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The International Journal of... Jan 2014Bone formation is controlled by osteoblasts, but the signaling proteins that control osteoblast differentiation and function are still unclear. We examined if the...
Bone formation is controlled by osteoblasts, but the signaling proteins that control osteoblast differentiation and function are still unclear. We examined if the dynamin GTPase, which is associated with actin remodeling and migration in other cells, plays a role in osteoblast differentiation and migration. Dynamin mRNA was expressed in primary osteoblasts throughout differentiation (0-21 days). However, alkaline phosphatase (ALP) activity, a marker of osteoblast differentiation, was decreased in osteoblasts over-expressing dynamin. Conversely, ALP activity was increased following shRNA-mediated knockdown of dynamin and in osteoblasts treated with the dynamin inhibitor, dynasore. Dynasore also reduced c-fos and osterix expression, markers of early osteoblasts, suggesting a role for dynamin in pre-osteoblast to osteoblast differentiation. Since dynamin GTPase activity is regulated by tyrosine phosphorylation, we examined the mechanism of dynamin dephosphorylation in osteoblasts. Dynamin formed a protein complex with the tyrosine phosphatase PTP-PEST and inhibition of phosphatase activity increased the level of phosphorylated dynamin. Further, PTP-PEST blocked the Src-mediated increase in the phosphorylation and GTPase activity of wild-type dynamin but not the phosphorylation mutant dynY231F/Y597F. Although ALP activity was increased in osteoblasts expressing GTPase-defective dynK44A, and to a lesser extent dynY231F/Y597F, osteoblast migration was significantly inhibited by dynK44A and dynY231F/Y597F. These studies demonstrate a novel role for dynamin GTPase activity and phosphorylation in osteoblast differentiation and migration, which may be important for bone formation.
Topics: Animals; Cell Differentiation; Cell Movement; Dynamins; Gene Knockdown Techniques; HEK293 Cells; Humans; Mice; Osteoblasts; Phosphorylation
PubMed: 24387844
DOI: 10.1016/j.biocel.2013.10.008 -
Biological Chemistry Nov 2018Dynamins are essential as membrane remodelers in various cellular processes, like receptor-mediated endocytosis, synaptic vesicle recycling and spermatogenesis.... (Review)
Review
Dynamins are essential as membrane remodelers in various cellular processes, like receptor-mediated endocytosis, synaptic vesicle recycling and spermatogenesis. Moreover, dynamin is involved in the internalization of numerous viruses and in the motility of several cancer cell lines. As tools for dissecting the underlying mechanisms of these important biological processes and as potential future therapeutics, small molecules have been developed in the last two decades that modulate the functions of dynamin. In this review we give an overview of the compound classes that are currently in use and describe how they affect dynamin function.
Topics: Animals; Dynamins; Humans; Models, Molecular; Molecular Structure; Small Molecule Libraries
PubMed: 30067507
DOI: 10.1515/hsz-2018-0257 -
Cell Reports Aug 2015Membrane trafficking and spinogenesis contribute significantly to changes in synaptic strength during development and in various paradigms of synaptic plasticity....
Membrane trafficking and spinogenesis contribute significantly to changes in synaptic strength during development and in various paradigms of synaptic plasticity. GTPases of the dynamin family are key players regulating membrane trafficking. Here, we identify a brain-specific dynamin family GTPase, neurolastin (RNF112/Znf179), with closest homology to atlastin. We demonstrate that neurolastin has functional GTPase and RING domains, making it a unique protein identified with this multi-enzymatic domain organization. We also show that neurolastin is a peripheral membrane protein that localizes to endosomes and affects endosomal membrane dynamics via its RING domain. In addition, neurolastin knockout mice have fewer dendritic spines, and rescue of the wild-type phenotype requires both the GTPase and RING domains. Furthermore, we find fewer functional synapses and reduced paired pulse facilitation in neurolastin knockout mice. Thus, we identify neurolastin as a dynamin family GTPase that affects endosome size and spine density.
Topics: Animals; Dendrites; Dynamins; Endosomes; HeLa Cells; Humans; Mice; Mice, Knockout; Protein Structure, Tertiary; Rats; Rats, Sprague-Dawley; Synapses
PubMed: 26212327
DOI: 10.1016/j.celrep.2015.06.064 -
Journal of Translational Medicine Oct 2023Extracellular matrix stiffness is emerging as a crucial mechanical cue that drives the progression of various diseases, such as cancer, fibrosis, and inflammation. The...
BACKGROUND
Extracellular matrix stiffness is emerging as a crucial mechanical cue that drives the progression of various diseases, such as cancer, fibrosis, and inflammation. The matrix stiffness of the nucleus pulposus (NP) tissues increase gradually during intervertebral disc degeneration (IDD), while the mechanism through which NP cells sense and react to matrix stiffness remains unclear. In addition, mitochondrial dynamics play a key role in various cellular functions. An in-depth investigation of the pathogenesis of IDD can provide new insights for the development of effective therapies. In this study, we aim to investigate the effects of matrix stiffness on mitochondrial dynamics in IDD.
METHODS
To build the gradient stiffness model, NP cells were cultured on polystyrene plates with different stiffness. Western blot analysis, and immunofluorescence staining were used to detect the expression of mitochondrial dynamics-related proteins. Flow cytometry was used to detect the mitochondrial membrane potential and intracellular Ca levels. Apoptosis related proteins, ROS level, and TUNEL staining were performed to assess the effect of substrate stiffness on NP cells.
RESULTS
Stiff substrate increased phosphorylation of dynamin-related protein 1 (Drp1) at Ser616 by activating extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, which promoted mitochondrial fission and apoptosis in NP cells. Furthermore, Piezo1 activation was involved in the regulation of the post-translational modifications of Drp1 and mitochondrial fission caused by matrix stiffness. Inhibition of Piezo1 and ERK1/2 can effectively reduce stiffness-induced ROS elevation and apoptosis in NP cells.
CONCLUSIONS
Our results revealed that stiff substrate causes Piezo1 activation and Ca influx, results in ERK1/2 activation and phosphorylation of Drp1 at S616, and finally leads to mitochondrial fission and apoptosis in NP cells. These findings reveal a new mechanism of mechanotransduction in NP cells, providing novel insights into the development of therapies for treating IDD.
Topics: Humans; Intervertebral Disc Degeneration; Mitochondrial Dynamics; Mechanotransduction, Cellular; Reactive Oxygen Species; Apoptosis; Dynamins; Intervertebral Disc
PubMed: 37817199
DOI: 10.1186/s12967-023-04590-w -
The EMBO Journal Feb 2016Vesicle release upon endocytosis requires membrane fission, catalyzed by the large GTPase dynamin. Dynamin contains five domains that together orchestrate its...
Vesicle release upon endocytosis requires membrane fission, catalyzed by the large GTPase dynamin. Dynamin contains five domains that together orchestrate its mechanochemical activity. Hydrogen-deuterium exchange coupled with mass spectrometry revealed global nucleotide- and membrane-binding-dependent conformational changes, as well as the existence of an allosteric relay element in the α2(S) helix of the dynamin stalk domain. As predicted from structural studies, FRET analyses detect large movements of the pleckstrin homology domain (PHD) from a 'closed' conformation docked near the stalk to an 'open' conformation able to interact with membranes. We engineered dynamin constructs locked in either the closed or open state by chemical cross-linking or deletion mutagenesis and showed that PHD movements function as a conformational switch to regulate dynamin self-assembly, membrane binding, and fission. This PHD conformational switch is impaired by a centronuclear myopathy-causing disease mutation, S619L, highlighting the physiological significance of its role in regulating dynamin function. Together, these data provide new insight into coordinated conformational changes that regulate dynamin function and couple membrane binding, oligomerization, and GTPase activity during dynamin-catalyzed membrane fission.
Topics: Cell Line; Dynamins; Fluorescence Resonance Energy Transfer; Guanosine Triphosphate; Humans; Hydrolysis; Intracellular Membranes; Magnetic Resonance Spectroscopy; Mutant Proteins; Protein Conformation; Protein Multimerization; Sequence Deletion
PubMed: 26783363
DOI: 10.15252/embj.201593477 -
Biochimica Et Biophysica Acta Jan 2013The studies addressing the molecular mechanisms governing mitochondrial fusion and fission have brought to light a small group of dynamin-like GTPases... (Review)
Review
The studies addressing the molecular mechanisms governing mitochondrial fusion and fission have brought to light a small group of dynamin-like GTPases (Guanosine-Triphosphate hydrolase) as central regulators of mitochondrial morphology and cristae remodeling, apoptosis, calcium signaling, and metabolism. One of them is the mammalian OPA1 (Optic atrophy 1) protein, which resides inside the mitochondrion anchored to the inner membrane and, in a cleaved form, is associated to oligomeric complexes, in the intermembrane space of the organelle. Here, we review the studies that have made OPA1 emerge as the best understood regulator of mitochondrial inner membrane fusion and cristae remodeling. Further, we re-examine the findings behind the recent claim that OPA1 mediates adrenergic control of lipolysis by functioning as a cytosolic A-kinase anchoring protein (AKAP), on the hemimembrane that envelops the lipid droplet. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.
Topics: Animals; Dynamins; GTP Phosphohydrolases; Gene Expression Regulation, Enzymologic; Humans; Lipolysis; Mitochondria; Mitochondrial Dynamics; Models, Biological; Yeasts
PubMed: 22902477
DOI: 10.1016/j.bbamcr.2012.08.004 -
Biomedicine & Pharmacotherapy =... Sep 2023Mitochondrial dysfunction, especially in terms of mitochondrial dynamics, has been reported to be closely associated with neuronal outcomes and neurological impairment... (Review)
Review
Mitochondrial dysfunction, especially in terms of mitochondrial dynamics, has been reported to be closely associated with neuronal outcomes and neurological impairment in cerebral ischemia/hypoxia injury. Dynamin-related protein 1 (Drp1) is a cytoplasmic GTPase that mediates mitochondrial fission and participates in neuronal cell death, calcium signaling, and oxidative stress. The neuroprotective role of Drp1 inhibition has been confirmed in several central nervous system disease models, demonstrating that targeting Drp1 may shed light on novel approaches for the treatment of cerebral ischemia/hypoxia injury. In this review, we aimed to highlight the roles of Drp1 in programmed cell death, oxidative stress, mitophagy, and mitochondrial function to provide a better understanding of mitochondrial disturbances in cerebral ischemia/hypoxia injury, and we also summarize the advances in novel chemical compounds targeting Drp1 to provide new insights into potential therapies for cerebral ischemia/hypoxia injury.
Topics: Humans; Brain Ischemia; Dynamins; Hypoxia; Mitochondria; Neurons; Animals
PubMed: 37516018
DOI: 10.1016/j.biopha.2023.115247 -
American Journal of Physiology. Cell... Jul 2018The constant physiological flux of mitochondrial fission and fusion is inextricably tied to the maintenance of cellular bioenergetics and the fluidity of mitochondrial... (Review)
Review
The constant physiological flux of mitochondrial fission and fusion is inextricably tied to the maintenance of cellular bioenergetics and the fluidity of mitochondrial networks. Yet, the intricacies of this dynamic duo remain unclear in diseases that encompass mitochondrial dysregulation. Particularly, the role of the GTPase fission protein dynamin-related protein 1 (Drp1) is of profound interest. Studies have identified that Drp1 participates in complex signaling pathways, suggesting that the function of mitochondria in pathophysiology may extend far beyond energetics alone. Research indicates that, in stressed conditions, Drp1 translocation to the mitochondria leads to elevated fragmentation and mitophagy; however, despite this, there is limited knowledge about the mechanistic regulation of Drp1 in disease conditions. This review highlights literature about fission, fusion, and, more importantly, discusses Drp1 in cardiac, neural, carcinogenic, renal, and pulmonary diseases. The therapeutic desirability for further research into its contribution to diseases that involve mitochondrial dysregulation is also discussed.
Topics: Animals; Dynamins; GTP Phosphohydrolases; Humans; Mitochondria; Mitochondrial Dynamics; Mitophagy
PubMed: 29669222
DOI: 10.1152/ajpcell.00042.2018 -
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 -
Cell Feb 2014Biological membranes undergo constant remodeling by membrane fission and fusion to change their shape and to exchange material between subcellular compartments. During... (Review)
Review
Biological membranes undergo constant remodeling by membrane fission and fusion to change their shape and to exchange material between subcellular compartments. During clathrin-mediated endocytosis, the dynamic assembly and disassembly of protein scaffolds comprising members of the bin-amphiphysin-rvs (BAR) domain protein superfamily constrain the membrane into distinct shapes as the pathway progresses toward fission by the GTPase dynamin. In this Review, we discuss how BAR domain protein assembly and disassembly are controlled in space and time and which structural and biochemical features allow the tight regulation of their shape and function to enable dynamin-mediated membrane fission.
Topics: Animals; Cell Membrane; Clathrin-Coated Vesicles; Dynamins; Endocytosis; Humans; Protein Structure, Tertiary
PubMed: 24581490
DOI: 10.1016/j.cell.2014.02.017