Bromodomain and extra-terminal (BET) family proteins: New therapeutic targets in major diseases

The bromodomains and extra-terminal domain (BET) family proteins recognize acetylated chromatin through their bromodomains (BDs) and help in regulating gene expression. BDs are chromatin ‘readers’: by interacting with acetylated lysines on the histone tails, they recruit chromatin-regulating proteins on the promoter region to regulate gene expression and repression. Extensive efforts have been employed by scientific communities worldwide to identify and develop potential inhibitors of BET family BDs to regulate protein expression by inhibiting acetylated histone (H3/H4) interactions. Several small molecule inhibitors have been reported, which not only have high affinity but also have high specificity to BET BDs. These developments make BET family proteins an important therapeutic targets for major diseases such as cancer, neurological disorders, obesity and inflammation. Here, we review and discuss the structural biology of BET family BDs and their applications in major diseases.     

The NH2 terminus of RCK1 domain regulates Ca2+-dependent BK(Ca) channel gating

Large conductance, voltage- and Ca2+-activated K+ (BK(Ca)) channels regulate blood vessel tone, synaptic transmission, and hearing owing to dual activation by membrane depolarization and intracellular Ca2+. Similar to an archeon Ca2+-activated K+ channel, MthK, each of four alpha subunits of BK(Ca) may contain two cytosolic RCK domains and eight of which may form a gating ring. The structure of the MthK channel suggests that the RCK domains reorient with one another upon Ca2+ binding to change the gating ring conformation and open the activation gate. Here we report that the conformational changes of the NH2 terminus of RCK1 (AC region) modulate BK(Ca) gating. Such modulation depends on Ca2+ occupancy and activation states, but is not directly related to the Ca2+ binding sites. These results demonstrate that AC region is important in the allosteric coupling between Ca2+ binding and channel opening. Thus, the conformational changes of the AC region within each RCK domain is likely to be an important step in addition to the reorientation of RCK domains leading to the opening of the BK(Ca) activation gate. Our observations are consistent with a mechanism for Ca2+-dependent activation of BK(Ca) channels such that the AC region inhibits channel activation when the channel is at the closed state in the absence of Ca2+; Ca2+ binding and depolarization relieve this inhibition.     

Sheltering behaviour of<Emphasis Type="Italic"> Macrobrachium nobilii</Emphasis> (Henderson and Matthai, 1910)

Shelter acquisition seems to be one of the main causes for agonistic interactions in the communal culturing of decapod crustaceans, leading to reduction in survival and growth-rate values. Understanding how to reduce aggressive behaviour among individuals by providing suitable shelters would promote production efficiency and welfare in such aquaculture environments. Factors influencing the sheltering behaviour of a freshwater prawn, Macrobrachium nobilii, were studied in laboratory conditions. Prior ownership significantly increased the ability to retain a shelter; males were significantly more likely to acquire and retain a shelter than females, except females carrying eggs. Various movements of the prawn while acquiring the shelter and the behaviour pattern involved in evicting an occupant are described. The size of the shelter selected by an animal is directly related to its body size. Regarding the choice of the colour of the shelter, juveniles and adults preferred dark shelters over light-coloured shelters and never chose a transparent shelter. Communicated by R.F. Oliveira     

Effects of diallyl disulfide (DADS) on expression of apoptosis associated proteins in androgen independent human prostate cancer cells (PC-3)

Prostate cancer is a leading cause of death among the aging men. Surgical or radiotherapy is effective when the cancer is confined to the prostate gland but once the cancer spreads beyond the pelvis even chemotherapy and hormonal ablation therapy fails in curing this disease. Our previous studies have shown that diallyl disulfide (DADS) induces cell cycle arrest and also induces apoptosis in PC-3 cells. And now the present study is focused to see whether there is an activation of caspase cascade pathway. Hence, in the present study the apoptotic effect of DADS is studied by Western blot analysis of caspase-3, -9, -10 and Bcl-2, Bad, and Bax protein. The Apoptotic cells were assessed by Hoechst 33342 staining with 25 and 40 microM concentrations of DADS for 24 h. The results have shown that DADS at 25 and 40 microM concentrations has induced the activation of caspases. There is a significant increase in the expression of caspases (3, 9, and 10). The proapoptotic protein Bax has significantly increased at 40 microM of DADS treatment and there is significant increase of Bad protein at both the concentration. Bcl-2 protein has significantly decreased in DADS treated cells. Therefore, the present investigation serves as evidence that DADS may be a therapeutic drug in the treatment of prostate cancer.     

Views on artificial intelligence (AI) assisted clinical trials

It is of interest to document the views of medical professionals on the application of artificial intelligence (using known data for the prediction of unknown events) in clinical trials using a web survery with a structured questionnaire from 377 subjects. The questionnaire contained 17 statements which were categorised into awareness (1,2 statements), perception (3-10 statements) and opinion (11-17 statements). The data obtained was compared between the subjects using two tailed Fisher''s exact test with p-value <0.05 for data significance analysis. Data shows that majority of professionals have possitive views on the application of artificial intelligence in clinical trials. This will accelarrate the drug evaluation process. However, the use of emerging tools such as AI will not replace human subjects in this context.     

Purification and Characterization of Polygalacturonase-3 from Jamaica cherry (Muntingia calabura Linn)

Endo-polygalacturonase-3 (PG-3), the key enzyme of fruit ripening was purified to near homogeneity as judged by native PAGE from the fruit tissues of Jamaica cherry (Muntingia calabura) using ammonium sulphate fractionation, followed by anion-exchange, gel filtration and affinity chromatography. The molecular mass of the PG-3 enzyme was determined as 85 kD, by size exclusion chromatography. SDS-PAGE of PG-3 revealed two dissimilar bands of 62 and 21 kD as heterogenous subunits. The optimum pH of PG-3 was found to be 4.0. The enzyme had an optimum temperature of 40°C and was relatively stable at 50°C and 60°C. K_m for the substrate polygalacturonic acid was found to be 0.27%. The purified enzyme was a glycoprotein with 6.6 % carbohydrate content.     

Virus hunters: catching bugs in the field

Densely populated areas in rural China require constant vigilance and state-of-the-art technology to stop new pandemics in their tracks. Hurdles are not only scientific in some parts of the developing world.     

Apoptosis inducing effect of plumbagin on colonic cancer cells depends on expression of COX-2

Plumbagin, a quinonoid found in the plants of the Plumbaginaceae, possesses medicinal properties. In this study we investigated the anti-proliferative and apoptotic activity of plumbagin by using two human colonic cancer cell lines, HT29 and HCT15. IC50 of Plumbagin for HCT15 and HT29 cells (22.5 μM and 62.5 μM, respectively) were significantly different. To study the response of cancer cells during treatment strategies, cells were treated with two different concentrations, 15 μM, 30 μM for HCT15 and 50 μM, 75 μM for HT29 cells. Though activation of NFκB, Caspases-3, elevated levels of TNF-α, cytosolic Cytochrome C were seen in both HCT15 cells HT29 treated with plumbagin, aberrant apoptosis with decreased level of pEGFR, pAkt, pGsk-3β, PCNA and Cyclin D1was observed only in 15 μM and 30 μM plumbagin treated HCT15 and 75 μM plumbagin treated HT29 cells. This suggests that plumbagin induces apoptosis in both HCT15 cells and HT29 treated, whereas, proliferation was inhibited only in 15 μM and 30 μM plumbagin treated HCT15 and 75 μM plumbagin treated HT29 cells, but not in 50 μM plumbagin treated HT29 cells. Expression of COX-2 was decreased in 75 μM plumbagin treated HT29 cells when compared to 50 μM plumbagin treated HT29 cells, whereas HCT15 cells lack COX. Hence the observed resistance to induction of apoptosis in 50 μM plumbagin treated HT29 cells are attributed to the expression of COX-2. In conclusion, plumbagin induces apoptosis in colonic cancer cells through TNF-α mediated pathway depending on expression of COX-2 expression.