Adhesion stimulates Scar/WAVE phosphorylation in mammalian cells

The Scar/WAVE complex catalyzes the protrusion of pseudopods and lamellipods, and is therefore a principal regulator of cell migration. However, it is unclear how its activity is regulated, beyond a dependence on Rac. Phosphorylation of the proline-rich region, by kinases such as Erk2, has been suggested as an upstream activator. We have recently reported that phosphorylation is not required for complex activation. Rather, it occurs after Scar/WAVE has been activated, and acts as a modulator. Neither chemoattractant signaling nor Erk2 affects the amount of phosphorylation, though in Dictyostelium it is promoted by cell-substrate adhesion. We now report that cell-substrate adhesion also promotes Scar/WAVE2 phosphorylation in mammalian cells, suggesting that the process is evolutionarily conserved

Attributes of Seabuckthorn (Hippophae rhamnoides L.) to Meet Nutritional Requirements in High Altitude.

The diet of humans living in different geographical and climatic regions of the earth varies greatly in both quantity and composition of foods. Evidence is accumulating that indicates that there is a high risk of malnutrition at high altitude because of the usual lack of fresh food and environmental factors. Lack of nutritious diet in the difficult terrain is a potential stressor that elicits oxidative stress. The excretion of minerals from the body is higher in high altitude condition. The altered nutritional requirement can be met to a large extend by regular consumption of locally grown fruits and vegetables. Results of analysis of Seabuckthorn growing in Leh valley of Trans-Himalaya showed the presence of high content of multivitamins including vitamin C (275 mg/100g), vitamin A (432.4 IU/100g), vitamin E (3.54 mg/100g), Riboflavin (1.45 mg/100g), Niacin (68.4 mg/100g), Pantothenic acid (0.85 mcg/100g), vitamin B-6 (1.12 mg/100g), and vitamin B-2 (5.4 mcg/100g). Similarly, mineral elements composition revealed high amount of minerals including potassium (647.2 mg/l), calcium (176.6 mg/l), iron (30.9 mg/l), magnesium (22.5 mg/l), phosphorous (84.2 mg/l), sodium (414.2 mg/l), zinc (1.4 mg/l), copper (0.7 mg/l), manganese (1.06 mg/l) and selenium (0.53 mg/l).Defence Science Journal, 2010, 60(2), pp.226-230, DOI:http://dx.doi.org/10.14429/dsj.60.34

Extracellular signalling modulates Scar/WAVE complex activity through Abi phosphorylation

The lamellipodia and pseudopodia of migrating cells are produced and maintained by the Scar/WAVE complex. Thus, actin-based cell migration is largely controlled through regulation of Scar/WAVE. Here, we report that the Abi subunit—but not Scar—is phosphorylated in response to extracellular signalling in Dictyostelium cells. Like Scar, Abi is phosphorylated after the complex has been activated, implying that Abi phosphorylation modulates pseudopodia, rather than causing new ones to be made. Consistent with this, Scar complex mutants that cannot bind Rac are also not phosphorylated. Several environmental cues also affect Abi phosphorylation—cell-substrate adhesion promotes it and increased extracellular osmolarity diminishes it. Both unphosphorylatable and phosphomimetic Abi efficiently rescue the chemotaxis of Abi KO cells and pseudopodia formation, confirming that Abi phosphorylation is not required for activation or inactivation of the Scar/WAVE complex. However, pseudopodia and Scar patches in the cells with unphosphorylatable Abi protrude for longer, altering pseudopod dynamics and cell speed. Dictyostelium, in which Scar and Abi are both unphosphorylatable, can still form pseudopods, but migrate substantially faster. We conclude that extracellular signals and environmental responses modulate cell migration by tuning the behaviour of the Scar/WAVE complex after it has been activated

AKT and SGK kinases regulate cell migration by altering Scar/WAVE complex activation and Arp2/3 complex recruitment

Cell polarity and cell migration both depend on pseudopodia and lamellipodia formation. These are regulated by coordinated signaling acting through G-protein coupled receptors and kinases such as PKB/AKT and SGK, as well as the actin cytoskeletal machinery. Here we show that both Dictyostelium PKB and SGK kinases (encoded by pkbA and pkgB) are dispensable for chemotaxis towards folate. However, both are involved in the regulation of pseudopod formation and thus cell motility. Cells lacking pkbA and pkgB showed a substantial drop in cell speed. Actin polymerization is perturbed in pkbA- and reduced in pkgB- and pkbA-/pkgB- mutants. The Scar/WAVE complex, key catalyst of pseudopod formation, is recruited normally to the fronts of all mutant cells (pkbA-, pkgB- and pkbA-/pkgB-), but is unexpectedly unable to recruit the Arp2/3 complex in cells lacking SGK. Consequently, loss of SGK causes a near-complete loss of normal actin pseudopodia, though this can be rescued by overexpression of PKB. Hence both PKB and SGK are required for correct assembly of F-actin and recruitment of the Arp2/3 complex by the Scar/WAVE complex during pseudopodia formation

Regulation of multiple tip formation by caffeine in cellular slime molds

Background: The multicellular slug in Dictyostelium has a single tip that acts as an organising centre patterning the rest of the slug. High adenosine levels at the tip are believed to be responsible for this tip dominance and the adenosine antagonist, caffeine overrides this dominance promoting multiple tip formation. Results: Caffeine induced multiple tip effect is conserved in all the Dictyostelids tested. Two key components of cAMP relay namely, cAMP phosphodiesterase (Pde4) and adenyl cyclase-A (AcaA) levels get reduced during secondary tip formation in Dictyostelium discoideum. Pharmacological inhibition of cAMP phosphodiesterase also resulted in multiple tips. Caffeine reduces cAMP levels by 16.4, 2.34, 4.71 and 6.30 folds, respectively in D. discoideum, D. aureostipes, D. minutum and Polysphondylium pallidum. We propose that altered cAMP levels, perturbed cAMP gradient and impaired signalling may be the critical factors for the origin of multiple tips in other Dictyostelids as well. In the presence of caffeine, slug cell movement gets impaired and restricted. The cell type specific markers, ecmA (prestalk) and pspA (prespore) cells are not equally contributing during additional tip formation. During additional tip emergence, prespore cells transdifferentiate to compensate the loss of prestalk cells. Conclusion: Caffeine decreases adenyl cyclase–A (AcaA) levels and as a consequence low cAMP is synthesised altering the gradient. Further if cAMP phosphodiesterase (Pde4) levels go down in the presence of caffeine, the cAMP gradient breaks down. When there is no cAMP gradient, directional movement is inhibited and might favour re-differentiation of prespore to prestalk cells

Chemical composition and antioxidant capacities of phytococktail extracts from trans-Himalayan cold desert

BACKGROUND: Himalayan plants are widely used in traditional system of medicine both as prophylactics and therapeutics for high altitude maladies. Our aim was to evaluate the antioxidant capacities and bioactive compounds of methanol and n-hexane extracts of the phytococktail comprising of sea buckthorn (Hippophae rhamnoides), apricot (Prunus armeniaca) and roseroot (Rhodiola imbricata) from trans-Himalaya. METHODS: The 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and nitric oxide (NO) radical scavenging capacities and lipid peroxidation inhibition (LPI) property of the extracts were determined. Total antioxidant power was determined by ferric reducing/antioxidant power (FRAP) assay. Total polyphenol, flavonoid, flavonol, proanthocyanidin and carotenoid were also estimated for both extracts. We have identified and quantified the phyto-chemotypes present in the methanol and n-hexane extracts by hyphenated gas chromatography/mass spectrometry (GC/MS) technique. RESULTS: Antioxidant capacity assays using DPPH, ABTS, NO, LPI and FRAP exhibited analogous results where the phytococktail showed high antioxidant action. The phytococktail was also found to possess high quantity of total polyphenol, flavonoid, flavonol and carotenoid. A significant and linear correlation was found between the antioxidant capacities and bioactive principles. A total of 32 phyto-chemotypes were identified from these extracts by GC/MS chemometric fingerprinting. Major phyto-chemotypes identified by GC/MS were glycosides, phenylpropanoids and derivatives, terpenoids, alkaloids, phytosterols, fatty acids and esters, alkaloids and derivatives, organic acid esters and aromatic ethers with positive biological and pharmacological actions. CONCLUSION: The phytococktail extracts were found to contain considerable amount of diverse bioactive compounds with high antioxidant capacities. The presence of hydrophilic and lipophilic antioxidants in the phytococktail could have contributed to the higher antioxidant values. Hence, the phytococktail could be used as natural source of antioxidants to ameliorate disorders associated with oxidative stress

Status of Plasmodium Falciparum and Vivax in Jharkhand: A Five Year (2004-08) Retrospective Study at Rajendra Institute of Medical Sciences, Ranchi

ABSTRACT Malaria is well known for its fatalities worldwide. In India, it is still endemic in many areas where two species of Plasmodium namely Plasmodium vivax and Plasmodium falciparum are reported. P.vivax is widespread, creating lots of morbidities across the country. P. falciparum, on the other hand, though comparatively narrow in its infectious volume, is a serious cause of mortalities in India. A five year survey was conducted from 2004 to 2008 in a high malaria-hit district, Ranchi. Thick and thin blood smears were made at the Department of Clinical Pathology, Rajendra Institute of Medical Sciences (RIMS), where the microscopic examinations were carried out. The overall reported and examined cases at RIMS included 36643 suspected malaria cases, out of which, 21833(59.5%) were found positive. Out of these positive cases, 6842(31.3%) were confirmed as P. falciparum patients and 14991(68.6%) as P. vivax cases respectively. Number of negative cases was 14811 (40.4%). In this study, it was observed that after the year 2005, incidence of malaria suddenly dropped by 50% and remained almost static on the same level in the following years with only some seasonal variations. However, it was observed that P. falciparum steadily became more dangerous. It is therefore highly necessary to take immediate and effective measures to minimize the complications of P. falciparum along with P. vivax to prevent death toll in these areas

Facile synthesis of diverse N-Acyl Anthranilamides and quinazolin-4-ones as HMG-CoA reductase inhibitor via Pd-catalyzed cascade reaction

This manuscript describes the design and synthesis of a series of diverse N-Acyl Anthranilamides and quinazolin-4-ones derivatives (3a-3n, and 4a-4d) inhibitors of HMG-CoA reductase for the treatment of hypercholesterolemia. A series of N-Acyl Anthranilamides and quinazolin-4-ones derivatives (3a-3n, and 4a-4d) were synthesized and their chemical structures were confirmed by 1 H, 13C NMR and mass spectral data. Analogs were optimized using structure-based design and physical property considerations resulting in the identification of 4b and 3d, a hepatoselective HMG-CoA reductase inhibitor with excellent acute and chronic efficacy in a vitro model

Synthesis and biological evaluation of 2,4-diaminopyrimidine-5-carbonitrile and N-(2-amino-5-cyanopyrimidin-4-yl)benzamide derivatives as EGFR inhibitors

A series of 2,4-diaminopyrimidine-5-carbonitrile and N-(2-amino-5-cyanopyrimidin-4-yl) benzamide derivatives (5–14) were synthesized and their chemical structures were confirmed by 1 H, 13C NMR and mass spectral data. Anticancer activity of all the synthesized compounds were evaluated for in vitro cytotoxic activity against a panel of four human cancer cell lines i.e., human breast (MCF-7,), cervical cancer (C33A), oral (KB) and prostrate (DU-145). All the examined compounds, demonstrated potent to moderate anticancer activity. Among all the synthesized compounds, 6 and 11 were exhibited more potent activity. Docking studies for 6 and 11 into EGFR active site was carried out to investigate their potential binding modes. Therefore, compounds 6 and 11 can be considered as fascinating candidates for further expansion of more potent anticancer agents