The role of TEFM in mitochondrial gene expression [smallRNA]
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE102253 | GEO | 2019/04/01
REPOSITORIES: GEO
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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: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:Mammalian mitochondrial DNA (mtDNA) is coated with mitochondrial transcription factor A (TFAM) and compacted into nucleoids. TFAM is not only the main component of mitochondrial nucleoids but its levels can also control mtDNA copy number. Here we show that the TFAM-to-mtDNA ratio is critical for maintaining normal mtDNA expression in different tissues of the mouse. BAC transgenic mice with a 1.5-fold increase in TFAM protein levels maintain a normal TFAM-to-mtDNA ratio in different tissues and as a consequence mitochondrial gene expression, nucleoid distribution and whole animal metabolism are all unaltered. In contrast, mice expressing TFAM from the CAG promoter in the ROSA26 locus have 4.5-fold increase of TFAM protein levels in heart and skeletal muscle and develop pathology leading to early postnatal lethality. The TFAM-to-mtDNA ratio varies widely between tissues in these mice and is very high in skeletal muscle where it causes strong repression of mtDNA expression and deficient oxidative phosphorylation (OXPHOS) despite normal mtDNA levels. In heart, mtDNA copy number is increased leading to a near normal TFAM-to-mtDNA ratio and maintained OXPHOS capacity. In the liver, mtDNA expression is maintained despite increased TFAM levels and normal mtDNA levels. Here, tissue-specific induction of the LONP1 protease and mitochondrial RNA polymerase (POLRMT) expression counteracts the silencing effect of high TFAM levels. We conclude that the TFAM-to-mtDNA ratio has an important role in maintaining mtDNA expression in vivo. TFAM acts as a general repressor of mtDNA expression and this effect can be counterbalance by tissue-specific expression of regulatory factors.
2021-08-18 | PXD023050 | Pride
Project description:Mitochondria are vital in providing cellular energy via their oxidative phosphorylation system, which requires the coordinated expression of genes encoded by both the nuclear and mitochondrial genomes (mtDNA). Transcription of the circular mammalian mtDNA depends on a single mitochondrial RNA polymerase (POLRMT). Although the transcription initiation process is well understood, it remains highly controversial if POLRMT also serves as the primase for initiation of mtDNA replication. In the nucleus, the RNA polymerases needed for gene expression have no such role. Conditional knockout of Polrmt in heart results in severe mitochondrial dysfunction causing dilated cardiomyopathy in young mice. We further studied the molecular consequences of different expression levels of POLRMT and found that POLRMT is essential for primer synthesis to initiate mtDNA replication in vivo. Furthermore, transcription initiation for primer formation has priority over gene expression. Surprisingly, mitochondrial transcription factor A (TFAM) exists in an mtDNA-free pool in the Polrmt knockout mice. TFAM levels remain unchanged despite strong mtDNA depletion and TFAM is thus protected from degradation of the AAA+ Lon protease in absence of POLRMT. Lastly, mitochondrial transcription elongation factor (TEFM) can compensate for a partial depletion of POLRMT in heterozygous Polrmt knockout mice, indicating a direct regulatory role for this factor in transcription. In conclusion, we present here the first in vivo evidence that POLRMT has a key regulatory role in replication of mammalian mtDNA and is part of a mechanism that provides a switch between RNA primer formation for mtDNA replication and mtDNA expression. Isolated heart mitochondria from three control mice (L/L) and three Polrmt knockout mice (L/L, cre), aged 3-4 weeks, were sequenced and analyzed for differential expression.
2016-08-05 | E-GEOD-83368 | biostudies-arrayexpress
Project description:RNA Sequencing of skeletal muscle and heart of mice with distinct mitochondrial mutations revealed a differential transcriptomic response to endurance exercise training and altered determinants of exercise capacity and response.
2022-04-01 | GSE198229 | GEO
Project description:To determine the error rate of mitochondrial transcription, we ananlyzed 33 and 37 million reads respectively for wild type (WT) and mutant (E423P) mitochondrial RNA polymerase (POLRMT) overexpression flies and found that the error frequency of mitochondrial transcripts were over 5 fold higher in E423P flies than that of WT. To gain more insight into the molecular mechanisms that drive the error rate of transcription by POLRMT, we examined its distribution of errors along the mitochondrial genome. We also evaluated mitochondrial RNA processing by quantifying the frequency of a single read spanning two adjacent genes. There was no significant increase of unprocessed RNAs in E423P than that of WT. These observations concluded that overexpression of E423P POLRMT in adult flies leads to a statistically significant increase of mitochondrial transcripts errors.
2020-07-14 | GSE154310 | GEO
Project description:Caloric restriction (CR) without malnutrition appears to mitigate many detrimental effects of aging, in particular the age-related decline in skeletal muscle mitochondrial function. Although the mechanisms responsible for this protective effect remain unclear, CR is commonly believed to increase mitochondrial biogenesis; a concept that is now demanding closer scrutiny. Here we show that lifelong CR in mice prevents age-related loss of mitochondrial function, measured in isolated mitochondria and permeabilized muscle fibers. We find that these beneficial effects of CR occur without increasing mitochondrial abundance. Furthermore, whole-genome expression profiling and large-scale proteomic surveys revealed expression patterns inconsistent with increased mitochondrial biogenesis. These observations, combined with lower protein synthesis rates support an alternative hypothesis that CR preserves mitochondrial function not by increasing mitochondrial biogenesis, but rather by decreasing mitochondrial oxidant emission, increasing antioxidant scavenging, thereby minimizing oxidative damage to cellular components. Cross-sectional comparison of skeletal muscle from young (8mo), old (24mo) and old caloric restricted mice, obtained from the colony maintained on behalf of the National Institute on Aging.
2013-01-01 | E-GEOD-36285 | biostudies-arrayexpress
Project description:Calorie restriction (CR) is a dietary intervention that extends lifespan and healthspan in a variety of organisms. CR improves mitochondrial energy production, fuel oxidation and reactive oxygen species scavenging in skeletal muscle and other tissues, and these processes are thought to be critical to the benefits of CR. PGC-1a is a transcriptional coactivator that regulates mitochondrial function and is induced by CR. Consequently, many of the mitochondrial and metabolic benefits of CR are attributed to increased PGC-1a activity. To test this model for the first time, we examined the metabolic and mitochondrial response to CR in mice lacking skeletal muscle PGC-1a (MKO). Surprisingly, MKO mice demonstrated a normal improvement in glucose homeostasis in response to CR, indicating that skeletal muscle PGC-1a is dispensable for the whole-body benefits of CR. In contrast, gene expression profiling and electron microscopy demonstrated that PGC-1a is required for the full CR-induced increases in mitochondrial gene expression and mitochondrial density in skeletal muscle. These results demonstrate that PGC-1a is a major regulator of the mitochondrial response to CR in skeletal muscle, but surprisingly show that neither PGC-1a nor mitochondrial biogenesis in skeletal muscle are required for the metabolic benefits of CR. Control (FLOX) and PGC-1a skeletal muscle specific knock out (MKO) mice were placed on a control diet [C] or a calorie restriction diet [CR] for 12 weeks. RNA was isolated from TA/EDL muscles for microarray analysis. The following numbers of mice were analyzed from each group: C FLOX: n = 6; C MKO: n = 7; CR FLOX: n = 6; CR MKO: n = 7. Mice were mixed C57/BL6 and 129 background.
2012-02-04 | E-GEOD-34773 | biostudies-arrayexpress
Project description:Global gene expression analysis was performed comparing human skeletal muscle samples from patients with various forms of muscular dystrophy and mitochondrial myopathies in order to identify specific gene expression changes associated with collagen VI deficiency (leading to UllrichM-BM-4s Congenital Muscular Dystrophy) and depletion of mitochondrial DNA relative to other mitochondrial myopathies We analysed the gene expression profile of skeletal muscle from children suffering from mitochondrial myopathies and various forms of muscular dystrophy relative to skeletal muscle from healthy children using commercially available arrays that represents the complete human genome (Agilent Human SurePrintGE, 8x60K )
2015-01-20 | E-GEOD-43698 | biostudies-arrayexpress
Project description:The goal of this study is to compare the frequency of unprocessed preRNAs in mitochondria. Total mitochondrial RNA profiles of adult flies were generated in triplicates. We analyzed over 100 million reads for each group and used featureCounts to perform quantification allowing a read to be assigned to more than one gene. Using this analysis pipe line, we mapped about 30 million reads per sample to the Drosophila mitochondrial genome and identified a fequency of unprocessed preRNAs as 0.43% in PolrMT group, which is similar to that in PolrMT-E423P flies. These result revealed that overexpression of PolrMT-E423P does not contribute to pre-RNA processing.
2021-12-23 | GSE192549 | GEO