ING2 (Inhibitor of Growth 2) is a tumor suppressor gene that has been implicated in critical biological functions (cell-cycle regulation, replicative senescence, DNA repair and DNA replication), most ...of which are recognized hallmarks of tumorigenesis occurring in the cell nucleus. As its close homolog ING1 has been recently observed in the mitochondrial compartment, we hypothesized that ING2 could also translocate into the mitochondria and be involved in new biological functions. In the present study, we demonstrate that ING2 is imported in the inner mitochondrial fraction in a redox-sensitive manner in human cells and that this mechanism is modulated by 14-3-3η protein expression. Remarkably, ING2 is necessary to maintain mitochondrial ultrastructure integrity without interfering with mitochondrial networks or polarization. We observed an interaction between ING2 and mtDNA under basal conditions. This interaction appears to be mediated by TFAM, a critical regulator of mtDNA integrity. The loss of mitochondrial ING2 does not impair mtDNA repair, replication or transcription but leads to a decrease in mitochondrial ROS production, suggesting a detrimental impact on OXPHOS activity. We finally show using multiple models that ING2 is involved in mitochondrial respiration and that its loss confers a protection against mitochondrial respiratory chain inhibition in vitro. Consequently, we propose a new tumor suppressor role for ING2 protein in the mitochondria as a metabolic shift gatekeeper during tumorigenesis.
Visual deficit is one of the complications of Huntington disease (HD), a fatal neurological disorder caused by CAG trinucleotide expansions in the
gene, leading to the production of mutant Huntingtin ...(mHTT) protein. Transgenic HD R6/1 mice expressing human HTT exon1 with 115 CAG repeats recapitulate major features of the human pathology and exhibit a degeneration of the retina. Our aim was to gain insight into the ultrastructure of the pathological HD R6/1 retina by electron microscopy (EM). We show that the HD R6/1 retina is enriched with unusual organelles myelinosomes, produced by retinal neurons and glia. Myelinosomes are present in all nuclear and plexiform layers, in the synaptic terminals of photoreceptors, in the processes of retinal neurons and glial cells, and in the subretinal space. In vitro study shows that myelinosomes secreted by human retinal glial Müller MIO-M1 cells transfected with
carry EGFP-mHTT-exon1 protein, as revealed by immuno-EM and Western-blotting. Myelinosomes loaded with mHTT-exon1 are incorporated by naive neuronal/neuroblastoma SH-SY5Y cells. This results in the emergence of mHTT-exon1 in recipient cells. This process is blocked by membrane fusion inhibitor MDL 28170. Conclusion: Incorporation of myelinosomes carrying mHTT-exon1 in recipient cells may contribute to HD spreading in the retina. Exploring ocular fluids for myelinosome presence could bring an additional biomarker for HD diagnostics.
Marine microalgae are known to be a source of bioactive molecules of interest to human health, such as n-3 polyunsaturated fatty acids (n-3 PUFAs) and carotenoids. The fact that some of these natural ...compounds are known to exhibit anti-inflammatory, antioxidant, anti-proliferative, and apoptosis-inducing effects, demonstrates their potential use in preventing cancers and cardiovascular diseases (CVDs). Benzoapyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), is an ubiquitous environmental pollutant known to contribute to the development or aggravation of human diseases, such as cancer, CVDs, and immune dysfunction. Most of these deleterious effects are related to the activation of the polycyclic aromatic hydrocarbon receptor (AhR). In this context, two ethanolic microalgal extracts with concentrations of 0.1 to 5 µg/mL are tested,
(OT) and
(PT), in order to evaluate and compare their potential effects towards BaP-induced toxicity in endothelial HMEC-1 cells. Our results indicate that the OT extract can influence the toxicity of BaP. Indeed, apoptosis and the production of extracellular vesicles were decreased, likely through the reduction of the expression of CYP1A1, a BaP bioactivation enzyme. Furthermore, the BaP-induced expression of the inflammatory cytokines IL-8 and IL1-β was reduced. The PT extract only inhibited the expression of the BaP-induced cytokine IL-8 expression. The OT extract therefore seems to be a good candidate for counteracting the BaP toxicity.
Aluminum (Al) is one of the most common elements in the earth crust and increasingly used in food, consumer products and packaging. Its hazard potential for humans is still not completely understood. ...Besides the metallic form, Al also exists as mineral, including the insoluble oxide, and in soluble ionic forms. Representatives of these three species, namely a metallic and an oxidic species of Al-containing nanoparticles and soluble aluminum chloride, were applied to human intestinal cell lines as models for the intestinal barrier. We characterized physicochemical particle parameters, protein corona composition, ion release and cellular uptake. Different in vitro assays were performed to determine potential effects and molecular modes of action related to the individual chemical species. For a deeper insight into signaling processes, microarray transcriptome analyses followed by bioinformatic data analysis were employed. The particulate Al species showed different solubility in biological media. Metallic Al nanoparticles released more ions than Al
O
nanoparticles, while AlCl
showed a mixture of dissolved and agglomerated particulate entities in biological media. The protein corona composition differed between both nanoparticle species. Cellular uptake, investigated in transwell experiments, occurred predominantly in particulate form, whereas ionic Al was not taken up by intestinal cell lines. Transcellular transport was not observed. None of the Al species showed cytotoxic effects up to 200 µg Al/mL. The transcriptome analysis indicated mainly effects on oxidative stress pathways, xenobiotic metabolism and metal homeostasis. We have shown for the first time that intestinal cellular uptake of Al occurs preferably in the particle form, while toxicological effects appear to be ion-related.
Most tumors undergo metabolic reprogramming towards glycolysis, the so-called Warburg effect, to support growth and survival. Overexpression of IF1, the physiological inhibitor of the F0F1ATPase, has ...been related to this phenomenon and appears to be a relevant marker in cancer. Environmental contributions to cancer development are now widely accepted but little is known about the underlying intracellular mechanisms. Among the environmental pollutants humans are commonly exposed to, benzoapyrene (BaP), the prototype molecule of polycyclic aromatic hydrocarbons (PAHs), is a well-known human carcinogen. Besides apoptotic signals, BaP can also induce survival signals in liver cells, both likely involved in cancer promotion. Our previous works showed that BaP elicited a Warburg-like effect, thus favoring cell survival. The present study aimed at further elucidating the molecular mechanisms involved in the BaP-induced metabolic reprogramming, by testing the possible involvement of IF1. We presently demonstrate, both in vitro and in vivo, that PAHs, especially BaP, strongly increase IF1 expression. Such an increase, which might rely on β2-adrenergic receptor activation, notably participates to the BaP-induced glycolytic shift and cell survival in liver cells. By identifying IF1 as a target of PAHs, this study provides new insights about how environmental factors may contribute to related carcinogenesis.
Staphylococcus aureus is an important opportunistic pathogen of humans and animals. It produces extracellular vesicles (EVs) that are involved in cellular communication and enable inter-kingdom ...crosstalk, the delivery of virulence factors and modulation of the host immune response. The protein content of EVs determines their biological functions. Clarifying which proteins are selected, and how, is of crucial value to understanding the role of EVs in pathogenesis and the development of molecular delivery systems. Here, we postulated that S. aureus EVs share a common proteome containing components involved in cargo sorting. The EV proteomes of five S. aureus strains originating from human, bovine, and ovine hosts were characterised. The clustering of EV proteomes reflected the diversity of the producing strains. A total of 253 proteins were identified, 119 of which composed a core EV proteome with functions in bacterial survival, pathogenesis, and putatively in EV biology. We also identified features in the sequences of EV proteins and the corresponding genes that could account for their packaging into EVs. Our findings corroborate the hypothesis of a selective sorting of proteins into EVs and offer new perspectives concerning the roles of EVs in S. aureus pathogenesis in specific host niches.
sprG1/
SprF1 is a type I toxin-antitoxin system located on
Staphylococcus aureus
prophage. It has previously been shown that the two toxins, SprG1
31
and SprG1
44
, encoded by the
sprG1
gene, are two ...membrane-associated peptides structured in a single α-helix. Overexpression of these two peptides leads to growth inhibition and even
S. aureus
death. In this study, we investigated the involvement of each peptide in this toxicity, the sequence requirements necessary for SprG1
31
toxicity, and the mechanism of action of these two peptides. Our findings show that both peptides, when expressed individually, are able to stop growth, with higher toxicity observed for SprG1
31
. The combination of a hydrophobic domain and a charged domain located only at the C-terminus is necessary for this toxicity, likely to retain the orientation of the transmembrane domain. A net cationic charge for SprG1
31
is not essential to induce a growth defect in
S. aureus
. Furthermore, we established a chronology of toxic events following overexpression to gain insights into the mode of action of SprG1
44
and SprG1
31
. We demonstrated that mesosome-like structures are already formed when membrane is depolarized, about 20 min after peptides induction. This membrane depolarization occurs concomitantly with a depletion of intracellular ATP, leading to
S. aureus
growth arrest. Moreover, we hypothesized that SprG1
44
and SprG1
31
do not form large pores in the
S. aureus
membrane, as ATP is not excreted into the extracellular medium, and membrane permeabilization is delayed relative to membrane depolarization. The next challenge is to identify the conditions under which SprG1
44
and SprG1
31
are naturally expressed, and to uncover their potential roles during staphylococcal growth, colonization, and infection.
► We investigated the effect of nanosized Mo6 clusters on the growth of rapeseed plants. ► The aggregation state of the clusters depends on the dispersion medium. ► The concentration-dependant ...toxicity of the clusters depends on aggregation state. ► We took into account the possible contribution to toxicity of dissolved ionic species. ► The root uptake of the clusters was followed by NanoSIMS.
Here are examined the root uptake and phytotoxicity of octahedral hexamolybdenum clusters on rapeseed plants using the solid state compound Cs2Mo6Br14 as cluster precursor. Mo6Br142− cluster units are nanosized entities offering a strong and stable emission in the near-infrared region with numerous applications in biotechnology. To investigate cluster toxicity on rapeseed plants, two different culture systems have been set up, using either a water-sorbing suspension of cluster aggregates or an ethanol-sorbing solution of dispersed nanosized clusters. Size, shape, surface area and state of clusters in both medium were analyzed by FE-SEM, BET and XPS. The potential contribution of cluster dissolution to phytotoxicity was evaluated by ICP-OES and toxicity analysis of Mo, Br and Cs. We showed that the clusters did not affect seed germination but greatly inhibited plant growth. This inhibition was much more important when plants were treated with nanosized entities than with microsized cluster aggregates. In addition, nanosized clusters affected the root morphology in a different manner than microsized cluster aggregates, as shown by FE-SEM observations. The root penetration of the clusters was followed by secondary ion mass spectroscopy with high spatial resolution (NanoSIMS) and was also found to be much more important for treatments with nanosized clusters.
TiO.sub.2 nanomaterials (NMs) are present in a variety of food and personal hygiene products, and consumers are exposed daily to these NMs through oral exposition. While the bulk of ingested ...TiO.sub.2 NMs are eliminated rapidly in stool, a fraction is able to cross the intestinal epithelial barrier and enter systemic circulation from where NMs can be distributed to tissues, primarily liver and spleen. Daily exposure to TiO.sub.2 NMs, in combination with a slow rate of elimination from tissues, results in their accumulation within different tissues. Considerable evidence suggests that following oral exposure to TiO.sub.2 NMs, the presence of NMs in tissues is associated with a number of adverse effects, both in intestine and liver. Although numerous studies have been performed in vitro investigating the acute effects of TiO.sub.2 NMs in intestinal and hepatic cell models, considerably less is known about the effect of repeated exposure on these models. In this study, we investigated the cytotoxic effects of repeated exposure of relevant models of intestine and liver to two TiO.sub.2 NMs differing in hydrophobicity for 24 h, 1 week and 2 weeks at concentrations ranging from 0.3 to 80 microg/cm.sup.2. To study the persistence of these two NMs in cells, we included a 1-week recovery period following 24 h and 1-week treatments. Cellular uptake by TEM and ToF-SIMS analyses, as well as the viability and pro-inflammatory response were evaluated. Changes in the membrane composition in Caco-2 and HepaRG cells treated with TiO.sub.2 NMs for up to 2 weeks were also studied. Despite the uptake of NM-103 and NM-104 in cells, no significant cytotoxic effects were observed in either Caco-2 or HepaRG cells treated for up to 2 weeks at NM concentrations up to 80 microg/cm.sup.2.sub.. In addition, no significant effects on IL-8 secretion were observed. However, significant changes in membrane composition were observed in both cell lines. Interestingly, while most of these phospholipid modifications were reversed following a 1-week recovery, others were not affected by the recovery period. These findings indicate that although no clear effects on cytotoxicity were observed following repeated exposure of differentiated Caco-2 and HepaRG cells to TiO.sub.2 NMs, subtle effects on membrane composition could induce potential adverse effects in the long-term.
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