Mitochondrial biogenesis in cultured mammalian cells II. Mitochondrial protein and phospholipid synthesis in chloramphenicol-treated BHK-21 cells

The complete cDNA for a human mitochondrial protein designated P1, which was previously identified as a microtubule-related protein, has been cloned and sequenced. The deduced amino acid sequence of P1 shows strong homology (40 to 50% identical residues and an additional 20% conservative replacements) to the 65-kilodalton major antigen of mycobacteria, to the GroEL protein of Escherichia coli, and to the ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) subunit binding protein of plant chloroplasts. Similar to the case with the latter two proteins, which have been shown to act as chaperonins in the posttranslational assembly of oligomeric protein structures, it is suggested that P1 may play a similar role in mammalian cells. The observed high degree of homology between human P1 and mycobacterial antigen also suggests the possible involvement of this protein in certain autoimmune diseases.

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Rpm2, the Protein Subunit of Mitochondrial RNase P in Saccharomyces cerevisiae, Also Has a Role in the Translation of Mitochondrially Encoded Subunits of Cytochrome c Oxidase

Genetics ◽

10.1093/genetics/158.2.573 ◽

2001 ◽

Vol 158 (2) ◽

pp. 573-585

Author(s):

Vilius Stribinskis ◽

Guo-Jian Gao ◽

Steven R Ellis ◽

Nancy C Martin

Keyword(s):

Saccharomyces Cerevisiae ◽

Cytochrome C ◽

Cytochrome C Oxidase ◽

Mitochondrial Biogenesis ◽

Mitochondrial Protein ◽

Nuclear Gene ◽

Rnase P ◽

Wild Type ◽

Protein Subunit ◽

Mitochondrial Translation

Abstract RPM2 is a Saccharomyces cerevisiae nuclear gene that encodes the protein subunit of mitochondrial RNase P and has an unknown function essential for fermentative growth. Cells lacking mitochondrial RNase P cannot respire and accumulate lesions in their mitochondrial DNA. The effects of a new RPM2 allele, rpm2-100, reveal a novel function of RPM2 in mitochondrial biogenesis. Cells with rpm2-100 as their only source of Rpm2p have correctly processed mitochondrial tRNAs but are still respiratory deficient. Mitochondrial mRNA and rRNA levels are reduced in rpm2-100 cells compared to wild type. The general reduction in mRNA is not reflected in a similar reduction in mitochondrial protein synthesis. Incorporation of labeled precursors into mitochondrially encoded Atp6, Atp8, Atp9, and Cytb protein was enhanced in the mutant relative to wild type, while incorporation into Cox1p, Cox2p, Cox3p, and Var1p was reduced. Pulse-chase analysis of mitochondrial translation revealed decreased rates of translation of COX1, COX2, and COX3 mRNAs. This decrease leads to low steady-state levels of Cox1p, Cox2p, and Cox3p, loss of visible spectra of aa3 cytochromes, and low cytochrome c oxidase activity in mutant mitochondria. Thus, RPM2 has a previously unrecognized role in mitochondrial biogenesis, in addition to its role as a subunit of mitochondrial RNase P. Moreover, there is a synthetic lethal interaction between the disruption of this novel respiratory function and the loss of wild-type mtDNA. This synthetic interaction explains why a complete deletion of RPM2 is lethal.

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Phospholipid synthesis in mammalian cells

10.1016/b978-0-12-824048-9.00004-3 ◽

2021 ◽

pp. 227-258

Author(s):

Neale D. Ridgway

Keyword(s):

Mammalian Cells ◽

Phospholipid Synthesis

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1 Phospholipid synthesis in mammalian cells

Lipid Metabolism and Membrane Biogenesis - Topics in Current Genetics ◽

10.1007/978-3-540-40999-1_2 ◽

2003 ◽

pp. 5-88 ◽

Cited By ~ 1

Author(s):

Christopher R. McMaster ◽

Trevor R. Jackson

Keyword(s):

Mammalian Cells ◽

Phospholipid Synthesis

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Fundc1 is necessary for proper body axis formation during embryogenesis in zebrafish

Scientific Reports ◽

10.1038/s41598-019-55415-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Gongyu Xu ◽

Hao Shen ◽

Emile Nibona ◽

Kongyue Wu ◽

Xiaomei Ke ◽

...

Keyword(s):

T Cells ◽

Mammalian Cells ◽

Mitochondrial Protein ◽

Ectopic Expression ◽

The Body ◽

Body Axis ◽

Terminal Deoxynucleotidyl Transferase ◽

Mitochondrial Outer Membrane ◽

Axis Formation ◽

Rare Minnow

AbstractFUN14 domain-containing protein 1 (FUNDC1) is a mitochondrial outer membrane protein which is responsible for hypoxia-induced mitophagy in mammalian cells. Knockdown of fundc1 is known to cause severe defects in the body axis of a rare minnow. To understand the role of Fundc1 in embryogenesis, we used zebrafish in this study. We used bioimaging to locate zebrafish Fundc1 (DrFundc1) with MitoTracker, a marker of mitochondria, and/or CellLight Lysosomes-GFP, a label of lysosomes, in the transfected ovary cells of grass carp. The use of Western blotting detected DrFundc1 as a component of mitochondrial proteins with endogenous COX IV, LC3B, and FUNDC1 in transgenic human embryonic kidney 293 T cells. DrFundc1 induced LC3B activation. The ectopic expression of Drfundc1 caused cell death and apoptosis as well as impairing cell proliferation in the 293 T cell line, as detected by Trypan blue, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and incorporation of BrdU. DrFundc1 up-regulated expression of both autophagy- and apoptosis-related genes, including ATG5, ATG7, LC3B, BECLIN1, and BAX in transgenic 293 T cells. A knockdown of Drfundc1 using short hairpin RNA (shRNA) led to midline bifurcation with two notochords and two spinal cords in zebrafish embryos. Co-injection of Drfundc1 mRNA repaired defects resulting from shRNA. Knockdown of Drfundc1 resulted in up- or down-regulation of genes related to autophagy and apoptosis, as well as decreased expression of neural genes such as cyclinD1, pax2a, opl, and neuroD1. In summary, DrFundc1 is a mitochondrial protein which is involved in mitophagy and is critical for typical body axis development in zebrafish.

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Mitochondrial assembly: protein import

Proceedings of The Nutrition Society ◽

10.1079/pns2004342 ◽

2004 ◽

Vol 63 (2) ◽

pp. 293-300 ◽

Cited By ~ 26

Author(s):

David A. Hood ◽

Anna-Maria Joseph

Keyword(s):

Molecular Chaperones ◽

Mammalian Cells ◽

Protein Import ◽

Contractile Activity ◽

Mitochondrial Protein ◽

Energy Status ◽

Mitochondrial Protein Import ◽

Physiological Importance ◽

The Matrix ◽

Import Receptors

The protein import process of mitochondria is vital for the assembly of the hundreds of nuclear-derived proteins into an expanding organelle reticulum. Most of our knowledge of this complex multisubunit network comes from studies of yeast and fungal systems, with little information known about the protein import process in mammalian cells, particularly skeletal muscle. However, growing evidence indicates that the protein import machinery can respond to changes in the energy status of the cell. In particular, contractile activity, a powerful inducer of mitochondrial biogenesis, has been shown to alter the stoichiometry of the protein import apparatus via changes in several protein import machinery components. These adaptations include the induction of cytosolic molecular chaperones that transport precursors to the matrix, the up-regulation of outer membrane import receptors, and the increase in matrix chaperonins that facilitate the import and proper folding of the protein for subsequent compartmentation in the matrix or inner membrane. The physiological importance of these changes is an increased capacity for import into the organelle at any given precursor concentration. Defects in the protein import machinery components have been associated with mitochondrial disorders. Thus, contractile activity may serve as a possible mechanism for up-regulation of mitochondrial protein import and compensation for mitochondrial phenotype alterations observed in diseased muscle.

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Glutamyl-tRNAGln amidotransferase is essential for mammalian mitochondrial translation in vivo

Biochemical Journal ◽

10.1042/bj20131107 ◽

2014 ◽

Vol 460 (1) ◽

pp. 91-101 ◽

Cited By ~ 20

Author(s):

Lucía Echevarría ◽

Paula Clemente ◽

Rosana Hernández-Sierra ◽

María Esther Gallardo ◽

Miguel A. Fernández-Moreno ◽

...

Keyword(s):

Protein Synthesis ◽

Mammalian Cells ◽

Mitochondrial Protein ◽

Mitochondrial Protein Synthesis ◽

Indirect Pathway ◽

Mitochondrial Translation

We have demonstrated that in mitochondria of mammalian cells the aminoacylation of tRNAGln is produced by an indirect pathway involving the enzyme glutamyl-tRNAGln amidotransferase. Misaminoacylated Glu-tRNAGln is rejected from the ribosomes maintaining the fidelity of the mitochondrial protein synthesis.

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Cell cycle-dependent mitochondrial biogenesis and dynamics in mammalian cells

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2007.03.091 ◽

2007 ◽

Vol 357 (1) ◽

pp. 111-117 ◽

Cited By ~ 49

Author(s):

Seungmin Lee ◽

Sujeong Kim ◽

Xuejun Sun ◽

Jae-Ho Lee ◽

Hyeseong Cho

Keyword(s):

Cell Cycle ◽

Mitochondrial Biogenesis ◽

Mammalian Cells ◽

Cycle Dependent

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Functional consequences of thyroid hormone-induced changes in the mitochondrial protein import pathway

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00294.2002 ◽

2003 ◽

Vol 284 (1) ◽

pp. E29-E35 ◽

Cited By ~ 21

Author(s):

Marco Colavecchia ◽

Loraine N. Christie ◽

Yashpal S. Kanwar ◽

David A. Hood

Keyword(s):

Thyroid Hormone ◽

Mitochondrial Biogenesis ◽

Protein Import ◽

Mitochondrial Protein ◽

Cardiac Cells ◽

Mrna Levels ◽

Functional Changes ◽

Functional Consequences ◽

Induced Changes ◽

In Cells

Thyroid hormone [3,5,3′-triiodo-l-thyronine (T3)] induces phenotypic alterations in cardiac mitochondria, in part by influencing protein import and the expression of the import motor mitochondrial heat shock protein (mtHsp70). Here we examined the adaptability of translocases of the inner membrane (Tim) proteins, as well as the outer membrane receptor Tom34, to T3. Administration of T3 to rats for 5 days increased cardiac Tim23 and Tim44 mRNA levels by 55 and 50%, respectively, but had no effect on Tim17. T3 treatment also induced a 45% increase in Tom34 mRNA, with no accompanying changes at the protein level, suggesting regulation at the posttranscriptional level. In H9c2 cardiac cells, Tim17 mRNA was elevated by 114% by 9 days of differentiation, whereas Tim23 and Tim44 declined by 25 and 29%, respectively. To determine the functional consequences of these T3-induced changes, malate dehydrogenase (MDH) import rates were measured in H9c2 cells stably overexpressing Tim44 and mtHsp70, either alone or in combination. MDH import remained unaltered in cells overexpressing Tim44 or in cells overexpressing both Tim44 and mtHsp70. However, when mtHsp70 was overexpressed alone, a 13% ( P < 0.05) increase in MDH import rate was observed. These findings indicate that import machinery components are differentially regulated in response to stimuli that induce mitochondrial biogenesis, like T3 and differentiation. In addition, the induction of an import machinery component in response to T3 may not necessarily result in functional changes in protein import during mitochondrial biogenesis. Finally, mtHsp70 may play a regulatory role in the import process that is independent of its interaction with Tim44.

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