scholarly journals A Human Mitochondrial Transcription Factor Is Related to RNA Adenine Methyltransferases and Binds S-Adenosylmethionine

2002 ◽  
Vol 22 (4) ◽  
pp. 1116-1125 ◽  
Author(s):  
Vicki McCulloch ◽  
Bonnie L. Seidel-Rogol ◽  
Gerald S. Shadel
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Mitochondrial Gene ◽  
Factor H ◽  
Model Systems ◽  
Mitochondrial Gene Expression ◽  
Mitochondrial Transcription ◽  
Mitochondrial Transcription Factor

ABSTRACT A critical step toward understanding mitochondrial genetics and its impact on human disease is to identify and characterize the full complement of nucleus-encoded factors required for mitochondrial gene expression and mitochondrial DNA (mtDNA) replication. Two factors required for transcription initiation from a human mitochondrial promoter are h-mtRNA polymerase and the DNA binding transcription factor, h-mtTFA. However, based on studies in model systems, the existence of a second human mitochondrial transcription factor has been postulated. Here we report the isolation of a cDNA encoding h-mtTFB, the human homolog of Saccharomyces cerevisiae mitochondrial transcription factor B (sc-mtTFB) and the first metazoan member of this class of transcription factors to which a gene has been assigned. Recombinant h-mtTFB is capable of binding mtDNA in a non-sequence-specific fashion and activates transcription from the human mitochondrial light-strand promoter in the presence of h-mtTFA in vitro. Remarkably, h-mtTFB and its fungal homologs are related in primary sequence to a superfamily of N6 adenine RNA methyltransferases. This observation, coupled with the ability of recombinant h-mtTFB to bind S-adenosylmethionine in vitro, suggests that a structural, and perhaps functional, relationship exists between this class of transcription factors and this family of RNA modification enzymes and that h-mtTFB may perform dual functions during mitochondrial gene expression.

scholarly journals Human Mitochondrial Transcription Factor B1 Interacts with the C-Terminal Activation Region of h-mtTFA and Stimulates Transcription Independently of Its RNA Methyltransferase Activity

2003 ◽  
Vol 23 (16) ◽  
pp. 5816-5824 ◽  
Author(s):  
Vicki McCulloch ◽  
Gerald S. Shadel
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activation ◽  
Transcription Initiation ◽  
Mitochondrial Gene ◽  
Factor H ◽  
Dual Function ◽  
Mitochondrial Rna ◽  
Methyltransferase Activity ◽  
Mitochondrial Transcription

ABSTRACT A significant advancement in understanding mitochondrial gene expression is the recent identification of two new human mitochondrial transcription factors, h-mtTFB1 and h-mtTFB2. Both proteins stimulate transcription in collaboration with the high-mobility group box transcription factor, h-mtTFA, and are homologous to rRNA methyltransferases. In fact, the dual-function nature of h-mtTFB1 was recently demonstrated by its ability to methylate a conserved rRNA substrate. Here, we demonstrate that h-mtTFB1 binds h-mtTFA both in HeLa cell mitochondrial extracts and in direct-binding assays via an interaction that requires the C-terminal tail of h-mtTFA, a region necessary for transcriptional activation. In addition, point mutations in conserved methyltransferase motifs of h-mtTFB1 revealed that it stimulates transcription in vitro independently of S-adenosylmethionine binding and rRNA methyltransferase activity. Furthermore, one mutation (G65A) eliminated the ability of h-mtTFB1 to bind DNA yet did not affect transcriptional activation. These results, coupled with the observation that h-mtTFB1 and human mitochondrial RNA (h-mtRNA) polymerase can also be coimmunoprecipitated, lead us to propose a model in which h-mtTFA demarcates mitochondrial promoter locations and where h-mtTFB proteins bridge an interaction between the C-terminal tail of h-mtTFA and mtRNA polymerase to facilitate specific initiation of transcription. Altogether, these data provide important new insight into the mechanism of transcription initiation in human mitochondria and indicate that the dual functions of h-mtTFB1 can be separated.

scholarly journals The Effect of Sodium Selenite on Expression of Mitochondrial Transcription Factor A during In Vitro Maturation of Mouse Oocyte

2021 ◽  
Author(s):  
Tina Moshaashaee ◽  
Saeed Zavareh ◽  
Shahram Pourbeiranvand ◽  
Mojdeh Salehnia
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Oocyte Maturation ◽  
Sodium Selenite ◽  
In Vitro Maturation ◽  
Mitochondrial Transcription ◽  
Mitochondrial Transcription Factor ◽  
Mitochondrial Transcription Factor A ◽  
Experimental Group

Background: The aim of the present study was to investigate the effect of Sodium Selenite (SS) supplemented media on oocyte maturation, expression of mitochondrial transcription factor A (TFAM) and embryo quality. Methods: Mouse Germinal Vesicle (GV) oocytes were collected after administration of Pregnant Mare Serum Gonadotropin (PMSG); in experimental group 1, oocytes were cultured and then subjected for in vitro maturation in the absence of SS, and in experimental group 2, they were matured in vitro in the presence of 10 ng/ml of SS up to 16 hr. The control group included MII oocytes obtained from the fallopian tubes after ovarian stimulation with PMSG, followed by human chorionic gonadotropin. Then, the expression of TFAM in MII oocytes in all three groups was investigated using real-time RT-PCR. The fertilization and embryo developmental rates were assessed, and finally the quality of the blastocysts was evaluated using propidium iodide staining. Results: The oocyte maturation rate to MII stage in SS treated group was significantly higher than non-treated oocytes (75.65 vs. 68.17%, p<0.05). Also, the rates of fertilization, embryo development to blastocyst stage as well as the cell number of blastocyst in SS supplemented group were higher than other experimental group (p<0.05). There was a significant decrease in TFAM gene expression in both in vitro groups compared to the group with in vivo obtained oocytes (p<0.05). Moreover, there was a significant increase in TFAM gene expression in oocytes that matured in the presence of SS compared to that of the group without SS (p<0.05). Conclusion: Supplementation of oocyte maturation culture media with SS improved the development rate of oocytes and embryo and also enhanced TFAM expression in MII oocytes which can affect the mitochondrial biogenesis of oocytes.

Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression

2005 ◽  
Vol 83 (4) ◽  
pp. 535-547 ◽  
Author(s):  
Gareth N Corry ◽  
D Alan Underhill
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Transcriptional Activation ◽  
Current Knowledge ◽  
Nuclear Architecture ◽  
Subnuclear Localization ◽  
Modular Structures

To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein–protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.Key words: transcription, subnuclear localization, chromatin, gene expression, nuclear architecture.

scholarly journals Quantitative proteomics revealed C6orf203/MTRES1 as a factor preventing stress-induced transcription deficiency in human mitochondria

2019 ◽  
Vol 47 (14) ◽  
pp. 7502-7517 ◽  
Author(s):  
Anna V Kotrys ◽  
Dominik Cysewski ◽  
Sylwia D Czarnomska ◽  
Zbigniew Pietras ◽  
Lukasz S Borowski ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Binding ◽  
Mitochondrial Gene ◽  
Binding Activity ◽  
Stress Conditions ◽  
Mitochondrial Rna ◽  
Mitochondrial Gene Expression ◽  
Compensatory Mechanisms ◽  
Temporary Reduction ◽  
Mitochondrial Transcription

AbstractMaintenance of mitochondrial gene expression is crucial for cellular homeostasis. Stress conditions may lead to a temporary reduction of mitochondrial genome copy number, raising the risk of insufficient expression of mitochondrial encoded genes. Little is known how compensatory mechanisms operate to maintain proper mitochondrial transcripts levels upon disturbed transcription and which proteins are involved in them. Here we performed a quantitative proteomic screen to search for proteins that sustain expression of mtDNA under stress conditions. Analysis of stress-induced changes of the human mitochondrial proteome led to the identification of several proteins with poorly defined functions among which we focused on C6orf203, which we named MTRES1 (Mitochondrial Transcription Rescue Factor 1). We found that the level of MTRES1 is elevated in cells under stress and we show that this upregulation of MTRES1 prevents mitochondrial transcript loss under perturbed mitochondrial gene expression. This protective effect depends on the RNA binding activity of MTRES1. Functional analysis revealed that MTRES1 associates with mitochondrial RNA polymerase POLRMT and acts by increasing mitochondrial transcription, without changing the stability of mitochondrial RNAs. We propose that MTRES1 is an example of a protein that protects the cell from mitochondrial RNA loss during stress.

A human mitochondrial transcriptional activator can functionally replace a yeast mitochondrial HMG-box protein both in vivo and in vitro

1993 ◽  
Vol 13 (3) ◽  
pp. 1951-1961
Author(s):  
M A Parisi ◽  
B Xu ◽  
D A Clayton
Keyword(s):  
Transcription Factor ◽  
Mitochondrial Dna ◽  
Nuclear Gene ◽  
Transcriptional Activator ◽  
Yeast Mitochondria ◽  
Yeast Protein ◽  
Mitochondrial Transcription ◽  
Mitochondrial Transcription Factor ◽  
Mitochondrial Transcription Factor A

Human mitochondrial transcription factor A is a 25-kDa protein that binds immediately upstream of the two major mitochondrial promoters, thereby leading to correct and efficient initiation of transcription. Although the nature of yeast mitochondrial promoters is significantly different from that of human promoters, a potential functional homolog of the human transcriptional activator protein has been previously identified in yeast mitochondria. The importance of the yeast protein in yeast mitochondrial DNA function has been shown by inactivation of its nuclear gene (ABF2) in Saccharomyces cerevisiae cells resulting in loss of mitochondrial DNA. We report here that the nuclear gene for human mitochondrial transcription factor A can be stably expressed in yeast cells devoid of the yeast homolog protein. The human protein is imported efficiently into yeast mitochondria, is processed correctly, and rescues the loss-of-mitochondrial DNA phenotype in a yeast abf2 strain, thus functionally substituting for the yeast protein. Both human and yeast proteins affect yeast mitochondrial transcription initiation in vitro, suggesting that the two proteins may have a common role in this fundamental process.

Abstract 16765: Cyclophilin-D: A Regulator of Mitochondrial Gene Expression

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jeejabai Radhakrishnan ◽  
Raúl J Gazmuri
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Electron Transport ◽  
Respiratory Chain ◽  
Post Infection ◽  
Mitochondrial Gene ◽  
Cellular Respiration ◽  
Mitochondrial Gene Expression ◽  
Cyclophilin D ◽  
Heavy Strand

Background: Cyclophilin-D (Cyp-D) is a peptidyl-prolyl isomerase resident in the mitochondrial matrix; and like other cyclophilins it can catalyze conformational changes of proteins. Cyp-D is best known for its role in lowering the threshold for opening of the mitochondrial permeability transition pore. However, a serendipitous observation by us, whereby Cyp-D silencing halted cell proliferation, and reports by others that Cyp-D could interact with nuclear transcription factors that have translocated to mitochondria, prompted us to hypothesize that Cyp-D could interact with native mitochondrial transcription factors (mTFs; TFB1M, TFB2M, and TFAM) and therefore be a key regulator of mitochondrial gene expression. Given that all 13 mitochondrial-encoded proteins are components of respiratory chain complexes, our hypothesis would support a central role of Cyp-D in cellular respiration. Methods and Results: We first analyzed the interaction of Cyp-D with mTFs by co-immunoprecipitation (co-IP) and reverse co-IP after transfection of constructs expressing FLAG-tagged Cyp-D and V5-tagged mTFs in HEK 293T cells, showing specific interactions of Cyp-D with TFB1M and with TFB2M but not with TFAM. We then quantitated by real time qPCR mitochondrial-encoded respiratory chain transcripts in HEK 293T cells at day 8 post-infection with lentiviruses encoding shRNA against Cyp-D, showing striking reductions in transcripts ND1, COX1, and ATP6 (initiated from the heavy strand promoter 2) but not in transcript ND6 (initiated from the light strand promoter). Finally, we measured cellular oxygen consumption, also on post-infection day 8, and found it reduced without improvement after uncoupling of electron transport from ATP synthesis with FCCP, consistent with the aforementioned reductions in mitochondrial transcripts of electron transport complexes. At the same time, mitochondrial mass, expression of nuclear genes, and cell viability were all preserved. Conclusion: In HEK 293 T cells, Cyp-D is required for mitochondrial gene expression modulating transcription possibly through the heavy strand promoter 2 suggesting a novel Cyp-D function as regulator of oxidative phosphorylation and thus of the fundamental process of cellular respiration.

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