LENG8 regulation of mRNA processing is responsible for the control of mitochondrial activity

Abstract The processing of mRNA is essential for the maintenance of cellular and tissue homeostasis. However, the precise regulation of this process in mammalian cells, remains largely unknown. Here we have found that LENG8 represents the mammalian orthologue of the yeast mRNA processing factor Thp3 and Sac3. We go on to demonstrate that LENG8 binds to mRNAs, associates with components of mRNA processing machinery (the TREX complex) and contributes to mRNA nuclear export to the cytoplasm. Loss of LENG8 , leads to aberrant accumulation of poly (A) + RNA in the nucleus, in both Hela cells and murine fibroblasts. Furthermore, the precipitation of LENG8, is associated with an enrichment of both mRNAs and lncRNAs, and approximately half of these are also bound by the TREX component, THOC1. However, LENG8 preferentially binds mRNAs encoding for mitochondrial proteins and depletion of this processing factor, causes a dramatic breakdown in mitochondrial ultrastructure and a reduction in mitochondrial respiratory activity. Conditional deletion of Leng8 in mouse adipose tissues lead to a decreased body weight, and increased adipose thermogenesis. Our work has found an evolutionarily conserved mRNA processing factor that can control mitochondrial activity.

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LENG8 regulation of mRNA processing, is responsible for the control of mitochondrial activity

10.1101/2021.07.17.452750 ◽

2021 ◽

Author(s):

Yongxu Zhao ◽

Xiaoting Wang ◽

Niannian Li ◽

Yuenan Liu ◽

Zhigang Sun ◽

...

Keyword(s):

Nuclear Export ◽

Mammalian Cells ◽

Respiratory Activity ◽

Mrna Processing ◽

Mitochondrial Activity ◽

Processing Factor ◽

Conditional Deletion ◽

Evolutionarily Conserved ◽

Murine Fibroblasts ◽

Mitochondrial Respiratory Activity

The processing of mRNA is essential for the maintenance of cellular and tissue homeostasis. However, the precise regulation of this process in mammalian cells, remains largely unknown. Here we have found that LENG8 represents the mammalian orthologue of the yeast mRNA processing factor Thp3 and Sac3. We go on to demonstrate that LENG8 binds to mRNAs, associates with components of mRNA processing machinery (the TREX complex) and contributes to mRNA nuclear export to the cytoplasm. Loss of LENG8, leads to aberrant accumulation of poly (A)+ RNA in the nucleus, in both Hela cells and murine fibroblasts. Furthermore, the precipitation of LENG8, is associated with an enrichment of both mRNAs and lncRNAs, and approximately half of these are also bound by the TREX component, THOC1. However, LENG8 preferentially binds mRNAs encoding for mitochondrial proteins and depletion of this processing factor, causes a dramatic breakdown in mitochondrial ultrastructure and a reduction in mitochondrial respiratory activity. Conditional deletion of Leng8 in mouse adipose tissues lead to a decreased body weight, and increased adipose thermogenesis. Our work has found an evolutionarily conserved mRNA processing factor that can control mitochondrial activity.

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Apoptosis and development

Essays in Biochemistry ◽

10.1042/bse0390011 ◽

2003 ◽

Vol 39 ◽

pp. 11-24 ◽

Cited By ~ 6

Author(s):

Justin V McCarthy

Keyword(s):

Drosophila Melanogaster ◽

Mammalian Cells ◽

Cell Number ◽

Model Organisms ◽

Biological Processes ◽

Nematode Caenorhabditis Elegans ◽

Apoptotic Pathway ◽

Genetic Pathways ◽

Evolutionarily Conserved ◽

Multicellular Organisms

Apoptosis is an evolutionarily conserved process used by multicellular organisms to developmentally regulate cell number or to eliminate cells that are potentially detrimental to the organism. The large diversity of regulators of apoptosis in mammalian cells and their numerous interactions complicate the analysis of their individual functions, particularly in development. The remarkable conservation of apoptotic mechanisms across species has allowed the genetic pathways of apoptosis determined in lower species, such as the nematode Caenorhabditis elegans and the fruitfly Drosophila melanogaster, to act as models for understanding the biology of apoptosis in mammalian cells. Though many components of the apoptotic pathway are conserved between species, the use of additional model organisms has revealed several important differences and supports the use of model organisms in deciphering complex biological processes such as apoptosis.

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Nuclear export of signal recognition particle RNA in mammalian cells

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2003.11.126 ◽

2004 ◽

Vol 313 (2) ◽

pp. 351-355 ◽

Cited By ~ 18

Author(s):

Christina N. Alavian ◽

Joan C. Ritland Politz ◽

Laura B. Lewandowski ◽

Christine M. Powers ◽

Thoru Pederson

Keyword(s):

Nuclear Export ◽

Mammalian Cells ◽

Signal Recognition Particle ◽

Signal Recognition

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Muscle Transcriptional Profile Based on Muscle Fiber, Mitochondrial Respiratory Activity, and Metabolic Enzymes

International Journal of Biological Sciences ◽

10.7150/ijbs.13132 ◽

2015 ◽

Vol 11 (12) ◽

pp. 1348-1362 ◽

Cited By ~ 10

Author(s):

Xuan Liu ◽

Yang Du ◽

Nares Trakooljul ◽

Bodo Brand ◽

Eduard Muráni ◽

...

Keyword(s):

Muscle Fiber ◽

Respiratory Activity ◽

Metabolic Enzymes ◽

Transcriptional Profile ◽

Mitochondrial Respiratory Activity ◽

Mitochondrial Respiratory

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Staufen1 is imported into the nucleolus via a bipartite nuclear localization signal and several modulatory determinants

Biochemical Journal ◽

10.1042/bj20050694 ◽

2005 ◽

Vol 393 (1) ◽

pp. 245-254 ◽

Cited By ~ 32

Author(s):

Catherine Martel ◽

Paolo Macchi ◽

Luc Furic ◽

Michael A. Kiebler ◽

Luc Desgroseillers

Keyword(s):

Nuclear Localization ◽

Nuclear Localization Signal ◽

Nuclear Export ◽

Mammalian Cells ◽

Rna Binding ◽

Binding Activity ◽

Nuclear Trafficking ◽

Binding Domains ◽

Bipartite Nuclear Localization Signal ◽

Localization Signal

Mammalian Stau1 (Staufen1), a modular protein composed of several dsRBDs (double-stranded RNA-binding domains), is probably involved in mRNA localization. Although Stau1 is mostly described in association with the rough endoplasmic reticulum and ribosomes in the cytoplasm, recent studies suggest that it may transit through the nucleus/nucleolus. Using a sensitive yeast import assay, we show that Stau1 is actively imported into the nucleus through a newly identified bipartite nuclear localization signal. As in yeast, the bipartite nuclear localization signal is necessary for Stau1 nuclear import in mammalian cells. It is also required for Stau1 nucleolar trafficking. However, Stau1 nuclear transit seems to be regulated by mechanisms that involve cytoplasmic retention and/or facilitated nuclear export. Cytoplasmic retention is mainly achieved through the action of dsRBD3, with dsRBD2 playing a supporting role in this function. Similarly, dsRBD3, but not its RNA-binding activity, is critical for Stau1 nucleolar trafficking. The function of dsRBD3 is strengthened or stabilized by the presence of dsRBD4 but prevented by the interdomain between dsRBD2 and dsRBD3. Altogether, these results suggest that Stau1 nuclear trafficking is a highly regulated process involving several determinants. The presence of Stau1 in the nucleus/nucleolus suggests that it may be involved in ribonucleoprotein formation in the nucleus and/or in other nuclear functions not necessarily related to mRNA transport.

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Spatial and developmental changes in the respiratory activity of mitochondria in early Drosophila embryos

Development ◽

10.1242/dev.115.4.1175 ◽

1992 ◽

Vol 115 (4) ◽

pp. 1175-1182 ◽

Cited By ~ 1

Author(s):

T. Akiyama ◽

M. Okada

Keyword(s):

Respiratory Activity ◽

Cell Formation ◽

Rhodamine 123 ◽

Mitochondrial Activity ◽

Early Cleavage ◽

Pole Cell ◽

Posterior Group ◽

Cleavage Stages ◽

Pole Cells ◽

Drosophila Embryos

Mitochondria of early Drosophila embryos were observed with a transmission electron microscope and a fluorescent microscope after vital staining with rhodamine 123, which accumulates only in active mitochondria. Rhodamine 123 accumulated particularly in the posterior pole region in early cleavage embryos, whereas the spatial distribution of mitochondria in an embryo was uniform throughout cleavage stages. In late cleavage stages, the dye showed very weak and uniform accumulation in all regions of periplasm. Polar plasm, sequestered in pole cells, restored the ability to accumulate the dye. Therefore, it is concluded that the respiratory activity of mitochondria is higher in the polar plasm than in the other regions of periplasm in early embryos, and this changes during development. The temporal changes in rhodamine 123-staining of polar plasm were not affected by u.v. irradiation at the posterior of early cleavage embryos at a sufficient dosage to prevent pole cell formation. This suggests that the inhibition of pole cell formation by u.v. irradiation is not due to the inactivation of the respiratory activities of mitochondria. In addition, we found that the anterior of Bicaudal-D mutant embryos at cleavage stage was stained with rhodamine 123 with the same intensity as the posterior of wild-type embryos. No pole cells form in the anterior of Bic-D embryos, where no restoration of mitochondrial activity occurs in the blastoderm stage. The posterior group mutations that we tested (staufen, oskar, tudor, nanos) and the terminal mutation (torso) did not alter staining pattern of the posterior with rhodamine 123.

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β-Catenin is a pH sensor with decreased stability at higher intracellular pH

The Journal of Cell Biology ◽

10.1083/jcb.201712041 ◽

2018 ◽

Vol 217 (11) ◽

pp. 3965-3976 ◽

Cited By ~ 17

Author(s):

Katharine A. White ◽

Bree K. Grillo-Hill ◽

Mario Esquivel ◽

Jobelle Peralta ◽

Vivian N. Bui ◽

...

Keyword(s):

Intracellular Ph ◽

Protein Interactions ◽

Mammalian Cells ◽

Ph Sensor ◽

Adherens Junction ◽

Protein Protein Interactions ◽

Adherens Junction Protein ◽

Junction Protein ◽

Evolutionarily Conserved ◽

Ph Dependent

β-Catenin functions as an adherens junction protein for cell–cell adhesion and as a signaling protein. β-catenin function is dependent on its stability, which is regulated by protein–protein interactions that stabilize β-catenin or target it for proteasome-mediated degradation. In this study, we show that β-catenin stability is regulated by intracellular pH (pHi) dynamics, with decreased stability at higher pHi in both mammalian cells and Drosophila melanogaster. β-Catenin degradation requires phosphorylation of N-terminal residues for recognition by the E3 ligase β-TrCP. While β-catenin phosphorylation was pH independent, higher pHi induced increased β-TrCP binding and decreased β-catenin stability. An evolutionarily conserved histidine in β-catenin (found in the β-TrCP DSGIHS destruction motif) is required for pH-dependent binding to β-TrCP. Expressing a cancer-associated H36R–β-catenin mutant in the Drosophila eye was sufficient to induce Wnt signaling and produced pronounced tumors not seen with other oncogenic β-catenin alleles. We identify pHi dynamics as a previously unrecognized regulator of β-catenin stability, functioning in coincidence with phosphorylation.

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U1 small nuclear RNAs with altered specificity can be stably expressed in mammalian cells and promote permanent changes in pre-mRNA splicing.

Molecular and Cellular Biology ◽

10.1128/mcb.13.5.2666 ◽

1993 ◽

Vol 13 (5) ◽

pp. 2666-2676 ◽

Cited By ~ 14

Author(s):

J B Cohen ◽

S D Broz ◽

A D Levinson

Keyword(s):

Splice Site ◽

Mammalian Cells ◽

Mrna Processing ◽

Mrna Splicing ◽

Small Nuclear Rna ◽

Splice Sites ◽

Gene Complementation ◽

Small Nuclear Rnas ◽

Nuclear Rna ◽

Mutant Genes

Pre-mRNA 5' splice site activity depends, at least in part, on base complementarity to U1 small nuclear RNA. In transient coexpression assays, defective 5' splice sites can regain activity in the presence of U1 carrying compensatory changes, but it is unclear whether such mutant U1 RNAs can be permanently expressed in mammalian cells. We have explored this issue to determine whether U1 small nuclear RNAs with altered specificity may be of value to rescue targeted mutant genes or alter pre-mRNA processing profiles. This effort was initiated following our observation that U1 with specificity for a splice site associated with an alternative H-ras exon substantially reduced the synthesis of the potentially oncogenic p21ras protein in transient assays. We describe the development of a mammalian complementation system that selects for removal of a splicing-defective intron placed within a drug resistance gene. Complementation was observed in proportion to the degree of complementarity between transfected mutant U1 genes and different defective splice sites, and all cells selected in this manner were found to express mutant U1 RNA. In addition, these cells showed specific activation of defective splice sites presented by an unlinked reporter gene. We discuss the prospects of this approach to permanently alter the expression of targeted genes in mammalian cells.

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