scholarly journals Drosophila MICOS knockdown impairs mitochondrial structure and function and promotes mitophagy in muscle tissue

Biology Open ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. bio054262
Author(s):  
Li-jie Wang ◽  
Tian Hsu ◽  
Hsiang-ling Lin ◽  
Chi-yu Fu
Keyword(s):  
Muscle Tissue ◽  
Mammalian Cells ◽  
Structure And Function ◽  
Tissue Homeostasis ◽  
Mitochondrial Morphology ◽  
Mitochondrial Structure ◽  
And Function ◽  
Nucleoid Structure

ABSTRACTThe mitochondrial contact site and cristae organizing system (MICOS) is a multi-protein interaction hub that helps define mitochondrial ultrastructure. While the functional importance of MICOS is mostly characterized in yeast and mammalian cells in culture, the contributions of MICOS to tissue homeostasis in vivo remain further elucidation. In this study, we examined how knocking down expression of Drosophila MICOS genes affects mitochondrial function and muscle tissue homeostasis. We found that CG5903/MIC26-MIC27 colocalizes and functions with Mitofilin/MIC60 and QIL1/MIC13 as a Drosophila MICOS component; knocking down expression of any of these three genes predictably altered mitochondrial morphology, causing loss of cristae junctions, and disruption of cristae packing. Furthermore, the knockdown flies exhibited low mitochondrial membrane potential, fusion/fission imbalances, increased mitophagy, and limited cell death. Reductions in climbing ability indicated deficits in muscle function. Knocking down MICOS genes also caused reduced mtDNA content and fragmented mitochondrial nucleoid structure in Drosophila. Together, our data demonstrate an essential role of Drosophila MICOS in maintaining proper homeostasis of mitochondrial structure and function to promote the function of muscle tissue.

scholarly journals Heterochronic Parabiosis: Old Blood Induces Changes in Mitochondrial Structure and Function of Young Mice

2020 ◽  
Author(s):  
Jenny L Gonzalez-Armenta ◽  
Ning Li ◽  
Rae-Ling Lee ◽  
Baisong Lu ◽  
Anthony J A Molina
Keyword(s):  
Mitochondrial Respiration ◽  
Complex I ◽  
Structure And Function ◽  
Muscle Performance ◽  
Mitochondrial Morphology ◽  
Positive Effects ◽  
Mitochondrial Structure ◽  
And Function ◽  
Old Mice ◽  
Young Mice

Abstract Heterochronic parabiosis models have been utilized to demonstrate the role of blood-borne circulating factors in systemic effects of aging. In previous studies, heterochronic parabiosis has shown positive effects across multiple tissues in old mice. More recently, a study demonstrated old blood had a more profound negative effect on muscle performance and neurogenesis of young mice. In this study, we used heterochronic parabiosis to test the hypothesis that circulating factors mediate mitochondrial bioenergetic decline, a well-established biological hallmark of aging. We examined mitochondrial morphology, expression of mitochondrial complexes, and mitochondrial respiration from skeletal muscle of mice connected as heterochronic pairs, as well as young and old isochronic controls. Our results indicate that young heterochronic mice had significantly lower total mitochondrial content and on average had significantly smaller mitochondria compared to young isochronic controls. Expression of complex IV followed a similar pattern: young heterochronic mice had a trend for lower expression compared to young isochronic controls. Additionally, respirometric analyses indicate that young heterochronic mice had significantly lower complex I, complex I + II, and maximal mitochondrial respiration and a trend for lower complex II-driven respiration compared to young isochronic controls. Interestingly, we did not observe significant improvements in old heterochronic mice compared to old isochronic controls, demonstrating the profound deleterious effects of circulating factors from old mice on mitochondrial structure and function. We also found no significant differences between the young and old heterochronic mice, demonstrating that circulating factors can be a driver of age-related differences in mitochondrial structure and function.

Chromatin structure and function: the heretical path to an RNA transcription factor

1996 ◽  
Vol 74 (5) ◽  
pp. 623-632 ◽  
Author(s):  
Margarida O. Krause
Keyword(s):  
Chromatin Structure ◽  
Mammalian Cells ◽  
T Antigen ◽  
Temperature Sensitive ◽  
Mobility Shift ◽  
Cell Extracts ◽  
Myc Gene ◽  
And Function

This review represents a synthesis of the work of the author and her collaborators through 40 years of research aimed at an understanding of chromatin composition and functional arrangement. It describes the progressive experimental stages, starting with autoradiography and protein analysis and continuing on to a more functional approach testing the template properties of intact nuclei, as well as nuclei depleted of, or reconstituted with, defined fractions extracted from the chromatin of other cell lines or tissues. As new questions were raised at each phase of these studies, the investigation was shifted from chromosomal proteins to the role of a small RNA that coextracted with one protein fraction and whose properties suggested a transcription-activating function. The active RNA was identified as a class in RNA, designated as 7 SK. Its properties suggested a role in the activation of two oncogenes, the SV 40 T-antigen and the mammalian c-myc gene. A detailed analysis of the c-myc gene expression during transformation induction in temperature-sensitive mammalian cells finally culminated in in vivo evidence for a role of 7 SK in c-myc deregulation, using cells transfected with antisense oligonucleotides to block 7 SK activity. This was followed by an investigation of promoter targeting by 7 SK RNP using electrophoretic mobility shift assays with whole or 7 SK-depleted cell extracts. Taken together, these studies indicate that 7 SK RNP participates in transformation-dependent deregulation of the c-myc gene by activation of two c-myc minor promoters. The implications of these findings are discussed.Key words: chromatin structure, histones, nonhistones, 7 SK RNA, the c-myc gene, transcription regulation, SV 40, transformation.

scholarly journals The role of nonbilayer phospholipids in mitochondrial structure and function

FEBS Letters ◽  
2017 ◽  
Vol 592 (8) ◽  
pp. 1273-1290 ◽  
Author(s):  
Writoban Basu Ball ◽  
John K. Neff ◽  
Vishal M. Gohil
Keyword(s):  
Structure And Function ◽  
Mitochondrial Structure ◽  
And Function

scholarly journals The role of TORC1 in muscle development in Drosophila.

2014 ◽  
Author(s):  
Isabelle Hatfield ◽  
Innocence Harvey ◽  
Erika R. Yates ◽  
JeAnna R. Redd ◽  
Lawrence T. Reiter ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Muscle Development ◽  
Myosin Heavy Chain Isoforms ◽  
C2c12 Cells ◽  
Important Process ◽  
Mtorc1 Pathway ◽  
And Function ◽  
Muscle Precursor Cells

Myogenesis is an important process during both development and muscle repair. Previous studies suggest that mTORC1 plays a role in the formation of mature muscle from immature muscle precursor cells. Here we show that gene expression for several myogenic transcription factors including Myf5, Myog and Mef2c but not MyoD and myosin heavy chain isoforms decrease when C2C12 cells are treated with rapamycin, supporting a role for mTORC1 pathway during muscle development. To investigate the possibility that mTORC1 can regulate muscle in vivo we ablated the essential dTORC1 subunit Raptor in Drosophila melanogaster and found that muscle-specific knockdown of Raptor causes flies to be too weak to emerge from their pupal cases during eclosion. Using a series of GAL4 drivers we also show that muscle-specific Raptor knockdown also causes shortened lifespan, even when eclosure is unaffected. Together these results highlight an important role for TORC1 in muscle development, integrity and function in both Drosophila and mammalian cells.

scholarly journals Myc Stimulates Nuclearly Encoded Mitochondrial Genes and Mitochondrial Biogenesis

2005 ◽  
Vol 25 (14) ◽  
pp. 6225-6234 ◽  
Author(s):  
Feng Li ◽  
Yunyue Wang ◽  
Karen I. Zeller ◽  
James J. Potter ◽  
Diane R. Wonsey ◽  
...  
Keyword(s):  
Mitochondrial Biogenesis ◽  
Structure And Function ◽  
Wild Type ◽  
Primary Hepatocytes ◽  
Mitochondrial Mass ◽  
Mitochondrial Structure ◽  
Direct Binding ◽  
Rat Fibroblasts ◽  
And Function

ABSTRACT Although several genes involved in mitochondrial function are direct Myc targets, the role of Myc in mitochondrial biogenesis has not been directly established. We determined the effects of ectopic Myc expression or the loss of Myc on mitochondrial biogenesis. Induction of Myc in P493-6 cells resulted in increased oxygen consumption and mitochondrial mass and function. Conversely, compared to wild-type Myc fibroblasts, Myc null rat fibroblasts have diminished mitochondrial mass and decreased number of normal mitochondria. Reconstitution of Myc expression in Myc null fibroblasts partially restored mitochondrial mass and function and normal-appearing mitochondria. Concordantly, we also observed in primary hepatocytes that acute deletion of floxed murine Myc by Cre recombinase resulted in diminished mitochondrial mass in primary hepatocytes. Our microarray analysis of genes responsive to Myc in human P493-6 B lymphocytes supports a role for Myc in mitochondrial biogenesis, since genes involved in mitochondrial structure and function are overrepresented among the Myc-induced genes. In addition to the known direct binding of Myc to many genes involved in mitochondrial structure and function, we found that Myc binds the TFAM gene, which encodes a key transcriptional regulator and mitochondrial DNA replication factor, both in P493-6 lymphocytes with high ectopic MYC expression and in serum-stimulated primary human 2091 fibroblasts with induced endogenous MYC. These observations support a pivotal role for Myc in regulating mitochondrial biogenesis.

The role of recovery of mitochondrial structure and function in desiccation tolerance of pea seeds

2011 ◽  
Vol 144 (1) ◽  
pp. 20-34 ◽  
Author(s):  
Wei-Qing Wang ◽  
Hong-Yan Cheng ◽  
Ian M. Møller ◽  
Song-Quan Song
Keyword(s):  
Desiccation Tolerance ◽  
Structure And Function ◽  
Mitochondrial Structure ◽  
Pea Seeds ◽  
And Function

scholarly journals Role of Mitochondria-Cytoskeleton Interactions in the Regulation of Mitochondrial Structure and Function in Cancer Stem Cells

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1691
Author(s):  
Jungmin Kim ◽  
Jae-Ho Cheong
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
Energy Requirement ◽  
High Energy ◽  
Structure And Function ◽  
Mitochondrial Morphology ◽  
Voltage Dependent Anion Channel ◽  
Mesenchymal Transition ◽  
Mitochondrial Structure ◽  
And Function

Despite the promise of cancer medicine, major challenges currently confronting the treatment of cancer patients include chemoresistance and recurrence. The existence of subpopulations of cancer cells, known as cancer stem cells (CSCs), contributes to the failure of cancer therapies and is associated with poor clinical outcomes. Of note, one of the recently characterized features of CSCs is augmented mitochondrial function. The cytoskeleton network is essential in regulating mitochondrial morphology and rearrangement, which are inextricably linked to its functions, such as oxidative phosphorylation (OXPHOS). The interaction between the cytoskeleton and mitochondria can enable CSCs to adapt to challenging conditions, such as a lack of energy sources, and to maintain their stemness. Cytoskeleton-mediated mitochondrial trafficking and relocating to the high energy requirement region are crucial steps in epithelial-to-mesenchymal transition (EMT). In addition, the cytoskeleton itself interplays with and blocks the voltage-dependent anion channel (VDAC) to directly regulate bioenergetics. In this review, we describe the regulation of cellular bioenergetics in CSCs, focusing on the cytoskeleton-mediated dynamic control of mitochondrial structure and function.

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