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Redox Biology Jan 2021Mitochondria are strategically trafficked throughout the cell by the action of microtubule motors, the actin cytoskeleton and adapter proteins. The intracellular...
Mitochondria are strategically trafficked throughout the cell by the action of microtubule motors, the actin cytoskeleton and adapter proteins. The intracellular positioning of mitochondria supports subcellular levels of ATP, Ca and reactive oxygen species (ROS, i.e. hydrogen peroxide, HO). Previous work from our group showed that deletion of the mitochondrial adapter protein Miro1 leads to perinuclear clustering of mitochondria, leaving the cell periphery devoid of mitochondria which compromises peripheral energy status. Herein, we report that deletion of Miro1 significantly restricts subcellular HO levels to the perinuclear space which directly affects intracellular responses to elevated mitochondrial ROS. Using the genetically encoded HO-responsive fluorescent biosensor HyPer7, we show that the highest levels of subcellular HO map to sites of increased mitochondrial density. Deletion of Miro1 or disruption of microtubule dynamics with Taxol significantly reduces peripheral HO levels. Following inhibition of mitochondrial complex 1 with rotenone we observe elevated spikes of HO in the cell periphery and complementary oxidation of mitochondrial peroxiredoxin 3 (PRX3) and cytosolic peroxiredoxin 2 (PRX2). Conversely, in cells lacking Miro1, rotenone did not increase peripheral HO or PRX2 oxidation but rather lead to increased nuclear HO and an elevated DNA-damage response. Lastly, local levels of HyPer7 oxidation correlate with the size and abundance of focal adhesions (FAs) in MEFs and cells lacking Miro1 have significantly smaller focal adhesions and reduced phosphorylation levels of vinculin and p130Cas compared to Miro1 MEFs. Together, we present evidence that the intracellular distribution of mitochondria influences subcellular HO levels and local cellular responses dependent on mitochondrial ROS.
Topics: Hydrogen Peroxide; Mitochondria; Mitochondrial Proteins; Oxidation-Reduction; Reactive Oxygen Species
PubMed: 33341544
DOI: 10.1016/j.redox.2020.101818 -
Plants (Basel, Switzerland) Feb 2022The response of chloroplasts to adverse environmental cues, principally increases in light intensity, stimulates chloroplast-to-nucleus retrograde signalling, which... (Review)
Review
The response of chloroplasts to adverse environmental cues, principally increases in light intensity, stimulates chloroplast-to-nucleus retrograde signalling, which leads to the induction of immediate protective responses and longer-term acclimation. Hydrogen peroxide (HO), generated during photosynthesis, is proposed to both initiate and transduce a retrograde signal in response to photoinhibitory light intensities. Signalling specificity achieved by chloroplast-sourced HO for signal transduction may be dependent upon the oft-observed close association of a proportion of these organelles with the nucleus. In this review, we consider more precisely the nature of the close association between a chloroplast appressed to the nucleus and the requirement for HO to cross both the double membranes of the chloroplast and nuclear envelopes. Of particular relevance is that the endoplasmic reticulum (ER) has close physical contact with chloroplasts and is contiguous with the nuclear envelope. Therefore, the perinuclear space, which transducing HO molecules would have to cross, may have an oxidising environment the same as the ER lumen. Based on studies in animal cells, the ER lumen may be a significant source of HO in plant cells arising from the oxidative folding of proteins. If this is the case, then there is potential for the ER lumen/perinuclear space to be an important location to modify chloroplast-to-nucleus HO signal transduction and thereby introduce modulation of it by additional different environmental cues. These would include for example, heat stress and pathogen infection, which induce the unfolded protein response characterised by an increased HO level in the ER lumen.
PubMed: 35214888
DOI: 10.3390/plants11040552 -
Nephrology, Dialysis, Transplantation :... 2002Adaptation to hypoxia is a topic of considerable clinical relevance, as it influences the pathophysiology of anaemia, polycythaemia, tissue ischaemia and cancer. A... (Review)
Review
Adaptation to hypoxia is a topic of considerable clinical relevance, as it influences the pathophysiology of anaemia, polycythaemia, tissue ischaemia and cancer. A growing number of physiologically relevant genes are regulated in response to changes in intracellular oxygen tension. These include genes encoding erythropoietin, vascular endothelial growth factor and tyrosine hydroxylase. Studies on the regulation of the erythropoietin gene have provided insights into the common mechanism of oxygen sensing and signal transduction, leading to activation of the hypoxia-inducible transcription factor 1 (HIF-1). Activation of HIF-1 by hypoxia depends on rescue of its alpha-subunit from oxygen-dependent degradation in the proteasome, allowing it to form a heterodimer with HIF-1 beta. This then translocates to the nucleus. There, HIF-1 assembles with a highly conserved orphan nuclear receptor, HNF-4, and a critical transcriptional adaptor, p300. This complex binds to a 3' enhancer on the erythropoietin gene, enabling transcription of erythropoietin. HIF-1 also activates other genes, the cis-acting elements of which contain cognate hypoxia response elements. There is growing evidence that the oxygen sensor is a flavohaem protein and that the signal transduction pathway involves changes in the level of intracellular reactive oxygen intermediates. We have recently cloned a novel fusion protein called cytochrome b5/b5 reductase, which is a cyanide-insensitive NADPH oxidase and, therefore, a candidate to be the oxygen sensor. This flavohaem protein is widely expressed in cell lines and tissues, with localization in the perinuclear space. In the presence of oxygen and iron, it may induce oxidative modifications that target HIF-1 alpha for ubiquitination and degradation.
Topics: Adaptation, Physiological; DNA-Binding Proteins; Erythropoietin; Gene Expression Regulation; Humans; Hypoxia; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Models, Biological; Nuclear Proteins; Oxygen; Structure-Activity Relationship; Transcription Factors
PubMed: 11812905
DOI: 10.1093/ndt/17.suppl_1.3 -
Frontiers in Endocrinology 2021Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that have become globally ubiquitous in humans and the environment. PFAS exposure is...
BACKGROUND
Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that have become globally ubiquitous in humans and the environment. PFAS exposure is associated with neurodevelopmental effects; however, the mechanism is poorly understood. Brain-derived neurotrophic factor (BDNF) signaling is critical to fetal neurodevelopment during pregnancy and maintains important regulatory roles later in life. This study aims to characterize placental BDNF signaling and investigate whether PFAS exposure disrupts the signaling pathway in placental trophoblast cells.
METHODS
The expression and localization of BDNF receptors-p75 and TrkB-in first trimester and term human placentas and trophoblast cells were investigated by immunofluorescence staining. To assess the effects of PFAS exposure on the BDNF pathway, BeWo cells were treated with PFAS mixtures that mimicked blood levels in a highly exposed population and major PFAS compounds in the mixture at 0.01, 0.1, 1, and 10 µM concentrations. Changes in pro-BDNF levels and phosphorylation of TrkB receptors were examined by Western blot.
RESULTS
In first trimester human placentas, TrkB and p75 receptors were primarily localized to syncytiotrophoblast and cytotrophoblast cells. At term, TrkB and p75 receptors were primarily observed in the placental villous stroma. TrkB receptor staining in trophoblasts was reduced at term, while p75 receptor staining was negative. TrkB receptors were confined to the nuclear and perinuclear spaces, and phosphorylation occurred at the Tyr816 residue in BeWo cells. Exposure to PFOS, PFOA, PFBS, and the six-PFAS mixture did not significantly affect BDNF levels or activation (phosphorylation) of TrkB. Treating cells with 1 μM and 10 μM of PFNA resulted in increased TrkB phosphorylation compared to unexposed controls, but BDNF levels were unchanged.
CONCLUSIONS
BDNF receptors are present in different regions of human placental villi, indicating diverse functions of BDNF signaling in placental development. Our findings suggest that the BDNF pathway in placental trophoblast cells is not disrupted by exposures to PFOS, PFOA, PFBS, and a PFAS mixture, but may be affected by PFNA exposures. Further investigation is needed on how PFAS affects other critical signaling pathways during fetal neurodevelopment.
Topics: Brain-Derived Neurotrophic Factor; Female; Fluorocarbons; Humans; Maternal Exposure; Membrane Glycoproteins; Phosphorylation; Placenta; Placentation; Pregnancy; Pregnancy Trimester, First; Receptor, trkB; Signal Transduction; Trophoblasts; Tumor Cells, Cultured
PubMed: 34394001
DOI: 10.3389/fendo.2021.694885 -
The Journal of Cell Biology Aug 2009The nucleus is the most prominent cellular organelle, and its sharp boundaries suggest the compartmentalization of the nucleoplasm from the cytoplasm. However, the... (Review)
Review
The nucleus is the most prominent cellular organelle, and its sharp boundaries suggest the compartmentalization of the nucleoplasm from the cytoplasm. However, the recent identification of evolutionarily conserved linkers of the nucleoskeleton to the cytoskeleton (LINC) complexes, a family of macromolecular assemblies that span the double membrane of the nuclear envelope, reveals tight physical connections between the two compartments. Here, we review the structure and evolutionary conservation of SUN and KASH domain-containing proteins, whose interaction within the perinuclear space forms the "nuts and bolts" of LINC complexes. Moreover, we discuss the function of these complexes in nuclear, centrosomal, and chromosome dynamics, and their connection to human disease.
Topics: Amino Acid Sequence; Animals; Cell Nucleus; Centrosome; Cytoskeleton; Evolution, Molecular; Humans; Membrane Proteins; Models, Molecular; Molecular Sequence Data; Multiprotein Complexes; Nuclear Envelope; Protein Structure, Tertiary; Sequence Alignment; Sequence Homology, Amino Acid
PubMed: 19687252
DOI: 10.1083/jcb.200906068 -
Advanced Science (Weinheim,... Nov 2023Advancing the technologies for cellular reprogramming with high efficiency has significant impact on regenerative therapy, disease modeling, and drug discovery....
Advancing the technologies for cellular reprogramming with high efficiency has significant impact on regenerative therapy, disease modeling, and drug discovery. Biophysical cues can tune the cell fate, yet the precise role of external physical forces during reprogramming remains elusive. Here the authors show that temporal cyclic-stretching of fibroblasts significantly enhances the efficiency of induced pluripotent stem cell (iPSC) production. Generated iPSCs are proven to express pluripotency markers and exhibit in vivo functionality. Bulk RNA-sequencing reveales that cyclic-stretching enhances biological characteristics required for pluripotency acquisition, including increased cell division and mesenchymal-epithelial transition. Of note, cyclic-stretching activates key mechanosensitive molecules (integrins, perinuclear actins, nesprin-2, and YAP), across the cytoskeletal-to-nuclear space. Furthermore, stretch-mediated cytoskeletal-nuclear mechano-coupling leads to altered epigenetic modifications, mainly downregulation in H3K9 methylation, and its global gene occupancy change, as revealed by genome-wide ChIP-sequencing and pharmacological inhibition tests. Single cell RNA-sequencing further identifies subcluster of mechano-responsive iPSCs and key epigenetic modifier in stretched cells. Collectively, cyclic-stretching activates iPSC reprogramming through mechanotransduction process and epigenetic changes accompanied by altered occupancy of mechanosensitive genes. This study highlights the strong link between external physical forces with subsequent mechanotransduction process and the epigenetic changes with expression of related genes in cellular reprogramming, holding substantial implications in the field of cell biology, tissue engineering, and regenerative medicine.
Topics: Mechanotransduction, Cellular; Cellular Reprogramming; Induced Pluripotent Stem Cells; Epigenesis, Genetic; RNA
PubMed: 37727069
DOI: 10.1002/advs.202303395 -
Diseases (Basel, Switzerland) Jun 2023Oxymetholone is one of the anabolic steroids that has widely been used among teenagers and athletes to increase their muscle bulk. It has undesirable effects on male...
Oxymetholone is one of the anabolic steroids that has widely been used among teenagers and athletes to increase their muscle bulk. It has undesirable effects on male health and fertility. In this study, the therapeutic effects of platelet-rich plasma (PRP) on oxymetholone-induced testicular toxicity were investigated in adult albino rats. During the experiments, 49 adult male albino rats were divided into 4 main groups: Group 0 (donor group) included 10 rats for the donation of PRP, Group I (control group) included 15 rats, Group II included 8 rats that received 10 mg/kg of oxymetholone orally, once daily, for 30 days, and Group III included 16 rats and was subdivided into 2 subgroups (IIIa and IIIb) that received oxymetholone the same as group II and then received PRP once and twice, respectively. Testicular tissues of all examined rats were obtained for processing and histological examination and sperm smears were stained and examined for sperm morphology. Oxymetholone-treated rats revealed wide spaces in between the tubules, vacuolated cytoplasm, and dark pyknotic nuclei of most cells, as well as deposition of homogenous acidophilic material between the tubules. Electron microscopic examination showed vacuolated cytoplasm of most cells, swollen mitochondria, and perinuclear dilatation. Concerning subgroup IIIa (PRP once), there was a partial improvement in the form of decreased vacuolations and regeneration of spermatogenic cells, as well as a reasonable improvement in sperm morphology. Regarding subgroup IIIb (PRP twice), histological sections revealed restoration of the normal testicular structure to a great extent, regeneration of the spermatogenic cells, and most sperms had normal morphology. Thus, it is recommended to use PRP to minimize structural changes in the testis of adult albino rats caused by oxymetholone.
PubMed: 37366872
DOI: 10.3390/diseases11020084 -
Cell Dec 2016In this issue of Cell, Skau et al. show that the formin FMN2 organizes a perinuclear actin cytoskeleton that protects the nucleus and its genomic content of migrating...
In this issue of Cell, Skau et al. show that the formin FMN2 organizes a perinuclear actin cytoskeleton that protects the nucleus and its genomic content of migrating cells squeezing through small spaces.
Topics: Actin Cytoskeleton; Actins; Cell Nucleus; Humans; Microfilament Proteins
PubMed: 27912053
DOI: 10.1016/j.cell.2016.11.024 -
Journal of Cell Science Mar 2009Positioning the nucleus is essential for the formation of polarized cells, pronuclear migration, cell division, cell migration and the organization of specialized... (Review)
Review
Positioning the nucleus is essential for the formation of polarized cells, pronuclear migration, cell division, cell migration and the organization of specialized syncytia such as mammalian skeletal muscles. Proteins that are required for nuclear positioning also function during chromosome movement and pairing in meiosis. Defects in these processes lead to human diseases including laminopathies. To properly position the nucleus or move chromosomes within the nucleus, the cell must specify the outer surface of the nucleus and transfer forces across both membranes of the nuclear envelope. KASH proteins are specifically recruited to the outer nuclear membrane by SUN proteins, which reside in the inner nuclear membrane. KASH and SUN proteins physically interact in the perinuclear space, forming a bridge across the two membranes of the nuclear envelope. The divergent N-terminal domains of KASH proteins extend from the surface of the nucleus into the cytoplasm and interact with the cytoskeleton, whereas the N-termini of SUN proteins extend into the nucleoplasm to interact with the lamina or chromatin. The bridge of SUN and KASH across the nuclear envelope functions to transfer forces that are generated in the cytoplasm into the nucleoplasm during nuclear migration, nuclear anchorage, centrosome attachment, intermediate-filament association and telomere clustering.
Topics: Animals; Cell Line; Cell Nucleus; Chromosomes; Humans; Models, Biological; Nuclear Envelope; Nuclear Proteins
PubMed: 19225124
DOI: 10.1242/jcs.037622 -
BioRxiv : the Preprint Server For... Jul 2023TorsinA is an atypical ATPase that lacks intrinsic activity unless it is bound to its activators lamina-associated polypeptide 1 (LAP1) in the perinuclear space or...
TorsinA is an atypical ATPase that lacks intrinsic activity unless it is bound to its activators lamina-associated polypeptide 1 (LAP1) in the perinuclear space or luminal domain-like LAP1 (LULL1) throughout the endoplasmic reticulum. However, the interaction of torsinA with LAP1 and LULL1 has not yet been shown to modulate a defined physiological process in mammals . We previously demonstrated that depletion of torsinA from mouse hepatocytes leads to reduced liver triglyceride secretion and marked steatosis, whereas depletion of LAP1 had more modest similar effects. We now show that depletion of LULL1 alone does not significantly decrease liver triglyceride secretion or cause steatosis. However, simultaneous depletion of both LAP1 and LULL1 from hepatocytes leads to defective triglyceride secretion and marked steatosis similar to that observed with depletion of torsinA. Our results demonstrate that torsinA and its activators dynamically regulate a physiological process in mammals .
PubMed: 37547008
DOI: 10.1101/2023.06.21.545957