Biology subjects

Moreira, J.

Publications and source records attributed to Moreira, J..

4 recordsLinked to original sources

bioRxiv2026

Antimicrobial and Cytotoxic Lysolipins I-M Isolated from Streptomyces sp. P8-2B18

Lysolipin I (1) is a highly bioactive xanthone with strong antibacterial and cytotoxic properties. Given the limited number of lysolipin analogues, discovery of new natural lysolipin derivatives is important for understanding their structure-activity relationships. A soil-derived Streptomyces sp. P8-2B18 harbors a putative lysolipin biosynthetic gene cluster and LC-MS based metabolomic analysis revealed the production of lysolipin I along with unreported analogues. Large-scale fermentation followed by isolation led to the discovery of four new analogues, lysolipins J-M (2- 5), the structures of which were elucidated by mass spectrometric and NMR spectroscopic data analyses. Lysolipin L features a five-membered lactam F ring, which was unprecedented in reported lysolipins. Lysolipin M has a novel skeleton, with an extra methyl (Me-36) and a glycosyl group replacing a 1,3-oxane ring in lysolipin I. While lysolipins I, J and K displayed strong activity against Staphylococcus aureus and Aspergillus flavus with MIC values ranging from 0.25 to 4 g/mL and lysolipin L showed only moderate activities, lysolipin M was inactive (>50 g/mL). Lysolipins I-K showed potent cytotoxic activity against prostate cancer cell lines LNCaP and C4-2B, with IC50 values in the submicromolar range. In contrast, lysolipin L exhibited no cytotoxicity and lysolipin M exhibited substantially reduced potency. Their broad, non-selective bioactivities restricted their applicability as therapeutic agents.

microbiology↗

bioRxiv2023

Divergent Molecular Pathways for Toxicity of Selected Mutant C9ORF72-derived Dipeptide Repeats

Expansion of a hexanucleotide repeat in a noncoding region of the C9ORF72 gene is responsible for a significant fraction of Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD) cases, but mechanisms linking mutant gene products to neuronal toxicity remain debatable. Pathogenesis was proposed to involve the production of toxic RNA species and/or accumulation of toxic dipeptide repeats (DPRs) but distinguishing between these mechanisms has been challenging. In this study, we first use complementary model systems for analyzing pathogenesis in adult-onset neurodegenerative diseases to characterize the pathogenicity of DPRs produced by Repeat Associated Non-ATG translation of C9ORF72 in specific cellular compartments: isolated axoplasm and giant synapse from the squid. Results showed selective axonal and presynaptic toxicity of GP-DPRs, independent of associated RNA. These effects involved a MAPK signaling pathway that affects fast axonal transport and synaptic function, a pathogenic mechanism shared with other mutant proteins associated with familial ALS, like SOD1 and FUS. In primary cultured neurons, GP but not other DPRs promote the "dying-back" axonopathy seen in ALS. Interestingly, GR- and PR-DPRs, which had no effect on axonal transport or synaptic transmission, were found to disrupt the nuclear membrane, promoting "dying-forward" neuropathy. All C9-DPR-mediated toxic effects observed in these studies are independent of whether the corresponding mRNAs contained hexanucleotide repeats or alternative codons. Finally, C9ORF72 human tissues confirmed a close association between GP and active P38 in degenerating motor neurons as well as GR-associated nuclear damage in the cortex. Collectively, our studies establish compartment-specific toxic effects of C9-DPRs associated with degeneration, suggesting that two independent pathogenic mechanisms may contribute to disease heterogeneity and/or synergize on disease progression in C9ORF72 patients with ALS and/or FTD symptoms. Graphical AbstractActivation of protein kinases and inhibition of axonal transport, synaptic transmission, and nuclear structure are toxic effects common to unrelated FALS-related gene products. FALS-related mutant forms of SOD1 (mSOD1), FUS (mFUS), and C9-GP-DPRs (GP(n)) activate specific ASK1-MAPK pathway. Within axons, active ASK1-p38 pathway phosphorylates various substrates, including conventional kinesin, leading to the inhibition of fast axonal transport mediated by the translocation of this motor protein along microtubules. ASK1 can also inhibit synaptic transmission via JNK activation. Both pathways cause reductions in the availability of critical synaptic cargoes, synaptic dysfunction, and "dying-back" degeneration of neurons. On the other hand, C9- PR and GR-DPRs (PR(n) and GR(n)) activate other pathways, leading to aberrant alterations in nuclear structure and function and "dying-forward" degeneration of neurons, consistent with reports of transcriptional changes and activation of apoptosis in ALS. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/558663v2_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@162cbbeorg.highwire.dtl.DTLVardef@12e54caorg.highwire.dtl.DTLVardef@c0cdaborg.highwire.dtl.DTLVardef@1feb8d0_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2020

Targeting Scavenger Receptor Type B1 In Cholesterol-Addicted Lymphomas Abolishes Glutathione Peroxidase 4 and Results in Ferroptosis

Normal human cells can either synthesize or uptake cholesterol from lipoproteins to meet their metabolic requirements. Some malignant cells absolutely require cholesterol uptake from lipoproteins for survival because de novo cholesterol synthesis genes are transcriptionally silent or mutated. Recent data suggest that lymphoma cells dependent upon lipoprotein-mediated cholesterol uptake are also dependent on the expression of the lipid hydroperoxidase enzyme glutathione peroxidase 4 (GPX4) to prevent cell death by ferroptosis. Ferroptosis is an oxygen-and iron-dependent cell death mechanism that results from the accumulation of oxidized lipids in cell membranes. To study mechanisms linking cholesterol uptake with ferroptosis, we employed lymphoma cell lines known to be sensitive to cholesterol uptake depletion and treated them with high-density lipoprotein-like (HDL) nanoparticles (HDL NPs). HDL NPs are a cholesterol-poor ligand of the receptor for cholesterol-rich HDL, scavenger receptor type B-1 (SCARB1). Our data reveal that HDL NP treatment activates a compensatory metabolic response in treated cells favoring de novo cholesterol synthesis, which is accompanied by reduced expression of GPX4. As a result, accumulation of oxidized membrane lipids leads to cell death through a mechanism consistent with ferroptosis. Furthermore, ferroptosis was validated in vivo after systemic administration of HDL NPs in mouse lymphoma xenografts and in primary samples obtained from patients with lymphoma. In summary, targeting SCARB1 with HDL NPs in cholesterol uptake addicted lymphoma cells abolishes GPX4 and cancer cell death ensues through a mechanism consistent with ferroptosis.

cancer biology↗

bioRxiv2019

A preliminary study of the cytotoxicity of the protein extract of Chrysobalanus icaco L. and Eugenia astringens Cambess., commercialized in markets

The use of plants and their products for medical treatment is very common procedure in Brazil, especially for treatment of diabetes. In fact, several plants can demonstrate hypoglycemic effects in vitro assays. However, the use for human treatment requires the knowledge of their toxicological properties. The aim of this study was to evaluate the effect of protein extracts of Chrysobalanus icaco collected from natural habitats and of Eugenia astringens acquired from the market of Rio de Janeiro on the viability and migration of fibroblasts. E. astringens has a similar morphology as C. icaco and it is sold as Chrysobalanus in a popular market in Rio de Janeiro. Being a different plant, E. astringens expresses different proteins, and its protein extract has proved to possess higher toxic properties than C. icaco does. Cytotoxicity assays indicated that, as the protein extract concentration increases, fibroblast viability decreases. Only the E. astringens extract displayed cytotoxicity at all concentrations, in addition to reduced fibroblast migration. The results obtained in this study demonstrates that its necessary integrative policies for rational use of medicinal plants and their commercialization, since the current use of medicinal plants may be inadequate and it is of great importance for Public Health.

plant biology↗