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EMBO Reports Jun 2023Mycobacterium tuberculosis (Mtb) secretes extracellular vesicles (EVs) containing a variety of proteins, lipoproteins, and lipoglycans. While emerging evidence suggests...
Mycobacterium tuberculosis (Mtb) secretes extracellular vesicles (EVs) containing a variety of proteins, lipoproteins, and lipoglycans. While emerging evidence suggests that EVs contribute to tuberculosis pathogenesis, the factors and molecular mechanisms involved in mycobacterial EV production have not been identified. In this study, we use a genetic approach to identify Mtb proteins that mediate vesicle release in response to iron limitation and antibiotic exposure. We uncover a critical role for the isoniazid-induced, dynamin-like proteins, IniA and IniC, in mycobacterial EV biogenesis. Further characterization of a Mtb iniA mutant shows that the production of EVs enables intracellular Mtb to export bacterial components into the extracellular environment to communicate with host cells and potentially modulate the immune response. The findings advance our understanding of the biogenesis and functions of mycobacterial EVs and provide an avenue for targeting vesicle production in vivo.
Topics: Humans; Mycobacterium tuberculosis; Tuberculosis; Extracellular Vesicles; Isoniazid; Dynamins
PubMed: 37079766
DOI: 10.15252/embr.202255593 -
Cells Jul 2023Mitochondria, which generate ATP through aerobic respiration, also have important noncanonical functions. Mitochondria are dynamic organelles, that engage in fission... (Review)
Review
Mitochondria, which generate ATP through aerobic respiration, also have important noncanonical functions. Mitochondria are dynamic organelles, that engage in fission (division), fusion (joining) and translocation. They also regulate intracellular calcium homeostasis, serve as oxygen-sensors, regulate inflammation, participate in cellular and organellar quality control and regulate the cell cycle. Mitochondrial fission is mediated by the large GTPase, dynamin-related protein 1 (Drp1) which, when activated, translocates to the outer mitochondrial membrane (OMM) where it interacts with binding proteins (Fis1, MFF, MiD49 and MiD51). At a site demarcated by the endoplasmic reticulum, fission proteins create a macromolecular ring that divides the organelle. The functional consequence of fission is contextual. Physiological fission in healthy, nonproliferating cells mediates organellar quality control, eliminating dysfunctional portions of the mitochondria via mitophagy. Pathological fission in somatic cells generates reactive oxygen species and triggers cell death. In dividing cells, Drp1-mediated mitotic fission is critical to cell cycle progression, ensuring that daughter cells receive equitable distribution of mitochondria. Mitochondrial fusion is regulated by the large GTPases mitofusin-1 (Mfn1) and mitofusin-2 (Mfn2), which fuse the OMM, and optic atrophy 1 (OPA-1), which fuses the inner mitochondrial membrane. Mitochondrial fusion mediates complementation, an important mitochondrial quality control mechanism. Fusion also favors oxidative metabolism, intracellular calcium homeostasis and inhibits cell proliferation. Mitochondrial lipids, cardiolipin and phosphatidic acid, also regulate fission and fusion, respectively. Here we review the role of mitochondrial dynamics in health and disease and discuss emerging concepts in the field, such as the role of central versus peripheral fission and the potential role of dynamin 2 (DNM2) as a fission mediator. In hyperproliferative diseases, such as pulmonary arterial hypertension and cancer, Drp1 and its binding partners are upregulated and activated, positing mitochondrial fission as an emerging therapeutic target.
Topics: Humans; Mitochondrial Dynamics; Pulmonary Arterial Hypertension; Calcium; Dynamins; GTP Phosphohydrolases; Cell Cycle; Neoplasms
PubMed: 37508561
DOI: 10.3390/cells12141897 -
International Journal of Molecular... Mar 2018The endosymbiosis of a free-living cyanobacterium into an ancestral eukaryote led to the evolution of the chloroplast (plastid) more than one billion years ago. Given... (Review)
Review
The endosymbiosis of a free-living cyanobacterium into an ancestral eukaryote led to the evolution of the chloroplast (plastid) more than one billion years ago. Given their independent origins, plastid proliferation is restricted to the binary fission of pre-existing plastids within a cell. In the last 25 years, the structure of the supramolecular machinery regulating plastid division has been discovered, and some of its component proteins identified. More recently, isolated plastid-division machineries have been examined to elucidate their structural and mechanistic details. Furthermore, complex studies have revealed how the plastid-division machinery morphologically transforms during plastid division, and which of its component proteins play a critical role in generating the contractile force. Identifying the three-dimensional structures and putative functional domains of the component proteins has given us hints about the mechanisms driving the machinery. Surprisingly, the mechanisms driving plastid division resemble those of mitochondrial division, indicating that these division machineries likely developed from the same evolutionary origin, providing a key insight into how endosymbiotic organelles were established. These findings have opened new avenues of research into organelle proliferation mechanisms and the evolution of organelles.
Topics: Arabidopsis Proteins; Chloroplasts; Dynamins; Organelle Biogenesis
PubMed: 29510533
DOI: 10.3390/ijms19030733 -
Hypertension (Dallas, Tex. : 1979) Jul 2020Endothelial inflammation and mitochondrial dysfunction have been implicated in cardiovascular diseases, yet, a unifying mechanism tying them together remains limited....
Endothelial inflammation and mitochondrial dysfunction have been implicated in cardiovascular diseases, yet, a unifying mechanism tying them together remains limited. Mitochondrial dysfunction is frequently associated with mitochondrial fission/fragmentation mediated by the GTPase Drp1 (dynamin-related protein 1). Nuclear factor (NF)-κB, a master regulator of inflammation, is implicated in endothelial dysfunction and resultant complications. Here, we explore a causal relationship between mitochondrial fission and NF-κB activation in endothelial inflammatory responses. In cultured endothelial cells, TNF-α (tumor necrosis factor-α) or lipopolysaccharide induces mitochondrial fragmentation. Inhibition of Drp1 activity or expression suppresses mitochondrial fission, NF-κB activation, vascular cell adhesion molecule-1 induction, and leukocyte adhesion induced by these proinflammatory factors. Moreover, attenuations of inflammatory leukocyte adhesion were observed in Drp1 heterodeficient mice as well as endothelial Drp1 silenced mice. Intriguingly, inhibition of the canonical NF-κB signaling suppresses endothelial mitochondrial fission. Mechanistically, NF-κB p65/RelA seems to mediate inflammatory mitochondrial fission in endothelial cells. In addition, the classical anti-inflammatory drug, salicylate, seems to maintain mitochondrial fission/fusion balance against TNF-α via inhibition of NF-κB. In conclusion, our results suggest a previously unknown mechanism whereby the canonical NF-κB cascade and a mitochondrial fission pathway interdependently regulate endothelial inflammation.
Topics: 3T3 Cells; Animals; Aorta; Cell Adhesion; Cells, Cultured; Dynamins; Endothelial Cells; Endothelium, Vascular; Leukocytes, Mononuclear; Membrane Proteins; Mice; Mitochondrial Dynamics; Mitochondrial Proteins; Mutation, Missense; NF-kappa B; Phosphorylation; Phosphoserine; Protein Processing, Post-Translational; Proteome; RNA Interference; RNA, Small Interfering; Rats; Sodium Salicylate; Tumor Necrosis Factor-alpha; Vascular Cell Adhesion Molecule-1; Vasculitis
PubMed: 32389075
DOI: 10.1161/HYPERTENSIONAHA.120.14686 -
Biochemistry. Biokhimiia Sep 2014In addition to the intracellular transport of particles (cargo) along microtubules, there are in the cell two actin-based transport systems. In the actomyosin system the... (Review)
Review
In addition to the intracellular transport of particles (cargo) along microtubules, there are in the cell two actin-based transport systems. In the actomyosin system the transport is driven by myosin, which moves the cargo along actin microfilaments. This transport requires the hydrolysis of ATP in the myosin molecule motor domain that induces conformational changes in the molecule resulting in the myosin movement along the actin filament. The other actin-based transport system of the cell does not involve myosin or other motor proteins. This system is based on a unidirectional actin polymerization, which depends on ATP hydrolysis in actin polymers and is initiated by proteins bound to the surface of transported particles. Obligatory components of the actin-based transport are proteins of the WASP/Scar family and a complex of Arp2/3 proteins. Moreover, the actin-based systems often contain dynamin and cortactin. It is known that a system of actin filaments formed on the surface of particles, the so-called "comet-like tail", is responsible for intracellular movements of pathogenic bacteria, micropinocytotic vesicles, clathrin-coated vesicles, and phagosomes. This movement is reproduced in a cell-free system containing extract of Xenopus oocytes. The formation of a comet-like structure capable of transporting vesicles from the plasma membrane into the cell depth has been studied in detail by high performance electron microscopy combined with electron tomography. A similar mechanism provides the movement of vesicles containing membrane rafts enriched with sphingolipids and cholesterol, changes in position of the nuclear spindle at meiosis, and other processes. This review will consider current ideas about actin polymerization and its regulation by actin-binding proteins and show how these mechanisms are realized in the intracellular actin-based vesicular transport system.
Topics: Actins; Animals; Bacteria; Biological Transport; Cytoplasmic Vesicles; Dynamins; Humans; Microtubules; Movement; Polymerization
PubMed: 25385019
DOI: 10.1134/S0006297914090089 -
The FEBS Journal Jun 2022Nek4 is a serine/threonine kinase which has been implicated in primary cilia stabilization, DNA damage response, autophagy and epithelial-to-mesenchymal transition. The...
Nek4 is a serine/threonine kinase which has been implicated in primary cilia stabilization, DNA damage response, autophagy and epithelial-to-mesenchymal transition. The role of Nek4 in cancer cell survival and chemotherapy resistance has also been shown. However, the precise mechanisms by which Nek4 operates remain to be elucidated. Here, we show that Nek4 overexpression activates mitochondrial respiration coupled to ATP production, which is paralleled by increased mitochondrial membrane potential, and resistance to mitochondrial DNA damage. Congruently, Nek4 depletion reduced mitochondrial respiration and mtDNA integrity. Nek4 deficiency caused mitochondrial elongation, probably via reduced activity of the fission protein DRP1. In Nek4 overexpressing cells, the increase in mitochondrial fission was concomitant to enhanced phosphorylation of DRP1 and Erk1/2 proteins, and the effects on mitochondrial respiration were abolished in the presence of a DRP1 inhibitor. This study shows Nek4 as a novel regulator of mitochondrial function that may explain the joint appearance of high mitochondrial respiration and mitochondrial fragmentation.
Topics: DNA, Mitochondrial; Dynamins; Mitochondria; Mitochondrial Dynamics; Mitochondrial Proteins; Phosphorylation; Respiration
PubMed: 34986513
DOI: 10.1111/febs.16343 -
Proceedings of the National Academy of... Aug 2021Pancreatic β cells operate with a high rate of membrane recycling for insulin secretion, yet endocytosis in these cells is not fully understood. We investigate this...
Pancreatic β cells operate with a high rate of membrane recycling for insulin secretion, yet endocytosis in these cells is not fully understood. We investigate this process in mature mouse β cells by genetically deleting dynamin GTPase, the membrane fission machinery essential for clathrin-mediated endocytosis. Unexpectedly, the mice lacking all three dynamin genes (, , ) in their β cells are viable, and their β cells still contain numerous insulin granules. Endocytosis in these β cells is severely impaired, resulting in abnormal endocytic intermediates on the plasma membrane. Although insulin granules are abundant, their release upon glucose stimulation is blunted in both the first and second phases, leading to hyperglycemia and glucose intolerance in mice. Dynamin triple deletion impairs insulin granule exocytosis and decreases intracellular Ca responses and granule docking. The docking defect is correlated with reduced expression of Munc13-1 and RIM1 and reorganization of cortical F-actin in β cells. Collectively, these findings uncover the role of dynamin in dense-core vesicle endocytosis and secretory capacity. Insulin secretion deficiency in the absence of dynamin-mediated endocytosis highlights the risk of impaired membrane trafficking in endocrine failure and diabetes pathogenesis.
Topics: Animals; Blood Glucose; Calcium Signaling; Dense Core Vesicles; Dynamin II; Dynamins; Endocytosis; Female; GTP-Binding Proteins; Hyperglycemia; Insulin Secretion; Insulin-Secreting Cells; Male; Mice, Knockout; Mice, Transgenic; Nerve Tissue Proteins; Mice
PubMed: 34362840
DOI: 10.1073/pnas.2021764118 -
Critical Reviews in Oncogenesis 2015Dynamins and BAR proteins are crucial in a wide variety of cellular processes for their ability to mediate membrane remodeling, such as membrane curvature and membrane... (Review)
Review
Dynamins and BAR proteins are crucial in a wide variety of cellular processes for their ability to mediate membrane remodeling, such as membrane curvature and membrane fission and fusion. In this review, we highlight dynamins and BAR proteins and the cellular mechanisms that are involved in the initiation and progression of cancer. We specifically discuss the roles of the seproteinsin endocytosis, endo-lysosomal trafficking, autophagy, and apoptosis as these processes are all tightly linked to membrane remodeling and cancer.
Topics: Animals; Apoptosis; Autophagy; Cell Transformation, Neoplastic; Dynamins; Endocytosis; Female; GTP Phosphohydrolases; Humans; Male; Neoplasms
PubMed: 27279242
DOI: 10.1615/CritRevOncog.v20.i5-6.160 -
Cells Aug 2019The purpose of this article is to highlight the role of dynamin-related protein 1 (Drp1) in abnormal mitochondrial dynamics, mitochondrial fragmentation,... (Review)
Review
The purpose of this article is to highlight the role of dynamin-related protein 1 (Drp1) in abnormal mitochondrial dynamics, mitochondrial fragmentation, autophagy/mitophagy, and neuronal damage in Alzheimer's disease (AD) and other neurological diseases, including Parkinson's, Huntington's, amyotrophic lateral sclerosis, multiple sclerosis, diabetes, and obesity. Dynamin-related protein 1 is one of the evolutionarily highly conserved large family of GTPase proteins. Drp1 is critical for mitochondrial division, size, shape, and distribution throughout the neuron, from cell body to axons, dendrites, and nerve terminals. Several decades of intense research from several groups revealed that Drp1 is enriched at neuronal terminals and involved in synapse formation and synaptic sprouting. Different phosphorylated forms of Drp1 acts as both increased fragmentation and/or increased fusion of mitochondria. Increased levels of Drp1 were found in diseased states and caused excessive fragmentation of mitochondria, leading to mitochondrial dysfunction and neuronal damage. In the last two decades, several Drp1 inhibitors have been developed, including Mdivi-1, Dynasore, P110, and DDQ and their beneficial effects tested using cell cultures and mouse models of neurodegenerative diseases. Recent research using genetic crossing studies revealed that a partial reduction of Drp1 is protective against mutant protein(s)-induced mitochondrial and synaptic toxicities. Based on findings from cell cultures, mouse models and postmortem brains of AD and other neurodegenerative disease, we cautiously conclude that reduced Drp1 is a promising therapeutic target for AD and other neurological diseases.
Topics: Animals; Dynamins; Humans; Mice; Mitochondria; Neurodegenerative Diseases
PubMed: 31450774
DOI: 10.3390/cells8090961 -
Oncotarget Jun 2017Dynamins and their related proteins participate in the regulation of neurotransmission, antigen presentation, receptor internalization, growth factor signalling,... (Review)
Review
Dynamins and their related proteins participate in the regulation of neurotransmission, antigen presentation, receptor internalization, growth factor signalling, nutrient uptake, and pathogen infection. Recently, emerging findings have shown dynamin proteins can also contribute to the genesis of cancer. This up-to-date review herein focuses on the functionality of dynamin in cancer development. Dynamin 1 and 2 both enhance cancer cell proliferation, tumor invasion and metastasis, whereas dynamin 3 has tumor suppression role. Antisense RNAs encoded on the DNA strand opposite a dynamin gene regulate the function of dynamin, and manipulate oncogenes and tumor suppressor genes. Certain dynamin-related proteins are also upregulated in distinct cancer conditions, resulting in apoptotic resistance, cell migration and poor prognosis. Altogether, dynamins are potential biomarkers as well as representing promising novel therapeutic targets for cancer treatment. This study also summarizes the current available dynamin-targeted therapeutics and suggests the potential strategy based on signalling pathways involved, providing important information to aid the future development of novel cancer therapeutics by targeting these dynamin family members.
Topics: Biological Transport; Carcinogenesis; Dynamins; Humans; Neoplasms; Protein Isoforms
PubMed: 28402939
DOI: 10.18632/oncotarget.16678