MiRNA-21/DDAH1 pathway regulates pulmonary vascular responses to hypoxia
The nitric oxide synthase (NOS) inhibitor, asymmetric dimethylarginine (ADMA), contributes to the pathogenesis of pulmonary hypertension. Reduced levels of the enzymes metabolising ADMA, dimethylarginine dimethylaminohydrolases (DDAH1 and DDAH2) and increased levels of miRNA-21 are linked to disease pathology, but the mechanisms are not understood.
Here we studied the potential role of miRNA-21 in the regulation of hypoxia-induced changes in ADMA metabolism in vitro and in vivo. Hypoxia inhibited DDAH1 and DDAH2 expression and increased ADMA levels in cultured human pulmonary endothelial cells. In contrast, in human pulm...
Source: BJ Cell - June 4, 2014 Category: Biochemistry Authors: L Iannone, L Zhao, O Dubois, L Duluc, C J. Rhodes, J Wharton, M R. Wilkins, J Leiper, B Wojciak-Stothard Tags: BJ Cell Source Type: research
Recombinant form of mammalian gp91phox is active in the absence of p22phox
In this study, we have generated in Pichia pastoris for the first time an active form of bovine gp91phox able to carry out the entire NADPH oxidase activity in the absence of p22phox. Collected information on the maturation and the activity of the recombinant gp91phox and the participation of individual cytosolic subunits in the active complex allowed us also to propose, in the absence of p22phox, an unconventional stabilized complex compared to the heterodimer. (Source: BJ Cell)
Source: BJ Cell - June 3, 2014 Category: Biochemistry Authors: A Ezzine, H Souabni, T Bizouarn, L Baciou Tags: BJ Biomolecules Source Type: research
Autophagy is required and protects against apoptosis during myoblast differentiation
Several degradative systems assist in formation of multinucleated, terminally differentiated myotubes. However, the role of autophagy in this process has not been examined. GFP-LC3B puncta, LC3B-II protein, and LysoTracker fluorescence increased during C2C12 differentiation. Importantly, accumulation of LC3B-II protein occurred in chloroquine (CQ) treated cells throughout differentiation. Furthermore, BECN1, ATG7, and ATG12-5 protein increased, while SQSTM1/p62 protein was rapidly reduced during differentiation. A transient decrease in BECN1:BCL2 association was observed from D0.5 to D2 of differentiation. Chemical inhibit...
Source: BJ Cell - May 28, 2014 Category: Biochemistry Authors: E M. McMillan, J Quadrilatero Tags: BJ Cell Source Type: research
Protein kinase inhibitor beta enhances the constitutive activity of G-protein coupled zinc receptor GPR39
GPR39 is a G-protein-coupled zinc receptor that protects against diverse effectors of cell death. Its protective activity is mediated via constitutive activation of Ga13 and the RhoA pathway, leading to increased serum response element (SRE)-dependent transcription; the zinc-dependent immediate activation of GPR39 involves Gq-mediated increases in cytosolic Ca2+ and Gs coupling leading to increased cyclic AMP levels. We used the cytosolic and soluble C-terminus of GPR39 in a yeast-2-hybrid screen for interacting proteins, thus identifying the protein kinase A inhibitor beta (PKIB). Co-expression of GPR39 with PKIB i...
Source: BJ Cell - May 28, 2014 Category: Biochemistry Authors: Z Kovacs, T Schacht, A Herrmann, P Albrecht, K Lefkimmiatis, A Methner Tags: BJ Signal Source Type: research
Chaperone protein involved in transmembrane transport of iron
In this study, we have identified poly(rC)-binding protein 2 (PCBP2) as a DMT1 binding protein. The N-terminal cytoplasmic region of DMT1 was the binding domain for PCBP2. An interaction between DMT1 and PCBP1, which is known to be a paralog of PCBP2, could not be demonstrated in vivo or in vitro. Iron uptake and subsequent ferritin expression were suppressed by either DMT1 or PCBP2 knockdown. Iron-associated DMT1 could interact with PCBP2 in vitro, while iron-chelated DMT1 could not. These results indicated that ferrous iron imported by DMT1 was transferred directly to PCBP2. Moreover, we demonstrated PCBP2 could bind to ...
Source: BJ Cell - May 23, 2014 Category: Biochemistry Authors: I Yanatori, Y Yasui, M Tabuchi, F Kishi Tags: BJ Cell Source Type: research
Overlapping binding sites for importin {beta}1 and Suppressor of Fused on Glioma-associated oncogene homolog 1 (Gli1) regulate its nuclear localisation
A key factor in oncogenesis is the transport into the nucleus of oncogenic signalling molecules, such as Gli1 (Glioma-associated oncogene homolog 1), the central transcriptional activator in the Hedgehog signalling pathway. Little is known, however, how factors such as Gli are transported into the nucleus, and how this may be regulated by interaction with other cellular factors, such as the negative regulator Suppressor of Fused (SuFu). Here we show for the first time that nuclear entry of Gli1 is regulated by a unique mechanism through mutually exclusive binding by its nuclear import factor, importin (Imp) β1, and ...
Source: BJ Cell - May 22, 2014 Category: Biochemistry Authors: A Szczepny, K M. Wagstaff, M Dias, K Gajewska, C Wang, R G Davies, G Kaur, J Ly-Huynh, K L. Loveland, D A. Jans Tags: BJ Cell Source Type: research
Fibrin binds to collagen and provides a bridge for {alpha}V{beta}3 integrin-dependent contraction of collagen gels
The functional significance of fibrin deposits typically seen in inflammatory lesions, carcinomas and in healing wounds is not fully understood. We demonstrate that fibrinogen/fibrin specifically bound to native collagen type I (Col I) and used the Col I fiber network as a base to providing a functional interface matrix that connects cells to the Col I fibers through αVβ3 integrins. This allowed murine myoblast C2C12 cells to contract the collagenous composite gel via αVβ3 integrin. We show that fibrinogen specifically bound to immobilized native Col I at the site known to bind matrix-metallopro...
Source: BJ Cell - May 20, 2014 Category: Biochemistry Authors: V Reyhani, P Seddigh, B Guss, R Gustafsson, L Rask, K Rubin Tags: BJ Cell Source Type: research
PIKfyve, MTMR3 and their product PtdIns5P regulate cancer cell migration and invasion through activation of Rac1
Recently, we have shown that the phosphoinositide metabolizing enzymes PIKfyve and MTMR3, together with their lipid product phosphatidylinositol 5-phosphate (PtdIns5P), are important for migration of normal human fibroblasts. As these proteins are a kinase and a phosphatase, respectively, and thereby considered druggable, we wanted to test their involvement in cancer cell migration and invasion. First, we showed that PIKfyve and MTMR3 are expressed in most cancer cells. Next we demonstrated that depletion of PIKfyve or MTMR3 resulted in decreased velocity in three different cancer cell lines by using new software for cell ...
Source: BJ Cell - May 19, 2014 Category: Biochemistry Authors: A Oppelt, E Margrethe Haugsten, T Zech, H E Danielsen, A Sveen, V H Lobert, R I Skotheim, J Wesche Tags: BJ Cell Source Type: research
Holocarboxylase synthetase interacts physically with the nuclear receptor corepressor, histone deacetylase 1, and a novel splicing variant of histone deacteylase 1 to repress repeats
Holocarboxylase synthetase (HLCS) is a nuclear protein that catalyzes the binding of biotin to distinct lysine residues in chromatin proteins. HLCS-dependent epigenetic marks are overrepresented in repressed genomic loci, particularly in repeats. Evidence is mounting that HLCS is a member of a multi-protein gene repression complex, which determines its localization in chromatin. Here we tested the hypothesis that HLCS interacts physically with nuclear receptor corepressor (N-CoR) and histone deacetylase 1 (HDAC1), thereby contributing toward the removal of lysine-9 acetylated histone H3 (H3K9ac) gene activation marks and t...
Source: BJ Cell - May 19, 2014 Category: Biochemistry Authors: D Liu, J Zempleni Tags: BJ Gene Source Type: research
TMPRSS13 deficiency impairs stratum corneum formation and epidermal barrier acquisition
In this study, we used mice with the Tmprss13 gene disrupted by a β-galactosidase-neomycin fusion gene insertion to study the expression and function of the membrane-anchored serine protease. High levels of Tmprss13 expression were found in the epithelia of the oral cavity, upper digestive tract, and skin. Compatible with this expression pattern, Tmprss13-deficient mice displayed abnormal skin development leading to a compromised barrier function, as measured by trans-epidermal fluid loss rate of newborn mice. The study provides the first biological function for the transmembrane serine protease, TMPRSS13. (Source: BJ Cell)
Source: BJ Cell - May 16, 2014 Category: Biochemistry Authors: D H Madsen, R Szabo, A A Molinolo, T H Bugge Tags: BJ Cell Source Type: research
c-Fos-activated Synthesis of Nuclear Phosphatidyl Inositol-4,5-bisphosphate [PtdIns(4,5)P2] Promotes Global Transcriptional Changes
c-Fos is a well-recognized member of the AP-1 family of transcription factors. In addition to this canonical activity, we previously showed that cytoplasmic c-Fos activates phospholipid synthesis through a mechanism independent of its genomic AP-1 activity. c-Fos associates with particular enzymes of the pathway of synthesis of lipids at the endoplasmic reticulum and increases the Vmax of the reactions without modifying the Km values. This lipid synthesis activation is associated to events of differentiation and proliferation that require high rates of membrane biogenesis. Since lipid synthesis also occurs in the nucleus, ...
Source: BJ Cell - May 13, 2014 Category: Biochemistry Authors: G O. Ferrero, M L. Renner, G A. Gil, L RodrÃguez-Berdini, B L. Caputto Tags: BJ Cell Source Type: research
Reversible disassembly of the yeast V-ATPase revisited under in vivo conditions
Primary active proton transport by eukaryotic V-ATPases is regulated via the reversible disassembly of the V1VO holoenzyme into its peripheral, catalytic V1 complex and its membrane bound, proton translocating VO complex. This nutrient dependent phenomenon had been first detected in the midgut epithelium of non-feeding, moulting tobacco hornworms (Manduca sexta), and in glucose deprived yeast cells (Saccharomyces cerevisiae). Since reversible disassembly so far had been investigated mostly in vitro, we wanted to test this phenomenon under in vivo conditions. We used living yeast cells with V-ATPase subunits fused to green,...
Source: BJ Cell - May 7, 2014 Category: Biochemistry Authors: K Tabke, A Albertmelcher, O Vitavska, M Huss, H Schmitz, H Wieczorek Tags: BJ Cell Source Type: research
NRBF2 Regulates Macroautophagy as a Component of Vps34 Complex I
We have identified Nuclear Receptor Binding Factor 2 (NRBF2) as member of the autophagy-related Vps34 Complex1, which includes Vps34, Vps15, Beclin-1 and ATG-14L, but not UVRAG. NRBF2 directly interacts with Vps15 via the Vps15 WD40 domain as well as other regions of Vps15. The formation of GFP-LC3 punctae and LC3-II in serum-starved cells was inhibited by NRBF2 knockdown in the absence and presence of lysosomal inhibitors, and p62 levels were increased. Thus, NRBF2 plays a critical role in the induction of starvation-induced autophagy as a specific member of Vps34 Complex I. (Source: BJ Cell)
Source: BJ Cell - May 1, 2014 Category: Biochemistry Authors: Y Cao, Y Wang, W F. Abi Saab, F Yang, J E Pessin, J M. Backer Tags: BJ Signal Source Type: research
Biochemical analysis of TssK, a core component of the bacterial Type VI secretion system, reveals distinct oligomeric states of TssK and identifies a TssK-TssFG sub-complex
Gram-negative bacteria use the Type VI secretion system (T6SS) to inject toxic proteins into rival bacteria or eukaryotic cells. However the mechanism of the T6SS is incompletely understood. Here we studied a conserved component of the T6SS, TssK, using the anti-bacterial T6SS of Serratia marcescens as a model system. TssK was confirmed to be essential for effector secretion by the T6SS. The native protein, whilst not an integral membrane protein, appeared to localise to the inner membrane, consistent with its presence within a membrane-anchored assembly. Recombinant TssK purified from S. marcescens was found to exist in s...
Source: BJ Cell - April 29, 2014 Category: Biochemistry Authors: G English, O Byron, F R Cianfanelli, A R Prescott, S J Coulthurst Tags: BJ Biomolecules Source Type: research
Early and Late HIV-1 Membrane Fusion Events are Impaired by Sphinganine Lipidated Peptides that Target the Fusion Site
Lipid conjugated peptides have advanced the understanding of membrane protein functions and the roles of lipids in the membrane milieu. These lipo-peptides modulate various biological systems such as viral fusion. A single function has been suggested for the lipid, which is binding to the membrane, thus elevating the peptide’s local concentration at the target site. Here, we challenged this argument by exploring in-depth the antiviral mechanism of lipo-peptides, which are comprised of sphinganine, the lipid backbone of dihydrosphingomyelin (DHSM), and an HIV-1 envelope derived peptide. Surprisingly, we discovered a ...
Source: BJ Cell - April 25, 2014 Category: Biochemistry Authors: Y Alexander Klug, A Ashkenazi, M Viard, Z Porat, R Blumenthal, Y Shai Tags: BJ Cell Source Type: research
