Arginine methylation: the promise of a ‘silver bullet’ for brain tumours?

Despite intense research efforts, our pharmaceutical repertoire against high-grade brain tumours has not been able to increase patient survival for a decade and life expectancy remains at less than 16 months after diagnosis, on average. Inhibitors of protein arginine methyltransferases (PRMTs) have been developed and investigated over the past 15 years and have now entered oncology clinical trials, including for brain tumours. This review collates recent advances in the understanding of the role of PRMTs and arginine methylation in brain tumours. We provide an up-to-date literature review on the mechanisms for PRMT regulation. These include endogenous modulators such as alternative splicing, miRNA, post-translational modifications and PRMT–protein interactions, and synthetic inhibitors. We discuss the relevance of PRMTs in brain tumours with a particular focus on PRMT1, -2, -5 and -8. Finally, we include a future perspective where we discuss possible routes for further research on arginine methylation and on the use of PRMT inhibitors in the context of brain tumours.

     

Computer-Guided Trypanocidal Activity of Natural Lactones Produced by Endophytic Fungus of Euphorbia umbellata

Hundreds of millions of people worldwide are affected by Chagas’ disease caused by Trypanosoma cruzi. Since the current treatment lack efficacy, specificity, and suffers from several side-effects, novel therapeutics are mandatory. Natural products from endophytic fungi have been useful sources of lead compounds. In this study, three lactones isolated from an endophytic strain culture were in silico evaluated for rational guidance of their bioassay screening. All lactones displayed in vitro activity against T. cruzi epimastigote and trypomastigote forms. Notably, the IC₅₀ values of (+)-phomolactone were lower than benznidazole (0.86 vs. 30.78 μM against epimastigotes and 0.41 vs. 4.88 μM against trypomastigotes). Target-based studies suggested that lactones displayed their trypanocidal activities due to T. cruzi glyceraldehyde-3-phosphate dehydrogenase (TcGAPDH) inhibition, and the binding free energy for all three TcGAPDH-lactone complexes suggested that (+)-phomolactone has a lower score value (−3.38), corroborating with IC₅₀ assays. These results highlight the potential of these lactones for further anti-T. cruzi drug development.     

MAC-T Cells as a Tool to Evaluate Lentiviral Vector Construction Targeting Recombinant Protein Expression in Milk

Prior to generating transgenic animals for bioreactors, it is important to evaluate the vector constructed to avoid poor protein expression. Mammary epithelial cells cultured in vitro have been proposed as a model to reproduce the biology of the mammary gland. In the present work, three lentiviral vectors were constructed for the human growth hormone (GH), interleukin 2 (IL2), and granulocyte colony-stimulating factor 3 (CSF3) genes driven by the bovine β-casein promoter. The lentiviruses were used to transduce mammary epithelial cells (MAC-T), and the transformed cells were cultured on polystyrene in culture medium with and without prolactin. The gene expression of transgenes was evaluated by PCR using cDNA, and recombinant protein expression was evaluated by Western-blotting using concentrated medium and cellular extracts. The gene expression, of the three introduced genes, was detected in both induced and non induced MAC-T cells. The human GH protein was detected in the concentrated medium, whereas CSF3 was detected in the cellular extract. Apparently, the cellular extract is more appropriate than the concentrated medium to detect recombinant protein, principally because concentrated medium has a high concentration of bovine serum albumin. The results suggest that MAC-T cells may be a good system to evaluate vector construction targeting recombinant protein expression in milk.     

Quantitative assessment of the accuracy for three interpolation techniques in kinematic analysis of human movement

Marker obstruction during human movement analyses requires interpolation to reconstruct missing kinematic data. This investigation quantifies errors associated with three interpolation techniques and varying interpolated durations. Right ulnar styloid kinematics from 13 participants performing manual wheelchair ramp ascent were reconstructed using linear, cubic spline and local coordinate system (LCS) interpolation from 11–90% of one propulsive cycle. Elbow angles (flexion/extension and pronation/supination) were calculated using real and reconstructed kinematics. Reconstructed kinematics produced maximum elbow flexion/extension errors of 37.1 (linear), 23.4 (spline) and 9.3 (LCS) degrees. Reconstruction errors are unavoidable [minimum errors of 6.7 mm (LCS); 0.29 mm (spline); 0.42 mm (linear)], emphasising careful motion capture system setup must be performed to minimise data interpolation. For the observed movement, LCS-based interpolation (average error of 14.3 mm; correlation of 0.976 for elbow flexion/extension) was most suitable for reconstructing durations longer than 200 ms. Spline interpolation was superior for shorter durations.     

Nighttime Sugar Starvation Orchestrates Gibberellin Biosynthesis and Plant Growth in Arabidopsis

A plant’s eventual size depends on the integration of its genetic program with environmental cues, which vary on a daily basis. Both efficient carbon metabolism and the plant hormone gibberellin are required to guarantee optimal plant growth. Yet, little is known about the interplay between carbon metabolism and gibberellins that modulates plant growth. Here, we show that sugar starvation in Arabidopsis thaliana arising from inefficient starch metabolism at night strongly reduces the expression of ent-kaurene synthase, a key regulatory enzyme for gibberellin synthesis, the following day. Our results demonstrate that plants integrate the efficiency of photosynthesis over a period of days, which is transduced into a daily rate of gibberellin biosynthesis. This enables a plant to grow to a size that is compatible with its environment.     

Slow rise of Ca2+ and slow release of reactive oxygen species are two cross-talked events important in tumour necrosis factor-α-mediated apoptosis

Tumour necrosis factor-α(TNF-α) was found to be a cell cycle-independent apoptogenic cytokine in cultured fibroblast L929 cells. This assertion is based on the observations (1) TNF-α increased the number of cells with hypo-diploid DNA in a time dependent manner as revealed by flow cytometry, and (2) TNF-α induced DNA fragmentation as resolved by agarose gel electrophoresis. When cells were exposed to TNF-α (50ng/ml), a slow rise in intracellular free Ca²⁺ level and a delayed increase in the production of reactive oxygen species (ROS) (both observed 3h after the addition of TNF-α) were observed in fluo-3 and furared or dichlorofluorescein loaded cells, respectively. Interestingly, challenge of cells with TNF-α in the presence of BAPTA/AM, an intracellular Ca²⁺ chelator, decreased the release of ROS. Removal of ROS by 4-hydroxy 2,2,6,6-tetra-methyl-piperidinooxy (4OH-TEMPO) blocked the TNF-α-mediated Ca²⁺ rise. Moreover, when cells were exposed to TNF-α with both 4OH-TEMPO and BAPTA/AM, more viable cells were found than from treatment with either BAPTA/AM or 4OH-TEMPO. These results suggest that ROS and cellular Ca²⁺ are two cross-talk messengers important in TNF-α-mediated apoptosis.