Radioprotective mechanism of Podophyllum hexandrum during spermatogenesis

RP-1, a herbal preparation of Podophyllum hexandrum has already been reported to provide protection against whole body lethal gamma irradiation (10 Gy). It has also been reported to render radioprotection to germ cells during spermatogenesis. Present study was undertaken to unravel the cellular and molecular mechanism of action of RP-1 on testicular system in strain 'A' mice. Various antioxidant parameters such as thiol content, glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) enzyme activity, lipid peroxidation (LPO) and total protein levels were investigated. Thiol content was seen to increase significantly (p < 0.05) in both RP-1 alone and RP-1 pretreated irradiated groups over the irradiated groups at 8, 16 and 24 h. Irradiation (10 Gy) significantly decreased GPx, GST and GR activity in comparison to untreated control but RP-1 treatment before irradiation significantly (p < 0.05) countered radiation-induced decrease in the activity of these enzymes. Radiation-induced LPO was also found to be reduced at all time intervals by RP-1 treatment before irradiation. As compared to irradiated group the protein content in testicular tissue was increased in RP-1 pretreated irradiated group at 4 and 16 h significantly (p < 0.05). Comets revealed by single-cell gel electrophoresis were significantly longer (p < 0.001) in irradiated mice than in unirradiated control. RP-1 treatment before irradiation, however, rendered significant increase (p < 0.05) in comet length over the corresponding control and irradiated group initially at 4 h but at later time points, this was reduced significantly (p < 0.01) as compared to the irradiated group. RP-1 treatment alone rendered shorter comets at 8, 16 and 24 h than irradiated groups (p < 0.001). This study implies that RP-1 offers radioprotection at biochemical and cytogenetic level by protecting antioxidant enzymes, reducing LPO and increasing thiol content.     

Evolutionary constraints associated with functional specificity of the CMGC protein kinases MAPK, CDK, GSK, SRPK, DYRK, and CK2alpha

Amino acid residues associated with functional specificity of cyclin-dependent kinases (CDKs), mitogen-activated protein kinases (MAPKs), glycogen synthase kinases (GSKs), and CDK-like kinases (CLKs), which are collectively termed the CMGC group, were identified by categorizing and quantifying the selective constraints acting upon these proteins during evolution. Many constraints specific to CMGC kinases correspond to residues between the N-terminal end of the activation segment and a CMGC-conserved insert segment associated with coprotein binding. The strongest such constraint is imposed on a "CMGC-arginine" near the substrate phosphorylation site with a side chain that plays a role both in substrate recognition and in kinase activation. Two nearby buried waters, which are also present in non-CMGC kinases, typically position the main chain of this arginine relative to the catalytic loop. These and other CMGC-specific features suggest a structural linkage between coprotein binding, substrate recognition, and kinase activation. Constraints specific to individual subfamilies point to mechanisms for CMGC kinase specialization. Within casein kinase 2alpha (CK2alpha), for example, the binding of one of the buried waters appears prohibited by the side chain of a leucine that is highly conserved within CK2alpha and that, along with substitution of lysine for the CMGC-arginine, may contribute to the broad substrate specificity of CK2alpha by relaxing characteristically conserved, precise interactions near the active site. This leucine is replaced by a conserved isoleucine or valine in other CMGC kinases, thereby illustrating the potential functional significance of subtle amino acid substitutions. Analysis of other CMGC kinases similarly suggests candidate family-specific residues for experimental follow-up.     

Diagnostic pitfalls in fine needle aspiration cytology of pleomorphic lipoma. A case report

BACKGROUND: Pleomorphic lipoma is an unusual pseudosarcomatous condition with characteristic morphology. Despite its pleomorphic appearance, it follows a benign course and does not recur or metastasize if completely excised. CASE: A 66-year-old man presented with swelling in the back of the neck of approximately six months' duration. The focally cellular aspirate revealed round to oval, hyperchromatic cells, rare multinucleated cells and fragments of mature adipose tissue. On initial evaluation, the smear pattern suggested a malignant neoplasm. However, upon review of the cytologic material along with histology, the characteristic pattern, including floret cells, was recognized. CONCLUSION: The rarity of pleomorphic lipoma and the atypical cellular features of the aspirate can cause difficulty in diagnosing this entity. Awareness of this rare but not-uncommon entity, along with clinical correlation, is crucial in arriving at the correct diagnosis.     

FGF receptor mutations: dimerization syndromes, cell growth suppression, and animal models

This review describes recent progress in the field of fibroblast growth factor receptors (FGFRs) with an emphasis on the role of FGFR mutants in skeletal malformations. This family of four receptors contains the most frequent germline mutations in humans. More than 75 mutations have been recorded, which account for more than seven skeletal syndromes. The common cause for all the mutant phenotypes is gain-of-function by receptor activation through three major mechanisms: receptor dimerization, kinase activation, and increased affinity for FGF. The severity of the disease is correlated with both the extent of receptor activation and the specific tissue in which the mutant receptor form is expressed. Paradoxically, the consequence of receptor activation is inhibition of chondrocyte cell growth through signaling pathways that are cell-type specific. The structure of the FGFR-FGF complex and its possible ternary complex with heparin explain the mechanism of receptor dimerization in the ectodomain and the possible contribution by some of the mutations to this process. Analysis of FGFR3 mutant mice produced by gene targeting as models for human disease, and studies in cell lines, have begun to delineate the novel signaling pathways of FGFR3 and to define possible targets for therapy.     

An evolutionary perspective on the kinome of malaria parasites

Malaria parasites belong to an ancient lineage that diverged very early from the main branch of eukaryotes. The approximately 90-member plasmodial kinome includes a majority of eukaryotic protein kinases that clearly cluster within the AGC, CMGC, TKL, CaMK and CK1 groups found in yeast, plants and mammals, testifying to the ancient ancestry of these families. However, several hundred millions years of independent evolution, and the specific pressures brought about by first a photosynthetic and then a parasitic lifestyle, led to the emergence of unique features in the plasmodial kinome. These include taxon-restricted kinase families, and unique peculiarities of individual enzymes even when they have homologues in other eukaryotes. Here, we merge essential aspects of all three malaria-related communications that were presented at the Evolution of Protein Phosphorylation meeting, and propose an integrated discussion of the specific features of the parasite's kinome and phosphoproteome.     

Extracellular biosynthesis of iron oxide nanoparticles by Bacillus subtilis strains isolated from rhizosphere soil

The biological synthesis of nanoparticles is emerging as a potential method for nanoparticle synthesis due to its non-toxicity and simplicity. We report the ability of Bacillus subtilis strains isolated from rhizosphere soil to produce iron oxide nanoparticles. B. subtilis strains having the potential for the extracellular biosynthesis of Fe₃O₄nanoparticles were isolated from rhizosphere soil, identified and characterized. A bactericidal protein subtilin was isolated from all the isolates of B. subtilis, which is a characteristic for the species. The isolated subtilin was tested against the bacterial strain, E. coli. The supernatant of the bacterial culture was used for the synthesis of Fe₃O₄ nanoparticles. The formation of nanoparticles was assessed by using UV-Visible spectrophotometer. FTIR and SEM analysis were used in order to confirm the formation and size of the nanoparticles. Further, the effect of incubation time, pH, and temperature on the formation of Fe₃O₄ nanoparticles was studied. The successful synthesis of stabilized Fe₃O₄ nanoparticles, which was capped by the organic group, indicates the applicability of the isolated B. subtilis strain for the bulk synthesis of iron oxide nanoparticles.     

Protective efficacy of ellagic acid on glycoproteins, hematological parameters, biochemical changes, and electrolytes in myocardial infarcted rats

The cardioprotective property of ellagic acid in rats has been reported previously. The present study reveals the protective role of ellagic acid in biochemical parameters including serum iron, plasma iron binding capacity, uric acid, glycoprotein, and electrolytes along with hematological parameters. Rats were subcutaneously injected with isoproterenol (ISO) (100 mg/kg) for 2 days to induce myocardial infarction. ISO-induced rats showed a significant increase in their levels of serum iron, serum uric acid, and blood glucose, and a significant decrease in their levels of plasma iron binding capacity, serum total protein, albumin/globulin ratio, and heart glycogen, when compared with normal control rats. The altered hematological parameters were also observed in ISO-induced rats when compared with normal control rats. Pretreatment with ellagic acid at doses of 7.5 and 15 mg/kg produced significant beneficial effect by returning all the above-mentioned biochemical and hematological parameters to near normal levels.     

The E3 ligase Cdh1-anaphase promoting complex operates upstream of the E3 ligase Smurf1 in the control of axon growth

Axon growth is an essential event during brain development and is extremely limited due to extrinsic and intrinsic inhibition in the adult brain. The E3 ubiquitin ligase Cdh1-anaphase promoting complex (APC) has emerged as an important intrinsic suppressor of axon growth. In this study, we identify in rodents the E3 ligase Smurf1 as a novel substrate of Cdh1-APC and that Cdh1 targets Smurf1 for degradation in a destruction box-dependent manner. We find that Smurf1 acts downstream of Cdh1-APC in axon growth and that the turnover of RhoA by Smurf1 is important in this process. In addition, we demonstrate that acute knockdown of Smurf1 in vivo in the developing cerebellar cortex results in impaired axonal growth and migration. Finally, we show that a stabilized form of Smurf1 overrides the inhibition of axon growth by myelin. Taken together, we uncovered a Cdh1-APC/Smurf1/RhoA pathway that mediates axonal growth suppression in the developing mammalian brain.     

The peptide-receptive transition state of MHC class I molecules: insight from structure and molecular dynamics

MHC class I (MHC-I) proteins of the adaptive immune system require antigenic peptides for maintenance of mature conformation and immune function via specific recognition by MHC-I-restricted CD8(+) T lymphocytes. New MHC-I molecules in the endoplasmic reticulum are held by chaperones in a peptide-receptive (PR) transition state pending release by tightly binding peptides. In this study, we show, by crystallographic, docking, and molecular dynamics methods, dramatic movement of a hinged unit containing a conserved 3(10) helix that flips from an exposed "open" position in the PR transition state to a "closed" position with buried hydrophobic side chains in the peptide-loaded mature molecule. Crystallography of hinged unit residues 46-53 of murine H-2L(d) MHC-I H chain, complexed with mAb 64-3-7, demonstrates solvent exposure of these residues in the PR conformation. Docking and molecular dynamics predict how this segment moves to help form the A and B pockets crucial for the tight peptide binding needed for stability of the mature peptide-loaded conformation, chaperone dissociation, and Ag presentation.