Fe65 Ser228 is Phosphorylated by ATM/ATR and Inhibits Fe65-APP-Mediated Gene Transcription
In this study, we identified Fe65 Ser228 as a novel target of the ATM and ATR protein kinases, in a reaction that occurred independently of APP. Neither phosphorylation nor mutation of Ser228 affected the Fe65-APP protein complex, though this was markedly decreased after UV treatment, with a concomitant decrease in the protein levels of APP in cells. Finally, mutation of Ser228 to Ala (thus blocking phosphorylation) caused a significant increase in Fe65-APP transcriptional activity, whereas phosphomimetic mutants (S228D and S228E) showed decreased transcriptional activity. These studies identify a novel phosphorylation sit...
Source: BJ Cell - November 14, 2014 Category: Biochemistry Authors: P A Jowsey, P G Blain Tags: BJ Cell Source Type: research
Plasmodium falciparum mitochondria import tRNAs along with {Soft hyphen}{Soft hyphen}{Soft hyphen}{Soft hyphen}an active phenylalanyl-tRNA synthetase{Soft hyphen}{Soft hyphen}{Soft hyphen}{Soft hyphen}
Plasmodium falciparum protein translation enzymes aminoacyl-tRNA synthetases (aaRSs) are an emergent family of drug targets. The aaRS ensemble catalyzes transfer of amino acids to cognate transfer RNAs (tRNAs), thus providing charged tRNAs for ribosomal consumption. P. falciparum proteome expression relies on total of 36 aaRSs for the three translationally independent compartments of cytoplasm, apicoplast and mitochondria. Here we show that of this set of 36, a single genomic copy of phenylalanyl-tRNA synthetase (mFRS) is targeted to the parasite mitochondria, and that mFRS gene is exclusive to malaria parasites within the...
Source: BJ Cell - November 13, 2014 Category: Biochemistry Authors: A Sharma, A Sharma Tags: BJ Cell Source Type: research
Characterization of excitation-contraction coupling components in human extraocular muscles
Excitation-contraction coupling is the physiological mechanism whereby an electrical signal detected by the dihydropyridine receptor, is converted into an increase in [Ca2+], via activation of ryanodine receptors. Mutations in RYR1, the gene encoding ryanodine receptor 1, are the underlying cause of various congenital myopathies including Central Core Disease, Multiminicore disease, some forms of Centronuclear myopathy and Congenital Fiber Type Disproportion. Interestingly, patients with recessive but not dominant RYR1 mutations show a significant reduction of ryanodine receptor protein in muscle biopsies as well as...
Source: BJ Cell - November 11, 2014 Category: Biochemistry Authors: M Sekulic-Jablanovic, A Palmowski-Wolfe, F Zorzato, S Treves Tags: BJ Cell Source Type: research
Gremlin1 preferentially binds to Bone Morphogenetic Protein-2 (BMP-2) and BMP-4 over BMP-7
Gremlin (Grem1) is a member of the DAN family of secreted bone morphogenetic protein (BMP) antagonists. Bone morphogenetic protein-7 (BMP-7) mediates protective effects during renal fibrosis-associated with diabetes and other renal diseases. The pathogenic mechanism of Grem1 during DN has been suggested to be binding and inhibition of BMP-7. However, the precise interactions between Grem1, BMP-7 and other BMPs have not been accurately defined. Here we show the affinity of Grem1 for BMP-7 is lower than that of BMP-2 and BMP-4, using a combination of surface plasmon resonance and cell culture techniques. Using kidney proxima...
Source: BJ Cell - November 7, 2014 Category: Biochemistry Authors: R H Church, A Krishnakumar, A Urbanek, S Geschwindner, J Meneely, A Bianchi, B Basta, S Monaghan, C Elliott, M Stromstedt, N Ferguson, F Martin, D P Brazil Tags: BJ Biomolecules Source Type: research
Calcium-Ask1-MKK7-JNK2-c-Src Signaling Cascade Mediates Disruption of Intestinal Epithelial Tight Junctions by Dextran Sulfate Sodium
This study demonstrates that Ca2+-Ask1-MKK7-JNK2-cSrc signaling cascade mediates DSS-induced tight junction disruption and barrier dysfunction. (Source: BJ Cell)
Source: BJ Cell - November 7, 2014 Category: Biochemistry Authors: G Samak, K K Chaudhry, R Gangwar, D Narayanan, J H Jaggar, R Krishna Rao Tags: BJ Signal Source Type: research
Identification of Leishmania donovani Peroxin 14 Residues Required for Binding the Peroxin 5 Receptor Proteins
Trafficking of PTS-1 proteins to the Leishmania glycosome is dependent on the docking of the LdPEX5 receptor to LdPEX14 on the glycosomal membrane. A combination of deletion and random mutagenesis was used to identify residues in the LdPEX14 N-terminal region that are critical for mediating the LdPEX5-LdPEX14 interaction. These studies highlighted residues 35-75 on ldpex14 as the core domain required for binding LdPEX5. Single point mutation within this core domain generally did not affect the ldpex5 (203-391)-ldpex14 (1-120) interaction; notable exception were substitutions at F40, V46, or F57 which completely abolished o...
Source: BJ Cell - November 5, 2014 Category: Biochemistry Authors: H Hojjat, A Jardim Tags: BJ Biomolecules Source Type: research
Vinculin-dependent actin bundling regulates cell migration and traction forces
In this study,we found mutation (R1049E) of the vinculin tail impairs its ability to bind F-actin, stimulate actin polymerization, and bundle F-actin in vitro. Further, mutant (R1049E) vinculin expressing cells are altered in cell migration, which is accompanied by changes in cell adhesion, cell spreading, and cell generation of traction forces, providing direct evidence for the critical role of vinculin in mechanotransduction at adhesion sites. Lastly, we herein discuss the viability of models detailing the F-actin-binding surface on vinculin in context of our mutational analysis. (Source: BJ Cell)
Source: BJ Cell - October 31, 2014 Category: Biochemistry Authors: K M Jannie, S M. Ellerbroek, D W. Zhou, S Chen, D J. Crompton, A J Garcia, K A. DeMali Tags: BJ Cell Source Type: research
Exchange Protein Directly Activated by cAMP (EPAC1) Modulates Regulatory T Cell-Mediated Immune Suppression
In this study we examined the role of the cAMP/EPAC1 (exchange protein directly activated by cAMP) axis in regulatory T-cell (Treg)-mediated immune suppression using genetic and pharmacologic approaches. Genetic deletion of EPAC1 in Treg and effector T-cells (Teff) synergistically attenuated Treg-mediated suppression of Teff. Mechanistically, EPAC1 inhibition enhanced activation of the transcription factor STAT3 and up-regulated SMAD7 expression while down-regulating expression of SMAD4. Consequently, CD4+T-cells were desensitized to TGF-β1, a cytokine employed by Treg cells to exert a broad inhibitory functi...
Source: BJ Cell - October 23, 2014 Category: Biochemistry Authors: M Almahariq, F Mei, H Wang, A T. Cao, S Yao, L Soong, J Sun, Y Cong, J Chen, X Cheng Tags: BJ Signal Source Type: research
Late stages of the synchronized macrophage fusion in osteoclast formation depend on dynamin
Macrophage fusion that leads to osteoclast formation is one of the most important examples of cell-to-cell fusion in development, tissue homeostasis and immune response. Protein machinery that fuses macrophages remains to be identified. Here we explored fusion stage of osteoclast formation for RAW macrophage-like murine cells and for macrophages derived from human monocytes. To uncouple fusion from the preceding differentiation processes, we accumulated fusion-committed cells in the presence of lysophosphatidylcholine (LPC) that reversibly blocks membrane merger. 16h later we removed LPC and observed cell fusion events tha...
Source: BJ Cell - October 22, 2014 Category: Biochemistry Authors: S K Verma, E Leikina, K Melikov, L V Chernomordik Tags: BJ Cell Source Type: research
Identification of peptides in human Hsp20 and Hsp27 that possess molecular chaperone and anti-apoptotic activities
Previous studies have identified peptides in the ‘crystallin-domain’ of the small heat shock protein α-crystallin with chaperone and anti-apoptotic activities. We found that peptides in Hsp20 (71GHFSVLLDVKHFSPEEIAVK91) and Hsp27 (93DRWRVSLDVNHFAPDELTVK113) with sequence homology to α-crystallin also have robust chaperone and anti-apoptotic activities. Both peptides inhibited hyperthermic and chemically induced aggregation of client proteins. The scrambled peptides of Hsp20 and Hsp27 showed no such effects. The chaperone activities of the peptides were better than those from αA- and ;...
Source: BJ Cell - October 21, 2014 Category: Biochemistry Authors: R B Nahomi, M A DiMauro, B Wang, R H Nagaraj Tags: BJ ChemBio Source Type: research
The Formation of a Chloride Channel at the Interface between the Transport and Trimerisation Domains of a Glutamate Transporter
The concentration of glutamate within the glutamatergic synapse is tightly regulated by the excitatory amino acid transporters (EAATs). In addition to their primary role of clearing extracellular glutamate, the EAATs also possess a thermodynamically uncoupled Cl- conductance. Several crystal structures of an archaeal EAAT homologue, GltPh, at different stages of the transport cycle have been solved. In a recent structure, an aqueous cavity located at the interface of the transport and trimerisation domains has been identified. This cavity is lined by polar residues, several of which have been implicated in Cl− perme...
Source: BJ Cell - October 20, 2014 Category: Biochemistry Authors: R J Cater, R J Vandenberg, R M Ryan Tags: BJ Cell Source Type: research
p58(IPK) is an Inhibitor of the eIF2{alpha} Kinase GCN2 and its Localisation and Expression Underpin Protein Synthesis and ER Processing Capacity
One of the key cellular responses to stress is the attenuation of mRNA translation and protein synthesis via the phosphorylation of eIF2α. This is mediated by four eIF2α kinases and it has been suggested that each kinase is specific to the cellular stress imposed. Herein we show that both PERK and GCN2 are required for the stress responses associated with conditions encountered by cells overexpressing secreted recombinant protein. Importantly, whereas GCN2 is the kinase that is activated following cold-shock/hypothermic culturing of mammalian cells, PERK and GCN2 have overlapping functions since knockdown of ...
Source: BJ Cell - October 20, 2014 Category: Biochemistry Authors: A Roobol, J Roobol, A Bastide, J RP Knight, A E Willis, C Mark Smales Tags: BJ Gene Source Type: research
miR-29b Modulates Intestinal Epithelium Homeostasis by Repressing Menin Translation
Menin regulates distinct cellular functions by regulating gene transcription through its interaction with partner transcription factors, but the exact mechanisms that control Menin levels remain largely unknown. Here we report that Men1 mRNA, encoding Menin, is a novel target of microRNA-29b (miR-29b) and that miR-29b/Men1 mRNA association regulates Menin expression posttranscriptionally in rat intestinal epithelial cells (IECs). Overexpression of a miR-29b precursor lowered modestly the levels of Men1 mRNA, but reduced robustly the de novo synthesis of Menin; conversely, antagonization of miR-29b enhanced Menin protein sy...
Source: BJ Cell - October 15, 2014 Category: Biochemistry Authors: M Ouyang, W Su, L Xiao, J N Rao, L Jiang, Y Li, D J. Turner, M Gorospe, J Wang Tags: BJ Cell Source Type: research
Osteopontin mediates mineralization and not osteogenic cell development in vitro
Biomineralization is a complex process in the development of mineralized tissues such as bone, and pathological calcifications such as atherosclerotic plaques, kidney stones, gout, and others. Osteopontin (OPN), an anionic phosphoprotein, is expressed in mineralizing tissues and has previously been demonstrated to be a potent inhibitor of hydroxyapatite formation. The OPN-deficient (Opn-/-) mouse displays a hypermineralized bone phenotype starting at 12 weeks post-natally. By isolating and culturing Opn-/- and wild-type (WT) osteoblasts, we sought to determine the role of OPN and two of its functional peptides in osteoblas...
Source: BJ Cell - October 13, 2014 Category: Biochemistry Authors: E Holm, J S Gleberzon, Y Liao, E S Sørensen, F Beier, G K Hunter, H A Goldberg Tags: BJ Cell Source Type: research
Missing-in-Metastasis regulates cell motility and invasion via PTP{delta}-mediated changes in SRC activity
This study illustrates that both SRC and PTPδ have the potential to be therapeutic targets for metastatic tumors associated with loss of MIM. (Source: BJ Cell)
Source: BJ Cell - October 7, 2014 Category: Biochemistry Authors: F Chaudhary, R Lucito, N K Tonks Tags: BJ Cell Source Type: research
