on Uterine corpus endometrial carcinoma (UCEC) progression remains unclear. The present study aims to investigate the expression of TEFM in tumor tissue of UCEC and the effect of abnormal TEFM expression on malignant phenotype of UCEC cells. Methods: The expressions of TEFM were measured in tumor tissues and cell lines of UCEC by immunohistochemistry, Western blotting, and real-time quantitative PCR assays. Besides, the effects of TEFM knockdown or overexpression on UCEC cell growth, metastasis, apoptosis, and autophagy were also determined using EdU, colony formation, flow cytometry, TUNEL, transmission electron microscopy assays. Xenograft model was used to confirm the role of TEFM on proliferative potential of UECE cells in vivo. Results: Our bioinformatics analysis of CPTAC data showed that TEFM is abnormally overexpressed in UCEC and its upregulation was significantly associated with poor survival of patients with UCEC. We found that TEFM upregulation significantly promoted the growth and metastasis of UCEC cells. Mechanically, TEFM upregulation impaired the function of mitochondria, decreased their membrane potential and activated the AKT-NFκB pathway by promoting reactive oxygen species (ROS) production, leading to enhanced intracellular autophagy and thus UCEC growth and metastasis. Conclusion: This study demonstrates that TEFM positively regulates autophagy to promote the growth and metastasis of UCEC cells, which provides potential prognostic biomarker and therapeutic target for the treatment of UCEC.
2025-01-02 | GSE253883 | GEO
Project description:We investigated the role of TEFM in vivo by creating heart- and skeletal-muscle specific knockout of this gene. We identified that TEFM is required for the processivity of POLRMT and its loss leads to significantly decreased mitochondrial transcription.
2019-04-01 | GSE102254 | GEO
Project description:We investigated the role of TEFM in vivo by creating heart- and skeletal-muscle specific knockout of this gene. We identified that TEFM is required for the processivity of POLRMT and its loss leads to significantly decreased mitochondrial transcription.
2019-04-01 | GSE102253 | GEO
Project description:The PDE12 gene codes for the poly(A)-specific exoribonuclease, involved in the quality control of mitochondrial non-coding RNAs. Here, we report that disease-causing PDE12 variants in three unrelated families are associated with mitochondrial respiratory chain deficiencies. Clinically, they presented in utero and within the neonatal period with muscle and brain involvement leading to marked cytochrome c oxidase (COX) deficiency in muscle and severe lactic acidosis. To analyze perturbations in specific cellular pathways contributing to pathogenesis in our patient cohort, we used Affymetrix Clariom D transcriptome arrays to study the RNA levels in fibroblasts derived from two patient (Patient 2 and patient 3), comparing these to age-matched controls.
2024-09-29 | E-MTAB-14251 | biostudies-arrayexpress
Project description:The role of TEFM in mitochondrial gene expression
| PRJNA397134 | ENA
Project description:While >300 disease-causing variants have been identified in the mitochondrial DNA (mtDNA) polymerase γ, no mitochondrial phenotypes have been associated with POLRMT, the RNA polymerase responsible for transcription of the mitochondrial genome. Here, we characterise the clinical and molecular nature of POLRMT variants in eight individuals from seven unrelated families. Patients present with global developmental delay, hypotonia, short stature, and speech/intellectual disability in childhood; one subject displayed an indolent progressive external ophthalmoplegia phenotype. Massive parallel sequencing of all subjects identifies recessive and dominant variants in the POLRMT gene. Patient fibroblasts have a defect in mitochondrial mRNA synthesis, but no mtDNA deletions or copy number abnormalities. The in vitro characterisation of the recombinant POLRMT mutants reveals variable, but deleterious effects on mitochondrial transcription. Together, our in vivo and in vitro functional studies of POLRMT variants establish defective mitochondrial transcription as an important disease mechanism.
| S-EPMC7893070 | biostudies-literature