Ribonucleases as a host-defense family: Evidence of evolutionary conserved antimicrobial activity at the N-terminus.
Vertebrate secreted ribonucleases (RNases) are small proteins that play important roles in RNA metabolism, angiogenesis or host defense.
In the present study we describe the antimicrobial properties of the N-terminal domain of the human canonical RNases (hcRNases) and show that its antimicrobial activity is well conserved among their lineage. Furthermore, all domains display a similar antimicrobial mechanism, characterized by bacteria agglutination followed by membrane permeabilization.
The results presented here show that, for all antimicrobial hcRNases, (i) activity is retained at the N-terminus; (ii) the antimicrobia...
Source: BJ Cell - August 20, 2013 Category: Biochemistry Authors: M Torrent, D Pulido, J Valle, M Nogués, D Andreu, E Boix Tags: BJ Cell Source Type: research
Lysine 1110 of TRPM2 is critical for channel activation
In this study, we investigated the functional role of lysine residue at position 1110 (K1110) in the membrane-proximal C-terminal region by site-directed mutagenesis. Substitution of the positive charged amino acid lysine (K1110) with neutral charged amino acid asparagine (K1110N) or negative charged amino acid glutamic acid (K1110E) generated mutants that failed to induce increase in free cytosolic calcium concentration ([Ca2+]i) not only by intracellular injection of chloride ion but also by H2O2 or ADPR. However, mutant generated by substitution of lysine with the same positive charged amino acid arginine (K1110R...
Source: BJ Cell - August 19, 2013 Category: Biochemistry Authors: T Kim, J Hyun Nam, W Ahn, N Kim, H Ham, C Hong, J Nam, J Lee, S Huh, I So, S Joon Kim, D Song Tags: BJ Signal Source Type: research
A Mechanism for Epithelial-Mesenchymal Transition and Anoikis Resistance in Breast Cancer Triggered by Zinc Channel ZIP6 and Signal Transducer and Activator of Transcription 3 (STAT3)
Genes involved in normal developmental processes attract attention as mediators of tumour progression as they facilitate migration of tumour cells. Epithelial-mesenchymal transition (EMT), an essential part of embryonic development, tissue remodelling and wound repair, is crucial for tumour metastasis. Previously zinc transporter ZIP6 (SLC39A6, LIV-1) was linked to EMT in zebrafish gastrulation through a STAT3 mechanism resulting in nuclear localisation of transcription factor Snail. Here we show that zinc transporter ZIP6 is transcriptionally induced by STAT3 and unprecedented among zinc transporters is activated by N-ter...
Source: BJ Cell - August 7, 2013 Category: Biochemistry Authors: C Hogstrand, P Kille, M Leigh Ackland, S Hiscox, K M Taylor Tags: BJ Cell Source Type: research
Mammalian ribosomal and chaperone protein RPS3A counteracts alpha-Synuclein aggregation and toxicity in a yeast model system
Accumulation of aggregated forms of alpha-synuclein (αSyn) into Lewy bodies is a known hallmark associated with neuronal cell death in Parkinson’s disease. When expressed in the yeast Saccharomyces cerevisiae, αSyn interacts with the plasma membrane, forms inclusions and causes a concentration-dependent growth defect. We have used a yeast mutant, cog6Δ, which is particularly sensitive to moderate αSyn expression, for screening a mouse brain-specific cDNA library in order to identify mammalian proteins that counteract αSyn toxicity. The mouse ribosomal and chaperone protein RPS3A wa...
Source: BJ Cell - August 7, 2013 Category: Biochemistry Authors: S De Graeve, S Marinelli, F Stolz, J Hendrickx, J Vandamme, Y Engelborghs, P Van Dijck, J M. Thevelein Tags: BJ Disease Source Type: research
In response to oxidative stress and energy restriction AMPK and PKC collaborate to induce the phosphorylation of Serine 413 on PIP5K1B resulting in decreased kinase activity and reduced PtdIns(4,5)P2 synthesis
In this study we have investigated the regulation of PIP5K1B by protein phosphorylation. Using mass spectrometric analysis we identified 12 phosphorylation sites on PIP5K1B. We developed a phospho-specific antibody to S413 and showed that its phosphorylation was increased in response to treatment of cells with phorbol ester, H2O2 or energy restriction. Using inhibitors, we define a stress dependent pathway that requires the activity of the cellular energy sensor AMP-Kinase (AMPK) and Protein Kinase C (PKC) to regulate S413 phosphorylation. Furthermore, we demonstrate that PKC can directly phosphorylate S413 in vitro. Mutat...
Source: BJ Cell - August 5, 2013 Category: Biochemistry Authors: I van den Bout, D R Jones, Z H Shah, J R Halstead, W Keune, S Mohammed, C S D'Santos, N Divecha Tags: BJ Signal Source Type: research
Nogo-A couples with Apg-1 through interaction and coordinate expression under hypoxic and oxidative stress
Nogo-A is the largest isoform of the Nogo/RTN4 proteins and has been characterized as a major myelin associated inhibitor of regenerative nerve growth in the adult central nervous system (CNS). Apart from the myelin sheath, Nogo-A is expressed at high levels in principal neurons of the CNS. The specificity of Nogo-A resides in its central domain, NiG. We identified Apg-1, a member of the stress induced Hsp110 family, as a novel interactor of NiG/Nogo-A. The interaction is selective because Apg-1 interacts with Nogo-A/RTN4-A but not with RTN1-A, the closest paralog of Nogo-A. Conversely, Nogo-A binds to Apg-1 but not to Apg...
Source: BJ Cell - August 2, 2013 Category: Biochemistry Authors: F Kern, R I. Stanika, B Sarg, M Offterdinger, D Hess, G J. Obermair, H Lindner, C E. Bandtlow, L Hengst, R Schweigreiter Tags: BJ Biomolecules Source Type: research
Establishment of a human skeletal muscle-derived cell line: biochemical, cellular and electrophysiological characterization
Excitation contraction coupling is the physiological mechanism occurring in muscle cells whereby an electrical signal sensed by the dihydropyridine receptor located on the transverse tubules is transformed into a chemical gradient (Ca2+ increase) by activation of the ryanodine receptor located on the sarcoplasmic reticulum membrane. In the present investigation we characterized for the first time the excitation contraction coupling machinery of an immortalized human skeletal muscle cell line. Intracellular Ca2+ measurements showed a normal response to pharmacological activation of the ryanodine receptor where...
Source: BJ Cell - August 1, 2013 Category: Biochemistry Authors: O Rokach, N D. Ullrich, M Rausch, V Mouly, H Zhou, F Muntoni, F Zorzato, S Treves Tags: BJ Cell Source Type: research
AKAP79 and PKC, PKA and PDE4, participate in a Gq-linked muscarinic receptor and adenylyl cyclase 2 cAMP signalling complex
Adenylyl cyclase (AC) 2 is stimulated by activation of Gq-coupled muscarinic receptors through PKC to generate localised cAMP in HEK-293 cells [1-3]. In the current study, we utilise a sensitive live cell imaging technique to unravel the proteins that play essential roles in a Gq-coupled muscarinic receptor-mediated cAMP signalling complex. We reveal that upon agonist binding to the Gq-coupled muscarinic receptor, AKAP79 recruits PKC to activate AC2 to produce cAMP. The cAMP formed is degraded by PDE4 activated by an AKAP anchored-PKA. Calcineurin, a phosphatase bound to AKAP79, is not involved in this regulation. Overall,...
Source: BJ Cell - July 29, 2013 Category: Biochemistry Authors: J X. Shen, D M.F. Cooper Tags: BJ Signal Source Type: research
Human cap methyltransferase (RNMT) N-terminal non-catalytic domain mediates recruitment to transcription initiation sites
We report that the RNMT N-terminal domain is necessary and sufficient for RNMT recruitment to transcription initiation sites and that recruitment occurs in a DRB-dependent manner. The RNMT-activating subunit, RAM, is also recruited to transcription initiation sites via an interaction with RNMT. The RNMT N-terminal domain is required for transcript expression, translation and cell proliferation. (Source: BJ Cell)
Source: BJ Cell - July 18, 2013 Category: Biochemistry Authors: M Aregger, V H Cowling Tags: BJ Gene Source Type: research
SatP (YaaH), a succinate-acetate transporter protein in Escherichia coli
In this work we describe a new carboxylic acid transporter in Escherichia coli encoded by the gene yaaH. In contrast to what had been described for other YaaH family members, the E. coli transporter is highly specific for acetic acid (a monocarboxylate) and for succinic acid (a dicarboxylate), presenting the following affinity constants at pH 6.0, 1.24 ± 0.13 mM acetic acid and 1.18 ± 0.10 mM succinic acid. In glucose grown-cells the ΔyaaH mutant is compromised for the uptake of both labelled acetic and succinic acids. YaaH, together with ActP, previously described as an acetate transporter, affect the...
Source: BJ Cell - July 11, 2013 Category: Biochemistry Authors: J Sá-Pessoa, S Paiva, D Ribas, I Jesus Silva, S Cristina Viegas, C Maria Arraiano, M Casal Tags: BJ Cell Source Type: research
Dynamics of G{alpha}i1 interaction with type 5 adenylyl cyclase reveal molecular basis for high sensitivity of Gi-mediated inhibition of cAMP production
Many physiological and pathophysiological processes are regulated by cAMP. Different therapies directly or indirectly influence the cellular concentration of this second messenger. A wide variety of receptors either activates or inhibits adenylyl cyclases in order to induce proper physiological responses. A key event in this signalling system is the direct and dynamic interaction of Gαi1 subunits with adenylyl cyclases. We established a FRET-based assay between G‑protein subunits and type 5 adenylyl cyclase (AC5) and monitored receptor-stimulated interactions between Gαi1 and AC5 in single intact cells...
Source: BJ Cell - July 10, 2013 Category: Biochemistry Authors: M Milde, A Rinne, F Wunder, S Engelhardt, M Bünemann Tags: BJ Signal Source Type: research
Protein Kinase D-mediated phosphorylation at serine 99 regulates localization of p21-activated kinase 4
p21-activated kinases (PAKs) are effectors of RhoGTPases. PAK4 contributes to regulation of cofilin at the leading edge of migrating cells through activation of Lin-11/Isl-1/Mec-3 kinase (LIMK). PAK4 activity is regulated by an autoinhibitory domain that is released upon RhoGTPase binding as well as phosphorylation at serine 474 in the activation loop of the kinase domain. We here add another level of complexity to PAK4 regulation by showing that phosphorylation at serine residue 99 is required for its targeting to the leading edge. This phosphorylation is mediated by protein kinase D1 (PKD1). Phosphorylation of PAK4 at S9...
Source: BJ Cell - July 10, 2013 Category: Biochemistry Authors: L I Bastea, H Doppler, S E Pearce, N Durand, S J Spratley, P Storz Tags: BJ Signal Source Type: research
Characterization of inflamin, the first member of a new family of snake venom proteins that induces inflammation
Unlike other sea snakes, Aipysurus eydouxii feeds exclusively on fish eggs. This unusual feeding habit prompted us to search for unique transcripts in their venom glands. Here, we expressed a novel cysteine-rich, secretory protein containing 94 amino acid residues that was identified in its cDNA library. As it induced inflammation and writhing in animals, this protein was named as inflamin. It induced two waves of prostanoids production. The first wave peaked at 10 min and 6-keto PGF1α was the major product. The second wave, specifically of 6-keto PGF1α and PGE2, started after 2 h. In RAW264.7 cells, COX-1 ac...
Source: BJ Cell - July 8, 2013 Category: Biochemistry Authors: B Barnwal, R Manjunatha Kini Tags: BJ Biomolecules Source Type: research
Subcellular potassium and sodium distribution in Saccharomyces cerevisiae wild type and vacuolar mutants
Living cells accumulate potassium to fulfill multiple functions. It is well documented that the model yeast Saccharomyces cerevisiae grows at very different concentrations of external alkali cations and keeps high and low intracellular concentrations of potassium and sodium respectively. However less attention has been paid to the study of the intracellular distribution of these cations. The most widely used experimental approach, plasma membrane permeabilization, produces incomplete results, since it usually considers only cytoplasm and vacuoles as compartments where the cations are present in significant amounts. By isol...
Source: BJ Cell - July 5, 2013 Category: Biochemistry Authors: R Herrera, M C Álvarez, S Gelis, J Ramos Tags: BJ Cell Source Type: research
Sorting nexin 27 (SNX27) associates with zona occludens-2 (ZO-2) and modulates the epithelial tight junction.
Proteins of the sorting nexin (SNX) superfamily are characterized by the presence of a phox-homology (PX) domain and associate with phosphatidylinositol-3-monophosphate (PtdIns3P) rich regions of the endosomal system. SNX27 is the only sorting nexin that contains a PDZ domain. Here, we used a proteomic approach to identify a novel interaction between SNX27 and zona occludens-2 (ZO-2, TJP2), a component of the epithelial tight junction. The SNX27-ZO-2 interaction requires the PDZ domain of SNX27 and the C-terminal PDZ-binding motif of ZO-2. When tight junctions were perturbed by chelation of intracellular Ca2+, ZO-2 transie...
Source: BJ Cell - July 4, 2013 Category: Biochemistry Authors: S Parker Zimmerman, C Lynn Hueschen, D Malide, S Lynn Milgram, M Peter Playford Tags: BJ Cell Source Type: research
