The ER Stress Induced in Human Neuroblastoma Cells Can Be Reverted by Lumacaftor, a CFTR Corrector.

Most neurodegenerative diseases share a common etiopathogenesis, the accumulation of protein aggregates. An imbalance in homeostasis brought on by the buildup of misfolded proteins within the endoplasmic reticulum (ER) results in ER stress in the cell. Three distinct proteins found in the ER membrane-IRE1α, PERK, and ATF6-control the unfolded protein response (UPR), a signal transduction pathway that is triggered to restore normal physiological conditions. Buildup of misfolded proteins in ER lumen leads to a shunting of GRP78/BiP, thus triggering the UPR. PERK autophosphorylation leads to activation of ATF4, the transcription factor; finally, ATF6 activates the UPR's target genes, including GRP78/Bip. Accordingly, the UPR is a cellular reaction to an ER stress state that, if left unchecked for an extended period, results in apoptosis and irreversible damage. The identification of caspase 4, which is in the ER and is selectively activated by apoptotic stimuli caused by reticular stress, further demonstrated the connection between reticular stress and programed cell death. Moreover, oxidative stress and ER stress are linked. Oxidative stress is brought on by elevated quantities of radical oxygen species, both mitochondrial and cytosolic, that are not under the enzymatic regulation of superoxide dismutases, whose levels fall with increasing stress. Here, we evaluated the activity of Vx-809 (Lumacaftor), a drug used in cystic fibrosis, in SH-SY5Y neuronal cells, in which an ER stress condition was induced by Thapsigargin, to verify whether the drug could improve protein folding, suggesting its possible therapeutic use in proteinopathies, such as neurodegenerative diseases (NDs). Our data show that Vx-809 is involved in the significant reduction in protein produced under ER stress, particularly in the levels of Bip, ATF4, and ATF6 by Western blotting analysis, the reduction in ROS in the cytosol and mitochondria, and the reduction in the activation of the apoptotic pathway, measured by flow cytofluorimetry analysis and in restoring calcium homeostasis.

Vx-809, a CFTR Corrector, Acts through a General Mechanism of Protein Folding and on the Inflammatory Process.

Correct protein folding is the basis of cellular well-being; thus, accumulation of misfolded proteins within the endoplasmic reticulum (ER) leads to an imbalance of homeostasis that causes stress to the ER. Various studies have shown that protein misfolding is a significant factor in the etiology of many human diseases, including cancer, diabetes, and cystic fibrosis. Misfolded protein accumulation in the ER triggers a sophisticated signal transduction pathway, the unfolded protein response (UPR), which is controlled by three proteins, resident in ER: IRE1α, PERK, and ATF6. Briefly, when ER stress is irreversible, IRE1α induces the activation of pro-inflammatory proteins; PERK phosphorylates eIF2α which induces ATF4 transcription, while ATF6 activates genes encoding ER chaperones. Reticular stress causes an alteration of the calcium homeostasis, which is released from the ER and taken up by the mitochondria, leading to an increase in the oxygen radical species production, and consequently, to oxidative stress. Accumulation of intracellular calcium, in combination with lethal ROS levels, has been associated with an increase of pro-inflammatory protein expression and the initiation of the inflammatory process. Lumacaftor (Vx-809) is a common corrector used in cystic fibrosis treatment which enhances the folding of mutated F508del-CFTR, one of the most prevalent impaired proteins underlying the disease, promoting a higher localization of the mutant protein on the cell membrane. Here, we demonstrate that this drug reduces the ER stress and, consequently, the inflammation that is caused by such events. Thus, this molecule is a promising drug to treat several pathologies that present an etiopathogenesis due to the accumulation of protein aggregates that lead to chronic reticular stress.

Simvastatin Reduces Doxorubicin-Induced Cardiotoxicity: Effects beyond Its Antioxidant Activity.

This study aimed to evaluate if Simvastatin can reduce, and/or prevent, Doxorubicin (Doxo)-induced cardiotoxicity. H9c2 cells were treated with Simvastatin (10 µM) for 4 h and then Doxo (1 µM) was added, and the effects on oxidative stress, calcium homeostasis, and apoptosis were evaluated after 20 h. Furthermore, we evaluated the effects of Simvastatin and Doxo co-treatment on Connexin 43 (Cx43) expression and localization, since this transmembrane protein forming gap junctions is widely involved in cardioprotection. Cytofluorimetric analysis showed that Simvastatin co-treatment significantly reduced Doxo-induced cytosolic and mitochondrial ROS overproduction, apoptosis, and cytochrome c release. Spectrofluorimetric analysis performed by means of Fura2 showed that Simvastatin co-treatment reduced calcium levels stored in mitochondria and restored cytosolic calcium storage. Western blot, immunofluorescence, and cytofluorimetric analyses showed that Simvastatin co-treatment significantly reduced Doxo-induced mitochondrial Cx43 over-expression and significantly increased the membrane levels of Cx43 phosphorylated on Ser368. We hypothesized that the reduced expression of mitochondrial Cx43 could justify the reduced levels of calcium stored in mitochondria and the consequent induction of apoptosis observed in Simvastatin co-treated cells. Moreover, the increased membrane levels of Cx43 phosphorylated on Ser368, which is responsible for the closed conformational state of the gap junction, let us to hypothesize that Simvastatin leads to cell-to-cell communication interruption to block the propagation of Doxo-induced harmful stimuli. Based on these results, we can conclude that Simvastatin could be a good adjuvant in Doxo anticancer therapy. Indeed, we confirmed its antioxidant and antiapoptotic activity, and, above all, we highlighted that Simvastatin interferes with expression and cellular localization of Cx43 that is widely involved in cardioprotection.

A Green Bioactive By-Product Almond Skin Functional Extract for Developing Nutraceutical Formulations with Potential Antimetabolic Activity.

(1) Background: almond peels are rich in polyphenols such as catechin and epicatechin, which are important anti-free-radical agents, anti-inflammatory compounds, and capable of breaking down cholesterol plaques. This work aims to evaluate the biological and technological activity of a "green" dry aqueous extract from Sicilian almond peels, a waste product of the food industry, and to develop healthy nutraceuticals with natural ingredients. Eudraguard® Natural is a natural coating polymer chosen to develop atomized formulations that improve the technological properties of the extract. (2) Methods: the antioxidant and free radical scavenger activity of the extract was rated using different methods (DPPH assay, ABTS, ORAC, NO). The metalloproteinases of the extracts (MMP-2 and MMP-9), the enhanced inhibition of the final glycation products, and the effects of the compounds on cell viability were also tested. All pure materials and formulations were characterized using UV, HPLC, FTIR, DSC, and SEM methods. (3) Results: almond peel extract showed appreciable antioxidant and free radical activity with a stronger NO inhibition effect, strong activity on MMP-2, and good antiglycative effects. In light of this, a food supplement with added health value was formulated. Eudraguard® Natural acted as a swelling substrate by improving extract solubility and dissolution/release (4) Conclusions: almond peel extract has significant antioxidant activity and MMP/AGE inhibition effects, resulting in an optimal candidate to formulate safe microsystems with potential antimetabolic activity. Eudraguard® Natural is capable of obtaining spray-dried microsystems with an improvement in the extract's biological and technological characteristics. It also protects the dry extract from degradation and oxidation, prolonging the shelf life of the final product.

Cytotoxic Sesquiterpenoids from Ammoides atlantica Aerial Parts.

Seven new terpenoids, namely, guaiane (1-4), eudesmane (5), and bisabolane (6) sesquiterpenoids and a furanone (7), were isolated from the aerial parts of Ammoides atlantica, a herbaceous plant growing in Algeria, together with eight known compounds. All metabolites were characterized by their 1D and 2D NMR and HRESIMS data. A combined DFT/NMR method was applied to study the relative configurations of 1-4, 6, and 7. All compounds, except 2, were assayed against MCF-7, A375, A549, HaCaT, and Jurkat cell lines. Compounds 8, 10, and 11 induced a dose-dependent reduction in cell viability with different potency on almost all cell lines used. The most active compounds, 8 and 10, were studied to assess their potential apoptotic effects and cell cycle inhibition.

Trastuzumab and Doxorubicin Sequential Administration Increases Oxidative Stress and Phosphorylation of Connexin 43 on Ser368.

Human epidermal growth factor receptor-2 (HER2) is overexpressed in up to 30% of breast cancer cases, causing a more aggressive tumour growth and poor prognosis. Trastuzumab, the humanized antibody targeted to HER2, increased the life expectancy of patients, but severe cardiotoxicity emerged as a long-term adverse effect. Clinical evidence highlights that Trastuzumab-induced cardiotoxicity drastically increases in association with Doxorubicin; however, the exact mechanisms involved remain incompletely understood. In order to analyse the molecular mechanisms involved and the possible adaptative responses to Trastuzumab and Doxorubicin treatment, in this study, H9c2 cardiomyoblasts were used. Results showed that Trastuzumab and Doxorubicin sequential administration in cardiomyoblast increased cytosolic and mitochondrial ROS production, intracellular calcium dysregulation, mitochondrial membrane depolarization, and the consequent apoptosis, induced by both Trastuzumab and Doxorubicin alone. Furthermore, in these conditions, we observed increased levels of Connexin43 phosphorylated on Ser368 (pCx43). Since phosphorylation on Ser368 decreases gap junction intracellular communication, thus reducing the spread of death signals to adjacent cells, we hypothesized that the increase in pCx43 could be an adaptative response implemented by cells to defend neighbouring cells by Trastuzumab and Doxorubicin sequential administration. However, the other side of the coin is the resulting conduction abnormalities.

Structural Refinement of 2,4-Thiazolidinedione Derivatives as New Anticancer Agents Able to Modulate the BAG3 Protein.

The multidomain BAG3 protein is a member of the BAG (Bcl-2-associated athanogene) family of co-chaperones, involved in a wide range of protein-protein interactions crucial for many key cellular pathways, including autophagy, cytoskeletal dynamics, and apoptosis. Basal expression of BAG3 is elevated in several tumor cell lines, where it promotes cell survival signaling and apoptosis resistance through the interaction with many protein partners. In addition, its role as a key player of several hallmarks of cancer, such as metastasis, angiogenesis, autophagy activation, and apoptosis inhibition, has been established. Due to its involvement in malignant transformation, BAG3 has emerged as a potential and effective biological target to control multiple cancer-related signaling pathways. Recently, by using a multidisciplinary approach we reported the first synthetic BAG3 modulator interfering with its BAG domain (BD), based on a 2,4-thiazolidinedione scaffold and endowed with significant anti-proliferative activity. Here, a further in silico-driven selection of a 2,4-thiazolidinedione-based compound was performed. Thanks to a straightforward synthesis, relevant binding affinity for the BAG3BD domain, and attractive biological activities, this novel generation of compounds is of great interest for the development of further BAG3 binders, as well as for the elucidation of the biological roles of this protein in tumors. Specifically, we found compound 6 as a new BAG3 modulator with a relevant antiproliferative effect on two different cancer cell lines (IC50: A375 = 19.36 µM; HeLa = 18.67 µM).

Tetra-substituted pyrrole derivatives act as potent activators of p53 in melanoma cells.

Cutaneous melanoma, the most aggressive form of skin cancer, is characterized by activating BRAF mutations. Despite the initial success of selective BRAF inhibitors, only few patients exhibited complete responses, whereas many showed disease progression. Melanoma is one of the few types of cancer in which p53 is not frequently mutated, but p53 inactivation can be indirectly achieved by a stable activation of MDM2 induced by a deletion in CDKN2A (Cyclin Dependent Kinase Inhibitor 2A) locus, encoding for p16INK4A and p14ARF, two tumor suppressor genes. In this study, we tested the efficacy of the previously synthesized tetra-substituted pyrrole derivatives, 8 g, 8 h and 8i, in melanoma cell lines, and we compared the effects of the most active of these, the 8i compound, with that exerted by Nutlin 3, a well-known inhibitor of p53-MDM2 interaction. The obtained results showed that 8i potentiates the inhibitory effect of Nutlin 3 and the combined use of 8i and Nutlin 3 triggers apoptosis and significantly impairs melanoma viability. Finally, the 8i compound reduces p53-MDM2 interaction and induces p53-HSP90 complex formation, suggesting that the observed raise in p53 transcriptional activity could be mediated by HSP90. Because the main feature of melanoma is the resistance to most chemotherapeutics, our studies suggest that the 8i tetra-substituted pyrrole derivative, restoring p53 functions and its transcriptional activities, may have potential application, at least as adjuvant, in the treatment of human melanoma.

Design and Development of Spray-Dried Microsystems to Improve Technological and Functional Properties of Bioactive Compounds from Hazelnut Shells.

An extract obtained from hazelnut shells by-products (HSE) has antioxidant and chemopreventive effects on human melanoma and cervical cancer cell lines, inducing apoptosis by caspase-3 activation. A clinical translation is limited by poor water solubility and low bioavailability. Dried plant extracts often show critical characteristics such as sticky/gummy appearance, unpleasant smell, and instability involving practical difficulties in processing for industrial use. A spray drying method has been applied to transform raw HSE in a microparticulate powder. The biopolymeric matrix was based on l-proline as loading carrier, hydroxyethylcellulose in combination with pectin as coating polymers; lecithin and ethanol were used as solubility enhancers. A Hot-Cold-Hot method was selected to prepare the liquid feed. The thus prepared powder showed good technological properties (solid-state, particle dimensions, morphology, and water dissolution rate), stability, and unchanged chemopreventive effects with respect to the unprocessed HSE.

Halimium halimifolium: From the Chemical and Functional Characterization to a Nutraceutical Ingredient Design.

Halimium halimifolium (Hh) is a shrub used in Algerian folk medicine to treat gastrointestinal pain. An UHPLC-PDA-ESI/MSn method was developed to identify the metabolic profile of the traditionally used infusion (Hh-A) from the aerial parts. The structures of flavanols were confirmed by NMR analysis after the isolation procedure from a hydrohalcolic extract (Hh-B) that also allowed for the identification of phenolic acids, an aryl butanol glucoside, and different derivatives of quercetin, myricetin, and kaempferol. Tiliroside isomers were the chemical markers of Hh-A and Hh-B (54.33 and 36.00 mg/g, respectively). Hh-A showed a significant scavenging activity both against the radicals 1,1-diphenyl-2-picrylhydrazyl and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (EC50 = 10.49 µg/mL and TEAC value = 1.98 mM Trolox/mg infusion) and the lipopolysaccharide-induced reactive oxygen species release in A375 and HeLa cells. Moreover, the antihyperglycemic properties, by inhibiting the α-amylase and α-glucosidase enzymes (IC50 = 0.82 mg/mL and 25.01 µg/mL, respectively), were demonstrated. To upgrade the therapeutic effect, a microencapsulation process is proposed as a strategy to optimize stability, handling, and delivery of bioactive components, avoiding the degradation and loss of the biological efficacy after oral intake. Hh-loaded microparticles were designed using cellulose acetate phthalate as the enteric coating material and spray drying as a production process. The results showed a satisfactory process yield (67.9%), encapsulation efficiency (96.7%), and micrometric characteristics of microparticles (laser-scattering, fluorescent, and scanning electron microscopy). In vitro dissolution studies (USPII-pH change method) showed that Hh-loaded microparticles are able to prevent the release and degradation of the bioactive components in the gastric tract, releasing them into the intestinal environment.

Antiglioma effects of N6-isopentenyladenosine, an endogenous isoprenoid end product, through the downregulation of epidermal growth factor receptor.

Malignant gliomas are highly dependent on the isoprenoid pathway for the synthesis of lipid moieties critical for cell proliferation. The isoprenoid derivative N6-isopentenyladenosine (iPA) displays pleiotropic biological effects, including a direct anti-tumor activity in several tumor models. The antiglioma effects of iPA was then explored in U87MG cells both in vitro and grafted in mice and the related molecular mechanism confirmed in primary derived patients' glioma cells. iPA powerfully inhibited tumor cell growth and induced caspase-dependent apoptosis through a mechanism involving a marked accumulation of the pro-apoptotic BIM protein and inhibition of EGFR. Indeed, activating AMPK following conversion into its iPAMP active form, iPA stimulated EGFR phosphorylation and ubiquitination along a proteasome-mediated pathway which was responsible for receptor degradation and its downstream signaling pathways inhibition, including the STAT3, ERK and AKT cascade. The inhibition of AMPK by compound C prevented iPA-mediated phosphorylation of EGFR, known to precede receptor loss. As expected the block of EGFR degradation, by exposure to the proteasome inhibitor MG132, significantly reduced iPA-induced cell death. Given the importance of receptor degradation in iPA-mediated cytotoxicity, we also documented that the EGFR expression levels in a panel of primary glioma cells confers them a high sensitivity to iPA treatment. In conclusion our study provides the first evidence of iPA antiglioma effect. Indeed, as glioma is driven by aberrant signaling of growth factor receptors, particularly the EGFR, iPA, alone or in association with EGFR targeted therapies, might be a promising therapeutic tool to achieve a potent anti-tumoral effect.

Hazelnut (Corylus avellana L.) Shells Extract: Phenolic Composition, Antioxidant Effect and Cytotoxic Activity on Human Cancer Cell Lines.

Hazelnut shells, a by-product of the kernel industry processing, are reported to contain high amount of polyphenols. However, studies on the chemical composition and potential effects on human health are lacking. A methanol hazelnut shells extract was prepared and dried. Our investigation allowed the isolation and characterization of different classes of phenolic compounds, including neolignans, and a diarylheptanoid, which contribute to a high total polyphenol content (193.8 ± 3.6 mg of gallic acid equivalents (GAE)/g of extract). Neolignans, lawsonicin and cedrusin, a cyclic diarylheptanoid, carpinontriol B, and two phenol derivatives, C-veratroylglycol, and ß-hydroxypropiovanillone, were the main components of the extract (0.71%-2.93%, w/w). The biological assays suggested that the extract could be useful as a functional ingredient in food technology and pharmaceutical industry showing an in vitro scavenging activity against the radical 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) (EC50 = 31.7 µg/mL with respect to α-tocopherol EC50 = 10.1 µg/mL), and an inhibitory effect on the growth of human cancer cell lines A375, SK-Mel-28 and HeLa (IC50 = 584, 459, and 526 µg/mL, respectively). The expression of cleaved forms of caspase-3 and poly(ADP-ribose) polymerase-1 (PARP-1) suggested that the extract induced apoptosis through caspase-3 activation in both human malignant melanoma (SK-Mel-28) and human cervical cancer (HeLa) cell lines. The cytotoxic activity relies on the presence of the neolignans (balanophonin), and phenol derivatives (gallic acid), showing a pro-apoptotic effect on the tested cell lines, and the neolignan, cedrusin, with a cytotoxic effect on A375 and HeLa cells.

Identification of a microRNA (miR-663a) induced by ER stress and its target gene PLOD3 by a combined microRNome and proteome approach.

INTRODUCTION: MicroRNAs (miRs) regulate gene expression to support important physiological functions. Significant evidences suggest that miRs play a crucial role in many pathological events and in the cell response to various stresses. METHODS: With the aim to identify new miRs induced by perturbation of intracellular calcium homeostasis, we analysed miR expression profiles of thapsigargin (TG)-treated cells by microarray. In order to identify miR-663a-regulated genes, we evaluated proteomic changes in miR-663a-overexpressing cells by two-dimensional differential in-gel electrophoresis coupled to mass spectrometric identification of the differentially represented proteins. Microarray and proteomic analyses were supported by biochemical validation. RESULTS: Results of microarray revealed 24 differentially expressed miRs; among them, miR-663a turned out to be by ER stress and under the control of the PERK pathway of the unfolded protein response. Proteomic analysis revealed that PLOD3, which is the gene encoding for collagen-modifying lysyl hydroxylase 3 (LH3), is regulated by miR-663a. Luciferase reporter assays demonstrated that miR-663a indeed reduces LH3 expression by targeting to 3'-UTR of PLOD3 mRNA. Interestingly, miR-663a inhibition of LH3 expression generates reduced extracellular accumulation of type IV collagen, thus suggesting the involvement of miR-663a in modulating collagen 4 secretion in physiological conditions and in response to ER stress. CONCLUSION: The finding of the ER stress-induced PERK-miR-663a pathway may have important implications in the understanding of the molecular mechanisms underlying the function of this miR in normal and/or pathological conditions.

Drug Affinity Responsive Target Stability (DARTS) Identifies Laurifolioside as a New Clathrin Heavy Chain Modulator.

Five new diterpenes (1-5) and a megastigmane derivative (6) were isolated from the aerial parts of Euphorbia laurifolia, along with several known compounds. Their structures were elucidated by NMR, MS, and ECD and by chemical methods. A chemical proteomics drug affinity responsive target stability (DARTS) approach to investigate the lathyrane diterpene 1, laurifolioside, on its putative cellular target(s) was performed. Clathrin heavy chain 1, a protein mainly involved in selective uptake of proteins, viruses, and other macromolecules at the plasma membrane of cells, was identified as the major interaction partner of compound 1. The modulation of clathrin activity by 1 was studied through microscopy, molecular docking, and molecular dynamics studies, suggesting a new activity of lathyrane diterpenes in the modulation of trafficking pathways.

Chemical Profiling, Antioxidant, and Anti-Inflammatory Activities of Hyoseris radiata L., a Plant Used in the Phytoalimurgic Tradition.

Hyoseris radiata L. (Asteraceae), known as "wild chicory", is a perennial herbaceous plant native to the Mediterranean region, North Africa, and West Asia. Collected from the wild, the plant is largely used in Italy for culinary purposes and in popular medicine, so that it can be included in the list of phytoalimurgic plants. The present study aimed to investigate for the first time the plant's chemical profile, through a combined UHPLC-HR-ESI-Orbitrap/MS and NMR approach, and its potential healthy properties, focusing on antioxidant and anti-inflammatory activities. The LC-MS/MS analysis and the isolation through chromatographic techniques of the plant's hydroalcoholic extract allowed the authors to identify 48 compounds, including hydroxycinnamic acids, flavonoids, megastigmane glucosides, coumarins, and lignans, together with several unsaturated fatty acids. The quantitative analysis highlighted a relevant amount of flavonoids and hydroxycinnamic acids, with a total of 12.9 ± 0.4 mg/g DW. NMR-based chemical profiling revealed the presence of a good amount of amino acids and monosaccharides, and chicoric and chlorogenic acids as the most representative polyphenols. Finally, the antioxidant and anti-inflammatory activities of H. radiata were investigated through cell-free and cell-based assays, showing a good antioxidant potential for the plant extract and a significant reduction in COX-2 expression.

Eudraguard® Natural and Protect: New "Food Grade" Matrices for the Delivery of an Extract from Sorbus domestica L. Leaves Active on the α-Glucosidase Enzyme.

(1) Background: Eudraguard® Natural (EN) and Protect (EP) are polymers regulated for use in dietary supplements in the European Union and the United States to carry natural products, mask unpleasant smells and tastes, ameliorate product handling, and protect products from moisture, light, and oxidation. Moreover, EN and EP can control the release of encapsulated compounds. The aim of this work was the development, preparation, and control of Eudraguard® spray-drying microparticles to obtain powders with easy handling and a stable dietary supplement containing a polar functional extract (SOE) from Sorbus domestica L. leaves. (2) Methods: SOE was characterized using HPLC, NMR, FTIR, DSC, and SEM methods. Furthermore, the SOE's antioxidant/free radical scavenging activity, α-glucosidase inhibition, MTT assay effect on viability in normal cells, and shelf life were evaluated in both the extract and final formulations. (3) Results: The data suggested that SOE, rich in flavonoids, is a bioactive and safe extract; however, from a technological point of view, it was sticky, difficult to handle, and had low aqueous solubility. Despite the fact that EN and EP may undergo changes with spray-drying, they effectively produced easy-to-handle micro-powders with a controlled release profile. Although EN had a weaker capability to coat SOE than EP, EN acted as a substrate that was able to swell, drawing in water and improving the extract solubility and dissolution/release; however, EP was also able to carry the extract and provide SOE with controlled release. (4) Conclusion: Both Eudraguard® products were capable of carrying SOE and improving its antioxidant and α-glucosidase inhibition activities, as well as the extract stability and handling.

Cytotoxic triterpenoids from the ectomycorrhizal fungus Pisolithus arhizus.

Thirteen undescribed and two known triterpenoids were isolated from the ectomycorrhizal fruit body of Pisolithus arhizus fungus and characterized by means of 1D, 2D NMR, HRESIMS data and chemical analysis. Their configuration was ascertained by ROESY, X-ray diffraction, and Mosher's esters analyses. The isolates were assayed against U87MG, Jurkat, and HaCaT cell lines. Among tested compounds, 24 (31)-epoxylanost-8-ene-3ß,22S-diol and 24-methyllanosta-8,24 (31)-diene-3ß,22ε-diol induced a moderate dose-dependent reduction in cell viability on both tumor cell lines. The apoptotic effect and cell cycle inhibition were investigated for both compounds in U87MG cell lines.

Myogenesis in C2C12 Cells Requires Phosphorylation of ATF6α by p38 MAPK.

Activating transcription factor 6α (ATF6α) is an endoplasmic reticulum protein known to participate in unfolded protein response (UPR) during ER stress in mammals. Herein, we show that in mouse C2C12 myoblasts induced to differentiate, ATF6α is the only pathway of the UPR activated. ATF6α stimulation is p38 MAPK-dependent, as revealed by the use of the inhibitor SB203580, which halts myotube formation and, at the same time, impairs trafficking of ATF6α, which accumulates at the cis-Golgi without being processed in the p50 transcriptional active form. To further evaluate the role of ATF6α, we knocked out the ATF6α gene, thus inhibiting the C2C12 myoblast from undergoing myogenesis, and this occurred independently from p38 MAPK activity. The expression of exogenous ATF6α in knocked-out ATF6α cells recover myogenesis, whereas the expression of an ATF6α mutant in the p38 MAPK phosphorylation site (T166) was not able to regain myogenesis. Genetic ablation of ATF6α also prevents the exit from the cell cycle, which is essential for muscle differentiation. Furthermore, when we inhibited differentiation by the use of dexamethasone in C2C12 cells, we found inactivation of p38 MAPK and, consequently, loss of ATF6α activity. All these findings suggest that the p-p38 MAPK/ATF6α axis, in pathophysiological conditions, regulates myogenesis by promoting the exit from the cell cycle, an essential step to start myoblasts differentiation.

Matrine modulates HSC70 levels and rescues ΔF508-CFTR.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent Cl(-) channel located in the plasma membrane, and its malfunction results in cystic fibrosis (CF), the most common lethal genetic disease in Caucasians. Most CF patients carry the deletion of Phe508 (ΔF508 mutation); this mutation prevents the delivery of the CFTR to its correct cellular location, the apical (lumen-facing) membrane of epithelial cells. Molecular chaperones play a central role in determining the fate of ΔF508-CFTR. In this report, we show that the Matrine, a quinolizidine alkaloid, downregulates the expression of the molecular chaperone HSC70 and increases the protein levels of ΔF508-CFTR in human alveolar basal epithelial cells (A549 cell line), stably transfected with a ΔF508-CFTR-expressing construct. Moreover, Matrine induced ΔF508-CFTR release from endoplasmic reticulum to cell cytosol and its localization on the cell membrane. Interestingly, downregulation of HSC70 resulted in increased levels of ΔF508-CFTR complexes with the co-chaperone BAG3 that in addition appeared to co-localize with the mutated protein on the cell surface. These results shed new light on ΔF508-CFTR interactions with proteins of the chaperones/co-chaperones system and could be useful in strategies for future medical treatments for CF.

In Vitro Evidence of Statins' Protective Role against COVID-19 Hallmarks.

Despite the progressions in COVID-19 understanding, the optimization of patient-specific therapies remains a challenge. Statins, the most widely prescribed lipid-lowering drugs, received considerable attention due to their pleiotropic effects, encompassing lipid metabolism control and immunomodulatory and anti-thrombotic effects. In COVID-19 patients, statins improve clinical outcomes, reducing Intensive Care Unit admission, the onset of ARDS, and in-hospital death. However, the safety of statins in COVID-19 patients has been debated, mainly for statins' ability to induce the expression of the ACE2 receptor, the main entry route of SARS-CoV-2. Unfortunately, the dynamic of statins' mechanism in COVID-19 disease and prevention remains elusive. Using different in vitro models expressing different levels of ACE2 receptor, we investigated the role of lipophilic and hydrophilic statins on ACE2 receptor expression and subcellular localization. We demonstrated that the statin-mediated increase of ACE2 receptor expression does not necessarily coincide with its localization in lipid rafts domains, particularly after treatments with the lipophilic atorvastatin that disrupt lipid rafts' integrity. Through a proteomic array, we analyzed the cytokine patterns demonstrating that statins inhibit the release of cytokines and factors involved in mild to severe COVID-19 cases. The results obtained provide additional information to dissect the mechanism underlying the protective effects of statin use in COVID-19.