Effects of the Toxic Non-Protein Amino Acid ß-Methylamino-L-Alanine (BMAA) on Intracellular Amino Acid Levels in Neuroblastoma Cells.

The cyanobacterial non-protein amino acid (AA) ß-Methylamino-L-alanine (BMAA) is considered to be a neurotoxin. BMAA caused histopathological changes in brains and spinal cords of primates consistent with some of those seen in early motor neuron disease; however, supplementation with L-serine protected against some of those changes. We examined the impact of BMAA on AA concentrations in human neuroblastoma cells in vitro. Cells were treated with 1000 µM BMAA and intracellular free AA concentrations in treated and control cells were compared at six time-points over a 48 h culture period. BMAA had a profound effect on intracellular AA levels at specific time points but in most cases, AA homeostasis was re-established in the cell. The most heavily impacted amino acid was serine which was depleted in BMAA-treated cells from 9 h onwards. Correction of serine depletion could be a factor in the observation that supplementation with L-serine protects against BMAA toxicity in vitro and in vivo. AAs that could potentially be involved in protection against BMAA-induced oxidation such as histidine, tyrosine, and phenylalanine were depleted in cells at later time points.

Linc00996 is a favorable prognostic factor in LUAD: Results from bioinformatics analysis and experimental validation.

Background: Linc00996 has been reported in a variety of malignant tumors, but its potential role and significance in lung adenocarcinoma (LUAD) are not fully understood. The authors investigated the expression and biological behavior of Linc00996 in LUAD and elucidated the function of its potential target genes. Materials and methods: The data of Linc00996 expression in cancers were derived from GEPIA. GEO and TCGA datasets were used to identify the differential expression of Linc00996 in LUAD and analyze the respective correlation between different expression levels and LUAD stage and survival prognosis. We further elucidated the potential biological processes and pathways involved with Linc00996 in LAUD by GSEA. ssGSEA was applied to explore the relationship between Linc00996 and immune activity. Finally, the clinical impact of Linc00996 was assessed in 61 patients with LUAD, and the biological functions of Linc00996 were determined by a series of experiments in vitro, such as CCK8, colony formation, migration, and invasion assays. Results: Compared with adjacent normal lung tissues, Linc00996 was significantly downregulated in LUAD, and its expression was negatively correlated with T stage, N stage, and pathological stage. An in vitro study suggested that enhanced Linc00996 expression could inhibit cell proliferation, clonal formation, migration, and invasion in LUAD cell lines. Via GSEA and ssGSEA, we observed that Linc00996 might be connected with immune infiltration in LUAD, and Linc00996 might inhibit tumorigenesis and metastasis by regulating antigen processing and presentation, JAK-STAT3, and cell adhesion molecular signaling pathways. Conclusion: Linc00996 is a novel tumor suppressor in LUAD and may suppress the tumorigenesis and metastasis of LUAD via the tumor-related signaling pathway, such as antigen processing and presentation, JAK-STAT3, and cell adhesion molecular signaling pathways.

Correction: Steele et al. Misincorporation Proteomics Technologies: A Review. Proteomes 2021, 9, 2.

In the original publication, there was a mistake in Table 2 as published [...].

Cysteine biosynthesis contributes to ß-methylamino-l-alanine tolerance in Escherichia coli.

In contrast to mammalian cells, bacteria such as Escherichia coli have been shown to display tolerance towards the neurotoxin ß-methylamino-l-alanine (BMAA) suggesting that these prokaryotes possess a way to metabolise BMAA or its products, resulting in their export, degradation, or detoxification. Single gene deletion mutants of E. coli K-12 with inactivated amino acid biosynthesis pathways were treated with 500 µg/ml BMAA and the resulting growth was monitored. Wild type E. coli and most of the gene deletion mutants displayed unaltered growth in the presence of BMAA over 12 h. Conversely, deletion of genes in the cysteine biosynthesis pathway, cysE, cysK or cysM resulted in a BMAA dose-dependent growth delay in minimal medium. Through further studies of the ΔcysE strain, we observed increased susceptibility to oxidative stress from H2O2 in minimal medium, and disruptions in glutathione levels and oxidation state. The cysteine biosynthesis pathway is therefore linked to the tolerance of BMAA and oxidative stress in E. coli, which potentially represents a mechanism of BMAA detoxification.

Misincorporation Proteomics Technologies: A Review.

Proteinopathies are diseases caused by factors that affect proteoform conformation. As such, a prevalent hypothesis is that the misincorporation of noncanonical amino acids into a proteoform results in detrimental structures. However, this hypothesis is missing proteomic evidence, specifically the detection of a noncanonical amino acid in a peptide sequence. This review aims to outline the current state of technology that can be used to investigate mistranslations and misincorporations whilst framing the pursuit as Misincorporation Proteomics (MiP). The current availability of technologies explored herein is mass spectrometry, sample enrichment/preparation, data analysis techniques, and the hyphenation of approaches. While many of these technologies show potential, our review reveals a need for further development and refinement of approaches is still required.