Phosphatidylserine and phosphatidylethanolamine regulate the structure and function of FVIIa and its interaction with soluble tissue factor

Cell membranes have important functions in many steps of the blood coagulation cascade, including the activation of factor X (FX) by the factor VIIa (FVIIa)-tissue factor (TF) complex (extrinsic X_ase). FVIIa shares structural similarity with factor IXa (FIXa) and FXa. FIXa and FXa are regulated by binding to phosphatidylserine (PS)-containing membranes via their γ-carboxyglutamic acid-rich domain (Gla) and epidermal growth-factor (EGF) domains. Although FVIIa also has a Gla-rich region, its affinity for PS-containing membranes is much lower compared with that of FIXa and FXa. Research suggests that a more common endothelial cell lipid, phosphatidylethanolamine (PE), might augment the contribution of PS in FVIIa membrane-binding and proteolytic activity. We used soluble forms of PS and PE (1,2-dicaproyl-sn-glycero-3-phospho-l-serine (C6PS), 1,2-dicaproyl-sn-glycero-3-phospho-ethanolamine (C6PE)) to test the hypothesis that the two lipids bind to FVIIa jointly to promote FVIIa membrane binding and proteolytic activity. By equilibrium dialysis and tryptophan fluorescence, we found two sites on FVIIa that bound equally to C6PE and C6PS with K_d of ∼ 150–160 μM, however, deletion of Gla domain reduced the binding affinity. Binding of lipids occurred with greater affinity (K_d∼70–80 μM) when monitored by FVIIa proteolytic activity. Global fitting of all datasets indicated independent binding of two molecules of each lipid. The proteolytic activity of FVIIa increased by ∼50–100-fold in the presence of soluble TF (sTF) plus C6PS/C6PE. However, the proteolytic activity of Gla-deleted FVIIa in the presence of sTF was reduced drastically, suggesting the importance of Gla domain to maintain full proteolytic activity.     

An integrative view on the physiology of human early placental villi

The placenta is an indispensable organ for intrauterine protection, development and growth of the embryo and fetus. It provides tight contact between mother and conceptus, enabling the exchange of gas, nutrients and waste products. The human placenta is discoidal in shape, and bears a hemo-monochorial interface as well as villous materno-fetal interdigitations. Since Peter Medawar's astonishment to the paradoxical nature of the mother–fetus relationship in 1953, substantial knowledge in the domain of placental physiology has been gathered. In the present essay, an attempt has been made to build an integrated understanding of morphological dynamics, cell biology, and functional aspects of genomic and proteomic expression of human early placental villous trophoblast cells followed by a commentary on the future directions of research in this field.     

Medicinal Chemistry Perspectives on Recent Advances in Src Kinase Inhibitors as a Potential Target for the Development of Anticancer Agents: Biological Profile,Selectivity, Structure-Activity Relationship

The physiological Src proto-oncogene is a protein tyrosine kinase receptor that served as the essential signaling pathway in different types of cancer. Src kinase receptor is divided into different domains: a unique domain, an SH3 domain, an SH2 domain, a protein tyrosine kinase domain, and a regulatory tail, which runs from the N-terminus to the C-terminus. Src kinase inhibitors bind in the kinase domain and are activated by phosphorylation. The etiology of cancer involved various signaling pathways and Src signaling pathways are also involved in those clusters. Although the dysregulation of Src kinase resulted in cancer being discovered in the late 19^th century it is still considered a cult pathway because it is not much explored by different medicinal chemists and oncologists. The Src kinase regulated through different kinase pathways (MAPK, PI3K/Akt/mTOR, JAK/STAT3, Hippo kinase, PEAK1, and Rho/ROCK pathways) and proceeded downstream signaling to conduct cell proliferation, angiogenesis, migration, invasion, and metastasis of cancer cells. There are numerous FDA-approved drugs flooded the market but still, there is a huge demand for the creation of novel anticancer drugs. As the existing drugs are accompanied by several adverse effects and drug resistance due to rapid mutation in proteins. In this review, we have elaborated about the structure and activation of Src kinase, as well as the development of Src kinase inhibitors. Our group also provided a comprehensive overview of Src inhibitors throughout the last two decades, including their biological activity, structure-activity relationship, and Src kinase selectivity. The Src binding pocket has been investigated in detail to better comprehend the interaction of Src inhibitors with amino acid residues. We have strengthened the literature with our contribution in terms of molecular docking and ADMET studies of top compounds. We hope that the current analysis will be a useful resource for researchers and provide glimpse of direction toward the design and development of more specific, selective, and potent Src kinase inhibitors.     

Regulation of endo-1,4-β-glucanase secretion fromTermitomyces clypeatus by carbon catabolic product(s)

Secretion of CMCase byTermitomyces clypeatus was only observed in the presence of a gluconeogenic amino acid, a citrate-cycle acid, maleate, subinhibitory concentrations of glucosamine, or fluoride in the medium. The enzyme was not secreted in the presence of caffeine or IBMX or theophylline, and these phosphodiesterase inhibitors lowered the secretion of CMCase by glutamate. The presence of both glucosamine and glutamate in a cellulose medium were, however, antagonistic to CMCase secretion. In a growth medium, xylose and glucose were equivalent carbon source for the fungus while succinate was a poor source and strongly repressed growth at higher concentrations. Growth ofT. clypeatus was highly favored in media containing xylose/glucose with succinate/glutamate. During growth ofT. clypeatus in a glucose medium, the intracellular glucose level was stabilized by the presence of succinate, glutamate or glucosamine in the medium. All these observation suggested that a negative cellular regulation, mediated by carbon catabolic product(s), existed inT. clypeatus which regulated the secretion of CMCase. A transient but significant increase of intracellular cAMP and cGMP levels was observed at the onset of mycelial growth in glucose and glucose/maleate media, respectively.     

Primary cilia and dendritic spines: Different but similar signaling compartments

Primary non-motile cilia and dendritic spines are cellular compartments that are specialized to sense and transduce environmental cues and presynaptic signals, respectively. Despite their unique cellular roles, both compartments exhibit remarkable parallels in the general principles, as well as molecular mechanisms, by which their protein composition, membrane domain architecture, cellular interactions, and structural and functional plasticity are regulated. We compare and contrast the pathways required for the generation and function of cilia and dendritic spines, and suggest that insights from the study of one may inform investigations into the other of these critically important signaling structures.     

Seasonal intensity of Angiostrongylus cantonensis in the intermediate host, Laevicaulis alte.

The slug, Laevicaulis alte, is a vector of Angiostrongylus cantonensis in the Greater Bombay area. The seasonal prevalence of A. cantonensis was investigated to determine the maximum intensity of the parasite in a field population occupying an area of approximately 400 m2. The maximum intensity of larvae was observed in the rainy months, June-November. Investigations showed that individual L. alte could tolerate an infecting dose of 150 first-stage A. cantonensis larvae before mortalities occurred.