New biochemical insights into the dynamics of water molecules at the GMP or IMP binding site of human GMPR enzyme: A molecular dynamics study

Human GMP reductase (hGMPR) enzyme is involved in a cellular metabolic pathway, converting GMP into IMP, and also it is an important target for anti-leukemic agents. Present computational investigations explain dynamical behavior of water molecules during the conformational transition process from GMP to IMP using molecular dynamics simulations. Residues at substrate-binding site of cancerous protein (PDB Id. 2C6Q) are mostly more dynamic in nature than the normal protein (PDB Id. 2BLE). Nineteen conserved water molecules are identified at the GMP/IMP binding site and are classified as (i) conserved stable dynamic and (ii) infrequent dynamic. Water molecules W11, W14, and W16 are classified as conserved stable dynamic due to their immobile character, whereas remaining water molecules (W1, W2, W3, W4, W5, W7, W8, W9, W10, W12, W13, W15, W17, W18, and W19) are infrequent with dynamic nature. Entrance or displacement of these infrequent water molecules at GMP/IMP sites may occur due to forward and backward movement of reference residues involving ligands. Four water molecules of hGMPR-I and nine water molecules of hGMPR-II are observed in repetitive transitions from GMP to IMP pathway, which indicates discrimination between two isoforms of hGMPRs. Water molecules in cancerous protein are more dynamic and unstable compared to normal protein. These water molecules execute rare dynamical events at GMP binding site and could assist in detailed understanding of conformational transitions that influence the hGMPR's biological functionality. The present study should be of interest to the experimental community engaged in leukemia research and drug discovery for CML cancer.     

Substrates for clinical applicability of stem cells

The capability of human pluripotent stem cells(h PSCs) to differentiate into a variety of cells in the human body holds great promise for regenerative medicine. Many substrates exist on which h PSCs can be self-renewed, maintained and expanded to further the goal of clinical application of stem cells. In this review, we highlight numerous extracellular matrix proteins, peptide and polymer based substrates, scaffolds and hydrogels that have been pioneered. We discuss their benefits and shortcomings and offer future directions as well as emphasize commercially available synthetic peptidesas a type of substrate that can bring the benefits of regenerative medicine to clinical settings.     

Erythropoietin gene expression in haemopoietic cell lines

Erythropoietin (Epo) gene expression was studied in a number of different haemopoietic cell lines by in situ hybridization and Northern Blot analysis using a radioisotope-labelled monkey Epo DNA probe. A positive message was expressed by a human cell line, CM-S, derived from a patient with congenital hypoplastic anemia, and by a murine erythro-leukaemic cell line, clone 707, derived from the spleen of Friend virus-infected mice. No message was detected in two megakaryoblastic cell lines, and in a monocytic cell line, derived from a patient with acute monocytic leukaemia. These data may fit with the hypothesis of expression of Epo and other growth factors by haemopoietic cells through a mechanism of so-called autocrine secretion.     

Differential binding of SARS-CoV-2 Spike protein variants to its cognate receptor hACE2 using molecular modeling based binding analysis

The current emergence of novel coronavirus, SARS-CoV-2 and its ceaseless expansion worldwide has posed a global health emergency that has adversely affected the humans. With the entire world striving to understand the newly emerged virus, differences in morbidity and infection rate of SARS-CoV-2 have been observed across varied geographic areas, which have been ascribed to viral mutation and evolution over time. The homotrimeric Spike (S) glycoprotein on the viral envelope surface is responsible for binding, priming, and initiating infection in the host. Our phylogeny analysis of 1947 sequences of S proteins indicated there is a change in amino acid (aa) from aspartate (Group-A) to glycine (Group-B) at position 614, near the receptor- binding domain (RBD; aa positions 331-524). The two variants are reported to be in circulation, disproportionately across the world, with Group-A dominant in Asia and Group-B in North America. The trimeric, monomeric, and RBD of S protein of both the variant groups (A & B) were modeled using the Swiss-Model server and were docked with the human receptor angiotensin-converting enzyme 2 (hACE2) employing the PatchDock server and visualized in PyMol. Group-A S protein''s RBD bound imperceptibly to the two binding clefts of the hACE2 protein, on the other hand, Group-B S protein''s RBD perfectly interacted inside the binding clefts of hACE2, with higher number of hydrogen and hydrophobic interactions. This implies that the S protein''s amino acid at position 614 near the core RBD influences its interaction with the cognate hACE2 receptor, which may induce its infectivity that should be explored further with molecular and biochemical studies.     

Meiotic studies in some selected members of Gamopetalae from Kashmir Himalaya

The present study is part of our research project on cytomorphology of gamopetalous flora of Kashmir Himalaya, a zone with rich biodiversity. Out of 134 species of Gamopetalae meiotically investigated, chromosome numbers for 30 accessions belonging to 17 species and six families are new or varied reports. Euphrasia paucifolia (n = 22), Lactuca decipiens (n = 8), Saussurea albescens (n = 17), Saussurea roylei (n = 16), Saussurea taraxacifolia (n = 16) and Veronica deltigera (n = 8) are first cytological reports for these species. Anaphalis nepalensis (n = 28), Codonopsis rotundifolia (n = 16) and Hieracium vulgatum (n = 27) are new euploid chromosome reports for these species suggesting potential speciation through chromosomal evolution. Besides, Androsace mucronifolia (n = 10), A. sempervivoides (n = 10), Cicerbita lessertiana (n = 8), Dracocephalum nutans (n = 5), Erigeron patentisquama (n = 9), Galium pauciflorum (n = 11), Onopordum acanthium (n = 17) and Xanthium spinosum (n = 8) are the first chromosome reports to Indian accessions of the species. Out of the 17 species, 9 species (52.9 %) viz. A. nepalensis, C. lessertiana, C. rotundifolia, D. nutans, E. patentisquama, Euphrasia paucifolia, L. decipiens, O. acanthium and V. deltigera show abnormal meiosis/microsporogenesis of one or other type, thereby leading to pollen anomalies.     

PAWR-mediated suppression of BCL2 promotes switching of 3-azido withaferin A (3-AWA)-induced autophagy to apoptosis in prostate cancer cells

An active medicinal component of plant origin with an ability to overcome autophagy by inducing apoptosis should be considered a therapeutically active lead pharmacophore to control malignancies. In this report, we studied the effect of concentration-dependent 3-AWA (3-azido withaferin A) sensitization to androgen-independent prostate cancer (CaP) cells which resulted in a distinct switching of 2 interrelated conserved biological processes, i.e. autophagy and apoptosis. We have observed 3 distinct parameters which are hallmarks of autophagy in our studies. First, a subtoxic concentration of 3-AWA resulted in an autophagic phenotype with an elevation of autophagy markers in prostate cancer cells. This led to a massive accumulation of MAP1LC3B and EGFP-LC3B puncta coupled with gradual degradation of SQSTM1. Second, higher toxic concentrations of 3-AWA stimulated ER stress in CaP cells to turn on apoptosis within 12 h by elevating the expression of the proapoptotic protein PAWR, which in turn suppressed the autophagy-related proteins BCL2 and BECN1. This inhibition of BECN1 in CaP cells, leading to the disruption of the BCL2-BECN1 interaction by overexpressed PAWR has not been reported so far. Third, we provide evidence that pawr-KO MEFs exhibited abundant autophagy signs even at toxic concentrations of 3-AWA underscoring the relevance of PAWR in switching of autophagy to apoptosis. Last but not least, overexpression of EGFP-LC3B and DS-Red-BECN1 revealed a delayed apoptosis turnover at a higher concentration of 3-AWA in CaP cells. In summary, this study provides evidence that 3-AWA is a strong anticancer candidate to abrogate protective autophagy. It also enhanced chemosensitivity by sensitizing prostate cancer cells to apoptosis through induction of PAWR endorsing its therapeutic potential.     

Robotically assisted coronary endarterectomy

Robotic assistance has enabled coronary artery bypass surgery to be performed safely in a completely endoscopic fashion, but diffusely diseased target vessels may pose a technical challenge. We present a case in which coronary endarterectomy was performed on the left anterior descending coronary artery during a two-vessel totally endoscopic coronary artery bypass procedure. A 52-year-old woman presented with intermittent substernal pain. Preoperative studies showed diffuse disease in the left coronary artery system. Bilateral internal mammary arteries were harvested robotically using a skeletonized technique in a completely endoscopic fashion. Cardiopulmonary bypass was achieved via peripheral cannulation, and the heart was arrested with intermittent cold antegrade hyperkalemic blood cardioplegia delivered via an ascending aortic occlusion balloon catheter. The first obtuse marginal anastomosis was performed. The left anterior descending coronary artery was diffusely diseased and heavily calcified. An end-to-side anastomosis was attempted to the right internal mammary artery with unsatisfactory results. A localized coronary endarterectomy was performed, and an extended anastomosis was completed using the right internal mammary artery. The patient recovered uneventfully and was discharged home on postoperative day 6. Diffuse coronary artery disease was once thought to be a prohibitive challenge for minimally invasive coronary bypass procedures. This case demonstrates that local coronary endarterectomy is feasible and safe in robotic totally endoscopic coronary artery bypass surgery.