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Chimia May 2018Our group at the University of Bern uses biochemical and biophysical techniques to unravel details of the molecular mechanism of membrane proteins. Of special interest...
Our group at the University of Bern uses biochemical and biophysical techniques to unravel details of the molecular mechanism of membrane proteins. Of special interest are the large multi-subunit complexes of the universally conserved respiratory chain and the ATP synthase that are found in mitochondria and aerobic bacteria. In a bottom-up approach using purified membrane proteins and synthetic lipids, we aim to mimic the basic processes of oxidative phosphorylation. We further develop methodologies to increase the complexity of such artificial systems, paving the way for a synthetic mitochondrion. In this minireview, we summarize recent efforts of our groups and others towards a synthetic respiratory chain.
Topics: Electron Transport; Mitochondria; Oxidative Phosphorylation
PubMed: 29789065
DOI: 10.2533/chimia.2018.291 -
Basic Research in Cardiology Sep 2023Giant mitochondria are frequently observed in different disease models within the brain, kidney, and liver. In cardiac muscle, these enlarged organelles are present... (Review)
Review
Giant mitochondria are frequently observed in different disease models within the brain, kidney, and liver. In cardiac muscle, these enlarged organelles are present across diverse physiological and pathophysiological conditions including in ageing and exercise, and clinically in alcohol-induced heart disease and various cardiomyopathies. This mitochondrial aberration is widely considered an early structural hallmark of disease leading to adverse organ function. In this thematic paper, we discuss the current state-of-knowledge on the presence, structure and functional implications of giant mitochondria in heart muscle. Despite its demonstrated reoccurrence in different heart diseases, the literature on this pathophysiological phenomenon remains relatively sparse since its initial observations in the early 60s. We review historical and contemporary investigations from cultured cardiomyocytes to human tissue samples to address the role of giant mitochondria in cardiac health and disease. Finally, we discuss their significance for the future development of novel mitochondria-targeted therapies to improve cardiac metabolism and functionality.
Topics: Humans; Myocytes, Cardiac; Mitochondrial Swelling; Mitochondria; Cardiomyopathies; Myocardium; Mitochondria, Heart
PubMed: 37775647
DOI: 10.1007/s00395-023-01011-3 -
Biochimica Et Biophysica Acta.... May 2022Mitochondrion is a double membrane organelle that is responsible for cellular respiration and production of most of the ATP in eukaryotic cells. Mitochondrial DNA... (Review)
Review
Mitochondrion is a double membrane organelle that is responsible for cellular respiration and production of most of the ATP in eukaryotic cells. Mitochondrial DNA (mtDNA) is the genetic material carried by mitochondria, which encodes some essential subunits of respiratory complexes independent of nuclear DNA. Normally, mtDNA binds to certain proteins to form a nucleoid that is stable in mitochondria. Nevertheless, a variety of physiological or pathological stresses can cause mtDNA damage, and the accumulation of damaged mtDNA in mitochondria leads to mitochondrial dysfunction, which triggers the occurrence of mitochondrial diseases in vivo. In response to mtDNA damage, cell initiates multiple pathways including mtDNA repair, degradation, clearance and release, to recover mtDNA, and maintain mitochondrial quality and cell homeostasis. In this review, we provide our current understanding of the fate of damaged mtDNA, focus on the pathways and mechanisms of removing damaged mtDNA in the cell.
Topics: DNA Damage; DNA Repair; DNA, Mitochondrial; Extracellular Vesicles; Humans; Mitochondria; Mitochondrial Diseases; Mitophagy; Signal Transduction; Ubiquitin-Protein Ligases
PubMed: 35131372
DOI: 10.1016/j.bbamcr.2022.119233 -
Biomolecules Dec 2023Mitochondria play a key role in cellular functions, including energy production and oxidative stress regulation. For this reason, maintaining mitochondrial homeostasis... (Review)
Review
Mitochondria play a key role in cellular functions, including energy production and oxidative stress regulation. For this reason, maintaining mitochondrial homeostasis and proteostasis (homeostasis of the proteome) is essential for cellular health. Therefore, there are different mitochondrial quality control mechanisms, such as mitochondrial biogenesis, mitochondrial dynamics, mitochondrial-derived vesicles (MDVs), mitophagy, or mitochondrial unfolded protein response (mtUPR). The last item is a stress response that occurs when stress is present within mitochondria and, especially, when the accumulation of unfolded and misfolded proteins in the mitochondrial matrix surpasses the folding capacity of the mitochondrion. In response to this, molecular chaperones and proteases as well as the mitochondrial antioxidant system are activated to restore mitochondrial proteostasis and cellular function. In disease contexts, mtUPR modulation holds therapeutic potential by mitigating mitochondrial dysfunction. In particular, in the case of neurodegenerative diseases, such as primary mitochondrial diseases, Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Amyotrophic Lateral Sclerosis (ALS), or Friedreich's Ataxia (FA), there is a wealth of evidence demonstrating that the modulation of mtUPR helps to reduce neurodegeneration and its associated symptoms in various cellular and animal models. These findings underscore mtUPR's role as a promising therapeutic target in combating these devastating disorders.
Topics: Animals; Neurodegenerative Diseases; Mitochondria; Mitochondrial Diseases; Aging; Unfolded Protein Response
PubMed: 38136659
DOI: 10.3390/biom13121789 -
International Journal of Molecular... Sep 2021In spite of the continuous improvement in our knowledge of the nature of cancer, the causes of its formation and the development of new treatment methods, our knowledge... (Review)
Review
In spite of the continuous improvement in our knowledge of the nature of cancer, the causes of its formation and the development of new treatment methods, our knowledge is still incomplete. A key issue is the difference in metabolism between normal and cancer cells. The features that distinguish cancer cells from normal cells are the increased proliferation and abnormal differentiation and maturation of these cells, which are due to regulatory changes in the emerging tumour. Normal cells use oxidative phosphorylation (OXPHOS) in the mitochondrion as a major source of energy during division. During OXPHOS, there are 36 ATP molecules produced from one molecule of glucose, in contrast to glycolysis which provides an ATP supply of only two molecules. Although aerobic glucose metabolism is more efficient, metabolism based on intensive glycolysis provides intermediate metabolites necessary for the synthesis of nucleic acids, proteins and lipids, which are in constant high demand due to the intense cell division in cancer. This is the main reason why the cancer cell does not "give up" on glycolysis despite the high demand for energy in the form of ATP. One of the evolving trends in the development of anti-cancer therapies is to exploit differences in the metabolism of normal cells and cancer cells. Currently constructed therapies, based on cell metabolism, focus on the attempt to reprogram the metabolic pathways of the cell in such a manner that it becomes possible to stop unrestrained proliferation.
Topics: Adenosine Triphosphate; Animals; Glucose; Glycolysis; Humans; Mitochondria; Neoplasms; Oxidative Phosphorylation
PubMed: 34502416
DOI: 10.3390/ijms22179507 -
Adipocyte Dec 2019Individual cell types vary enormously in the amount of different organelles they contain. One such organelle is the mitochondrion. Understanding how mitochondrial levels... (Review)
Review
Individual cell types vary enormously in the amount of different organelles they contain. One such organelle is the mitochondrion. Understanding how mitochondrial levels are controlled is essential since so many disease states seem to involve mitochondrial function. The beige adipocyte is an inducible form of adipocyte that emerges in response to cold exposure and some other external stimuli. To perform its thermogenic function, its level of mitochondria increases dramatically. If the stimuli are removed the mitochondrial levels return to base line. Following the withdrawal of external stimuli, beige adipocytes directly acquire a white fat-like phenotype through mitophagy-mediated mitochondrial degradation. The beige cell is therefore a dynamic model for studying the mechanism of mitochondrial biogenesis and degradation.
Topics: Adipocytes; Adipocytes, Beige; Adipose Tissue, Beige; Adipose Tissue, White; Animals; Humans; Mitochondria; Mitophagy; Organelle Biogenesis; Phenotype; Signal Transduction; Thermogenesis; Uncoupling Protein 1
PubMed: 30686106
DOI: 10.1080/21623945.2019.1574194 -
Molecular Medicine Reports May 2019Leucine zipper/EF‑hand‑containing transmembrane protein 1 (LETM1) has been identified as the gene responsible for Wolf‑Hirschhorn syndrome (WHS), which is... (Review)
Review
Leucine zipper/EF‑hand‑containing transmembrane protein 1 (LETM1) has been identified as the gene responsible for Wolf‑Hirschhorn syndrome (WHS), which is characterized by intellectual disability, epilepsy, growth delay and craniofacial dysgenesis. LETM1 is a mitochondrial inner membrane protein that encodes a homolog of the yeast protein Mdm38, which is involved in mitochondrial morphology. In the present review, the importance of LETM1 in WHS and its role within the mitochondrion was explored. LETM1 governs the mitochondrion ion channel and is involved in mitochondrial respiration. Recent studies have reported that LETM1 acts as a mitochondrial Ca2+/H+ antiporter. LETM1 has also been identified as a K+/H+ exchanger, and serves a role in Mg2+ homeostasis. The function of LETM1 in mitochondria regulation is regulated by its binding partners, carboxyl‑terminal modulator protein and mitochondrial ribosomal protein L36. Therefore, we describe the remarkable role of LETM1 in mitochondrial network physiology and its function in mitochondrion‑mediated cell death. In the context of these findings, we suggest that the participation of LETM1 in tumorigenesis through the alteration of cancer metabolism should be investigated. This review provides a comprehensive description of LETM1 function, which is required for mitochondrial homeostasis and cellular viability.
Topics: Animals; Calcium-Binding Proteins; Cell Survival; Cell Transformation, Neoplastic; Energy Metabolism; Homeostasis; Humans; Membrane Proteins; Mitochondria; Structure-Activity Relationship
PubMed: 30896806
DOI: 10.3892/mmr.2019.10041 -
Proceedings of the National Academy of... Apr 2023Coenzyme A (CoA) biosynthesis is an excellent target for antimalarial intervention. While most studies have focused on the use of CoA to produce acetyl-CoA in the...
Coenzyme A (CoA) biosynthesis is an excellent target for antimalarial intervention. While most studies have focused on the use of CoA to produce acetyl-CoA in the apicoplast and the cytosol of malaria parasites, mitochondrial acetyl-CoA production is less well understood. In the current study, we performed metabolite-labeling experiments to measure endogenous metabolites in lines with genetic deletions affecting mitochondrial dehydrogenase activity. Our results show that the mitochondrion is required for cellular acetyl-CoA biosynthesis and identify a synthetic lethal relationship between the two main ketoacid dehydrogenase enzymes. The activity of these enzymes is dependent on the lipoate attachment enzyme LipL2, which is essential for parasite survival solely based on its role in supporting acetyl-CoA metabolism. We also find that acetyl-CoA produced in the mitochondrion is essential for the acetylation of histones and other proteins outside of the mitochondrion. Taken together, our results demonstrate that the mitochondrion is required for cellular acetyl-CoA metabolism and protein acetylation essential for parasite survival.
Topics: Plasmodium falciparum; Acetyl Coenzyme A; Acetylation; Mitochondria; Oxidoreductases
PubMed: 37068227
DOI: 10.1073/pnas.2210929120 -
Oxidative Medicine and Cellular... 2016Reactive oxygen species (ROS) play a crucial role in the inflammatory response and cytokine outbreak, such as during virus infections, diabetes, cancer, cardiovascular... (Review)
Review
Reactive oxygen species (ROS) play a crucial role in the inflammatory response and cytokine outbreak, such as during virus infections, diabetes, cancer, cardiovascular diseases, and neurodegenerative diseases. Therefore, antioxidant is an important medicine to ROS-related diseases. For example, ascorbic acid (vitamin C, VC) was suggested as the candidate antioxidant to treat multiple diseases. However, long-term use of high-dose VC causes many side effects. In this review, we compare and analyze all kinds of mitochondrion-permeable antioxidants, including edaravone, idebenone, α-Lipoic acid, carotenoids, vitamin E, and coenzyme Q10, and mitochondria-targeted antioxidants MitoQ and SkQ and propose astaxanthin (a special carotenoid) to be the best antioxidant for ROS-burst-mediated acute diseases, like avian influenza infection and ischemia-reperfusion. Nevertheless, astaxanthins are so unstable that most of them are inactivated after oral administration. Therefore, astaxanthin injection is suggested hypothetically. The drawbacks of the antioxidants are also reviewed, which limit the use of antioxidants as coadjuvants in the treatment of ROS-associated disorders.
Topics: Acute Disease; Administration, Oral; Animals; Antioxidants; Humans; Mitochondria; Reactive Oxygen Species; Respiratory Burst
PubMed: 26649144
DOI: 10.1155/2016/6859523 -
Antioxidants & Redox Signaling May 2011The mitochondrion is an organelle that carries out a number of important metabolic processes such as fatty acid oxidation, the citric acid cycle, and oxidative... (Review)
Review
The mitochondrion is an organelle that carries out a number of important metabolic processes such as fatty acid oxidation, the citric acid cycle, and oxidative phosphorylation. However, this multitasking organelle also generates reactive oxygen species (ROS), which can cause oxidative stress resulting in self-damage. This type of mitochondrial damage can lead to the further production of ROS and a resulting downward spiral with regard to mitochondrial capability. This is extremely problematic because the accumulation of dysfunctional mitochondria is related to aging, cancer, and neurodegenerative diseases. Accordingly, appropriate quality control of this organelle is important to maintain proper cellular homeostasis. It has been thought that selective mitochondria autophagy (mitophagy) contributes to the maintenance of mitochondrial quality by eliminating damaged or excess mitochondria, although little is known about the mechanism. Recent studies in yeast identified several mitophagy-related proteins, which have been characterized with regard to their function and regulation. In this article, we review recent advances in the physiology and molecular mechanism of mitophagy and discuss the similarities and differences of this degradation process between yeast and mammalian cells.
Topics: Autophagy; Fungal Proteins; Mitochondria; Yeasts
PubMed: 21194379
DOI: 10.1089/ars.2010.3762