Voltage-gated sodium channels are essential proteins in brain physiology, as they generate the sodium currents that initiate neuronal action potentials. Voltage-gated sodium channels expression, localisation and function are regulated by a range of transcriptional and post-translational mechanisms. Here, we review our understanding of regulation of brain voltage-gated sodium channels, in particular SCN1A (NaV1.1), SCN2A (NaV1.2), SCN3A (NaV1.3) and SCN8A (NaV1.6), by transcription factors, by alternative splicing, and by post-translational modifications. Our focus is strongly centred on recent research lines, and newly generated knowledge.

The work calls for in-depth investigation of ArgMe in normal and diseased tissues using methods including clinical proteomics.

The antihyperglycaemic activity of Tetracarpidium conophorum nut (walnut) was investigated in albino rats. A total of 20 albino rats were used for the study. The rats were divided into five groups (A–E) of four rats each. Diabetes were induced in the rats except four which served as the positive control group A. Groups B (negative control), C, D, and E contain diabetic rats each with blood sugar level ≥17.00 mmol/L. Groups A and B were fed on 85.2 g of top feed grower over the test period. Test groups C, D, and E were fed on 21.3 g, 42.6 g, and 85.2 g of walnuts, respectively, and their fasting blood sugar (FBS) levels were checked on daily basis. Fasting blood glucose levels of the test groups were significantly lower than negative control P < 0.05, for 3rd, 7th, and 10th days of the test. There were also significant increase in the body weight and hemoglobin concentration and a decreased urine output of the test group compared with the controls. These results indicate that Tetracarpidium conophorum nut (walnut) has an antihyperglycemic effect in diabetic rats.

No abstract

BackgroundThe inhibitory subunit of cardiac troponin (cTnI) is a gold standard cardiac biomarker and also an essential protein in cardiomyocyte excitation-contraction coupling. The interactions of cTnI with other proteins are fine-tuned by post-translational modification of cTnI. Mutations in cTnI can lead to hypertrophic cardiomyopathy. Methods and ResultsHere we report, for the first time, that cTnI is modified by arginine methylation in human myocardium. Using Western blot, we observed reduced levels of cTnI arginine methylation in human hypertrophic cardiomyopathy compared to dilated cardiomyopathy biopsies. Similarly, using a rat model of cardiac hypertrophy we observed reduced levels of cTnI arginine methylation compared to sham controls. Using mass spectrometry, we identified cTnI methylation sites at R74/R79 and R146/R148 in human cardiac samples. R146 and R148 lie at the boundary between the critical cTnI inhibitory and switch peptides; PRMT1 methylated an extended inhibitory peptide at R146 and R148 in vitro. Mutations at R145 that have been associated with hypertrophic cardiomyopathy hampered R146/R148 methylation by PRMT1 in vitro. H9c2 cardiac-like cells transfected with plasmids encoding for a methylation-deficient R146A/R148A cTnI protein developed cell hypertrophy, with a 32% increase in cell size after 72 h, compared to control cells. DiscussionOur results provide evidence for a novel and significant cTnI post-translational modification. Our work opens the door to translational investigations of cTnI arginine methylation as a biomarker of disease, which can include e.g. cardiomyopathies, myocardial infarction and heart failure, and offers a novel way to investigate the effect of cTnI mutations in the inhibitory/switch peptides. Abbreviations: Arginine methylation (ArgMe), collision induced dissociation (CID), dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), matrix-assisted laser desorption ionisation -time of flight (MALDI-TOF), protein arginine methyltransferases (PRMTs), Sadenosyl-L-methionine (SAM).