scholarly journals Role of Structure-Based Changes due to Somatic Mutation in Highly Homologous DNA-Binding and DNA-Hydrolyzing Autoantibodies Exemplified by A23P Substitution in the VH Domain

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
A. V. Kozyr ◽  
A. V. Kolesnikov ◽  
A. E. Khlyntseva ◽  
A. G. Bogun ◽  
G. A. Savchenko ◽  
...  
Keyword(s):  
Dna Binding ◽  
Dna Cleavage ◽  
Nuclear Dna ◽  
Tissue Injury ◽  
3D Structure ◽  
Variable Region ◽  
Structure Identification ◽  
Significant Drop ◽  
Dna Cleaving ◽  
Vh Domain

Anti-DNA autoantibodies are responsible for tissue injury in lupus. A subset of DNA-specific antibodies capable of DNA cleavage can be even more harmful after entering the living cells by destroying nuclear DNA. Origins of anti-DNA autoantibodies are not fully understood, and the mechanism of induction of DNA-cleaving activity remains speculative. The autoantibody BV04-01 derived from lupus-prone mouse is the only DNA-hydrolyzing immunoglobulin with known 3D structure. Identification and analysis of antibodies homologous to BV04-01 may help to understand molecular bases and origins of DNA-cleaving activity of autoantibodies. BLAST search identified murine anti-DNA autoantibody MRL-4 with sequences of variable region genes highly homologous to those of autoantibody BV04-01. Despite significant homology to BV04-01, not only MRL-4 had no DNA-cleaving activity, but also reversion of its unusual P23 mutation to the germline alanine resulted in a dramatic loss of affinity to DNA. Contrary to this effect, transfer of the P23 mutation to the BV04-01 has resulted in a significant drop in DNA binding and almost complete loss of catalytic activity. In the present paper we analyzed the properties of two homologous autoantibodies and mutants thereof and discussed the implications of unusual somatic mutations for the development of autoantibodies with DNA-binding and DNA-hydrolyzing activity.

Oxygen radicals trigger activation of NF-κB and AP-1 and upregulation of ICAM-1 in reperfused canine heart

2002 ◽  
Vol 282 (5) ◽  
pp. H1778-H1786 ◽  
Author(s):  
Haiying Fan ◽  
Baogui Sun ◽  
Qiuping Gu ◽  
Anne Lafond-Walker ◽  
Suyi Cao ◽  
...  
Keyword(s):  
Dna Binding ◽  
Protein Expression ◽  
Vascular Endothelium ◽  
Oxygen Radicals ◽  
Nuclear Dna ◽  
Ischemia Reperfusion ◽  
Intercellular Adhesion Molecule ◽  
Radical Scavenger ◽  
Myeloperoxidase Activity ◽  
Canine Heart

We investigated whether oxygen radicals generated during ischemia-reperfusion trigger postischemic inflammation in the heart. Closed-chest dogs underwent 90-min coronary artery occlusion, followed by 1- or 3-h reperfusion: 10 dogs received the cell-permeant oxygen radical scavenger N-(2-mercaptopropionyl)-glycine (MPG; 8 mg · kg−1 · h−1intracoronary) beginning 5 min before reperfusion, and 9 dogs received vehicle. Blood flow (microspheres), intercellular adhesion molecule (ICAM)-1 protein expression (immunohistochemistry), ICAM-1 gene activation (Northern blotting), nuclear DNA binding activity of nuclear factor (NF)-κb and AP-1 (electrophoretic mobility shift assays), and neutrophil (PMN) accumulation (myeloperoxidase activity) were assessed in myocardial tissue samples. ICAM-1 protein expression was high in vascular endothelium after ischemia-reperfusion but was markedly reduced by MPG. MPG treatment also markedly decreased expression of ICAM-1 mRNA and tissue PMN accumulation. Nuclear DNA binding activities of NF-κB and AP-1, increased by ischemia-reperfusion, were both markedly decreased by MPG at 1 h of reperfusion. However, by 3 h, AP-1 activity was only modestly reduced by MPG and NF-κB activity was not significantly different from ischemic-reperfused controls. These results suggest that oxygen radicals generated in vivo during reperfusion trigger early activation of NF-κb and AP-1, resulting in upregulation of the ICAM-1 gene in vascular endothelium and subsequent tissue accumulation of activated PMNs.

scholarly journals Molecular characteristics of antibodies bearing an anti-DNA-associated idiotype.

1991 ◽  
Vol 174 (6) ◽  
pp. 1639-1652 ◽  
Author(s):  
A Manheimer-Lory ◽  
J B Katz ◽  
M Pillinger ◽  
C Ghossein ◽  
A Smith ◽  
...  
Keyword(s):  
B Cells ◽  
Dna Binding ◽  
Lupus Erythematosus ◽  
Germ Line ◽  
High Titer ◽  
Variable Region ◽  
Amino Acid Sequences ◽  
Molecular Characteristics ◽  
Systemic Lupus ◽  
Dna Antibodies

Anti-double-stranded DNA antibodies are the hallmark of the disease systemic lupus erythematosus and are believed to contribute to pathogenesis. While a large number of anti-DNA antibodies from mice with lupus-like syndromes have been characterized and their variable region genes sequenced, few human anti-DNA antibodies have been reported. We describe here the variable region gene sequences of eight antibodies produced by Epstein-Barr virus (EBV)-transformed B cells that bear the 3I idiotype, an idiotype expressed on anti-DNA antibodies and present in high titer in patients with systemic lupus. The comparison of these antibodies to the light chains of 3I+ myeloma proteins and serum antibodies reveals that EBV transformation yields B cells producing antibodies representative of the expressed antibody repertoire. The analysis of nucleotide and amino acid sequences of these antibodies suggests the first complementarity determining region of the light chain may be important in DNA binding and that paradigms previously generated to account for DNA binding require modification. The understanding of the molecular genetics of the anti-DNA response requires a more complete description of the immunoglobulin germ line repertoire, but data reported here suggest that somatic diversification is a characteristic of the anti-DNA response.

scholarly journals Synthesis, Characterization, DNA Binding, and Photocleavage Activity of Oxorhenium (V) Complexes withα-Diimine and Quinoxaline Ligands

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Christiana A. Mitsopoulou ◽  
Constantinos Dagas
Keyword(s):  
Cyclic Voltammetry ◽  
Dna Binding ◽  
Dna Cleavage ◽  
2D Nmr ◽  
Base Pairs ◽  
Binding Properties ◽  
Supercoiled Form ◽  
Dna Base ◽  
Dna Base Pairs ◽  
Dna Binding Properties

The complex [ReOCl3pq] (1) (where pq = 2-(2′pyridyl)quinoxaline) has been synthesized and fully characterized by UV-Vis, FTIR, 1 and 2D NMR, and cyclic voltammetry (CV). The DNA-binding properties of the complex1as well as of the compounds [ReOCl3bpy] (2), [ReOCl3phen] (3), and pq (4) were investigated by UV-spectrophotometric (melting curves), CV (cyclic voltammetry), and viscosity measurements. Experimental data suggest that complex1intercalates into the DNA base pairs. Upon irradiation, complex1was found to promote the cleavage of plasmid pBR 322 DNA from supercoiled form I to nicked form II. The mechanism of the DNA cleavage by complex1was also investigated.

A second c-myb protein is translated from an alternatively spliced mRNA expressed from normal and 5'-disrupted myb loci

1989 ◽  
Vol 9 (12) ◽  
pp. 5456-5463 ◽  
Author(s):  
G L Shen-Ong ◽  
B Lüscher ◽  
R N Eisenman
Keyword(s):  
Dna Binding ◽  
Nuclear Dna ◽  
Dna Binding Protein ◽  
Major Protein ◽  
Tumor Cell Lines ◽  
Binding Region ◽  
Large Intron ◽  
Alternatively Spliced ◽  
Myb Genes ◽  
Cryptic Splice Sites

The major protein encoded by the c-myb oncogene in many species has been identified as an unstable, nuclear DNA-binding protein with an apparent molecular mass of 75 to 80 kilodaltons (p75c-myb). Recently, an alternatively spliced form of c-myb-encoded mRNA has been identified in murine cells containing either normal or rearranged c-myb genes. This mRNA includes a new exon, termed E6A, formed through use of cryptic splice sites located in the large intron between c-myb exons vE6 and vE7. E6A is predicted to contribute an internal 121-residue in-frame insertion into a region C terminal of the DNA-binding domain the c-myb-encoded protein. Here we report the identification of an 85-kilodalton (p85c-myb-E6A) protein as the translation product of the alternatively spliced E6A c-myb mRNA. This protein as well as p75c-myb were precipitated with anti-Myb antibodies raised against the conserved DNA-binding region of c-Myb. Proteolytic mapping studies showed that the two proteins are highly related but not identical. However, only the p85 protein reacted with an antiserum prepared against the E6A region expressed in bacteria, demonstrating that p85 but not p75 contains E6A sequences. In addition, the mobilities of both p85 and p75 were increased in myeloid tumor cell lines containing proviral integrations upstream of the 5' coding exons of v-myb, indicating that both proteins are truncated forms of c-Myb expressed from the same disrupted allele. p75c-myb and p85c-myb-E6A were indistinguishable with respect to nuclear localization and protein half-life. Furthermore, both forms of Myb were synthesized continuously throughout the cell cycle in 70Z ore-B cells. The contribution of the E6A domain to c-myb function remains to be elucidated.

Synergistic action of interleukin-6 and glucocorticoids is mediated by the interleukin-6 response element of the rat alpha 2 macroglobulin gene

1992 ◽  
Vol 12 (5) ◽  
pp. 2282-2294
Author(s):  
G M Hocke ◽  
D Barry ◽  
G H Fey
Keyword(s):  
Dna Binding ◽  
Acute Phase ◽  
Interleukin 6 ◽  
Binding Proteins ◽  
Nuclear Dna ◽  
Acute Phase Proteins ◽  
Dna Binding Proteins ◽  
Human Hepatoma Cells ◽  
Response Element ◽  
Multiple Copies

One class of genes coding for the acute-phase proteins (acute-phase genes) is induced by interleukin 6 (IL-6) through the human transcription factor NF-IL-6 and its rat homolog IL-6-DBP/LAP. A second class, represented by the rat alpha 2 macroglobulin gene, utilizes a different IL-6 response element (IL-6-RE) and different DNA-binding proteins interacting with this element, the so-called IL-6-RE binding proteins (IL-6 RE-BPs). Human Hep3B and HepG2 hepatoma, U266 myeloma, and CESS lymphoblastoid cells contain IL-6 RE-BPs that form complexes, with the IL-6-RE, with gel mobilities indistinguishable from those of the corresponding complexes of rat liver cells. The ability to form these complexes was induced by IL-6 in human hepatoma cells with a maximum reached after 4 h and required ongoing protein synthesis. Multiple copies of an 18-bp element containing the IL-6-RE core were sufficient to confer both induction by IL-6 and a synergistic induction by IL-6 plus glucocorticoids to minimal promoters. The synergism was blocked by the receptor antagonist RU486 and thus was dependent on the glucocorticoid receptor (GR). However, the 18-bp element contained no consensus GR-binding site, and recombinant GR did not bind at this sequence. Therefore, the synergism was probably achieved by an indirect effect of a glucocorticoid-activated intermediate gene on the IL-6 RE-BPs. The rat IL-6 RE-BP had a molecular weight of 102 +/- 10 kDa and was thus distinct from NF-IL-6 and IL-6-DBP/LAP. Therefore, IL-6 must activate two different classes of liver acute-phase genes through at least two different nuclear DNA-binding proteins: NF-IL-6/IL-6-DBP/LAP and the IL-6 RE-BP.

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